Hybrid Backstepping and Fast Terminal Sliding Mode Control for Balancing of Two-Wheeled Mobile Robots

Abstract

This paper proposes a two-layer fast terminal sliding mode controller (FTSMC) combined with a conventional sliding mode control (SMC) to achieve both trajectory tracking and balance control for a two-wheeled balancing mobile robot (TWBMB). First, the modeling procedure of the TWBMR is examined using the Lagrangian approach, and the trajectory tracking error is formulated in the global coordinate system. Next, for trajectory tracking, the linear and angular velocities are controlled using a backstepping controller. Two SMCs are employed to regulate the wheel torque, ensuring balance and convergence of velocity to the backstepping reference: the two-layer FTSMC is responsible for velocity and balancing while conventional SMC manages tilt angle. Simulation results verify the fast response and superior velocity tracking, as well as the self-balancing performance of the developed controller.