The Application Of Grey Control Theory In Automotive Semi-active Suspension Control

Suspension is one of the most important parts of automobile. Whether the kind of its construction and the parameters of performances are reasonable or not has a direct influence on the ride stability and the comfort of automobile. The key technology of modern intelligent suspension is control strategy. Therefore this dissertation has deep studied the control strategy of the semi-active suspension that is one of the intelligent suspensions.It's difficult for traditional passive suspension to enhance the ride comfort. However, the semi-active suspension can meet the vehicle running need well because its suspension parameters such as damp coefficient or spring firmness can be adjustable. While compared with the active suspension, the semi-active suspension is more inexpensive and has simpler structure. Moreover, it hardly consumes engine power when it works. Above all the control effect is almost as same as the active suspension. Therefore, the semi-active suspension has been attached much importance by the automobile engineering industry.The control arithmetic, sensor technology and the development of executive mechanism are the three parts of intelligent suspension system. The core of suspension control system is the control strategy and the research of arithmetic. The semi-active suspension control methods mainly are Sky-hook Damper Control, Line Optimal Control, Preview Control, Adaptive Control, Fuzzy and Neutral Networks Control. These control methods whether they are classic or modern control theories all have both advantages and disadvantages. This dissertation introduces and compares these control methods. Some researchers have proposed to apply a new strategy--- grey theory into the automotive suspension control, because the suspension load and the road disturbance are both uncertain, in other words, or typical grey system.In this dissertation, an automotive vibration model of 1/4 body with 2 degree-of-freedom is created, which is based on the automotive dynamics theory. At the same time considering the great influence of the road disturbance on the suspension, the mathematical model of road surface irregularity with the kind of white noise is established. And the simulating input of road surface utilizes the C-class road. In this dissertation, a new control theory is brought forward. That is genetic algorithm based on semi-active suspension neural network of grey theory. And the semi-active suspension fuzzy controller is designed. Then it is by means ofMatlab6.5+Simulink to set up the simulating model of semi-active suspension to carry out these control strategies.Through the computer simulation verifies that this new control strategy— genetic algorithm based on semi-active suspension neural network of grey theory is feasible, and comparing it with the passive suspension and the semi-active suspension fuzzy control. The result concluded from the comparison proves this semi-active suspension control method referred to in this dissertation can greatly improve the integrated performances of automotive suspension.