| The rapid development of world economy and the improvement of human life promote the rapid development of automobile industry at home and abroad, and people have put forward higher and higher demands for the vehicle ride comfort and handle stability, not only just meet travel convenient means of transportation in everyday life. In the complicated vehicle vibration system, suspension system is the key part in the performance of the vehicle. The development of active suspension has opened up a new way to improve vehicle suspension performance, making it become a hotspot in research of suspension vibration control. In this paper, a deep research on control strategy of active suspension is made, which is including development of suspension test-bed.The dynamic characteristics of the automobile suspension system is analyzed with the theory of vehicle dynamics, and a1/4vehicle model of passive suspension and active suspension system with test-bed are established. This thesis established the overall program of active suspension hydraulic servo system, a mathematical model to derive the valve control cylinder, servo valves and servo amplifier, and got the transfer function of electro-hydraulic servo control system.After deriving a simple and available time domain random road excitation signal simulation model for vehicle ride comfort and control research provide reliable excitation signal, PID controller is adopted in the research of vibration response of the vibration hydraulic system to track the ideal pavement, in preparation for the control simulation.This thesis proposed the PID method and optimal control of cascade controller structure, and analyzed the stability of the cascade control system. Simulation model of vehicle model is established in Simulink simulation with vehicles in no-load, partly filled and packed working conditions under B and C level road. The results show that the active suspension under the inner and outer loop control method of vehicle riding comfort and the improvement of ride comfort are good effect, the steering stability in low frequency area also has a better improvement, and lay a good foundation for further experimental study. |
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