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 - Convergence of Distributed WSN Algorithms: The Wake-Up Scattering Problem T2 - Proc. of Hybrid Systems: Computation and Control Y1 - 2009 A1 - D. Fontanelli A1 - L. Palopoli A1 - R. Passerone ED - R. Majumdar ED - P. Tabuada KW - Robotics JF - Proc. of Hybrid Systems: Computation and Control PB - Springer-Verlag Berlin Heidelberg CY - San Francisco 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 - On the global convergence of a class of distributed algorithms for maximizing the coverage of a WSN T2 - Proc. IEEE Int. Conf. on Decision and Control Y1 - 2009 A1 - D. Fontanelli A1 - L. Palopoli A1 - R. Passerone KW - Robotics JF - Proc. IEEE Int. Conf. on Decision and Control CY - Shanghai (China) ER - TY - CONF T1 - Lifetime and Coverage Maximization in Wireless Sensor Networks T2 - Proc. IFAC Workshop on Estimation and Control of Networked Systems Y1 - 2009 A1 - D. Fontanelli A1 - L. Palopoli A1 - R. Passerone A1 - D. Macii A1 - D. Petri KW - Robotics JF - Proc. IFAC Workshop on Estimation and Control of Networked Systems CY - Venice, Italy ER - TY - CONF T1 - A Probabilistic Methodology for Predicting Injuries to Human Operators in Automated Production lines T2 - Proc. IEEE Int. Conf. on Emerging Technologies and Factory Automation (ETFA) Y1 - 2009 A1 - R. Asaula A1 - D. Fontanelli A1 - L. Palopoli KW - Robotics JF - Proc. IEEE Int. Conf. on Emerging Technologies and Factory Automation (ETFA) CY - Mallorca, Spain 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 - 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 - 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 - 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 - 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 - 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 -