The primary function of a vehicle suspension system is to isolate the road excitations experienced by the tyres from being transmitted to the passengers. In this paper, a suitable optimizing technique is applied at design stage to obtain the suspension parameters of a passive suspension and active suspension for a passenger car which satisfies the performance as per ISO 2631 standards. A number of objectives such as maximum bouncing acceleration of seat and sprung mass, root mean square (RMS) weighted acceleration of seat and sprung mass as per ISO2631 standards, jerk, suspension travel, road holding and tyre deflection are minimized subjected to a number of constraints. The constraints arise from the practical kinetic and comfortability considerations, such as limits of the maximum vertical acceleration of the passenger seat, tyre displacement and the suspension working space. The genetic algorithm (GA) is used to solve the problem and results were compared to those obtained by simulated annealing (SA) technique and found to yields similar performance measures. Both the passive and active suspension systems are compared in time domain analyses subjected to sinusoidal road input. Results show passenger bounce, passenger acceleration, and tyre displacement are reduced by 74.2%, 88.72% and 28.5% respectively, indicating active suspension system has better potential to improve both comfort and road holding.
ride comfort; road holding; LQR control; genetic algorithm; simulated annealing
