Passivity Based Cartesian Impedance Control for Flexible Joint Manipulators

Abstract The paper presents a Cartesian impedance controller for flexible joint robots based on the feedback of the complete state of the system, namely the motor position, the joint torque and their derivatives. The controller uses the torque feedback to shape the kinetic energy and the feedback of the motor position to shape the potential energy. By using a collocated feedback for shaping the potential energy, the passivity of the system can be ensured, while exactly satisfying all steady state requirements formulated in terms of the link side positions (such as desired stiffness and desired equilibrium position). The closed loop system can be seen as a feedback interconnection of passive systems and is proven to be asymptotically stable. Experimental results validate the proposed controller.

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