The Optimal Control Research Of Vehicle Air Suspension System

Air springs can change their stiffness characteristics flexibility by inflating and deflating the rubber balloon. An ideal stiffness curve satisfying the requirements can be designed. The dynamic load of wheels of vehicles with air suspension is small, and a comfort of riding, stability of handling, and safety of riding is provided. The damage of road from the high speed operation can also be reduced. The body's vibration acceleration can be reduced effectively, and the dynamic deformation and the dynamic load of tires are reduced, and the comfort of riding and the stability of handling are improved significantly by using the optimal control strategy. The suspension can play an important role by using the optimal control method. Therefore, the optimal control research of air suspension has significance to vehicles and drivers. In this paper, the following four aspects are investigated.A mechanical analysis on the air suspension vehicles with auxiliary air chamber is performed, and a nonlinear dynamic equation for air spring with auxiliary air chamber based on fluid mechanics is set up. Furthermore, state-space model of suspension systems with a two-degree-of-freedom is established.Based on the state-space model of suspension systems with a two-degree-of-freedom, the change of damping coefficient under the long time of operation of suspension is considered. The original damping coefficient is adjusted by adding auxiliary damping control, and a new state space model of vehicle suspension with two-degree-of-freedom is presented.In order to decrease the acceleration of vertical body and the dynamic deformation of tires, and improve the comfort, the air suspension systems with auxiliary air chamber are controlled by employing the optimal control. The adjustable and additional control damping is obtained by solving the optimal control, and the optimal control of air suspension is realized.An input model of road and select the appropriate vehicle parameters is presented, and a simulation analysis on the presented air suspension systems with auxiliary chamber is given by exploiting the MATLAB / Simulink technology. The simulation results show that we can reduce the body's vibration acceleration effectively, and reduce the dynamic deformation and the dynamic load of tires, and improve the comfort of riding and the stability of handling significantly by using the optimal control strategy.In this paper, the air suspension systems with auxiliary air chamber are investigaged, and a theoretical basis for the optimal design and control of the vehicle air suspension systems is provided.