Adaptive tracking control of a unicycle subject to uncertainties and perturbations

Abstract

An adaptive trajectory tracking control scheme is proposed for the command of a unicycle robot which is subject to dynamic uncertainties (inertia, mass, viscous parameter, etc), unmodeled dynamics, unknown disturbances, slipping effects, and loss of effectiveness (LOE). The latter are adaptively estimated and compensated in control laws. Moreover, projection algorithms are added to bound estimators, preventing them from drifting. The control objective is developed in two steps. First, a kinematic control law is designed to compute the necessary velocities (linear and angular velocities) that allow the robot to reach the desired trajectory. Afterward, sliding mode based adaptive control torques are developed in order to track velocities computed in the first step. The proposed control strategy guarantees the stability of the closed-loop system by ensuring the asymptotic convergence to both desired trajectory and necessary velocities. Finally, simulation results illustrate the applicability and effectiveness of the proposed control scheme.