Online immediate foot placement modification for humanoid robots by synthesis method

The mobility of humanoid robots are restrained by many natural constraints. Due to the unstable property of humanoid robots, they are usually controlled by a preplanning stable COG (center of gravity) trajectory subject to a properly designed ZMP (zero moment point) using inverted pendulum model. Despite the advantage of stability, the method becomes tricky to modify the preplanning footsteps randomly. Therefore, we propose the immediate modification of foot placement by synthesis, which ensures a low computational cost, smooth synthesized and stable trajectory. With our proposed method, the robot can modify the next footstep location or immediately stop immediately, even just before the end of previous step; otherwise, it might need two steps ahead to prepare for this change. The mobility of humanoid robot is therefore enhanced by our proposed method in both sagittal and lateral directions.