Abstract
This paper describes the development of PD, PID Computed-Torque (CT), and a PD digital motion controller for the autonomous navigation of a Wheeled Mobile Robot (WMR) in outdoor environments. The controllers select the suitable control torques, so that the WMR follows the desired path produced from a navigation algorithm described in a previous paper. PD CT, PID CT, and PD digital controllers were developed using a linear system design procedure to select the feedback control signal that stabilizes the tracking error equation. The torques needed for the motors were computed by using the inverse of the dynamic equation for the WMR. Simulation software was developed to simulate the performance and efficiency of the controllers. Simulation results verified the effectiveness of the controllers under different motion trajectories, comparing the performance of the three controllers shows that the PD digital controller was the best where the tracking error did not exceed .05 using 20 msec sample period. The significance of this work lies in the development of CT and digital controllers for WMR navigation, instead of robot manipulators. These CT controllers will facilitate the use of WMRs in many applications including defense, industrial, personal, and medical robots.
