A novel MATLAB/Simulink based modeling and simulation environment for the design and rapid prototyping of state-of-the-art aircraft control systems is proposed. The toolbox, named APRICOT, is able to simulate the longitudinal and laterodirectional dynamics of an aircraft separately, as well as the complete 6 degrees of freedom dynamics. All details of the dynamics can be easily customized in the toolbox, some examples are shown in the paper. Moreover, different aircraft models can be easily integrated. The main goal of APRICOT is to provide a simulation environment to test and validate different control laws with different aircraft models. Hence, the proposed toolbox has applicability both for educational purposes and control rapid prototyping. With respect to similar software packages, APRICOT is customizable in all its aspects, and has been released as open source software. An interface with Flightgear Simulator allows for online visualization of the flight. Examples of control design with simulation experiments are reported and commented.

JF - International Workshop on Modelling and Simulation for Autonomous Systems MESAS 2016 PB - Springer CY - Rome, Italy, June 15-16, 2016 VL - 9991 of the book series Lecture Notes in Computer Science (LNCS) UR - http://link.springer.com/chapter/10.1007/978-3-319-47605-6_11 ER - TY - JOUR T1 - Controllability analysis of a pair of 3D Dubins vehicles in formation JF - Robotics and Autonomous Systems Y1 - 2016 A1 - H. Marino A1 - Salaris, P. A1 - L. Pallottino KW - Embedded Control KW - Robotics AB -In this paper we consider the controllability problem for a system consisting of a pair of Dubins vehicles moving in a 3D space (i.e. pair of *3D–Dubins* vehicles) while maintaining constant distance. Necessary and sufficient conditions for the existence of a limited control effort to steer the system between any two configurations are provided. The proposed controllability analysis and the developed motion planning algorithm are a step toward the solution of planning problems for example in case the robots are physically constrained to a payload to be deployed. Moreover, results obtained in this paper are relevant in order to solve formation control problems for multiple robots as aerial or underwater vehicles, which move in 3D spaces. Simulation results highlight the sufficiency of the obtained conditions showing that even from critical configurations an admissible control can be determined.

This paper focuses on the convergence of information in distributed systems of agents communicating over a network.

The information on which the convergence is sought is not represented by real numbers, as often in the literature, rather by sets. The dynamics of the evolution of information across the network is accordingly described by set-valued iterative maps. While the study of convergence of set-valued iterative maps is highly complex in general, this paper focuses on Boolean maps, which are comprised of arbitrary combinations of unions, intersections, and complements of sets. For these important class of systems, we provide tools to study both global and local convergence. A distributed geographic information system, leading to successful information reconstruction from partial and corrupted data, is used to illustrate the applications of the proposed methods.

VL - 61
UR - http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7272075
IS - 6
ER -
TY - CONF
T1 - A game theoretic approach for antagonistic-task coordination of underwater autonomous robots in asymmetric threats scenarios
T2 - OCEANS 2016
Y1 - 2016
A1 - S. Nardi
A1 - T. Fabbri
A1 - A. Caiti
A1 - L. Pallottino
KW - Embedded Control
KW - Robotics
AB - This work proposes a game theoretic approach

to tackle the problem of multi-robot coordination

in critical scenarios where communication is

limited and the robots must accomplish different tasks

simultaneously. An important application falls in underwater

robotic framework where robots are used to

protect a ship against asymmetric threats guaranteeing

simultaneously the coverage of the area around the ship

and the tracking of a possible intruder. The problem is

modelled as a potential game for which novel learning

protocols are introduced. Indeed, a general extension

of pay-off based algorithms is herein proposed where

the main difference with state-of-the-art protocols is

that the trajectory optimization is considered instead

of single action optimization. Moreover, the proposed

T-algorithms, steer the robots toward Nash equilibria

that will be shown to correspond to the accomplishment

of different, possibly antagonistic, goals. Finally, performances

of the algorithms, under different scenarios,

have been evaluated in simulations.

Due to the increasing usage of service and industrial autonomous vehicles, a precise localisation is an essential component required in many applications, e.g. indoor robot navigation. In open outdoor environments, differential GPS systems can provide precise positioning information. However, there are many applications in which GPS cannot be used, such as indoor environments. In this work, we aim to increase robot autonomy providing a localisation system based on passive markers, that fuses three kinds of data through extended Kalman filters. With the use of low cost devices, the optical data are combined with other robots’ sensor signals, i.e. odometry and inertial measurement units (IMU) data, in order to obtain accurate localisation at higher tracking frequencies. The entire system has been developed fully integrated with the Robotic Operating System (ROS) and has been validated with real robots.

*NoStop* is an open source simulator dedicated to distributed and cooperative mobile robotics systems. It has been designed as a framework to design and test multi–agent collaborative algorithms in terms of performance and robustness. The particular application scenario of a team of autonomous guards that coordinate to protect an area from asymmetric threat is considered. *NoStop* system is an integrated tool able to both evaluate the coordination protocol performance and to design the team of guards involved in the asymmetric threat protection. Moreover, *NoStop* is designed to validate robustness of coordination protocol through the use of a remote pilot that control the intruder motion to escape from the guards that monitor the area and accomplish its mission. The project core is a simulation server with a dynamic engine and a synchronization facility. Different coordination protocol can be designed and easily integrated in *NoStop*. The framework is fully integrated with the Robot Operating System (ROS) and it is completed by a control station where the remote pilot moves the intruder following the guards evolution in a 3*D* viewer.

This paper addresses the problem of detecting possible misbehavior in a group of autonomous mobile robots, which coexist in a shared environment and interact with each other and coordinate according to a set of common *interaction rules*. Such rules specify what actions each robot is allowed to perform in order to interact with the other members of the group. The rules are distributed, i.e., they can be evaluated only starting from the knowledge of the individual robot and the information the robot gathers from neighboring robots. We consider *misbehaving* those robots which, because of either spontaneous failures or malicious tampering, do not follow the rules and whose behavior thus deviates from the nominal assigned one. The main contribution of the paper is to provide a methodology to detect such misbehavior by observing the congruence of actual behavior with the assigned rules as applied to the actual state of the system. The presented methodology is based on a consensus protocol on the events observed by robots. The methodology is fully distributed in the sense that it can be performed by individual robots based only on the local available information, it has been theoretically proven and validated with experiments involving real aerial heterogeneous robots.

planet

ER - TY - JOUR T1 - Epsilon-Optimal Synthesis for Unicycle-like Vehicles with Limited Field-Of-View Sensors JF - IEEE Transactions on Robotics (T-RO) Y1 - 2015 A1 - P Salaris A1 - A. Cristofaro A1 - L. Pallottino KW - Embedded Control KW - Robotics AB -In this paper we study the minimum length paths covered by the center of a unicycle equipped with a limited Field–Of–View (FOV) camera, which must keep a given landmark in sight. Previous works on this subject have provided the optimal synthesis for the cases in which the FOV is only limited in the horizontal directions (i.e. left and right bounds) or in the vertical directions (i.e. upper and lower bounds). In this paper we show how to merge previous results and hence obtaining, for a realistic image plane modeled as a rectangle, a finite alphabet of extremal arcs and the overall synthesis. As shown, this objective can not be straightforwardly achieved from previous results but needs further analysis and developments. Moreover, there are initial configurations such that there exists no optimal path. Nonetheless, we are always able to provide an e–optimal path whose length approximates arbitrarily well any other shorter path. As final results, we provide a partition of the motion plane in regions such that the optimal or e–optimal path from each point in thatregion is univocally determined.

VL - 31 IS - 6 ER - TY - JOUR T1 - Epsilon–optimal synthesis for vehicles with vertically bounded Field-Of-View JF - IEEE Transactions on Automatic Control Y1 - 2015 A1 - Salaris, P. A1 - Cristofaro, A. A1 - L. Pallottino A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper presents a contribution to the problem of obtaining an optimal synthesis for shortest paths for a unicycle guided by an on–board limited Field Of–View (FOV) sensor, which must keep a given landmark in sight. Previous works on this subject have provided an optimal synthesis for the case in which the FOV is limited in the horizontal directions (H– FOV, i.e. left and right boundaries). In this paper we study the complementary case in which the FOV is limited only in the vertical direction (V–FOV, i.e. upper and lower boundaries). With respect to the H–FOV case, the vertical limitation is all but a simple extension. Indeed, not only the geometry of extremal arcs is different, but also a more complex structure of the synthesis is revealed by analysis. We will indeed show that there exist initial configurations for which the optimal path does not exist. In such cases, we provide an e–optimal path whose length approximates arbitrarily well any other shorter path. Finally, we provide a partition of the motion plane in regions such that the optimal or e–optimal path from each point in that region is univocally determined.

VL - 60 IS - 5 ER - TY - CONF T1 - ASCARI: a component based simulator for distributed mobile robot systems T2 - Modelling & Simulation for Autonomous Systems - MESAS2014 Y1 - 2014 A1 - M. Ferrati A1 - A Settimi A1 - L. Pallottino KW - Embedded Control KW - Robotics JF - Modelling & Simulation for Autonomous Systems - MESAS2014 PB - Springer CY - Rome, 5-6 May 2014 VL - Lecture Notes in Computer Science, Volume 8906, 2014 ER - TY - CONF T1 - On Time-Optimal Trajectories for Differential Drive Vehicles with Field-Of-View Constraints T2 - IEEE Conference on Decision and Control (CDC2014) Y1 - 2014 A1 - Cristofaro, A. A1 - Salaris, P. A1 - L. Pallottino A1 - Giannoni, F. A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper presents the first step toward the study of minimum time trajectories for a differential drive robot, which is equipped with a fixed and limited Field-Of-View (FOV) camera, towards a desired configuration while keeping a given landmark in sight during maneuvers. While several previous works have provided a complete synthesis of shortest paths in case of both nonholonomic and FOV constraints, to the best of our knowledge, this paper represents the first analysis of minimum time trajectories with the two constraints. After showing the extremals of the problem at hand, i.e. straight lines, rotations on the spot, logarithmic spirals and involute of circles, we provide the optimal control laws that steer the vehicle along the path and the cost in terms of time along each extremal. Moreover, we compare some concatenations of extremals in order to reduce the complexity of the problem toward the definition of a sufficient finite set of optimal maneuvers.

JF - IEEE Conference on Decision and Control (CDC2014) PB - IEEE CY - Los Angeles, USA, December 15-17 SN - 978-1-4799-7746-8 UR - http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7039723 ER - TY - CONF T1 - Packet-based dynamic control for nonlinear networked systems T2 - IEEE International Conference on Decision and Control (CDC2013) Y1 - 2013 A1 - S. Falasca A1 - M. Gamba A1 - L. Greco A1 - A. Chaillet A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - IEEE International Conference on Decision and Control (CDC2013) CY - Florence, Italy ER - TY - CONF T1 - Packet-Based Dynamic Control of a Furuta Pendulum over Ethernet T2 - Mediterranean Conference on Control and Automation (MED '13) Y1 - 2013 A1 - T. Fabbri A1 - D. Fenucci A1 - S. Falasca A1 - M. Gamba A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper presents experimental results of the application of Packet-Based Control approach with dynamic controller on a real plant: the Furuta Pendulum. Despite its easiness of realization, Furuta Pendulum presents some features useful for our purposes, such as pretty non-linear dynamics, unstable equilibrium point and heavy dynamical inaccuracies. The network communication channel has been implemented using an Ethernet network. Packet-Based controller has been tested and compared with a classic local controller for different time-varying actuation delays. Results obtained corroborate the validity of the proposed architecture and highlight the robustness of this approach in the presence of actuation delays.

JF - Mediterranean Conference on Control and Automation (MED '13) CY - Platanias-Chania, Crete, Greece UR - http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=6608763&queryText%3Dfalasca+gamba ER - TY - JOUR T1 - On the Robust Synthesis of Logical Consensus Algorithms for Distributed Intrusion Detection JF - Automatica Y1 - 2013 A1 - A. Fagiolini A1 - A. Bicchi KW - Embedded Control KW - Robotics VL - 49 IS - 8 ER - TY - CONF T1 - A Strategy for Dynamic Controller Emulation in Packet-Based Networked Control T2 - International Conference on Informatics in Control (ICINCO ’13) Y1 - 2013 A1 - S. Falasca A1 - M. Gamba A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - International Conference on Informatics in Control (ICINCO ’13) CY - Reykjavík, Iceland ER - TY - JOUR T1 - Interacting with networks: How does structure relate to controllability in single-leader, consensus networks? JF - Control Systems Magazine Y1 - 2012 A1 - M. Egerstedt A1 - S. Martini A1 - M. Cao A1 - K. Camlibel A1 - A. Bicchi KW - Embedded Control KW - Robotics VL - 32 IS - 4 ER - TY - JOUR T1 - Secure Cooperation of Autonomous Mobile Sensors Using an Underwater Acoustic Network JF - SENSORS Y1 - 2012 A1 - A. Caiti A1 - V. Calabrò A1 - G. Dini A1 - A. Lo Duca A1 - A. Munafò KW - Embedded Control KW - Robotics VL - 12 UR - http://dx.medra.org/10.3390/s120201967 ER - TY - JOUR T1 - Autonomous underwater vehicle teams for adaptive ocean sampling: a data-driven approach JF - OCEAN DYNAMICS Y1 - 2011 A1 - A. Munafò A1 - E. Simetti A1 - A. Turetta A1 - G. Casalino A1 - A. Caiti KW - Embedded Control KW - Robotics VL - 61 UR - http://dx.medra.org/10.1007/s10236-011-0464-x ER - TY - CONF T1 - Behavior classification, security, and consensus in societies of robots T2 - Automatica.it 2011 Y1 - 2011 A1 - S. Martini A1 - A. Fagiolini A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Automatica.it 2011 CY - Pisa, Italy N1 -poster presentation

