HUMAN-LIKE CONTROL FOR SEMI-PASSIVE BIPEDAL ROBOT WALKING WITH VARIABLE LEG STIFFNESS1)

For the walking control of the semi-passive bipedal robot with variable stiffness, the human-like walking control strategy is adopted. By using the self-stabilizing characteristics of the bipedal spring loaded inverted pendulum model with variable stiffness, the rear leg stiffness is adjusted in the double support phase to keep the robot energy near the desired energy, and the position of the swinging leg touching down on the ground is adjusted in the single support phase to control the altitude and the forward velocity of the desired point. The simulation results show that the human-like control strategy can ensure a stable walking of the bipedal robot in the horizontal plane. The robot can achieve the passive periodic walking with zero-input when there is no disturbance. With the variable stiffness control of the leg, the total energy of the robot can be restored to a balance state, the robot can re-enter the steady-state walking, and the control system is robust to the external disturbance.