Design and control of stiffness coordination between knee and ankle joints for a hopping legged robot

Abstract

In order to improve the energy efficiency for the legged robot, we developed a one-legged robot which is inspired by biology to explore the locomotion principle of the legged robot. In this paper, one method is proposed for the stiffness coordination between the knee and ankle joints. We first defined the coordination and the evaluating indicator, and used the PSO algorithm to search the best optimal solution of the ankle spring. Then the control strategies were described for the hopping control, and realized the the continuous hopping by injecting extra energy to the knee joint. Finally, The experiments were implemented on the robot Tigger, whose ankle is just equipped with passive springs while the hip and knee are under actuation, and the effectiveness of our methods were validated through the experiments.