ER - TY - CONF T1 - Decentralized Coordination System for Multiple AGVs in a Structured Environment T2 - 2011 Congress of the International Federation of Automatic Control Y1 - 2011 A1 - S. Manca A1 - A. Fagiolini A1 - L. Pallottino KW - Embedded Control KW - Robotics JF - 2011 Congress of the International Federation of Automatic Control CY - Milano, italy ER - TY - CONF T1 - Decentralized Species Classification in Societies of Autonomous and Heterogenous Robots T2 - 2011 IEEE International Conference on Robotics and Automation Y1 - 2011 A1 - S. Martini A1 - A. Fagiolini A1 - G. Zichittella A1 - M. Egerstedt A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - 2011 IEEE International Conference on Robotics and Automation CY - Shangai, China ER - TY - JOUR T1 - Design and Stability Analysis for Anytime Control via Stochastic Scheduling JF - IEEE Trans. on Automat. Contr. Y1 - 2011 A1 - L. Greco A1 - D. Fontanelli A1 - A. Bicchi KW - Embedded Control KW - Robotics VL - 56 ER - TY - CONF T1 - Exploiting Packet Size in Uncertain Nonlinear Networked Control Systems T2 - 2011 Congress of the International Federation of Automatic Control - IFAC 2011 Y1 - 2011 A1 - L. Greco A1 - A. Chaillet A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - 2011 Congress of the International Federation of Automatic Control - IFAC 2011 CY - Milano, italy ER - TY - CONF T1 - From Optimal Planning to Visual Servoing with Limited FOV T2 - 2011 IEEE/RSJ International Conference on Intelligent RObots and Systems Y1 - 2011 A1 - P Salaris A1 - L. Pallottino A1 - S. Hutchinson A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - 2011 IEEE/RSJ International Conference on Intelligent RObots and Systems CY - S. Francisco, USA ER - TY - CONF T1 - Left invertibility of output-quantized MISO linear systems T2 - 2011 Congress of the International Federation of Automatic Control - IFAC2011 Y1 - 2011 A1 - N. Dubbini A1 - M. Monge A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper studies left invertibility of single-output discrete-time quantized linear systems. Quantized outputs are generated according to a given partition of the state-space, while inputs are sequences on a finite alphabet. Left invertibility deals with the possibility of recovering unknown inputs from the only knowledge of the outputs. It is reduced, under suitable conditions, to left D-invertibility: while left invertibility takes into account membership to sets of a given partition, left D-invertibility considers only membership to a single set, and is easily (and algorithmically) detectable. Our main result is a sufficient condition for the equivalence between left invertibility and left D-invertibility in MISO system. In unidimensional systems the equivalence is valid except at most a finite (and computable) number of cases. These results allows the effective detection of left invertibility by means of left Dinvertibility, which is algorithmically detectable. An example with effective computations is presented to show the application of the proposed method.

JF - 2011 Congress of the International Federation of Automatic Control - IFAC2011 CY - Milano, italy ER - TY - CONF T1 - Neighbourhood Monitoring for Decentralised Coordination in Multi-Agent Systems: A Case-Study T2 - IEEE Symposium on Computers and Communications Y1 - 2011 A1 - G. Dini A1 - Giurlanda, F. A1 - L. Pallottino KW - Embedded Control KW - Robotics AB -Decentralized coordination of multi-agents requires that every agent reliably and efficiently disseminates its state to neighbours

through a wireless network. If dissemination is unreliable, safety issues may ensue. Unfortunately, the broadcast service of

wireless network is efficient but unreliable (e. g., IEEE 802.11). The Neighbourhood Monitoring Protocol (NMP) [1] is an efficient

and scalable protocol that assures a reliable state dissemination between mobile agents, under some conditions of channel

utilization. NMP runs on top of IEEE 802.11. In this paper we evaluate NMP with a specific decentralized collision avoidance

algorithm based on the GRP policy [2]. The algorithm is particularly challenging because it accommodates an arbitrary number

non-holonomic agents. We show that NMP allows the system to scale well and provides a very high state delivery ratio even if it

operates on the unreliable broadcast service like 802.11. Doing so, NMP assures the correct state information to the collision

avoidance algorithm.

Technical Report

ER - TY - CONF T1 - Robust Network Agreement on Logical Information T2 - 2011 Congress of the International Federation of Automatic Control - IFAC 2011 Y1 - 2011 A1 - S. Martini A1 - D. Di Baccio A1 - A. Fagiolini A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - 2011 Congress of the International Federation of Automatic Control - IFAC 2011 CY - Milano, italy ER - TY - CONF T1 - Shortest Paths With Side Sensor T2 - 2011 IEEE International Conference on Robotics and Automation Y1 - 2011 A1 - P Salaris A1 - L. Pallottino A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - 2011 IEEE International Conference on Robotics and Automation CY - Shangai, China ER - TY - CONF T1 - 3 known landmarks are enough for solving planar bearing SLAM and fully reconstruct unknown inputs T2 - Intelligent Robots and Systems (IROS), 2010 IEEE/RSJ International Conference on Y1 - 2010 A1 - F. A. W. Belo A1 - P Salaris A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Intelligent Robots and Systems (IROS), 2010 IEEE/RSJ International Conference on CY - St. Louis MO USA ER - TY - JOUR T1 - Controllability analysis of multi-agent systems using relaxed equitable partitions JF - Int. J. Systems, Control and Communications Y1 - 2010 A1 - S. Martini A1 - M. Egerstedt A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper investigates the issue of how to make decentralised networks amenable to external control, i.e. how to ensure that they are appropriately organised so that they can be effectively

VL - 2 ER - TY - CONF T1 - Controllability for Pairs of Vehicles Maintaining Constant Distance T2 - IEEE International Conference on Robotics and Automation (ICRA2010) Y1 - 2010 A1 - H. Wang A1 - L. Pallottino A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - IEEE International Conference on Robotics and Automation (ICRA2010) CY - Anchorage, Alaska ER - TY - CONF T1 - Controllability Properties for Aircraft Formations T2 - International Conference on Decision and Control - CDC 2010 Y1 - 2010 A1 - H. Wang A1 - L. Pallottino A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - International Conference on Decision and Control - CDC 2010 ER - TY - CONF T1 - Design and Control of a Novel 3D Casting Manipulator T2 - IEEE International Conference on Robotics and Automation (ICRA2010) Y1 - 2010 A1 - A. Fagiolini A1 - F. A. W. Belo A1 - M. G. Catalano A1 - S. Alicino A1 - F. Bonomo A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - IEEE International Conference on Robotics and Automation (ICRA2010) CY - Anchorage, Alaska ER - TY - CONF T1 - Design for Variable Stiffness Actuation based on Enumeration and Analysis of Performance T2 - IEEE International Conference on Robotics and Automation (ICRA2010) Y1 - 2010 A1 - M. G. Catalano A1 - R. Schiavi A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - IEEE International Conference on Robotics and Automation (ICRA2010) CY - Anchorage, Alaska ER - TY - JOUR T1 - Design of Embedded Controllers Based on Anytime Computing JF - IEEE Trans. Industrial Infor. Y1 - 2010 A1 - A. Quagli A1 - D. Fontanelli A1 - L. Greco A1 - L. Palopoli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper, we present a methodology for designing embedded controllers based on the so-called anytime control paradigm. A control law is split into a sequence of subroutine calls, each one fulfilling a control goal and refining the result produced by the previous one. We propose a design methodology to define a feedback controller structured in accordance with this paradigm and show how a switching policy of selecting the controller subroutines can be designed that provides stability guarantees for the closed-loop system. The cornerstone of this construction is a stochastic model describing the probability of executing, in each activation of the controller, the different subroutines. We show how this model can be constructed for realistic real-time task sets and provide an experimental validation of the approach.

VL - 6 ER - TY - CONF T1 - Distributed Estimation and Detection under Local Information T2 - IFAC Workshop on Distributed Estimation and Control in Networked Systems Y1 - 2010 A1 - F. Pasqualetti A1 - R. Carli A1 - A. Bicchi A1 - F. Bullo KW - Embedded Control KW - Robotics JF - IFAC Workshop on Distributed Estimation and Control in Networked Systems CY - Annecy, France ER - TY - CONF T1 - Identifying Cyber Attacks via Local Model Information T2 - International Conference on Decision and Control - CDC 2010 Y1 - 2010 A1 - F. Pasqualetti A1 - R. Carli A1 - A. Bicchi A1 - F. Bullo KW - Embedded Control KW - Robotics JF - International Conference on Decision and Control - CDC 2010 CY - Atlanta, USA ER - TY - JOUR T1 - Left invertibility of discrete systems with finite inputs and quantized output JF - International Journal Of Control Y1 - 2010 A1 - N. Dubbini A1 - B. Piccoli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -The aim of this paper is to address left invertibility for dynamical systems with inputs and outputs in discrete sets. We study systems which evolve in discrete time within a continuous state-space; quantized outputs are generated by the system according to a given partition of the state-space, while inputs are arbitrary sequences of symbols in a finite alphabet, which are associated to specific actions on the system. Our main results are obtained under some contractivity hypotheses. The problem of left invertibility, i.e. recovering an unknown input sequence from the knowledge of the corresponding output string, is addressed using the theory of Iterated Function Systems (IFS), a tool developed for the study of fractals. We show how the IFS naturally associated to a system and the geometric properties of its attractor are linked to the invertibility property of the system. Our main result is a necessary and sufficient condition for left invertibility and uniform left invertibility for joint contractive systems. In addition, an algorithm is proposed to recover inputs from output strings. A few examples are presented to illustrate the application of the proposed method.

VL - 83 ER - TY - CONF T1 - A Modular and Layered Cosimulator for Networked Control Systems T2 - Mediterranean Conference on Control and Automation Y1 - 2010 A1 - S. Falasca A1 - C Belsito A1 - A. Quagli A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Mediterranean Conference on Control and Automation CY - Marrakech, Morocco ER - TY - CONF T1 - Motion planning for Formations of Dubins Vehicles T2 - International Conference on Decision and Control - CDC 2010 Y1 - 2010 A1 - H. Wang A1 - L. Pallottino A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - International Conference on Decision and Control - CDC 2010 ER - TY - CONF T1 - Observability and Controllability Detection of Multi-Agent Systems through Decentralized Laplacian Spectrum Estimation T2 - International Conference on Decision and Control - CDC 2010 Y1 - 2010 A1 - M. Franceschelli A1 - S. Martini A1 - M. Egerstedt A1 - A. Bicchi A1 - A. Giua KW - Embedded Control KW - Robotics JF - International Conference on Decision and Control - CDC 2010 ER - TY - CONF T1 - A Self-Routing Protocol for Distributed Consensus on Logical Information T2 - IEEE/RSJ International Conference on Intelligent Robots and Systems Y1 - 2010 A1 - A. Fagiolini A1 - S. Martini A1 - D. Di Baccio A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - IEEE/RSJ International Conference on Intelligent Robots and Systems CY - Taipei, Taiwan ER - TY - JOUR T1 - Shortest Paths for a Robot with Nonholonomic and Field-of-View Constraints JF - IEEE Trans. on Robotics Y1 - 2010 A1 - P Salaris A1 - D. Fontanelli A1 - L. Pallottino A1 - A. Bicchi KW - Embedded Control KW - Robotics VL - 26 ER - TY - CONF T1 - VSA-HD: From the Enumeration Analysis to the Prototypical Implementation T2 - IEEE/RSJ International Conference on Intelligent RObots and Systems Y1 - 2010 A1 - M. G. Catalano A1 - G. Grioli A1 - F. Bonomo A1 - R. Schiavi A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - IEEE/RSJ International Conference on Intelligent RObots and Systems CY - St. Louis MO USA ER - TY - CONF T1 - Constructive robustness analysis of a limited-information feedback approach for nonlinear systems T2 - Proc. IEEE International Conference on Decision and Control Y1 - 2009 A1 - A. Franci A1 - A. Chaillet KW - Embedded Control KW - Robotics AB -We analyze the robustness properties of a recently introduced strategy for stabilization with limited information. We show that if the nominal closed-loop system can be made Input-to-State Stable (ISS) with respect to measurement errors, parameter uncertainty and exogenous disturbances then this robustness is preserved when only limited information is available on the plant. More precisely, if a sufficiently bandwidth is available on the communication network, then the resulting closed-loop is semiglobally practically ISS.

JF - Proc. IEEE International Conference on Decision and Control CY - Shangai, China ER - TY - CONF T1 - Designing Real-Time Embedded Controllers using the Anytime Computing Paradigm T2 - IEEE International Conference on Emerging Technology and Factory Automation Y1 - 2009 A1 - A. Quagli A1 - D. Fontanelli A1 - L. Greco A1 - L. Palopoli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we present a methodology for designing embedded controllers with a variable accuracy. The adopted paradigm is the so called any-time control, which derives from the computing paradigm known as "imprecise computation". The most relevant contributions of the paper are a procedure for designing an incremental control law, whose different pieces cater for increasingly aggressive control requirements, and a modelling technique for the execution platform that allows us to design provably correct switching policies for the controllers. The methodology is validated by both simulations and experimental results.

