The Research Of Automotive ABS Control Method On Fuzzy Control Strategy

With the development of automobile industry,more and more demands to vehicle safety capability are taken into account. from the earliest requirement for automobile power and cross-country gradually to economy,comfortableness and safety. The brake system performance is one of the vehicle's main function. It directly has a bearing on the traffic safety, the serious accidents always relate to the too long brake distance, wheel brake with emergency brake and then led to sideslip, swing or lose direction stability. Anti-Braking lock System can automatically adjust brake line pressure when the brake happens, and lead no wheel braking lock.But the automobile having ABS, when urgent braking can raise the controlling stability maximumly in the course of automobile braking, and shorten the braking distance efficiently, so ensured the safety of travelling vehicle on certain level. Nowdays,ABS are widely equipted in all kinds of vehicles。As an effective approach to improve security of vehicles,ABS(Anti-lock Brake System)has been studied world-widely for a long time.It has most important significance to develop ABS products with intellectual property of China. Now the study and improvement in the field is still in progress in world, and most of researches are focused on the control strategy。Automobile ABS is a non-linear, variable time and indeterminacy system. The characteristics of the tyres and mode of the automobile are indeterminacyo .So the control method of ABS is one of the vital factors for deciding braking performance.It is impossible to establish a precise mathematical model to non-linear braking process. Fuzzy control eyes on how to control but not control object. Fuzzy control method is easier to realize the control for uncertain and non-linear control objects. It has a strong robust and anti-interfering characteristic, and just adapts to the ABS that is a variable work-condition and non-linear system. So an ideal control effect can be achieved. Based on the above problems, In this dissertation, fuzzy control theory application on automotive anti-lock system theory. is studied, based on combination of automotive theory and fuzzy contro After getting at shortcoming of previous general fuzzy control method improvement and development are done, and simulation test are carried out.For having analyzed the movement and force of the automobile which equipped when braking on road, have established the vehicle model when braking. The paper Build up the theoretical model of ABS. The paper anatomized the control principle of ABS, and based on it introduced the structures, species, every part functions of ABS.In the foundation of forefathers ,it establishes vehicle dynamical model of single wheel,mathematical models of tire and detent models . The establishment of the tire model is based on the magic formula and the model of Burckhardt. In the foundation of forefathers, it studies further fuzzy control theory .Fuzzifier, defuzzifier and fuzzy rules are established,and establishes fuzzy controller of ABS on the identific-ation algorithm of road surface with MATLAB fuzzy toolbox . After getting at shortcoming of original fuzzy control method improvement and development are done, it joins the PID control algorithm. Combined the Fuzzy thinking in Fuzzy control with the conventional PID control. Determined the error and the change rate of the error as a fuzzy inference input, then set the three parameters of the PID on-line.At last, establishes the parameter self-regulating PID controller based on wheel slip ratio.In vehicle dynamical model of single wheel foundation, it estab-lishes ABS fuzzy control system SIMULINK model and the parameter self-regulating PID control system SIMULINK model with the tool case of MATLAB/SIMULINK, which is emulated and analysed.Finally, in estab-lished ABS fuzzy control system SIMULINK model and the parameter self-regulating PID control system SIMULINK model foundation it is emulated and analysed. In the light of this analysis, it concludes that the two types controller both can be applied in the vehicle ABS.Contrast these two kinds of control strategy simulation results:First, compare from the braking distance,during the vehicle began to brake to the complete cessation, the simulation results of the two control show that these two control are both meet the minimum vehicle brake performance requirements. The result indicate that the application of these two methods in the ABS control are better-performing. The braking distance of the self-tuning parameters PID fuzzy control in ABS is shorter than that of the fuzzy control. By the curve of the slip rate,we can see it clearly that ,when using the Fuzzy control in ABS,the curve fluctuations is higher in the situation of the road with low attachment rate than that with high attachment rate.This shows that the Anti-spin ability of this control is poor. But the slip rate fluctuations have greatly changed when using the self-tuning parameters PID fuzzy control. It maintained the slip rate near the expections and increased the anti-skidding ability of vehicle. Therefor it improve the direction of the automobile braking manoeuvrable.Second, analysis from the time of braking,the result shows that the braking time is about three seconds in both of these two methods in high-adhesion road; the braking time is about five seconds in mid-adhesion road;it is about twelve seconds in the low-adhesion road.They are all consistent with the braking distance and they are all able to achieve good braking effect. The simulation results have concluded that the two fuzzy control method both can be used on the ABS of vehicle and both can be the ideal braking effect.This paper designed hardware circuit of fuzzy control system of ABS,including main chip choice,power circuit,signal acquisition and processing circuitry,electromag- netic valve drive control circuit,and pump motor drive control circuitry etc.Finally summary analysised implementation of software fuctions of ABS.It can improve interference rejection and the control precision of automobile ABS with fuzzy control. It establishes foundation through the research of this paper for the automobile ABS product of fuzzy control and has certain theoretical value and scientific meaning.