TRAJECTORY TRACKING CONTROLLER FOR WHEELED MOBILE ROBOT

Abstract

This thesis presents derivation of a trajectory tracking and posture stabilizing controller for a differentially-driven Wheeled Mobile Robot (WMR). The robot vehicle is a sturdy platform actuated by Direct Current (DC) motors capable of steering the WMR in different trajectories. For trajectory tracking, an essential capability for autonomous operation, a reliable and robust controller is needed. In addition, as the WMR-vehicle is unstable while moving, the controller is required to stabilize it during trajectory tracking process. The robot vehicle is modeled with three Degrees Of Freedom (3DOF) rigid body equations and an efficient control algorithm, called Lypaunov function direct method, is used to tackle the challenges posed by nonlinearities of the model. The main contribution of this work is analysis of 3DOF physical model and a consolidated stable control law for tracking and posture stabilizing of the mobile robot. Simulation results show the effectiveness of the controller. In addition, the proposed trajectory tracking controller has been benchmarked with the well-known Kanayama's controller. Further, several motion tasks are performed in order to examine the new controller motion capabilities, and the ability of carrying out motion with different trajectories shapes.