R.  Schiavi, Flacco, F., and Bicchi, A., ?Integration of Active and Passive Compliance Control for Safe Human-Robot Coexistence?, in Int. Conference of Robotics and Automation, Kobe, Japan, 2009, pp. 259 - 264. 

A.  De Luca, Flacco, F., Schiavi, R., and Bicchi, A., ?Nonlinear Decoupled Motion-Stiffness Control and Collision Detection/Reaction for the VSA-II Variable Stiffness Device?, in Proc. IEEE/RSJ International Conference on Intelligent RObots and Systems, St. Louis MO USA, 2009, pp. 5487-5494.