Trajectory Tracking of a Two-Wheeled Mobile Robot Using Backstepping and Nonlinear PID Controllers

Abstract

Many researchers have become interested in wheeled mobile robot (WMR) trajectory tracking control due to the increased application of mobile robots over the past three decades in the industry, in the military, at home, and in public service. Classically, the movement of WMR is controlled depending on its kinematic model. In practical applications, both the dynamic and kinematic models of robots and external disturbance and uncertaintyaffect system performance. In this research, a backstepping controller combined with a nonlinear proportional, integral, and derivative (NPID) controller is proposed for the trajectory tracking of a two-wheeled mobile robot (TWMR). The kinematic and dynamic models of the WMR are considered. The dynamic modeling was derived using a Lagrangian approach, and the stability of the system was achieved using the Lyapunov stability function. A backstepping controller is used for the position control and the NPID controller for the velocities of the robot. The proposed controller gains are optimized using a genetic algorithm (GA). The overall system with the proposed method is simulated onMatlab/Simulink software. The results show the best trajectory tracking performance in the presence of unknown disturbances and initial position change with a minimum error. In addition to this, the results show that the proposed controller outperforms the GA-based BSC+PID controller in terms of root-mean-square (RMS) of trajectory tracking error (47.36% in a linear and 60.32% in a nonlinear reference trajectory). The proposed controller also has better tracking performance than a GA-based BSC controller (which means trajectory tracking error is improved by 74.35% in the linear reference trajectory and 67.95% in the nonlinear reference trajectory). Finally, trajectory tracking of TWMR using backstepping and an NPID controller was performed effectively in the presence of unknown disturbance and initial position change.