Transmission torque linearization of quadruped robot with a two-joint simultaneous drive mechanism for gravity compensation

This paper proposes a transmission torque linearization method for a leg robot using bi-articular simultaneous drive mechanism. A planetary gear is the primary mechanism of a bi-articular simultaneous drive system. Energy consumed for walking is reduced by the use of bi-articular muscles. However, the planetary gear causes a torque transmission loss in the leg robot system. The proposed method linearizes the nonlinear torque transmission by using a disturbance observer and the estimated self-weight disturbance torque. The experimental results point out that the proposed method linearizes the transmission torque.