JF - IEEE International Conference on Emerging Technology and Factory Automation CY - Palma de Mallorca, Spain ER - TY - CONF T1 - Distributed Consensus on Boolean Information T2 - 1st IFAC Workshop on Estimation and Control of Networked Systems (NecSys'09) Y1 - 2009 A1 - A. Fagiolini A1 - S. Martini A1 - N. Dubbini A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we study the convergence towards consensus on information in a distributed system of agents communicating over a network. The particularity of this study is that the information on which the consensus is seeked is not represented by real numbers, rather by logical values or compact sets. Whereas the problems of allowing a network of agents to reach a consensus on logical functions of input events, and that of agreeing on set-valued information, have been separately addressed in previous work, in this paper we show that these problems can indeed be attacked in a unified way in the framework of Boolean distributed information systems. Based on a notion of contractivity for Boolean dynamical systems, a necessary and suficient condition ensuring the global convergence toward a unique equilibrium point is presented. This result can be seen as a first step toward the denition of a unified framework to uniformly address all consensus problems on Boolean algebras.

JF - 1st IFAC Workshop on Estimation and Control of Networked Systems (NecSys'09) CY - Venice, Italy ER - TY - CONF T1 - Dynamic Distributed Intrusion Detection for Secure Multi-Robot Systems T2 - Int. Conference of Robotics and Automation Y1 - 2009 A1 - A. Fagiolini A1 - F. Babboni A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Int. Conference of Robotics and Automation CY - Kobe, Japan ER - TY - CONF T1 - Integration of Active and Passive Compliance Control for Safe Human-Robot Coexistence T2 - Int. Conference of Robotics and Automation Y1 - 2009 A1 - R. Schiavi A1 - F. Flacco A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Int. Conference of Robotics and Automation CY - Kobe, Japan ER - TY - CONF T1 - Nonlinear Decoupled Motion-Stiffness Control and Collision Detection/Reaction for the VSA-II Variable Stiffness Device T2 - Proc. IEEE/RSJ International Conference on Intelligent RObots and Systems Y1 - 2009 A1 - A. De Luca A1 - F. Flacco A1 - R. Schiavi A1 - A. Bicchi KW - Embedded Control KW - Physical Human-Robot Interaction (pHRI) KW - Robotics AB -Variable Stiffness Actuation (VSA) devices are being used to jointly address the issues of safety and performance in physical human-robot interaction. With reference to the VSA-II prototype, we present a feedback linearization approach that allows the simultaneous decoupling and accurate tracking of motion and stiffness reference profiles. The operative condition that avoids control singularities is characterized. Moreover, a momentum-based collision detection scheme is introduced, which does not require joint torque sensing nor information on the time-varying stiffness of the device. Based on the residual signal, a collision reaction strategy is proposed that takes advantage of the proposed nonlinear control to rapidly let the arm bounce away after detecting the impact, while limiting contact forces through a sudden reduction of the stiffness. Simulations results are presented to illustrate the performance of the overall approach. Extensions to the multi-dof case of robot manipulators equipped with VSA-II devices are also considered.

JF - Proc. IEEE/RSJ International Conference on Intelligent RObots and Systems CY - St. Louis MO USA ER - TY - CONF T1 - Safety and Security in Networked Robotics Systems via Logical Consensus T2 - International Workshop on Networked embedded and control system technologies: European and Russian R&D cooperation (NESTER'09) Y1 - 2009 A1 - S. Martini A1 - A. Fagiolini A1 - G. Dini A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - International Workshop on Networked embedded and control system technologies: European and Russian R&D cooperation (NESTER'09) CY - Milan, Italy ER - TY - CONF T1 - On the Security of Linear Consensus Networks T2 - Proc. IEEE International Conference on Decision and Control Y1 - 2009 A1 - F. Pasqualetti A1 - A. Bicchi A1 - F. Bullo KW - Embedded Control KW - Robotics AB -The task of performing trustworthy computation in a network of autonomous agents in the presence of misbehaving components is the subject of this work. A solution to this problem is relevant for several coordination, formation, and synchronization tasks. Relying only on the information flow of the control protocol, uncooperative behaviors are revealed using an unknown input observer technique. Necessary and sufficient conditions to detect and correctly identify misbehaving nodes are given, together with a study of the genericity of such conditions. It is shown that generically any node of the network can correctly estimate the state of the other agents, and therefore compute any function of the state, provided that the connectivity of the communication graph is strictly greater than the number of misbehaving nodes. An intrusion detection and identification algorithm is described, and its effectiveness is confirmed through a numerical study.

JF - Proc. IEEE International Conference on Decision and Control CY - Shangai, China N1 -General Chairs Recognition Awards for Interactive Papers

ER - TY - CONF T1 - Set-Valued Consensus for Distributed Clock Synchronization T2 - Proc. IEEE Conference on Automation Science and Engineering Y1 - 2009 A1 - A. Fagiolini A1 - S. Martini A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper addresses the clock synchronization problem in a wireless sensor network (WSN) and proposes a distributed solution that consists of a form of consensus, where agents are able to exchange data representing intervals or sets. The solution is based on a centralized algorithm for clock synchronization, proposed by Marzullo, that determines the smallest interval that is in common with the maximum number of measured interval. We first show how to convert such an algorithm into a problem involving only operations on sets, and then we convert it into a set

JF - Proc. IEEE Conference on Automation Science and Engineering CY - Bangalore ER - TY - CONF T1 - Shortest Paths for Non-holonomic Vehicles with Limited Field of View Camera T2 - Proc. IEEE International Conference on Decision and Control Y1 - 2009 A1 - L. Pallottino A1 - P Salaris A1 - D. Fontanelli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper presents a complete characterization of shortest paths for unicycle-like nonholonomic mobile robots equipped with a pinhole camera rigidly fixed with limited Field-Of-View (FOV). We preliminarily provide an alphabet of optimal control words and then we demonstrate how to obtain the partition induced by shortest path in the vehicle plane. The word univocally associated to a region encodes the shortest path from any starting point in that region to the goal point of the mobile robot without violating the FOV constraints.

JF - Proc. IEEE International Conference on Decision and Control CY - Shangai, China ER - TY - JOUR T1 - Visual Servoing in the Large JF - International Journal of Robotics Research Y1 - 2009 A1 - D. Fontanelli A1 - A. Danesi A1 - F. A. W. Belo A1 - P Salaris A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we consider the problem of maneuvering an autonomous robot in complex unknown environments using vision. The goal is to accurately servo a wheeled vehicle to a desired posture using only feedback from an on-board camera, taking into account the nonholonomic nature of the vehicle kinematics and the limited field-ofview of the camera. With respect to existing visual servoing schemes, which achieve similar goals locally (i.e. when the desired and actual camera views are sufficiently similar), we propose a method to visually navigate the robot through an extended visual map before eventually reaching the desired goal. The map comprises a set of images, previously stored in an exploratory phase, that convey both topological and metric information regarding the connectivity through feasible robot paths and the geometry of the environment, respectively. Experimental results on a laboratory setup are reported showing the practicality of the proposed approach.

VL - 28 ER - TY - CONF T1 - Anytime Control Algorithms for Real-Time Embedded Systems T2 - Int Conf of Hybrid Systems: Computation and Control Y1 - 2008 A1 - D. Fontanelli A1 - L. Greco A1 - A. Bicchi ED - M. Egerstedt ED - B. Mishra KW - Embedded Control KW - Robotics AB -In this paper we consider the problem of designing controllers for linear plants to be implemented in embedded platforms under stringent real-time constraints. These include preemptive scheduling schemes, under which the maximum execution time allowed for control software tasks is uncertain. We propose an ``anytime control'' design approach, consisting in a hierarchy of controllers for the same plant. Higher controllers in the hierarchy provide better closed-loop performance, while typically requiring a larger worst-case execution time. We provide a procedure for the design of controllers which, together with a conditioning process of the stochastic scheduling, provides better performance than prevailing worst case-based design, while guaranteeing almost sure stability of the resulting switching system.

JF - Int Conf of Hybrid Systems: Computation and Control T3 - Lecture Notes in Computer Science PB - Springer-Verlag CY - St. Louis, MO VL - 4981/2008 ER - TY - CONF T1 - Consensus-based Distributed Intrusion Detection for Multi-Robot Systems T2 - Proc. IEEE Int. Conf. on Robotics and Automation Y1 - 2008 A1 - A. Fagiolini A1 - M. Pellinacci A1 - M. Valenti A1 - G. Dini A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper addresses a security problem in robotic multi-agent systems, where agents are supposed to cooperate according to a shared protocol. A distributed Intrusion Detection System (IDS) is proposed here, that detects possible non- cooperative agents. Previous work by the authors showed how single monitors embedded on-board the agents can detect non- cooperative behavior, using only locally available information. In this paper, we allow such monitors to share the collected information in order to overcome their sensing limitation. In this perspective, we show how an agreement on the type of behavior of a target-robot may be reached by the monitors, through execution of a suitable consensus algorithm. After formulating a consensus problem over non-scalar quantities, and with a generic update function, we provide conditions for the consensus convergence and an upper bound to its transient duration. Effectiveness of the proposed solution is finally shown through simulation of a case study.

JF - Proc. IEEE Int. Conf. on Robotics and Automation ER - TY - CONF T1 - Controllability Decompositions of Networked Systems Through Quotient Graphs T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2008 A1 - S. Martini A1 - M. Egerstedt A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CONF T1 - Decentralized Deployment of Mobile Sensors for Optimal Connected Sensing Coverage T2 - Distributed Computing in Sensor Systems Y1 - 2008 A1 - A. Fagiolini A1 - L. Tani A1 - A. Bicchi A1 - G. Dini KW - Embedded Control KW - Robotics AB -In this paper, we address the optimal connected sensing coverage problem, i.e., how mobile sensors with limited sensing capabilities can cooperatively adjust their locations so as to maximize the extension of the covered area while avoiding any internal "holes", areas that are not covered by any sensor. Our solution consists in a distributed motion algorithm that is based on an original extension of the Voronoi tessellation.

JF - Distributed Computing in Sensor Systems T3 - Lecture Notes in Computer Science PB - Springer Berlin / Heidelberg VL - 5067/2008 UR - http://dx.doi.org/10.1007/978-3-540-69170-9_34 ER - TY - CONF T1 - Delay compensation in packet-switching networked controlled systems T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2008 A1 - A. Chaillet A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CONF T1 - Hybrid system reduction T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2008 A1 - E. Mazzi A1 - A. Sangiovanni Vincentelli A1 - A. Balluchi A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - JOUR T1 - Hypercubes are minimal controlled invariants for discrete-time linear systems with quantized scalar input JF - Nonlinear Analysis. Hybrid systems Y1 - 2008 A1 - B. Picasso A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -Quantized linear systems are a widely studied class of nonlinear dynamics resulting from the control of a linear system through finite inputs. The stabilization problem for these models shall be studied in terms of the so called practical stability notion that essentially consists in confining the trajectories into sufficiently small neighborhoods of the equilibrium (ultimate boundedness) . In this paper, we study the problem of describing the smallest sets into which any feedback can ultimately confine the state, for a given linear single-input system with an assigned finite set of admissible input values (quantization). We show that a controlled invariant set of minimal size is contained in a family of sets (namely, hypercubes in controller-canonical form), previously introduced in [14, 15] . A comparison is presented which quantifies the improvement in tightness of the proposed analysis technique with respect to classical results using quadratic Lyapunov functions.

ER - TY - CONF T1 - Left invertibility of discrete systems with finite inputs and quantized output T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2008 A1 - N. Dubbini A1 - B. Piccoli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -The aim of this paper is to address left invertibility for dynamical systems with inputs and outputs in discrete sets. We study systems that evolve in discrete time within a continuous state-space. Quantized outputs are generated by the system according to a given partition of the state-space, while inputs are arbitrary sequences of symbols in a finite alphabet, which are associated to specific actions on the system. We restrict to the case of contractive dynamics for fixed inputs. The problem of left invertibility, i.e. recovering an unknown input sequence from the knowledge of the corresponding output string, is addressed using the theory of Iterated Function Systems (IFS), a tool developed for the study of fractals. We show how the IFS naturally associated to a system and the geometric properties of its attractor are linked to the left invertibility property of the system. Our main results are a necessary and sufficient condition for a given system to be left invertible with probability one on the space of inputs (i.e. for almost all input sequences), and necessary and sufficient conditions for left invertibility and uniform left invertibility under some weak additional hypotheses. A few examples are presented to illustrate the application of the proposed method.

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CONF T1 - Logical Consensus for Distributed Network Agreement T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2008 A1 - A. Fagiolini A1 - E.M. Visibelli A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Proc. IEEE Int. Conf. on Decision and Control N1 -Extended Version

ER - TY - CONF T1 - Neural network based robust adaptive control for a variable stiffness actuator T2 - Control and Automation, 16 th Mediterranean Conference on Control and Automation Y1 - 2008 A1 - S. Huh A1 - G. Tonietti A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we present a robust adaptive controller based on a neural network (NN) for a variable stiffness actuator (VSA). The controller is able to independently set the mechanical stiffness and position at the joint shaft to guarantee robustness with respect to slowly time-varying and unmodeled friction coefficients affecting the dynamics of the actuator. The lumped uncertainties of the VSA including unmodeled dynamics are considered and approximated by a simple NN so that the controlled system is asymptotically stable, and remains effective while process conditions vary. To cope with the reconstruction error of the NN, a sliding mode like additional robust control term is introduced. The proofs for the uniformly ultimately bounded (UUB) and uniform asymptotic (UAS) stabilities for the closed-loop system are provided in detail via Lyapunov theory. Simulation and experimental results are reported in support of both validity and performance of the proposed approach.

