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

This paper deals with an optimal landing motion of a 4-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 one for impact force and the one for joint torques. While the configuration where the leg is bent is advantageous in reducing the impact force, the configuration that is close to a singular configuration is advantageous in minimizing the joint torques. It is shown by numerical optimization results with different weights for the cost function.