The Research On Control Strategy Of Vehicle Active-suspension

Automotive suspension performances directly determine the ride comfort and the stability. However, the construction of traditional passive suspension determines that it can' t better these two performances at the same time. Some researchers started to study on the active suspension from 1950s. And it has become a new and important method to improve the suspension performance. From the day when the active suspension is produced on, many countries have done a great deal of researches either in theories or by tests. Our country also began to study the active suspension since 1980s. However compared with the abroad, we still dropped behind other countries about the key technology. Considering that the key technology of the active suspension is the design of control strategy, this dissertation focuses on this lack and researches on the control strategy.Depending on the suspension dynamic characteristic, this dissertation applies the modern control theories in the active suspension and brings forward a new control strategy- the PID control based on grey theory. This kind of strategy combines the advantages of both PID and grey control system consequently to better the active suspension system control performance.In this dissertation, a dynamic model of active suspension is created, which is based on the vehicle dynamics theory. The mathematical and simulating model of road surface irregularity is also established, which is the model of integral white noise. According to the different control theories, the dissertation individually designs active suspension PID controller and PID controller based on grey theory and the computer simulations are individually built with Matlab6. 5/Simulink to verify the robust of the control system. Then to run it can get the control simulation for different disturbance inputs.By analyzing the simulation results, we find that the active suspension PID control based on grey theory control strategy is more reasonable and feasible than any other control strategies. When being compared with PID control, this new control strategy can considerably depress severe vibration of the system in the vicinity of resonant frequencies, reduce the variety of the acceleration and better the control performance. The statistical results indicate that this control method has fairly good robustness and is more fit to the automotive suspension that is a non-linear and time-variable system.Given the time-variability parameters and the nonlinearities in automotive suspension, the new strategy combining the grey control theory and PID control theory is employed for the first time to control the active suspension system. It has been shown by simulation analysis that the active suspension PID control based on grey theory is applicable and remarkably effective. It also offers a new idea to the field of research on suspension control strategies.