Autonomous Balance of Wheel-Legged Robot Based on Backstepping Sliding Mode Control

To ensure the stable operation of the wheel-legged robot in the narrow underground space, this paper presents a backstepping sliding mode control method. First, the dynamic relationship between robot attitude and joint torque is established. Second, the coupling term, unmodeled part and external disturbance in the robot's attitude control system are expanded to new state variables, and an extended state observer is designed based on them. Third, based on the backstepping sliding mode method, an attitude controller is designed, which does not depend on the exact model of the system and the full state feedback of the system. The stability of the extended state observer and the closed-loop system is proved at last. The simulation results show that the fluctuation and error of the backstepping sliding mode controller are significantly reduced compared with the PID controller under the external disturbance, which verifies the high robustness and effectiveness of the controller.