| INTRODUCTION The air spring coil has nonlinear characteristic, its characteristic curve can be designed ideal shape. The air spring suspension system adjusts to load conditions automatically, providing a low rate suspension with light or no loads, and a high rate suspension with heavier loads, and the proper frequency of the suspension is constant. The different height of air sac is chosen to acquire ideal proper frequency, and to improve the ride comfort. Because of the light quantity of air suspension and the low stiffness of spring, while high speech driving , the adhesion ability of tire and ground is strongened, and the brake distance is shortened; The tendency of excessive turn lack turn minish on turns, the steering stability is strong, it increased the vehicle's handling stability. The height control lever will provide automatic filling or exhausting of the air spring s to maintain the truck's level. When the car drive, while road is suffering the static load, it still suffer the wallop which come from the tires, which is the dynamic load. The faster the speech is , the bigger the dynamic load is. Under the complex effect of the perpendicular force -. the longitudinal force and the side force of car wheel, it form the trim form of road, and make the road surface become the packs and waves, then form track . The bigger the car's tonnage is, the more serious the damages to the road surface is. However, while the vehicles that are equipped with air spring suspension systems remarkably decreases the damages to the road with high speed driving. Some developed countries, such as USA> Japan and Germany etc., have built rules and relative polices to encourage automobile companies to produce the vehicles with air spring suspension and consumers to use them, and have achieved remarkable benefits in economy and society. Now air spring suspension is a popularization in luxury passenger cars% city buses ^ heavy trucks and trailers, and is becoming the standard equipment on the luxury cars. In China, with the developing of the economy and the high way, road transportation will play a more important role, Some automobile companies have introduced the air spring suspension into China, and many universities and institutes have helped to research the function of air springs the matching with vehicle and the design of control arithmetic. The paper is just born of this background. It is based on the project of JiLin Science and technology's development in 2001 "The research of Automobile electronic control system for air spring suspension". It includes the key part of the research. The main work is to build control arithmetic and control system for air spring suspension. At the same time a test rig for air spring suspension has been designed. It can provide test method to verify the control arithmetic. THE TEXT CONTENT Chapter 1: On the basis of reading a great deal of the relevant research literature on air spring and air suspension and extensively investigating national related enterprise, we systematically analyze domestic and international air suspension history and present condition, and fully study the development courses and all kinds of control strategy of semi-active suspensions. Chapter 2: Introducing the variety of the air spring and the configuration and the outstanding advantage air spring and air suspension. Through the test and theories analysis, the stiffness of air spring enlarge with the filling time increasing but minish with the exhausting time increasing . And, The paper firstly analyze for nonlinear stiffness characteristic of the air spring and provide four type of hypothesis to nonlinear stiffness of the air spring, that is: rubber material nonlinear composite of rubber and lining cloth nonlinear ^ contact nonlinear and geometry nonlinear. Chapter 3: Through analysis fuzzy control method can be suitable for air spring suspension system. The main works of fuzzy control are designing of fuzzy controller. It includes: Confirming the structure of fuzzy controller; Determining the fuzzy linguistic descriptions of inputs and outputs; Putting control knowledgeinto rule-bases; Defuzzification. The dynamic model is built up in Matlab Simulink. Chapter 4: In order to increase performance of fuzzy controller further, Self-organizable fuzzy controller has been designed. Actual designing includes: To adjust the inputs and outputs gains according to the error and variability of error; To add a integrator after the output of fuzzy controller; Take the integral function-J\1L/±Cj) as target, and optimize the rule-bases to improve the adaptability to the changing structural parameters. The paper separately chooses the sinusoid and stochastic signal as the input of model. Finally, by comparing the acceleration RMSs and the tire's dynamic loads of the three kind of suspension, the paper scales the controller's validity. Chapter 5: We applied the fuzzy control arithmetic to the test system by the method of PLC, and compared the control results between controlled suspension and passive suspension. Obviously, for the suspension with fuzzy controller, the control targets—acceleration RMS and the tire's dynamic loads had been decreased. We drew the conclusion that the fuzzy arithmetic took on an effective control performance when applied to the test rig. Chapter 6: Summary and conclusion, and tabling some proposals on research for the future TEXTUAL RESEARCH MEANING The textual research meaning introduce: 1. In China this text takes the lead in opening out and researching the air suspension, and it gives designers experience and establish foundation for studies in the future. 2. This text constructs a new control system, the conventional air suspension with the mechanopneumatic valve is replaced with an electronically-controlled air suspension system, the core components of which are: modular solenoid valve block, height sensor, electronic control unit(ECU) and remote control unit. The system mostly improves the vehicle's handling stability and comfortable with high speed driving and decreases the damage to the high way surface. It is important that this system improves the technique of vehicles, and contracts the top class passenger cars and trucks of our country with those of oversea.
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