Modeling And Simulation Of A Novel Interconnected Suspension System And Optimization Of Its Structure Parameters

Suspension is one of the key systems of vehicle and has important effect on vehicleride comfort, handling stability, et.al. Therefore, well-designed suspension systems areessential for vehicles. However, modern vehicle suspensions are required to achieve anumber of often conflicting objectives, such as the trade-off between ride comfort andhandling stability. The structures of traditional suspensions keep unchanged after loading,but the vehicle’s driving conditions are ever-changing, so it is difficult to achieve the desiredresults to use single suspension structure to deal with changing driving conditions.Recently, active suspension and semi-active suspension, which generally include variable oradjustable stiffness or damping parameters are studied to overcome the inevitablecompromise between ride and handling encountered in conventional suspensions. Butthere are some drawbacks associated with these suspensions, such as increased cost,uncertain reliability, power consumption requirements and inherent complexity, for thereason, the application of these suspensions are limited. A novel suspensionsystem---hydraulically interconnected suspension (HIS) system, shows the potential ofovercoming the ride-handling compromise. The thesis is launched combined with theintelligent interconnected suspension developing program and is carried out in three aspectsas follows:Characteristic analysis of Damper Unit and modeling of HIS system. As the essentialcomponent of HIS system, the flow-pressure characteristics of Damper Unit are analyzedfirstly, then the dynamic model of Damper Unit is built and output force characteristics arestudied. According to the principle of Damper Unit, the mathematical models of two HISwith different interconnected configurations are then deducted, and the HIS models areintegrated into the vehicle model. The effects of different interconnection configurationson vehicle vertical and pitch vibration are analyzed based on random road input, the CarSimmodel is built which is suitable for handling, braking and acceleration simulation, the effects of different interconnection configurations on vehicle body gesture are studied ondouble-lane-change, braking and accelerating. The results show the interconnectionconfigurations have little influence on the vehicle vertical vibration but great influence onthe vehicle pitch vibration, body gesture.Manufacturing, assembling, and vehicle testing of HIS prototypes. The Damper Unitprototypes are manufactured, including hydraulic cylinder, damper valve and accumulator,and are adjusted according to the Damper Unit target characteristic of the Damper Unitmodel. Then the HIS with different interconnected configurations is assembled andinstalled on the SUV studied and the interconnected mode can be switched automaticallyand manually. At last, ride comfort test, handling stability test and accelerating/brake testare conducted respectively when the SUV is set different interconnected configurations.By comparing with the test results of the original vehicle, we learn that differentinterconnected mode shows desired performance as expected.Damper Unit structure parameters optimization. Damper Unit structure parametersoptimization is conducted. Optimization parameters are chosen as the damper unitstructure parameters, optimization objectives are set as achieving the best vehicle ridecomfort and body gesture. Then optimization is conducted by co-simulation amongMatlab, CarSim and Isight, with the method of NSGA-II. The results shows that vehicleride comfort and body gesture can improve obviously as long as Damper Unit parametersare chosen properly, and the optimization method can be used as a reference for furtherstudying.