JF - Control and Automation, 16 th Mediterranean Conference on Control and Automation ER - TY - CONF T1 - Physical Human-Robot Interaction: Dependability, Safety, and Performance T2 - Proc. 10th Intl. Workshop Advanced Motion Control Y1 - 2008 A1 - A. Bicchi A1 - M. Bavaro A1 - G. Boccadamo A1 - D. De Carli A1 - R. Filippini A1 - G. Grioli A1 - M. Piccigallo A1 - A. Rosi A1 - R. Schiavi A1 - S. Sen A1 - G. Tonietti KW - Embedded Control KW - Physical Human-Robot Interaction (pHRI) KW - Robotics AB -In this paper we discuss the problem of achieving good performance in accuracy and promptness by a robot manipulator under the condition that safety is guaranteed throughout task execution. Intuitively, while a rigid and powerful structure of the arm would favor its performance, lightweight compliant structures are more suitable for safe operation. The quantitative analysis of the resulting design trade-off between safety and performance has a strong impact on how robot mechanisms and controllers should be designed for human-interactive applications. We discuss few different possible concepts for safely actuating joints, and focus on aspects related to the implementation of the mechanics and control of this new class of robots.

JF - Proc. 10th Intl. Workshop Advanced Motion Control ER - TY - CONF T1 - Steering a Leader-Follower Team via Linear Consensus T2 - Hybrid Systems: Computation and Control Y1 - 2008 A1 - F. Pasqualetti A1 - S. Martini A1 - A. Bicchi ED - M. Egerstedt ED - B. Mishra KW - Embedded Control KW - Robotics AB -The paper considers the problem of driving a formation of autonomous mobile agents. The group of mobile devices is described as a leader–follower network, where the followers update their position using a simple local consensus procedure, while the leaders, whose positions represent the control inputs of the network, are free to move. We characterize the transient behavior of the network, and solve the containment problem without relying on auxiliary sensors.

JF - Hybrid Systems: Computation and Control T3 - Lecture Notes in Computer Science PB - Springer-Verlag VL - 4981/2008 ER - TY - CONF T1 - Tolerating Malicious Monitors in Detecting Misbehaving Robots T2 - IEEE International Workshop on Safety, Security, and Rescue Robotics Y1 - 2008 A1 - A. Fagiolini A1 - A. Bicchi A1 - G. Dini A1 - I. M. Savino KW - Embedded Control KW - Robotics JF - IEEE International Workshop on Safety, Security, and Rescue Robotics CY - Tohoku University Aobayama Campus, Sendai, Japan ER - TY - JOUR T1 - Toward Soft Robot you can Depend on JF - IEEE Robotics and Automation Magazine Y1 - 2008 A1 - R. Filippini A1 - S. Sen A1 - A. Bicchi KW - Embedded Control KW - Robotics VL - 15 ER - TY - CONF T1 - Almost Sure Stability of Anytime Controllers via Stochastic Scheduling T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2007 A1 - L. Greco A1 - D. Fontanelli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we consider scheduling the execution of a number of different software tasks implementing a hierarchy of real-time controllers for a given plant. Controllers are considered to be given and ordered according to a measure of the performance they provide. Software tasks implementing higher-performance controllers are assumed to require a larger worst-case execution time. Control tasks are to be scheduled within given availability limits on execution time, which change stochastically in time. The ensuing switching system is prone to instability, unless a very conservative policy is enforced of always using the simplest, least performant controller. The presented method allows to condition the stochastic scheduling of control tasks so as to obtain a better exploitation of computing capabilities, while guaranteeing almost sure stability of the resulting switching system.

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CONF T1 - A Component-Based Approach to Localization and Collision Avoidance for Mobile Multi-Agent Systems T2 - Proc. European Control Conference (ECC) Y1 - 2007 A1 - P. Alriksson A1 - J. Nordh A1 - K -E Arzén A1 - A. Bicchi A1 - A. Danesi A1 - R. Schiavi A1 - L. Pallottino KW - Embedded Control KW - Robotics AB -In the RUNES project a disaster relief tunnel scenario is being developed in which mobile robots are used to restore the radio network connectivity in a stationary sensor network. A component-based software development approach has been adopted. Two components are described in this paper. A localization component that uses ultrasound and dead reckoning to decide the robot positions and a collision avoidance component that ensures that the robots do not collide with each other.

JF - Proc. European Control Conference (ECC) ER - TY - JOUR T1 - A component-based approach to the design of networked control systems JF - European Journal of Control Y1 - 2007 A1 - K -E Arzén A1 - A. Bicchi A1 - G. Dini A1 - S. Hailes A1 - K. H. Johansson A1 - J. Lygeros A1 - A. Tzes KW - Embedded Control KW - Robotics AB -Component-based techniques revolve around composable, reusable software objects that shield the application level software from the details of the hardware and lowlevel software implementation and vice versa. Components provide many benefits that have led to their wide adoption in software and middleware developed for embedded systems: They are well-defined entities that can be replaced without affecting the rest of the systems, they can be developed and tested separately and integrated later, and they are reusable. Clearly such features are important for the design of large-scale complex systems more generally, beyond software architectures. We propose the use of a component approach to address embedded control problems. We outline a general componentbased framework to embedded control and show how it can be instantiated in specific problems that arise in the control over/of sensor networks. Building on the middleware component framework developed under the European project RUNES, we develop a number of control-oriented components necessary for the implementation of control applications and design their integration. The paper provides the overview of the approach, discusses a real life application where the approach has been tested and outlines a number of specific control problems that arise in this application.

VL - 13 N1 -Invited paper

ER - TY - JOUR T1 - Decentralized cooperative policy for conflict resolution in multi-vehicle systems JF - IEEE Trans. on Robotics Y1 - 2007 A1 - L. Pallottino A1 - V. G. Scordio A1 - E. Frazzoli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we propose a novel policy for steering multiple vehicles between assigned independent start and goal configurations and ensuring collision avoidance. The policy rests on the assumption that agents are all cooperating by implementing the same traffic rules. However, the policy is completely decentralized, as each agent decides its own motion by applying those rules only on locally available information, and totally scalable, in the sense that the amount of information processed by each agent and the computational complexity of the algorithms are not increasing with the number of agents in the scenario. The proposed policy applies to systems in which new vehicle may enter the scene and start interacting with existing ones at any time, while others may leave. Under mild conditions on the initial configurations, the policy is shown to be safe, i.e. to guarantee collision avoidance throughout the system evolution. In the paper, conditions are discussed on the desired configurations of agents under which the ultimate convergence of all vehicles to their goals can also be guaranteed. To show that such conditions are actually necessary and sufficient, which turns out to be a challenging liveness verification problem for a complex hybrid automaton, we employ a probabilistic verification method. The paper finally reports on simulations for systems of several tens of vehicles, and with some experimental implementation showing the practicality of the approach.

VL - 23 ER - TY - CONF T1 - Decentralized Intrusion Detection for Secure Cooperative Multi-Agent Systems T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2007 A1 - A. Fagiolini A1 - G. Valenti A1 - L. Pallottino A1 - G. Dini A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we address the problem of detecting faulty behaviors of cooperative mobile agents. A novel decentralized and scalable architecture that can be adopted to realize a monitor of the agents

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - ABST T1 - Decentralized Intrusion Detection in Cooperative Multi-Agent Systems Y1 - 2007 A1 - A. Fagiolini A1 - L. Pallottino A1 - G. Dini KW - Embedded Control KW - Robotics AB -We address the problem of detecting faulty behaviors of robots belonging to a multi-agent system. Our objective is to develop a scalable architecture that can be adopted to realize a completely decentralized intrusion detector monitoring the agents' behavior. We want the solution to be independent from the set of ``rules'' describing the interaction among the agents, and from their dynamics; (non-invasive) mainly based on HW/SW components that are already present on-board of each agent. We focus on systems with decentralized cooperation schemes where cooperation is obtained by sharing a set of ``rules'' by which each agent plans its next ``action'' and where some of the agents may act not according to the rules due to spontaneous failure, tampering, or malicious introduction.

N1 -Poster Presentation

ER - TY - CONF T1 - Distributed intrusion detection for secure consensus computations T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2007 A1 - F. Pasqualetti A1 - A. Bicchi A1 - F. Bullo KW - Embedded Control KW - Robotics AB -This paper focuses on trustworthy computation systems and proposes a novel intrusion detection scheme for averaging networks with misbehaving nodes. This prototypical control problem is relevant in network security applications. The objective is for each node to detect and isolate the misbehaving nodes using only the information flow adopted by standard averaging protocols. We focus on the single misbehaving node problem. Our technical approach is based on the theory of Unknown Input Observability. First, we give necessary and sufficient conditions for the misbehavior to be observable and for the identity of the faulty node to be detectable. Second, we design a distributed unknown input estimator, and we characterize its convergence rate in the

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CONF T1 - A Dynamic Programming Approach to Optimal Planning for Vehicles with Trailers T2 - Proc. IEEE Int. Conf. on Robotics and Automation Y1 - 2007 A1 - L. Pallottino A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we deal with the optimal feedback synthesis problem for robotic vehicles with trailers which can be modeled by differential equations in chained-form. With respect to classical methods for numerical evolution of optimal feedback synthesis via Dynamic Programming which are based on both input and state discretization, our method exploits the lattice structure naturally imposed on the reachable set by input quantization. A generalized Dijkstra algorithm can be used to obtain optimal feedback control laws, for chained-form vehicles with n-trailers, in an effective way.

JF - Proc. IEEE Int. Conf. on Robotics and Automation ER - TY - CONF T1 - A Fast RANSAC–Based Registration Algorithm for Accurate Localization in Unknown Environments using LIDAR Measurements T2 - Proc. IEEE Int. Conf. on Automation Science and Engineering Y1 - 2007 A1 - D. Fontanelli A1 - L. Ricciato A1 - S. Soatto KW - Embedded Control KW - Robotics AB -The problem of accurate localization using only measurements from a LIDAR sensor is analyzed in this paper. The sensor is rigidly fixed on a generic moving platform, which moves on a plane. Practical on–line applications of localization algorithms impose constraints on the execution time, problem that is addressed in this paper and compared with other existing solutions. Due to the nature of the sensor adopted, the localization algorithm is based on a fast and accurate {\em registration} algorithm, which is able to deal with noisy measurements, outliers and dynamic environments. The proposed solution relies on the RANSAC algorithm in combination with a Huber kernel in order to cope with typical nuisances in LIDAR measurements. The robust registration is successively used in combination with an Extended Kalman Filter to track the trajectory of the LIDAR over time, hence to solve the localization problem. Simulations and experimental results are reported to show the feasibility of the proposed approach.

JF - Proc. IEEE Int. Conf. on Automation Science and Engineering CY - Scottsdale, AZ, USA ER - TY - JOUR T1 - Hybrid Modeling and Control of the Common-Rail Injection System JF - Int. J. Control Y1 - 2007 A1 - A. Balluchi A1 - A. Bicchi A1 - E. Mazzi A1 - A. Sangiovanni-Vincentelli A1 - G. Serra KW - Automotive KW - Embedded Control AB - We present an industrial case study in automotive control of significant complexity: the new common rail fuel injection system for Diesel engines, currently under production by Magneti Marelli Powertrain.In this system, an inlet metering valve, introduced before the High Pressure (HP) pump, regulates the fuel flow that supplies the common rail according to the engine operating point (e.g. engine speed, desired torque). The standard approach followed in automotive control is to use a mean–value model for the plant and to develop a controller based on this model.I n this particular case, this approach does not provide a satisfactory solution as the discrete–continuous interactions in the fuel injection system, due to the slow time–varying frequency of the HP pump cycles and the fast sampling frequency of sensing and actuation, play a fundamental role.W e present a design approach based on a hybrid model of the Magneti Marelli Powertrain common–rail fuel–injection system for four-cylinder multi–jet engines and a hybrid approach to the design of a rail pressure controller.T he hybrid controller is compared with a classical mean–value based approach to automotive control design whereby the quality of the hybrid solution is demonstrated. VL - 80 ER - TY - CONF T1 - Hybrid Multi-rate Control of the Common-Rail T2 - European Control Conference Y1 - 2007 A1 - A. Balluchi A1 - A. Bicchi A1 - E. Mazzi A1 - A. Sangiovanni-Vincentelli A1 - G. Serra KW - Embedded Control KW - Robotics AB -We present an industrial case study in automotive control of significant complexity: the new common-rail fuel- injection system for Diesel engines developed by Magneti Marelli Powertrain. In this system, an inlet metering valve, inserted before the High Pressure (HP) pump, regulates the fuel flow that supplies the common rail according to the engine operating point (e.g. engine speed and torque). The standard approach to controller design adopted in the automotive in- dustry is based on mean-value models of the plant. However, the fuel injection system exhibits complex discrete-continuous interactions, due to the slow time-varying frequency of the HP pump cycles and the fast sampling frequency of sensing and actuation. Hence, a hybrid approach to controller design is very promising. In this paper, we present the synthesis of a hybrid multi-rate controller for a Magneti Marelli Powertrain common-rail fuel- injection system for four-cylinder multi-jet engines. Controller design is based on a hybrid model of the injection system. The resulting hybrid controller performs significantly better then previous controllers developed in the company on the basis of mean-value models of the plant.

