Full-body motion control integrated with Force Error Detection for wheelchair support

We propose a full-body controller system for a humanoid robot to achieve wheelchair support. There are two main problems in pushing control. One problem is that the controller system should decide pushing strategies based on whether the humanoid robot should adapt to the reaction forces from the pushed wheelchair or resist against them. Another problem is that the arms´s reachabilities decrease while walking because of upper body motion. We resolve these two problems by extending the full-body controller by detecting pushing error and by determining the place where the humanoid robot stands based on off-line computation of the arms´ reachabilities. Our system includes estimation of the friction forces based on on-line reaction force measurements. If the force error becomes large, the system suspends pushing control to switch a pushing strategy. We also show experimental results on the HRP-2 humanoid robot. In the experiment, the humanoid robot navigated a heavy wheelchair in environment including several furniture.