Sliding mode control based hybrid closed-loop design for stable walking of biped robot with heterogeneous legs

Biped robot with heterogeneous legs (BRHL) is a new kind of robotic mode consist of artificial leg (AL) used to simulate healthy lower limb and bionic leg corresponding to lower limb prosthesis worn by amputee. The bionic leg recognizes and tracks the gait of AL in real-time to realize stable walking of the whole robotic system. To achieve smooth, effective and human-like gait for AL, s-curve interpolation was employed to fit the discrete data points generated by linear inverted pendulum model. A hybrid closed-loop system was constructed to improve the gait tracking accuracy and sliding mode control was designed for outer loop of the joints´ servo system. Simulations and experiments were conducted under level walking condition. The results indicate the correctness and effectiveness of the proposed scheme.