Abstract: Aiming at the problem of white noise,the vehicle passive suspension model with four degrees of freedom is created,and the dynamic equation of the vehicle’s vertical direction is derived.The hybrid objective function is constructed,and the improved particle swarm optimization algorithm is used to optimize the parameters of the passive suspension model of four degrees of freedom quarter vehicle.The vehicle passive suspension system simulation model was established,and the dynamic simulation was carried out by Matlab/Simulink software at different speed,and the simulation results are compared with those before optimization.The simulation results show that the root mean square after optimization of vehicle passive vertical suspension driver head acceleration,sprung vertical stroke and unsprung vertical displacement of the maximum value were reduced by 51 %,45.4 % and 40.7 %,and the peak vibration of vehicle vertical direction was also reduced.Improved particle swarm optimization algorithm is used to optimize the vehicle passive suspension system,which can improve the stability of vehicle driving and improve the ride comfort of the vehicle.

Key words: improved particle swarm optimization algorithm, vehicle passive suspension, optimization, simulation