LPV Control of Full-Vehicle Vertical Dynamics using Semi-Active Dampers

Semi-active suspensions enable a mitigation of the design conflict between ride comfort and road-holding by allowing the continuous control of the damper force. During the design of control laws for semi-active dampers, the inherent actuator limits constitute a major performance restriction. Accordingly, these constraints should be explicitly considered during controller design. In this work, the actuator constraints are addressed by LPV control methods which offer a rigorous framework to incorporate them as so-called saturation indicator parameters in the LPV plant. Additionally, saturation indicator dependent weighting filters are employed in a mixed sensitivity scheme in order to honor stability over performance in the event of saturation. Furthermore, the LPV controller is synthesized using a full-vehicle model, which enables the individual tuning of the heave, pitch and roll motion. The full-vehicle model, however, leads to a significant increase in complexity of the controller synthesis problem compared to a quarter-vehicle model. Therefore, a disturbance-feed forward output-feedback controller design is adopted to exploit the separation principle. The performance of the proposed full-vehicle LPV controller is compared to two quarter-vehicle LPV controllers, a Skyhook/Groundhook controller and passive suspension configurations in an extensive simulation investigation. The results illustrate the improved pareto optimum of the LPV full-vehicle controller and the suitability of the proposed design scheme.