Path-following control of Mecanum-wheels omnidirectional mobile robots using nonsingular terminal sliding mode

Due to the superior mobility and maneuverability to move toward any position and attain any orientation simultaneously, Mecanum-wheels omnidirectional mobile robot (MWOMR) is playing a significant role in autonomous transportation and service. This paper proposes a robust nonsingular terminal sliding mode (NTSM) control scheme for the path-following problem of an MWOMR. First, a plant model is identified as a second-order state-space equation with four inputs and three outputs to describe the MWOMR's path-tracking kinematics and dynamics. Afterwards, a multi-input-multi-output NTSM controller is designed for the MWOMR, and the stability of the NTSM control system is verified by means of Lyapunov function. In addition, the setting guideline of control parameters is elaborated in detail, and a Runge-Kutta formula-based dead-reckoning algorithm is employed to calculate the position and yaw angle information of the robot in real time. Lastly, experiments are carried out to test the control performance in the scenarios of lateral movement and circular movement with initial offset. Experimental results demonstrate that the presented NTSM control strategy owns evident superiority in terms of higher tracking accuracy and stronger robustness against different movements in comparison with a conventional sliding mode (CSM) controller. (C) 2020 Elsevier Ltd. All rights reserved.