Multi-Objective Optimal Robust Seat Suspension Control of Off-Road Vehicles in the Presence of Disturbance and Parametric Uncertainty Using Metaheuristics

Abstract

Control of whole-body vibration (WBV) via a seat suspension in off-road vehicles is a challenging task due to the presence of severe external disturbances and parametric uncertainties. In this paper, a novel optimal robust (mixed ${\boldsymbol{H}_\infty }/{\boldsymbol{H}_2})$ controller is proposed to achieve enhanced vibration attenuation performance of seat suspensions considering the parametric uncertainties due to variations in driver mass and external disturbances encountered at the cabin floor including occasional shocks. A direct Lyapunov based LMI approach is employed to prove stability of the closed-loop system. In search of an optimal solution for the designed robust controller, a ${\boldsymbol{H}_\infty }$ disturbance attenuation performance together with the weighted ${\boldsymbol{H}_2}$ norm for minimizing the mean disturbance rejection, are considered using the Chaos-enhanced Accelerated Particle Swarm Optimization (CAPSO). The optimization problem for the proposed controller is formulated to minimize the frequency-weighted vibration dose value (VDV) due to acceleration response at the seat, while constraining the relative displacement between the seat and the seat base. The effectiveness of the proposed controller is illustrated through comparisons with performance achieved through some of the reported other seat suspension robust controllers in addition to a passive suspension. Results show that the proposed optimal robust controller could provide substantial reductions in the frequency-weighted acceleration at the seat and the VDV, measures of the force applied to the driver due to terrain induced vibration and shock, while limiting the relative displacement between the seat and the seat base.