Double hyperbolic sliding mode control of a three-legged robot with actuator constraints

This paper proposes an anti-wind up double hyperbolic sliding mode controller (AWDH-SMC) in the presence of torque constraints for a three-legged robot. The legged robot's dynamics are nonlinear, hybrid and complex. Based on the challenges mentioned, this study focuses on designing a sliding mode controller (SMC) for a fully actuated three-legged robot to achieve fast tracking and convergence. On the other hand, the torques generated by the actuators are limited. As a result, not only must the controller be fast so that the robot's balance is not disturbed, but it must also withstand applied torque constraints. Therefore, the double hyperbolic sliding mode controller is designed at first for fast tracking and convergence. Next, an anti-wind up compensator is used to apply torque constraints. Finally, using the theory of multiple Lyapunov functions, the stability of the closed-loop control system for the hybrid model of legged-robot is analyzed. Simulation results validate the effectiveness of the proposed control scheme.