Higher-Order Super-Twisting Control for Trajectory Tracking Control of Skid-Steered Mobile Robot

In this paper, Higher-Order Super-Twisting control (HOST) is designed and implemented for trajectory tracking control of four wheels Skid-Steered Mobile Robot (SSMR). The conventional Super-Twisting (ST) Second-Order Sliding Mode Control (SOSMC) is robust, yet it has two main drawbacks for such a system, 1) the chattering phenomena persists on the system inputs and outputs which leads to vibration in the robot motors and 2) the SSMR system has a relative degree equal to two. Therefore, the ST control design requires a sliding variable containing error derivatives, which only permit asymptotic convergence. For that, a higher-order controller is required for this control structure, which is designed for second order sliding variable, in order to obtain a robust controller with finite-time convergence. The HOST control can reduce chattering in steady-state compared with conventional ST-SOSMC and converge the state variables in finite time. The performance of this controller has been validated experimentally on Pioneer P3AT SSMR robot. The experimental results show good performance under parametric uncertainty variations and external disturbance with neglected chattering.