Dynamic Stepping on Unknown Obstacles With Upper-Body Compliance and Angular Momentum Damping From the Reaction Null-Space

摘要

Contact destabilization after an impact that occurs at high-speed, e.g. when a robot steps on an obstacle of unknown height, can be tackled by injecting angular momentum damping for a short time interval immediately after the impact. This is done by making use of the motion from within the reaction null-space (RNS). The angular momentum damping results in an appropriate arm motion that stabilizes the contacts. An impact at high-speed occurs when the stepping time is very short. In this case, conventional controllers cannot handle the reaction stemming from the swing leg dynamics. A general whole-body controller is designed that makes use of the relative angular acceleration control component to inject the angular momentum damping. The proposed control method is robust; it can deal with obstacles of various height and inclination without altering the feedback gains. The controller is fast since iterative optimization is avoided. The performance is examined via a simulated dynamic stepping.