Controllers for unicycle-type wheeled robots: Theoretical results and experimental validation

Mobile robots offer a typical example of systems with nonholonomic constraints. Several controllers have been proposed in the literature for stabilizing these systems. However, few experimental studies have been reported comparing the characteristics and the performance of these controllers with respect to neglected dynamics, quantization, noise, delays, etc. In this paper, we use a Khepera mobile robot to perform experimental comparison of several control laws. Khepera has two dc motor-powered wheels and introduces many realistic difficulties, such as different motor dynamics for the two wheels, time delay, quantization, sensor noise, and saturation. We emphasize the implementation difficulties of two discontinuous controllers proposed herein, and we compare their performance with several other controllers reported in the literature. Ways to improve the performance of each controller are also discussed