Hybrid control for biped robots using impedance control and computed-torque control

Proposes a hybrid control method of using the impedance control and the computed-torque control for biped robot locomotion. The computed-torque control is used for the supporting (constrained) leg. For the free leg, impedance control is used, where different values of impedance parameters are used depending on the gait phase of the biped robot. To reduce the magnitude of an impact and guarantee a stable footing when a foot contacts with the ground, the paper proposes to increase the damping of the leg drastically and to modify the reference trajectory of the leg. Computer simulations with a 3 DOF environment model for which a combination of a nonlinear and a linear compliant contact models is used, show that the proposed controller is superior to the computed-torque controllers in reducing impacts and stabilizing the footing