A method of deciding force feedback gain against external force for biped robot

A biped robot has great difficulty in keeping stable walk because it has no fixed points to the ground. Enhancement of stability is one of the most important topics of a biped robot. If a robot can walk stably even under unexpected external force, we can say that its stability is remarkably improved. Robot motion should be changed by the amount of external force. If the external force is small, the trajectory does not need to be modified actively. It is desired that designers input the same command of robot motion and passive robot motion against external force is achieved. Compliance control is commonly applied to realize passive motion. The characteristics of compliance control is generally determined set to the definite value without considering the walking stability. In this paper, we propose a novel stabilizing method that modifies the body motion by the variable force feedback gain of compliance control based on the position control. This feedback gain is determined by ZMP trajectory and external force only when external force was recognized, so a robot can move keeping its stability under unexpected external force