Biped robot walking using gravity-compensated inverted pendulum mode and computed torque control

This paper proposes a model called the gravity-compensated inverted pendulum mode (GCIPM) to generate a biped locomotion pattern that is similar to the one generated by the linear inverted pendulum mode, but accommodates the free leg dynamics based upon its predetermined trajectory. When the biped locomotion based upon the linear inverted pendulum mode is applied to real biped robots, the stability of the robot is disturbed due to the fact that the neglected dynamics of free legs is not actually negligible, moving the ZMP (zero moment point) away from the presumed fixed point. The GCIPM includes the effect of the dynamics of the free leg in a simple manner This paper also presents a control method for biped robots based upon the computed torque. Simulation results show that the biped robot is more stable with the walking pattern generated by the proposed method combined with the controller than with the one by the inverted pendulum mode.