Research On Structure And Control Of Electrorheological Shock Absorber

The suspension system determines the comfort and safety of a car, and it is an important index to measure the quality level of an automobile. With the rise of national highway level, the speed of the car is also in constant improvement,so, the car requires a higher quality of the suspension system, in turn, Semi-active suspension system arises. ER(electrorheological) fluid is a kind of intelligent material, and it’s properties can be changed by controlling the strength of the electric field to the ER fluid, the ER fluid produces additional shear yield stress, it shows that the ER fluid can be a kind of damping medium, and it makes the damper the intelligent ER shock absorber, this paper combines the semi-active suspension and the ER shock absorber, and makes the ER shock absorber the key component of the semi-active suspension, and it also has a research on the control strategies of the semi-active suspension, the main contents are as follows:Firstly, this paper studies the characteristics of the ER fluid, and introduces the ER technology and the ER effect, then this paper describes the composition and performance requirements of the ER fluid, and analyses the mechanical properties of the ER fluid, it discusses three working modes of the ER fluid. This paper formulates a kind of well performance ER fluid, and measures the relationship between the shear yield stress and the strength of the electric field, all these provide the basis for the follow-up study.Secondly, this paper designs the structure of the ER shock absorber, and proposes the design ideas and requirements of the ER shock absorber. On the basis of the property of the ER fluid, it designs the ER valve, according to the requirements of the common hydraulic shock absorber, it designs the inflatable structure and determines the position of the compensation chamber, and it discusses the relation between the piston and the piston rod, and it carries out the overall structure of the ER shock absorber, this paper also explains the working principle of the ER shock absorber.Thirdly, this paper builds the mathematical modeling of damping force of the ER shock absorber in compression stroke and stretch stroke, it suggests the damping force has two parts, the fixed damping and controlled damping force, and it builds the simulation model by simulink, and it determines the gap width and the compensating gas chamber pressure of the ER shock absorber, and it establishes the passive suspension model and the semi-active suspension model based on the ER damper, this prepares for the follow-up study of control.Finally, this paper establishes the random road model, and the skyhook controller, PID controller and fuzzy-PID controller based on the ER shock absorber, the three control strategies are compared with three aspects of the vertical acceleration of the vehicle body, the dynamic deflection of the suspension and the dynamic deformation of the tire. The Skyhook control strategy will strengthen the handling stability of vehicle, but the ride comfort has not increased, the PID control makes the car ride comfort and handling stability a little improvement, compared with PID control strategy, the fuzzy-PID control strategy has better advantage.The ER shock absorber overcomes the single damping coefficient of the traditional passive damper and the shortcoming of contradiction between the ride comfort and the handling stability, it provides a new idea for the research of semi- active suspension system and has great significance in improving the performance of the automobile suspension.