JF - European Control Conference ER - TY - CONF T1 - Local Monitor Implementation for Decentralized Intrusion Detection in Secure Multi-Agent Systems T2 - 3rd IEEE Conference on Automation Science and Engineering Y1 - 2007 A1 - A. Fagiolini A1 - G. Valenti A1 - L. Pallottino A1 - G. Dini A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper focuses on the detection of misbehaving agents within a group of mobile robots. A novel approach to automatically synthesize a decentralized Intrusion Detection System (IDS) as well as an efficient implementation of local monitors are presented. In our scenario, agents perform possibly different independent tasks, but cooperate to guarantee the entire system

JF - 3rd IEEE Conference on Automation Science and Engineering ER - TY - CONF T1 - Probabilistic verification of decentralized multi-agent control strategies: a case study in conflict avoidance T2 - American Control Conference (ACC) Y1 - 2007 A1 - L. Pallottino A1 - A. Bicchi A1 - E. Frazzoli KW - Embedded Control KW - Robotics AB -Many challenging verification problems arise from complex hybrid automata that model decentralized control systems. As an example, we will consider decentralized policies that steer multiple vehicles in a shared environment: properties of safety and liveness, such as collision avoidance and ultimate convergence of all vehicles to their goals, must be verified. To formally verify the behavior of proposed policies, it is desired to identify the broadest class of start and goal configurations, such that safety and liveness would be guaranteed. Simple conditions are proposed to identify such a class: ideally, a formal proof that such conditions are necessary and sufficient for safety and liveness is requested. Unfortunately, in decentralized control frameworks classical approaches are difficult to apply. Hence, probabilistic verification method can be applied to quantify the accuracy and the confidence of the veridicity of the desired predicate. The probabilistic verification method is applied to a recently proposed cooperative and completely decentralized collision avoidance policy for non-holonomic vehicles.

JF - American Control Conference (ACC) ER - TY - JOUR T1 - On the Stabilization of Linear Systems Under Assigned I/O Quantization JF - IEEE Transactions on Automatic Control Y1 - 2007 A1 - B. Picasso A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper is concerned with the stabilization of discrete-time linear systems with quantization of the input and output spaces, i.e., when available values of inputs and outputs are discrete. Unlike most of the existing literature, we assume that how the input and output spaces are quantized is a datum of the problem, rather than a degree of freedom in design. Our focus is hence on the existence and synthesis of symbolic feedback controllers, mapping output words into the input alphabet, to steer a quantized I/O system to within small invariant neighborhoods of the equilibrium starting from large attraction basins. We provide a detailed analysis of the practical stabilizability of systems in terms of the size of hypercubes bounding the initial conditions, the state transient and the steady state evolution. We also provide an explicit construction of a practically stabilizing controller for the quantized I/O case.

VL - 52 ER - TY - CONF T1 - Steering Dynamical Systems with Finite Plans and Limited Path Length T2 - European Control Conference Y1 - 2007 A1 - L. Greco A1 - A. Fagiolini A1 - A. Bicchi A1 - B. Piccoli KW - Embedded Control KW - Robotics AB -Complex dynamical systems can be steered by using symbolic input plans. These plans must have a finite descriptive length, and can be expressed by means of words chosen in an alphabet of symbols. In this way, such plans can be sent through a limited capacity channel to a remote system, where they are decoded in suitable control actions. The choice of this symbols is essential to efficiently encode steering plans. To this aim, in this paper, we state the problem of finding symbols maximizing the interval of points reachable by the system along paths with constrained length. We focus on the problem with two symbols, and compare the results with those produced by plans not accounting for the length constraint. Moreover, the behavior of a simple helicopter, steered by both kinds of plans, has been simulated, in order to illustrate the power of the overall control system, and to emphasize the improvements introduced by the new plans.

JF - European Control Conference ER - TY - JOUR T1 - Symbolic Planning and Control of Robot Motion: Finding the Missing Pieces of Current Methods and Ideas JF - Robotics and Automation Magazine Y1 - 2007 A1 - C. Belta A1 - A. Bicchi A1 - M. Egerstedt A1 - E. Frazzoli A1 - E. Klavins A1 - G. J. Pappas KW - Embedded Control KW - Robotics AB -Approaches to robot motion planning and control that involve tools such as automata, languages, temporal logics, and grammars, have been recently termed "symbolic." In this article, we review some existing results, discuss their relevance and applicability, and outline some of the main open questions and challenges in the area.

VL - 14 ER - TY - CONF T1 - Adaptive non Linear Control of Dynamic Mobile Robots with Parameters Uncertainty T2 - Int. IFAC Symp. on Robot Control Y1 - 2006 A1 - D. Fontanelli A1 - R. Viviani A1 - L. Greco A1 - A. Caiti A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -Research of a modular stabilizing control law for uncertain, nonholonomic mobile systems with actuators limitation has been investigated. Modular design allows the definition of a stabilizing control law for the kinematic model. The presence of uncertainties in the actuators parameters or in the vehicle dynamics has been treated both adding suitable components to the Lyapunov function and using parameters adaptation laws (e.g. adaptive control and backstepping techniques). Simulations are reported for the set point stabilization of a unicycle like vehicle showing the feasibility of the proposed approach. Torque limitations for a unicycle like vehicle has been investigated using backstepping techniques for the vehicle tracking problem. Simulations are reported.

JF - Int. IFAC Symp. on Robot Control CY - Bologna, Italy ER - TY - ABST T1 - Any Time Control Y1 - 2006 A1 - D. Fontanelli A1 - L. Greco KW - Embedded Control KW - Robotics AB -It is widely accepted in the control community that the Computer Controlled Systems (briefly, CCSs), have a lot of advantages based primarily on the high reconfigurability of the controller platform and the ability of making complex yet fast decisions. Such positive features make the CCS a useful platform for multitasking control, i.e. using only one single-processor platform to control several plants. Within this framework, the computer has to share its computational time to solve several critical tasks, each one with its priority. Taking into account schedulability and real time operating systems problems, it is just a step forward to realize that tasks with low priority could be interrupted any time, with unpredictable distributions, and it is just a logical intuition that not all the tasks can be at the highest priority. From a control point of view, each control task should compute a control input to the controlled system to prevent instability or to ensure the performances. This field seems to be at the border between the control community and the computer science community and it has not been widely investigated. Some work has been presented introducing more general scheduling models and methods for control systems, where control design methodology takes the availability of computing resources into account and allows the trade–offs between control performance and computer resources utilization, and also introducing the idea of any time CCS without solutions. In literature, the Control Server is introduced, allowing the separation between scheduling and control design by treating the controllers as scalable real–time components. Jitter and latency is included in the model and cannot be taken over. Furthermore, the interrupt time, the I/O operations and the overrun handling are not taken into account, simply imposing only soft real time control tasks. Useful tools for the analysis of real time control performance are the Jitterbug and the True Time that analyze the control performance once the control tasks are implemented as soft real time tasks.

PB - Interdepartmental Research Center E. Piaggio, University of Pisa CY - Pisa, Italy ER - TY - CHAP T1 - Controllo, Teoria del T2 - Enciclopedia Italiana di Scienze, Lettere ed Arti Y1 - 2006 A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Enciclopedia Italiana di Scienze, Lettere ed Arti PB - Istituto della Enciclopedia Italiana ``G. Treccani'' ER - TY - CONF T1 - Decentralized and scalable conflict resolution strategy for multi-agents systems T2 - Int. Symp. on Mathematical Theory of Networks and Systems Y1 - 2006 A1 - L. Pallottino A1 - V. G. Scordio A1 - E. Frazzoli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -A decentralized cooperative collision avoidance control policy for planar vehicle recently proposed is herein considered. Given some simple conditions on initial configurations of agents, the policy is known to ensure safety (i.e., collision avoidance) for an arbitrarily large number of vehicles. The method is highly scalable, and effective solutions can be obtained for several tens of autonomous agents. On the other hand, the liveness property of the policy, i.e. the capability of negotiating a solution in finite time, is not yet completely understood. First a 3D workspace extension is proposed. Furthermore, based on a condition on target configuration previously proposed, some general results on the liveness property are reported. Finally, qualitative evaluations on the strategy and on the proposed target sparsity condition are pointed out.

JF - Int. Symp. on Mathematical Theory of Networks and Systems ER - TY - CONF T1 - On the Design and Control of Wireless Networked Embedded Systems T2 - Int. Conf. on Computer Aided Control System Design - CACSD'06 Y1 - 2006 A1 - K -E Arzén A1 - A. Bicchi A1 - S. Hailes A1 - K. H. Johansson A1 - J. Lygeros KW - Embedded Control KW - Robotics AB -Wireless networked embedded systems are becoming increasingly important in a wide area of technical fields. In this tutorial paper we present recent results on design and control of these systems developed within the project Reconfigurable Ubiquitous Networked Embedded Systems (RUNES), which is an European Integrated Project with the aim to control complexity in networked embedded systems by developing robust and scalable middleware systems. New components for control under varying network conditions are discussed for the RUNES architecture. The complexity of the closed-loop system is increased due to the coupling with the disturbances introduced by the communication system. The network may introduce additional delays, jitter, data rate limitations, packet losses etc. Experimental work on integration test beds that demonstrates these results is shown together with motivating links to the RUNES disaster relief tunnel scenario.

JF - Int. Conf. on Computer Aided Control System Design - CACSD'06 PB - IEEE ER - TY - JOUR T1 - Feedback Encoding for Efficient Symbolic Control of Dynamical Systems JF - IEEE Trans. on Automatic Control Y1 - 2006 A1 - A. Bicchi A1 - A. Marigo A1 - B. Piccoli KW - Embedded Control KW - Robotics AB -The problem of efficiently steering dynamical systems by generating finite input plans is considered. Finite plans are finite–length words constructed on a finite alphabet of input symbols, which could be e.g. transmitted through a limited capacity channel to a remote system, where they can be decoded in suitable control actions. Efficiency is considered in terms of the computational complexity of plans, and in terms of their description length (in number of bits). We show that, by suitable choice of the control encoding, finite plans can be efficiently built for a wide class of dynamical systems, computing arbitrarily close approximations of a desired equilibrium in polynomial time. The paper also investigates how the efficiency of planning is affected by the choice of inputs, and provides some results as to optimal performance in terms of accuracy and range.

VL - 51 ER - TY - JOUR T1 - A Geometry-Based Algorithm for the Stability of Planar Switching Systems JF - Int. J. of Systems Science Y1 - 2006 A1 - L. Greco A1 - F. Tocchini A1 - M. Innocenti KW - Embedded Control KW - Robotics VL - 37 ER - TY - CONF T1 - Hybrid Modelling and Control of the Common Rail Injection System T2 - Hybrid Systems: Computation and Control Y1 - 2006 A1 - A. Balluchi A1 - A. Bicchi A1 - E. Mazzi A1 - A. Sangiovanni Vincentelli A1 - G. Serra ED - J. Hespanha ED - A. Tiwari KW - Embedded Control KW - Robotics AB -We present an industrial case study in automotive control of significant complexity: the new common rail fuel injection system for Diesel engines, currently under production by Magneti Marelli Powertrain. In this system, a flow-rate valve, introduced before the High Pressure (HP) pump, regulates the fuel flow that supplies the common rail according to the engine operating point. The standard approach followed in automotive control is to use a mean-value model for the plant and to develop a controller based on this model. In this particular case, this approach does not provide a satisfactory solution as the discrete-continuous interactions in the fuel injection system, due to the slow time-varying frequency of the HP pump cycles and the fast sampling frequency of sensing and actuation, play a fundamental role. We present a design approach based on a hybrid model of the Magneti Marelli Powertrain common-rail fuel-injection system for four-cylinder multi-jet engines and a hybrid approach to the design of a rail pressure controller. The hybrid controller is compared with a classical mean-value based approach to automotive control design whereby the quality of the hybrid solution is demonstrated.

JF - Hybrid Systems: Computation and Control T3 - Lecture Notes in Computer Science PB - Springer-Verlag VL - 3927 / 2006 ER - TY - CONF T1 - Improving efficiency of finite plans by optimal choice of input sets T2 - Hybrid Systems: Computation and Control Y1 - 2006 A1 - A. Bicchi A1 - A. Marigo A1 - B. Piccoli ED - J. Hespanha ED - A. Tiwari KW - Embedded Control KW - Robotics AB -Finite plans proved to be an efficient method to steer complex control systems via feedback quantization. Such finite plans can be encoded by finite–length words constructed on suitable alphabets, thus permitting transmission on limited capacity channels. In particular flat systems can be steered computing arbitrarily close approximations of a desired equilibrium in polynomial time. The paper investigates how the efficiency of planning is affected by the choice of inputs, and provides some results as to optimal performance in terms of accuracy and range. Efficiency is here measured in terms of computational complexity and description length (in number of bits) of finite plans.

JF - Hybrid Systems: Computation and Control T3 - Lecture Notes in Computer Science PB - Springer-Verlag VL - 3927 / 2006 ER - TY - CONF T1 - Practical stabilization of LTI SISO systems under assigned Input and Output quantization Y1 - 2006 A1 - B. Picasso A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This work is concerned with the practical stabilization of discrete–time SISO linear systems under assigned quantization of the input and output spaces. A controller is designed which guarantees effective practical stability properties. Unlike most of the existing literature, quantization is supposed to be a problem datum rather than a degree of freedom in design. Moreover, in the framework of control under assigned quantization, results are concerned with state quantization only and do not include the quantized output feedback case considered here. While standard stability analysis techniques are based on Lyapunov theory and invariant ellipsoids, our study of the closed loop dynamics involves a particularly suitable family of sets, which are hypercubes in controller form coordinates.

