Robust control for dynamic walking of a biped robot with ground contacting condition

A robust controller with the sliding mode is proposed for stable dynamic walking of a biped robot in this paper. The robot system is modeled as 14-DOF rigid bodies considering kinematic construction of a humanoid. The method of multibody dynamics is applied to construct the equations of motion for the complicated biped robot system. In order to obtain the optimized trunk trajectory, the modified FFT method is solved iteratively. The dynamic walking simulation is performed by using optimized trajectories of the trunk and each foot. Also, Hertz force model and hysteresis damping element are employed for the ground reaction and impact forces during contact with the ground. Finally, the sliding mode control is applied to solve the problems of modeling imprecisions or uncertainties. Under the assumption of the bounded estimation errors on the unknown parameters, the proposed controller provides a successful way to achieve the stability and good performance