Robust impedance control with applications to a series-elastic actuated system

Impedance control offers a theoretical basis for safe interaction between a robot and the environment, but model uncertainty, disturbances and actuation dynamics can compromise the accuracy of the rendered impedance in implementation. If both the interactive force and motion are directly sensed, the relationship between them can be robustly regulated to present the desired impedance dynamics. In this paper, a Disturbance Observer based controller architecture is presented which offers performance robustness for impedance control. Conditions for stability and passivity are developed, then this controller is analyzed on a series-elastic actuated system. The effect of actuation dynamics on both performance and stability is analyzed, then experimental results are presented.