Passivity Analysis and Control of Humanoid Robots on Movable Ground

Reliable and robust balancing controllers are key elements of whole-body control frameworks for humanoid robots. Passivity-based balancing controllers have been proposed and tested successfully in various scenarios involving different types of ground surfaces. This letter extends the passivity considerations for covering not only the robot and the controller but also the ground floor in order to guarantee an appropriate behavior, even when the underlying ground surface is not stable. The proposed extension is validated with experiments using the humanoid robot TOrque-controlled humanoid RObot (TORO).