N1 -ADHS'06

ER - TY - CONF T1 - Probabilistic verification of a decentralized policy for conflict resolution in multi-agent systems T2 - Proc. IEEE Int. Conf. on Robotics and Automation Y1 - 2006 A1 - L. Pallottino A1 - V. G. Scordio A1 - E. Frazzoli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper, we consider a decentralized cooperative control policy proposed recently for steering multiple non-holonomic vehicles between assigned start and goal configurations while avoiding collisions. The policy is known to ensure safety (i.e., collision avoidance) for an arbitrarily large number of vehicles, if initial configurations satisfy certain conditions. The method is highly scalable, and effective solutions can be obtained for several tens of autonomous agents. On the other hand, the liveness property of the policy, i.e. the capability of negotiating a solution in finite time, is not yet completely understood. In this paper, we introduce a condition on the final vehicle configurations, which we conjecture to be sufficient for guaranteeing liveness. Because of the overwhelming complexity of proving the sufficiency of such condition, we assess the correctness of the conjecture in probability through the analysis of the results of a large number of randomized experiments.

JF - Proc. IEEE Int. Conf. on Robotics and Automation N1 -Correct version

ER - TY - CONF T1 - A scalable platform for safe and secure decentralized traffic management of multiagent mobile systems T2 - ACM Workshop on Real-World Wireless Sensor Networks Y1 - 2006 A1 - A. Danesi A1 - A. Fagiolini A1 - I. Savino A1 - L. Pallottino A1 - R. Schiavi A1 - G. Dini A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we describe the application of wireless sensor networking techniques to address the realization of a safe and secure decentralized traffic management system. We consider systems of many heterogeneous autonomous vehicles moving in a shared environment. Each vehicle is assumed to have different and possibly unspecified tasks, but they cooperate to avoid collisions. We are interested in designing a scalable architecture capable of accommodating a very large and dynamically changing number of vehicles, guaranteeing their safety (i.e., collision avoidance), the achievement of their goals, and security against potential adversaries. By properly distributing and revoking cryptographic keys we are able to protect communications from an external adversary as well as to detect non-cooperative, possibly malicious vehicles and trigger suitable countermeasures. In our architecture, scalability is obtained by decentralization, i.e. each vehicle is regarded as an autonomous agent capable of processing information concerning its own state and the state of only a fixed, small number of ``neighboring'' agents. Ad-hoc wireless sensor networks are employed to provide support for this architecture.

JF - ACM Workshop on Real-World Wireless Sensor Networks ER - TY - CONF T1 - Security and Advanced Control Issues in a Robotic Platform for Monitoring and Relief T2 - Proc. of EWSN 2006 February 13-15, ETH Zurich Y1 - 2006 A1 - A. Danesi A1 - I. M. Savino A1 - R. Schiavi A1 - A. Bicchi A1 - G. Dini KW - Embedded Control KW - Robotics AB -This paper provides an architectural overview and a first implementation of an heterogeneous agent network composed by mobile robots of di

JF - Proc. of EWSN 2006 February 13-15, ETH Zurich ER - TY - CONF T1 - Symbolic Control for Underactuated Differentially Flat Systems T2 - Proc. IEEE Int. Conf. on Robotics and Automation Y1 - 2006 A1 - A. Fagiolini A1 - L. Greco A1 - A. Bicchi A1 - B. Piccoli A1 - A. Marigo KW - Embedded Control KW - Robotics AB -In this paper we address the problem of generating input plans to steer complex dynamical systems in an obstacle-free environment. Plans considered admit a finite description length and are constructed by words on an alphabet of input symbols, which could be e.g. transmitted through a limited capacity channel to a remote system, where they can be decoded in suitable control actions. We show that, by suitable choice of the control encoding, finite plans can be efficiently built for a wide class of dynamical systems, computing arbitrarily close approximations of a desired equilibrium in polynomial time. Moreover, we illustrate by simulations the power of the proposed method, solving the steering problem for two examples in the class of underactuated systems, which have attracted wide attention in the recent literature.

JF - Proc. IEEE Int. Conf. on Robotics and Automation ER - TY - ABST T1 - Adaptive nonlinear control of dynamic mobile robots with parameters uncertainty Y1 - 2005 A1 - A. Bicchi A1 - A. Caiti A1 - D. Fontanelli A1 - L. Greco A1 - R. Viviani KW - Embedded Control KW - Robotics AB -Research of a modular stabilizing control law for uncertain, nonholonomic mobile systems with actuators limitation has been investigated. Modular design allows the definition of a stabilizing control law for the kinematic model. The presence of uncertainties in the actuators parameters or in the vehicle dynamics has been treated both adding suitable components to the Lyapunov function and using parameters adaptation laws (e.g. adaptive control and backstepping techniques). Simulations are reported for the set point stabilization of a unicycle like vehicle showing the feasibility of the proposed approach. Torque limitations for a unicycle like vehicle has been investigated using backstepping techniques for the vehicle tracking problem. Simulations are reported.

PB - Dipartimento di Sistemi Elettrici e Automazione, Università di Pisa ER - TY - JOUR T1 - Control synthesis for practical stabilization of quantized linear systems JF - Rend. Sem. Mat. Univ. Pol. Torino, Control Theory and Stabil., I Y1 - 2005 A1 - B. Picasso A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this work we face the stability problem for quantized control systems (QCS). A discrete–time single–input linear model is considered and, motivated by technological applications, we assume that a uniform quantization of the control set is a priori fixed. As it is well known, for QCS only practical stability properties can be achieved, therefore we focus on the existence and construction of quantized controllers capable of steering a system to within invariant neighborhoods of the equilibrium. The main contribution of the paper consists in a theorem which provides a condition for the practical stabilization in a fixed number of steps: not only the result is interesting in itself, but also it enables to construct a family of stabilizing controllers by means of Model Predictive Control (MPC) techniques. In the last part of the paper some results on the characterization of controlled–invariant sets are reviewed and a lower bound on the size of invariant sets is provided.

VL - 63 ER - TY - CONF T1 - Decentralized Cooperative Conflict Resolution for Multiple Nonholonomic Vehicles T2 - Proc. AIAA COnf. on Guidance, Navigation and Control Y1 - 2005 A1 - L. Pallottino A1 - V. G. Scordio A1 - E. Frazzoli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper, we consider the problem of collision-free motion planning for multiple nonholonomic planar vehicles. Each vehicle is capable of moving at constant speed along paths with bounded curvature, and is aware of the position and heading of other vehicles within a certain sensing radius. No other information exchange is required between vehicles. We propose a spatially decentralized, cooperative hybrid control policy that ensures safety for arbitrary numbers of vehicles. Furthermore, we show that under certain conditions, the policy avoids dead- and livelock, and eventually all vehicles reach their intended targets. Simulations and experimental results are presented and discussed.

JF - Proc. AIAA COnf. on Guidance, Navigation and Control ER - TY - CONF T1 - Hybrid Modelling of an Electronically Controlled Limited Slip Differential Y1 - 2005 A1 - A. Bicchi A1 - G. Greco A1 - M. Guiggiani A1 - G. Tonietti KW - Embedded Control KW - Robotics ER - TY - JOUR T1 - Maximizing the stability radius of a set of systems under real-time scheduling constraints JF - IEEE Trans. on Automatic Control Y1 - 2005 A1 - L. Palopoli A1 - C. Pinello A1 - A. Bicchi A1 - A. L. Sangiovanni-Vincentelli KW - Embedded Control KW - Robotics AB -We address the problem of synthesising real-time embedded controllers taking into account constraints deriving from the implementation platform. Assuming a time-triggered model of computation for tasks controlling a set of independent systems and a real-time preemptive scheduling policy managing a single CPU processor board, we deal with two problems: 1- deciding whether a performance specification can be met on a given platform, 2- optimising performance on a platform. Decision variables of the design problems are the activation periods of the tasks , while the considered performance metric is the minimum stability radius attained over the different feedback loops, which is related to the technological feasibility of the controller and to the robustness of the controlled systems. The analytical formulation of the design problems enables efficient numerical solutions. The resulting control policies are directly implementable without performance degradation that may otherwise arise due to scheduling and execution delays.

VL - 50 ER - TY - JOUR T1 - Path-Following with a Bounded-Curvature Vehicle: a Hybrid Control Approach JF - International Journal of Control Y1 - 2005 A1 - A. Balluchi A1 - A. Bicchi A1 - P. Souères KW - Embedded Control KW - Robotics AB -In this paper, we consider the problem of stabilizing the kinematic model of a car to a path in the plane under rather general conditions. The path is subject to very mild restrictions, while the car model, although rather simplified, contains the most relevant limitations inherent in wheeled robots kinematics. Namely, the car can only move forward, its steering radius is lower bounded and a limited sensory information only provides a partial knowledge of some state parameters. In particular, we consider the case that the current distance and the heading angle error with respect to the closest point on the reference path can be measured but only the sign of the path curvature is detected. These constraints are such to make classical control techniques inefficient. As the feedback information is both continuous and discrete, the hybrid systems formalism turns out to be well appropriate to model the problem. The proposed approach is based on optimal control techniques successfully applied in a previous work for following rectilinear path. We propose here an extension to the tracking of more general paths with moderate curvature. The stability of the closed-loop system is proved by means of the hybrid system formalism and hybrid formal verification techniques. Finally, the practicality of the proposed approach, in spite of non–idealities in real-world applications, is discussed by reporting experimental results.

VL - 78 ER - TY - CONF T1 - Randomized Algorithms for Platform–based Design T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2005 A1 - A. Agostini A1 - A. Balluchi A1 - A. Bicchi A1 - B. Piccoli A1 - Sangiovanni Vincentelli, A. A1 - K. Zadarnowska KW - Embedded Control KW - Robotics AB -The design of automotive control systems is becoming increasingly complex as the level of performance required by car manufactures grows continuously and the constraints on cost and development time imposed by the market become tighter. A successful design, without costly and time consuming re-design cycles, can be achieved only by using an efficient design methodology that allows for component re-use and evaluation of platform requirements at the early stages of the design flow. In this paper, we illustrate a control-implementation design methodology for the development of embedded controllers by composition of algorithms picked up from libraries. Randomized algorithms and hybrid system theory are used to develop techniques for functional and architecture evaluations, which are implemented in a prototype tool.

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CONF T1 - Control of Distributed Embedded Systems in the Presence of Unknown–but–Bounded Noise T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2004 A1 - B. Picasso A1 - L. Palopoli A1 - A. Bicchi A1 - K. H. Johansson KW - Embedded Control KW - Robotics AB -In this paper we consider the problem of controlling multiple scalar systems through a limited capacity shared channel. Each system is affected by process noise and can be controlled byactuators with values in a {\em fixed}inite set. The control objective is to bound the evolution of the systems in specified sets (controlled invariance). Our goal is to find an optimal allocation of the shared communication resource to the different control activities and to identify correct choices for the design parameters. The paper provides fundamental conceptual tools to attack the design problem in the formal framework of an optimization problem. Namely, we give a feasibility criterion to decide whether a set of design parameters conforms with a control specification (i.e., with the controlled invariance of a specified set for each system). Moreover, we offer the explicit computation of the minimum bit rate necessary for the controlled invariance of a set, which is of utmost importance for solving the optimization problem.

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CONF T1 - Decentralized Cooperative Conflict Resolution Among Multiple Autonomous Mobile Agents T2 - cdc Y1 - 2004 A1 - L. Pallottino A1 - V. G. Scordio A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we consider policies for cooperative, decentralized traffic management among a number of autonomous mobile agents. The conflict resolution problem is addressed considering realistic restrictions on possible maneuvers. We formulate this problem as one in Mixed Integer Linear Programming (MILP). The method, which proves successful in a centralized implementation with a large number of cooperating agents, is also extended to a decentralized setting. Conditions for the existence of conflict avoidance maneuvers for a system of 5 autonomous agents with a transitive information structure are provided, along with the explicit policy to be applied by each agent.

JF - cdc ER - TY - CONF T1 - Discrete and Hybrid Nonholonomy T2 - Hybrid Systems: Computation and Control Y1 - 2004 A1 - A. Bicchi A1 - A. Marigo A1 - B. Piccoli ED - R. Alur ED - G. Pappas KW - Embedded Control KW - Robotics AB -In this paper we consider the generalization of the classical notion of nonholonomy of smooth constraints in analytical mechanics, to a substantially wider set of systems, allowing for discrete and hybrid (mixed continuous and discrete) configurations and transitions. We show that the general notion of nonholonomy can be captured by the definition of two different types of nonholonomicbehaviours, which we call {\em internal}nd {\em external}, respectively. Examples are reported of systems exhibiting either the former only, or the latter only, or both. For some classes of systems, we provide equivalent or sufficient characterizations of such definitions, which allow for practical tests.

JF - Hybrid Systems: Computation and Control T3 - LNCS PB - Springer-Verlag VL - 2993 ER - TY - JOUR T1 - A Hybrid-Control Approach to the Parking Problem of a Wheeled Vehicle Using Limited View-Angle Visual Feedback JF - Int. Jour. of Robotics Research Y1 - 2004 A1 - P. Murrieri A1 - D. Fontanelli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we consider the mobile robot parking problem, i.e. the stabilization of a wheeled vehicle to a given position and orientation, using only visual feedback from low-cost cameras. The practically most relevant problem of keeping the tracked features in sight of the camera while maneuvering to park the vehicle is taken into account. This constraint, often neglected in the literature, combines with the nonholonomic nature of the vehicle kinematics in a challenging controller design problem. We provide an effective solution to such problem by using a combination of previous results on non-smooth control synthesis and recently developed hybrid control techniques. Simulations and experimental results on a laboratory vehicle are reported, showing the practicality of the proposed approach.

