Robust Path Tracking Control of an Unmanned Eight-Wheeled Off-Road Vehicle in the Presence of Wheels' Slipping

The paper handles the problem of automatic path tracking by an autonomous off-road eightwheeled robotic vehicle subject to uncertain longitudinal and lateral wheel slips. A sliding mode guidance law is proposed that solves this problem, explicitly takes into account the constraints on the control inputs, and ensures tracking of any path whose contortion lies within given bounds. Necessary conditions for the mission feasibility are first established. Under slight and partly inevitable enhancement of them, nonlocal convergence and robust stability of the proposed guidance law are theoretically justified. In doing so, the slipping effects are treated as bounded uncertainties. Simulation results confirm the applicability and performance of the control law.