Optimization of spring stiffness in automotive and rail active suspension systems

Spring stiffness is the key parameter of an active suspension consisting of an actuator and a mechanical spring. The effects of the spring stiffness on suspension performances are investigated comprehensively. A novel multi-objective optimization technique of the spring stiffness in automotive active suspension systems is developed in this study. The novel optimization objective is proposed as the compromise among the root-mean-square (RMS) vertical unsprung-mass-to-road-surface displacement, the RMS vertical acceleration of the sprung mass, the RMS vertical sprung-mass-to-unsprung-mass displacement, the RMS active force, and the vertical sprung-mass-to-unsprung-mass displacement at steady-state. Consequently, the drive safety, the ride comfort, the actuator's weight and volume, and the fail-safe performance are taken into account in the proposed optimization method. The simulated results have demonstrated that the presented method is viable and effective. Therefore, this paper offers a new and valuable method for the parameter optimization of automotive active suspension systems as well as rail vehicle.