VL - 23 ER - TY - CONF T1 - Motion Planning through Symbols and Lattices T2 - Proc. IEEE Int. Conf. on Robotics and Automation Y1 - 2004 A1 - S. Pancanti A1 - L. Pallottino A1 - D. Salvadorini A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we propose a new approach to motion planning, based on the introduction of a lattice structure in the workspace of the robot, leading to efficient computations of plans for rather complex vehicles, and allowing for the implementation of optimization procedures in a rather straightforward way. The basic idea is the purposeful restriction of the set of possible inputfunctions to the vehicle to a finite set of symbols, or {\em control quanta},which, under suitable conditions, generate a regular lattice of reachable points. Once the lattice is generated and a convenient description computed, standard techniques in integer linear programming can be used to find a plan very efficiently. We also provide a correct and complete algorithm to the problem of finding an optimized plan (with respect e.g. to length minimization) consisting in a sequence of graph searches.

JF - Proc. IEEE Int. Conf. on Robotics and Automation ER - TY - CHAP T1 - On The Problem of Simultaneous Localization, Map Building, and Servoing of Autonomous Vehicles T2 - Advances in Control of Articulated and Mobile Robots Y1 - 2004 A1 - A. Bicchi A1 - F. Lorussi A1 - P. Murrieri A1 - V. G. Scordio ED - B. Siciliano ED - A. De Luca ED - C. Melchiorri ED - G. Casalino KW - Embedded Control KW - Robotics AB -In this chapter, we consider three of the main problems that arise in the navigation of autonomous vehicles in partially or totally unknown environments, i.e. building a map of the environment, self-localizing, and servoing the robot so as to achieve given goals based on sensorial information. As compared to most part of the existing literature on SLAM, we privilege here a system-theoretic view to the problem, which allows the localization and mapping problems to be cast in a unified framework with the control problem. The chapter is an overview of existing results in this vein, and of some interesting directions for research in the field. All chapters of this volume were revised and published online March 2005. The volume number was corrected from 4010 to 10.

JF - Advances in Control of Articulated and Mobile Robots T3 - STAR - Springer Tracts in Advanced Robotics PB - Springer Verlag ER - TY - CONF T1 - Quantised Control in Distributed Embedded Systems. T2 - Proc. 16th Int. Symp. on Mathematical Theory of Networks and Systems Y1 - 2004 A1 - A. Bicchi A1 - K. H. Johansson A1 - L. Palopoli A1 - B. Picasso KW - Embedded Control KW - Robotics AB -Traditional control design is based on ideal assumptions concerning the amount, type and accuracy of the information flow that can be circulated across the controller. Unfortunately, real implementation platforms exhibit non-idealities that may substantially invalidate such assumptions. As a result, the systems closed-loop performance can be severely affected and sometimes stability itself is jeopardised. These problems show up with particular strength when multiple feedback loops share a limited pool of computation and communication resources. In this case the designer is confronted with the challenging task of choosing at the same time the control law and the optimal allocation policy for the shared resources (control algortihm/system architecture co-design).

JF - Proc. 16th Int. Symp. on Mathematical Theory of Networks and Systems ER - TY - JOUR T1 - Reachability and Steering of Rolling Polyhedra: A Case Study in Discrete Nonholonomy JF - IEEE Trans. on Automatic Control Y1 - 2004 A1 - A. Bicchi A1 - Y. Chitour A1 - A. Marigo KW - Embedded Control KW - Robotics AB -Rolling a ball on a plane is a standard example of nonholonomy reported in many textbooks, and the problem is also well understood for any smooth deformation of the surfaces. For non-smoothly deformed surfaces, however, much less is known. Although it may seem intuitive that nonholonomy is conserved (think e.g. to polyhedral approximations of smooth surfaces), current definitions of ``nonholonomy'' are inherently referred to systems described by ordinary differential equations, and are thus inapplicable to such systems. \İn this paper we study the set of positions and orientations that a polyhedral part can reach by rolling on a plane through sequences of adjacent faces. We provide a description of such reachable set, discuss conditions under which the set is dense, or discrete, or has a compound structure, and provide a method for steering the system to a desired reachable configuration, robustly with respect to model uncertainties. \\Based on ideas and concepts encountered in this case study, and in some other examples we provide, we turn back to the most general aspects of the problem and investigate the possible generalization of the notion of (kinematic) nonholonomy to non-smooth, discrete, and hybrid dynamical systems. To capture the essence of phenomena commonly regarded as ``nonholonomic'', at least two irreducible concepts are to be defined, of ``internal'' and ``external'' nonholonomy, which may coexist in the same system. These definitions are instantiated by examples.

VL - 49 ER - TY - CONF T1 - Some relations between ergodicity and minimality properties of invariant sets in quantized control systems T2 - Bifurcations in nonsmooth and hybrid dynamical systems: analysis, control and applications Y1 - 2004 A1 - B. Picasso A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -Linear dynamical systems controlled by quantized inputs exhibit phenomena which are typically non-linear, including chaotic behaviours. We consider discrete-time single-input models of the type x(k+1)=Ax(k)+bu(k). The construction of invariant sets for this class of hybrid systems is of utmost importance for the stabilization problem. We first review a technique to construct invariant sets when an arbitrary quantized input set is assigned. We hence study minimality properties for invariant sets when inputs take integer values. There is a relation between a so-called strong minimality property and ergodicity of the closed-loop dynamics, in particular, ergodicity implies strong minimality. A condition ensuring strong minimality is given in terms of the coefficients of the characteristic polynomial of the matrix 'A'. Two examples are presented: the first one shows that strong minimality does not imply ergodicity. The second one shows that our condition for strong minimality is only sufficient: this is done by exhibition of an ergodic dynamics for which our condition is not satisfied.

JF - Bifurcations in nonsmooth and hybrid dynamical systems: analysis, control and applications T3 - S.I.C.C. (Società Italiana Caos e Complessità) CY - Milan N1 -poster presentation

ER - TY - CONF T1 - Towards Cooperative Visual-Based Localization, Mapping, and Servoing Y1 - 2004 A1 - A. Danesi A1 - D. Fontanelli A1 - A. Bicchi KW - Embedded Control KW - Robics AB -In this paper we consider the problem of navigating an autonomous robot using primarily vision for localizing the robot, building a map of the environment, and navigating through viapoints to goals. A visual servo scheme is used that can steer the wheeled vehicle among images. Goal images do not necessarily correspond to images physically taken from the desired vehicle posture, as servoing to reconstructed virtual images is possible. A topological image map is constructed to support this, based on images grabbed by on-board cameras, along with a global feature-based metric map, using extended Kalman filter techniques. The method also enables a team of multiple vehicles to merge their information, and to coordinate navigation using each other's images. Realistic assumptions on limited communication bandwidth between agents and available memory storage are taken into account considering informative, memory-safe maps. Simulations and preliminary experimental results on a laboratory setup are reported.

N1 -Proc. IEEE Mediterranean Conf.

ER - TY - CONF T1 - Cooperative Simultaneous Localization and Map Building for Servoing T2 - Proceedings of Multiagent Robotic Systems Trends and Industrial Application - Robocup 2003 Conference Y1 - 2003 A1 - A. Danesi A1 - D. Fontanelli A1 - P. Murrieri A1 - V. G. Scordio A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Proceedings of Multiagent Robotic Systems Trends and Industrial Application - Robocup 2003 Conference CY - Padova ER - TY - CONF T1 - Encoding steering control with symbols T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2003 A1 - A. Bicchi A1 - A. Marigo A1 - B. Piccoli KW - Embedded Control KW - Robotics AB -In this paper, we consider the problem of steering complex dynamical systems among equilibria in their state space in efficient ways. Efficiency is considered as the possibility of compactly representing the (typically very large, or infinite) set of reachable equilibria and quickly computing plans to move among them. To this purpose, we consider the possibility of building lattice structures by purposefully introducing quantization of inputs. We consider different ways in which control actions can be encoded in a finite or numerable set of symbols, review different applications where symbolic encoding of control actions can be employed with success, and provide a unified framework in which to study the many different possible manifestations of the idea.

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CONF T1 - From nominal to robust planning: The plate-ball manipulation system T2 - Proc. IEEE Int. Conf. on Robotics and Automation Y1 - 2003 A1 - G. Oriolo A1 - M. Vendittelli A1 - A. Marigo A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -Robotic manipulation by rolling contacts is an appealing method for achieving dexterity with relatively simple hardware. While there exist techniques for planning motions of rigid bodies in rolling contact under nominal conditions, an inescapable challenge is the design of robust controllers of provable performance in the presence of model perturbations. As a preliminary step in this direction, we present in this paper an iterative robust planner of arbitrary accuracy for the plate-ball manipulation system subject to perturbations on the sphere radius. The basic tool is an exact geometric planner for the nominal system, whose repeated application guarantees the desired robustness property on the basis of the Iterative Steering paradigm. Simulation results under perturbed conditions show the effectiveness of the method.

JF - Proc. IEEE Int. Conf. on Robotics and Automation CY - Taipei, Taiwan ER - TY - JOUR T1 - Necessary and Sufficient Conditions for Robust Perfect Tracking under Variable Structure Control JF - International Journal of Robust and Nonlinear Control Y1 - 2003 A1 - A. Balluchi A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -The tracking control of linear MIMO systems with structured uncertainty is considered. A necessary and sufficient condition for robust asymptotic tracking employing variable structure techniques in the presence of multiplicative uncertainty is derived. The constructive proof of the theorem provides an explicit formula for controller synthesis.

VL - 13 IS - 2 ER - TY - CONF T1 - Quality of service control in soft real-time applications T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2003 A1 - L. Palopoli A1 - T. Cucinotta A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we present results obtained in the context of Quality of Service (QoS) control for soft real-time applications. The discussion addresses the issue of dynamically adjusting the bandwidth for a set of periodic tasks, when a reservation-based (RB) CPU scheduling policy is used. RB techniques are particularly suitable for this kind of applications since they allow an accurate mathematical modelling of the dynamic evolution of the QoS experienced by tasks. Based on this model, a control policy guaranteeing specified QoS levels for different tasks is illustrated, along with necessary and sufficient conditions for its existence. Moreover, the problem of steering a task QoS back into its nominal level is tackled, in response to deviations due to temporary overload conditions. Simulation results are reported, for the purpose of validating the approach.

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CHAP T1 - Receding-Horizon Control of LTI Systems with Quantized Inputs T2 - Analysis and Design of Hybrid Systems 2003 Y1 - 2003 A1 - B. Picasso A1 - S. Pancanti A1 - A. Bemporad A1 - A. Bicchi ED - Gueguen Engell ED - Zaytoon KW - Embedded Control KW - Robotics AB -This paper deals with the stabilization problem for a particular class of hybrid systems, namely discrete-time linear systems subject to a uniform (a priori fixed) quantization of the control set. Results of our previous work on the subject provided a description of minimal (in a specific sense) invariant sets that could be rendered maximally attractive under any quantized feedback strategy. In this paper, we consider the design of stabilizing laws that optimize a given cost index on the state and input evolution on a finite, receding horizon. Application of Model Predictive Control techniques for the solution of similar hybrid control problems through Mixed Logical Dynamical reformulations can provide a stabilizing control law, provided that the feasibility hypotheses are met. In this paper, we discuss precisely what are the shortest horizon length and the minimal invariant terminal set for which it can be guaranteed a stabilizing MPC scheme. The final paper will provide an example and simulations of the application of the control scheme to a practical quantized control problem.

JF - Analysis and Design of Hybrid Systems 2003 PB - Elsevier ER - TY - CONF T1 - Stabilization of a class of discrete-time hybrid automata T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2003 A1 - M. Zoncu A1 - A. Balluchi A1 - A. Sangiovanni Vincentelli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper, the problem of stabilizing linear discrete time hybrid automata is considered. A synthesis methodology is obtained by extending to hybrid systems the stabilization techniques based on stable convex combinations, originally developed for switching systems. An algorithm to explore the candidate stabilizing controller actions is proposed and an application to an automotive engine control problem is described.

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CHAP T1 - Stabilization of LTI Systems with Quantized State-Quantized Input Static Feedback T2 - Hybrid Systems: Computation and Control Y1 - 2003 A1 - B. Picasso A1 - A. Bicchi ED - A. Pnueli ED - O. Maler KW - Embedded Control KW - Robotics AB -This paper is concerned with the stabilization problem for discrete-time linear systems subject to a uniform quantization of the control set and to a regular state quantization, both fixed a priori. As it is well known, for quantized systems only weak (practical) stability properties can be achieved. Therefore, we focus on the existence and construction of quantized controllers (mapping a quantized state into a quantized input set) capable of steering a system to within invariant neighbourhoods of the equilibrium. Such analysis is helpful because it allows to decide a priori whether adesired control objective can be achieved by using a \textit{given} technology (actuators, sensors, communication and computational means).

JF - Hybrid Systems: Computation and Control T3 - Lecture Notes in Computer Science PB - Springer-Verlag CY - Heidelberg, Germany VL - LNCS 2623 ER - TY - JOUR T1 - Conflict Resolution Problems for Air Traffic Management Systems Solved with Mixed Integer Programming JF - IEEE Trans. Intelligent Transportation Systems Y1 - 2002 A1 - L. Pallottino A1 - E. Feron A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -This paper considers the problem of solving conflicts arising among several aircraft that are assumed to move in a shared airspace. Aircraft can not get closer to each other than a given safety distance in order to avoid possible conflicts between different airplanes. For such system of multiple aircraft, we consider the path planning problem among given waypoints avoiding all possible conflicts. In particular we are interested in optimal paths, i.e. we want to minimize the total flight time. We propose two different formulations of the multi-aircraft conflict avoidance problem as a mixed-integer linear program: in the first case only velocity changes are admissible maneuvers, in the second one only heading angle changes are allowed. Due to the linear formulation of the two problems, solutions may be obtained quickly with standard optimization software, allowing our approach to be implemented in real time.

