Limit Cycle Control Using Energy Function Regulation With Friction Compensation

Gianluca Garofalo, Christian Ott
2016 IEEE Robotics and Automation Letters  
In this paper we consider the problem of generating periodic solutions for fully actuated robots with unknown disturbances, which can be modeled using a regressor matrix. We extend our previous work on limit cycle control based on energy function regulation for the case when disturbance torques are acting on the system, e.g. torques due to friction. Since the controller is designed in two independent steps, the compensation of the friction cannot be carried on with standard techniques and it
more » ... l be split in two steps as well. In the first one we reduce the dimension of the dynamical system and use a sliding mode approach for friction compensation, in the second we produce the desired limit cycle and use an adaptive approach for friction compensation. Crucial for the analysis is the concept of conditional attractiveness with semidefinite Lyapunov functions, that we formulate in this paper to show the attractiveness of the closed orbit of the whole system, even if it is designed assuming a reduced dynamics. Finally, we validate our approach with experiments on a humanoid robot.
doi:10.1109/lra.2015.2507784 dblp:journals/ral/GarofaloO16 fatcat:qyjodfom7zc65blfj2d7flzx7y