Research On Anti-lock Brake System Based On X-by-wire

With the increasing development of society and the continues improvement ofscience and technology, people put forward higher requirements for the safetyperformance of the car, Automotive active safety technology will be the future ofautomotive R&D focus. The braking performance of the car has important influenceon vehicle safe driving, the Anti-lock braking system (ABS) has an importantsignificance for improving the security of the automobile brake and reducing the riskof accidents. At present, most of the traditional ABS adopts the logic threshold controlmethod, however, the optimal ABS control system combining with vehicle dynamicsshould put controlling the wheel slip ratio as the target. Because of adopting modulestructure and shorter brake response time, Brake-by-wire (BBW) system providesconditions for optimizing the function of ABS. This dissertation studied the keytechnologies and realization method for the ABS of the BBW system based on slipratio, after reviewing the domestic and foreign relevant research literatures. The maincontents are as follows:1. The main structure and working principle of the brake-by-wire system ofvehicle were analyzed here, and the mathematical model of the main function modulewas also established.2. As soon as possible to eliminate brake clearance when the vehicle braking, thecurrent closed loop controller was designed and the process of eliminating the brakeclearance was studied through simulation, moreover, the control parameters of theclosed loop controller were tuned. Simulation results show that the designedcontroller can meet the requirements of control tasks.3. The optimal slip ratio on-line identification system was designed based on thetire model of Kiencke function and recursive least squares method with forgettingfactor, and recognition results show that the system has good reco gnition accuracy,provided a basis for the realization of the optimal control of ABS function based onthe slip ratio for the brake-by-wire system of vehicle.4. The sliding mode controller for the brake-by-wire system based on slip ratiowas designed and the fixed boundary layer method was adopted to suppress thechattering phenomenon of the sliding mode control. At the same time, in order tofurther weaken the chattering phenomenon and improve the performace of the controller, the fuzzy sliding mode controller based on the slip ratio of the brake-bywire system was designed. Compared with the sliding mode controller, simulationverifies that the fuzzy sliding mode controller has better control performance, andcompared the braking performance of the brake-by-wire system based on the fixedslip ratio and the optimal slip ratio.