VL - 3 ER - TY - CONF T1 - Construction of invariant and attractive sets for quantized-input linear systems T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2002 A1 - B. Picasso A1 - F. Gouaisbaut A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper, the problem of the stabilization of a discrete-time linear system subject to a fixed and uniformly quantized control set is considered. It is well known that, working with quantized inputs, the states of the system (except for a negligible set of initial conditions) cannot reach asymptotically the equilibrium point. Our aim is then to find an invariant and attractive neighborhood of the equilibrium and provide with a controller which steers the system into it. We construct a continuous and increasing family of invariant sets including one which is, in a specific sense, minimal. The invariance and attractivity properties of such sets are revised in the finite control set case: we propose a family of controllers taking on a finite number of values and ensuring the system convergence to the minimal invariant set. Some consequences of our technique are underlined with particular regard to the usage of Model Predictive Control tools. In the last section an example which shows the effectiveness of our results is presented.

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CONF T1 - Controllo Ibrido di Veicoli su Ruote con Retroazione Visiva T2 - Proc. 1st. Natl. Conf. and Exhibit on Autonomous Intelligent Systems and Advanced Robotics Y1 - 2002 A1 - P. Murrieri A1 - D. Fontanelli A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Proc. 1st. Natl. Conf. and Exhibit on Autonomous Intelligent Systems and Advanced Robotics CY - ENEA, Frascati ER - TY - CONF T1 - A Group-Theoretic Characterization of Quantized Control Systems T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2002 A1 - A. Marigo A1 - B. Piccoli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we consider the reachability problem for quantized control systems, i.e. systems that take inputs from a finite set of symbols. Previous work addressed this problem for linear systems and for some specific classes of nonlinear driftless systems. In this paper we attack the study of more general nonlinear systems. To do so we find it useful to pose the problem in more abstract terms, and make use of the wealth of tools available in group theory, which enables us to proceed in our agenda of better understanding effects of quantization of inputs on dynamic systems.

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CONF T1 - A local-local planning algorithm for rolling objects T2 - Proc. IEEE Int. Conf. on Robotics and Automation Y1 - 2002 A1 - A. Marigo A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper, we consider planning motions of objects of regular shape rolling on a plane among obstacles. Theoretical foundations and applications of this type of operations in robotic manipulation and locomotion have been discussed elsewhere. In this paper, we propose a novel algorithm that improves upon existing techniques in that: i) it is finitely computable and predictable (an upper bound on the computations necessary to reach a given goal within a tolerance can be given), and ii) it possesses a topological (local-local) property which enables obstacles and workspace limitations to be dealt with in an effective way.

JF - Proc. IEEE Int. Conf. on Robotics and Automation ER - TY - CONF T1 - Numerically efficient control of systems with communication constraints T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2002 A1 - L. Palopoli A1 - A. Bicchi A1 - A. L. Sangiovanni-Vincentelli KW - Embedded Control KW - Robotics AB -The problem of stabilization to the trivial equilibrium of a system with communication constraints is addressed. The communication constraints are related to the fact that commands are issued to different groups of actuators through a shared resource. We tackle the problem by using a Model Predictive Control scheme, which,at every step, decides the allocation of the bus {\em and} he control command values. After discussing two different alternatives for dealing with the scheduling constraints, we develop a formulation based on the generalized linear complementarity problem, which enables the application of efficient numerical solutions. Finally, we give some preliminary result on the parametric dependence of the problem's solution from the system's state.

JF - Proc. IEEE Int. Conf. on Decision and Control ER - TY - CHAP T1 - Optimal control of quantized input systems T2 - Hybrid Systems: Computation and Control Y1 - 2002 A1 - S. Pancanti A1 - L. Leonardi A1 - L. Pallottino A1 - A. Bicchi ED - C. Tomlin ED - M. Greenstreet KW - Embedded Control KW - Robotics AB -In this paper we consider the problem of optimal control (specifically, minimum-time steering) for systems with quantized inputs. In particular, we propose a new approach to the solution of the optimal control problem for an important class of nonlinear systems, i.e. chained-form systems. By exploiting results on the structure of the reachability set of these systems under quantized control, the optimal solution is determined solving an integer linear programming problem. Our algorithm represents an improvement with respect to classical approaches in terms of exactness, as it does not resort to any a priori state-space discretization. Although the computational complexity of the problem in our formulation is still formally exponential, it lends itself to application of Branch and Bound techniques, which substantially cuts down computations in many cases, as it has been experimentally observed.

JF - Hybrid Systems: Computation and Control T3 - Lecture Notes in Computer Science PB - Springer-Verlag CY - Heidelberg, Germany VL - LNCS 2289 ER - TY - CONF T1 - On Optimal Steering of Quantized Input Systems T2 - Proceedings of the NSF/ONR Workshop on Future Directions in Nonlinear Control of Mechanical Systems Y1 - 2002 A1 - S. Pancanti A1 - L. Pallottino A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we consider the problem of optimal control (specifically, minimum-time steering) for systems with quantized inputs. In particular, we propose a new approach to the solution of the optimal control problem for an important class of nonlinear systems, i.e. chained-form systems. By exploiting results on the structure of the reachability set of these systems under quantized control, the optimal solution is determined solving an integer linear programming problem. Our algorithm represents an improvement with respect to classical approaches in terms of exactness, as it does not resort to any a priori state-space discretization. Although the computational complexity of the problem in our formulation is still formally exponential, it lends itself to application of Branch and Bound techniques, which substantially cuts down computations in many cases, as it has been experimentally observed.

JF - Proceedings of the NSF/ONR Workshop on Future Directions in Nonlinear Control of Mechanical Systems CY - Urbana, IL. ER - TY - JOUR T1 - On the reachability of quantized control systems JF - IEEE Trans. on Automatic Control Y1 - 2002 A1 - A. Bicchi A1 - A. Marigo A1 - B. Piccoli KW - Embedded Control KW - Robotics AB -In this paper we study control systems whose input sets are quantized, i.e. finite or regularly distributed on a mesh. We specifically focus on problems relating to the structure of the reachable set of such systems, which may turn out to be either dense or discrete. We report results on the reachable set of linear quantized systems, and on a particular but interesting class of nonlinear systems, i.e. nonholonomic chained-form systems. For such systems, we provide a complete characterization of the reachable set, and, in the case the set is discrete, a computable method to completely and succinctly describe its structure. Implications and open problems in the analysis and synthesis of quantized control systems are addressed.

VL - 4 ER - TY - CONF T1 - Risoluzione ottima dei conflitti tra agenti autonomi: applicazione al controllo del traffico aereo T2 - Proc. 1st. Natl. Conf. and Exhibit on Autonomous Intelligent Systems and Advanced Robotics Y1 - 2002 A1 - L. Pallottino A1 - A. Bicchi KW - Embedded Control KW - Robotics JF - Proc. 1st. Natl. Conf. and Exhibit on Autonomous Intelligent Systems and Advanced Robotics CY - ENEA, Frascati ER - TY - CONF T1 - Safety of a decentralized scheme for Free-Flight ATMS using Mixed Integer Linear Programming T2 - American Control Conference Y1 - 2002 A1 - L. Pallottino A1 - A. Bicchi A1 - S. Pancanti KW - Embedded Control KW - Robotics AB -In this paper we consider policies for free-flight management of air traffic. We consider instantaneous and bounded heading angle deviation as conflict avoidance maneuvers. The corresponding model, resulting in a Mixed Integer Linear Programming (MILP) problem allow to solve both conflict detection and conflict resolution problems. The developed algorithm proved successful in a centralized implementation with a large number of cooperating aircraft. However, the application of such algorithm to a Free Flight environment, where cooperation can only be expected from neighboring aircraft, poses many challenges. We consider a model of the decentralized conflict resolution strategy that is based on a hybrid system, and sufficient conditions under which a 3-aircraft Free Flight MILP-based scheme guarantees safety of flight are provided.

JF - American Control Conference ER - TY - CHAP T1 - Synthesis of robust control systems under resource constraints T2 - Hybrid Systems: Computation and Control Y1 - 2002 A1 - L. Palopoli A1 - C. Pinello A1 - A. L. Sangiovanni-Vincentelli A1 - L. El-Ghaoui A1 - A. Bicchi ED - M. Greenstreet ED - C. Tomlin KW - Embedded Control KW - Robotics JF - Hybrid Systems: Computation and Control T3 - Lecture Notes in Computer Science PB - Springer-Verlag CY - Heidelberg, Germany VL - LNCS 2289 ER - TY - CHAP T1 - Visual-servoed parking with limited view angle T2 - Experimental Robotics VIII Y1 - 2002 A1 - P. Murrieri A1 - D. Fontanelli A1 - A. Bicchi ED - B. Siciliano ED - P. Dario KW - Embedded Control KW - Robotics AB -In this paper the problem of stabilizing a wheeled vehicle of unicycle type to a set point, using only visual feedback, is considered. The practically most relevant problem of keeping the tracked features in sight of the camera while maneuvering to park the vehicle is taken into account. This constraint, often neglected in the literature, combines with the nonholonomic nature of the vehicle kinematics in a challenging controller design problem. We provide an effective solution to such problem by using a combination of previous results on non-smooth control synthesis, and recently developed hybrid control techniques. Simulations and experimental results on a laboratory vehicle are reported, showing the practicality of the proposed approach.

JF - Experimental Robotics VIII T3 - Springer Tracts in Advanced Robotics (STAR) PB - Springer Verlag VL - 5 ER - TY - CONF T1 - Shortest paths for teams of vehicles T2 - Proc. WAC Int. Symp. on Robotics and Applications Y1 - 2000 A1 - L. Pallottino A1 - G. Parlangeli A1 - A. Bicchi KW - Embedded Control KW - Robotics AB -In this paper we consider the problem of planning motions of a team of vehicles that move in a planar environment. Each vehicle is modelled as a kinematic system with velocity constraints and curvature bounds. Vehicles can not get closer to each other than a predefined safety distance. When manipulating a common object cooperatively, further constraints apply. For such systems, we consider the problem of planning optimal paths in the absence of obstacles.

JF - Proc. WAC Int. Symp. on Robotics and Applications ER - TY - CHAP T1 - An experimental study of performance and fault tolerance of a hybrid free-flight control scheme T2 - Robustness in Identification and Control Y1 - 1999 A1 - A. Bicchi ED - A. Garulli ED - A. Tesi ED - A. Vicino KW - Embedded Control KW - Robotics JF - Robustness in Identification and Control T3 - LNCIS 245 PB - Springer Verlag CY - Berlin Heidelberg, Germany ER - TY - CONF T1 - Active Suspensions Decoupling by Algebraic Output Feedback T2 - Proc. IEEE Mediterranean Conf. On Control And Systems Y1 - 1998 A1 - D Prattichizzo A1 - P. Mercorelli A1 - A. Bicchi A1 - A. Vicino KW - Embedded Control KW - Robotics JF - Proc. IEEE Mediterranean Conf. On Control And Systems ER - TY - CHAP T1 - Rolling Polyhedra on a Plane: Analysis of the Reachable Set T2 - Algorithms for Robotic Motion and Manipulation Y1 - 1997 A1 - Y. Chitour A1 - A. Marigo A1 - D Prattichizzo A1 - A. Bicchi ED - J.P. Laumond ED - M. Overmars KW - Embedded Control KW - Robotics JF - Algorithms for Robotic Motion and Manipulation PB - A. K. Peters CY - Wellesley, MA, U.S.A. ER - TY - CONF T1 - Path Tracking Control for Dubin's Cars T2 - Proc. IEEE Int. Conf. on Robotics and Automation Y1 - 1996 A1 - A. Balluchi A1 - A. Bicchi A1 - A. Balestrino A1 - G. Casalino KW - Autonomous Vehicles KW - Embedded Control KW - Nonlinear Control Systems JF - Proc. IEEE Int. Conf. on Robotics and Automation ER - TY - CONF T1 - Quasi-Block Diagonal Dominance Condition for Robust Decentralized Tracking Control T2 - Proc. European Control Conference Y1 - 1995 A1 - A. Balluchi A1 - A. Bicchi A1 - A. Balestrino KW - Embedded Control KW - Nonlinear Control Systems JF - Proc. European Control Conference CY - Rome ER - TY - CONF T1 - Statically Stable Legged Locomotion with Leg Redundancy T2 - Proc. IASTED Int. Conf. on Robotics and Manufacturing Y1 - 1993 A1 - D Prattichizzo A1 - A. Bicchi A1 - G. Casalino KW - Embedded Control KW - Robotics JF - Proc. IASTED Int. Conf. on Robotics and Manufacturing PB - IASTED CY - Oxford, UK, september 23-25 1993 ER - TY - CONF T1 - Trajectory Planning of Industrial Robots in a Structured Environment T2 - Int. Conf. on CAD/CAM, Robotics and Factories of the Future Y1 - 1992 A1 - A. Balestrino A1 - A. Bicchi A1 - A. Landi KW - Embedded Control KW - Robotics JF - Int. Conf. on CAD/CAM, Robotics and Factories of the Future CY - Metz, France ER - TY - CONF T1 - Leg-Ankle-Foot System for Investigating Sensor Based Legged Locomotion T2 - Proc. IEEE/RSJ Int. Conf. on Intelligent Robots and Systems Y1 - 1989 A1 - A. Bicchi A1 - L. Bosio A1 - P. Dario A1 - M. Guiggiani A1 - E. Manfredi A1 - P. C. Pinotti KW - Embedded Control KW - Robotics JF - Proc. IEEE/RSJ Int. Conf. on Intelligent Robots and Systems CY - Tsukuba, Japan UR - http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=637970 ER -