Hassan Sayyaadi - School of Mechanical Engineering, Sharif University of Technology, Azadi Ave.,
Arash Gobal

Vehicle suspension plays a major role in providing passenger comfort. Usually, suspension design includes a trade-off between ride comfort, road holding and handling characteristics ofthe vehicle. This paper presents an optimization of a seven-degree-of-freedom full car model seat and suspension system to determine an optimum set of parameters for the stiffness anddamping of the system in order to achieve the best ride comfort for the vehicle. In order toprovide the highest level of comfort for the driver alongside the stability of the vehicle, not only the displacement of the suspension system, but also the body acceleration of the drivershould be minimized. Therefore, a multi objective function representing both the suspensiondisplacement and the RMS value of the body acceleration is used in the optimization process. The optimization process is carried out using gradient descent method in MATLAB/Simulink. The results of optimizing the passive seat and suspension system are compared with the results of using semi active Skyhook suspension in the model. It is shown that by optimizing the values of stiffness and damping of a passive suspension system, one couldeasily reach the ride comfort of semi active suspensions. Finally, the DC gain of the optimized suspension system is compared to the international ride comfort standards and its validity in application is investigated.

Vehicle Suspension Optimization; Ride Comfort; Vibration Control