Landing Motion of a Legged Robot with Minimization of Impact Force and Joint Torque

Abstract

This paper deals with an optimal landing motion of a four-link legged robot that minimizes the impact force at the contact point and the joint torques necessary during the motion. The cost function for optimization is given as the weighted sum of the impact force and the joint torques. The configuration of the robot that is close to a singular configuration is advantageous in minimizing the joint torques for a heavy torso, while the configuration where the leg is bent is advantageous in reducing the impact force. This is shown by numerical optimization results with different weights for the cost function and a theoretical analysis of a simplified model of the robot.