Motion Control System that Realizes Physical Interaction between Robot's Hands and Environment during Walk

This paper addresses a whole-body motion control system that realizes desired absolute hand position trajectory which can be given online during continuous walk. External force that is exerted to the hand can also be managed by the system. The system is based on a short cycle dynamically stable walking pattern generation system, which generates and updates a motion pattern at every 20 [ms]. Short cycle generation realizes quick response to the change of commanded hand position. It also enables the system to reflect force sensor information to the dynamics model which is used for dynamically stable pattern generation with small latency. The robot can maintain dynamic balance even when measurable force is exerted to its hands by using this characteristic. We also implemented impedance control of the hand position in order to realize stable contact when the hands touch surrounding objects. We implemented the system on a full size humanoid, HRP-2. Basic experiments and an experiment of pushing a table show the performance of the system.