Biped walking robot control with passive walker model by new VSC servo

Passive walking on a slope is known as the most efficient and natural walking style because there is no extra power without potential energy, and the motion occurs inherently according to its mechanical property. In this paper a walking control strategy which utilizes the dynamics of passive walking as a trajectory generator is introduced. A virtual model can generate a walking pattern by being given the feasible initial state corresponding to the direction of the virtual gravity field. To enhance the robustness of the implementation a new variable structure control (VSC) servo is proposed, and applied to walking control. This VSC law is obtained as an integral form of the sign function of a sliding mode. Hence there is less chattering which may damage the mechanical components. A discrete trajectory generator and discrete estimator which are needed for the digital implementation are mentioned too. The efficiency of the strategy is demonstrated by simulation