Integrated Path-Tracking and Combined-Slip Force Controls of Autonomous Ground Vehicles With Safe Constraints Adaptation
Ehsan Hashemi, Amir Khajepour
Abstract
A novel integrated stabilization and path tracking control framework, which includes the combined-slip effect, wheel dynamics, and tire force capacities, is developed for autonomous ground vehicles. The loss of cornering forces caused by increased longitudinal slip are considered in the prediction model of the developed receding horizon controls. Robustness to uncertainties in the road surface friction is addressed by an adaptive constraint scheme on the side handling-limit boundaries in order to provide a reliable stable performance. The integrated framework with constraint adaptation resolves possible conflicts of the multi-actuated system for lateral stabilization, while trajectory tracking on various surface conditions. The performance of the proposed approach, in terms of accuracy and computational efficiency, is evaluated by using hardware-in-the-loop real-time experiments and a high-fidelity CarSim model in various pure- and combined-slip maneuvers, under different road friction conditions. The real-time experiments confirm effectiveness and reliable performance of the proposed approach over existing algorithms, in dealing with reduced tire capacities in harsh obstacle avoidance and cornering scenarios, while path following, as a consequence of constraint adaptation and simultaneous vehicle-wheel stabilization.