Research On Sliding Mode Variable Structure For The Anti-Lock Braking System

Anti-lock Braking System (ABS) is a kind of new initiative equipment for security in vehicles. In order to shorten the braking length and obtain optimal braking efficiency, the main points of this system is to anticipate wheel lock during hard braking,for this, it can improve the performance of braking stabilization, make it more controllable. The application of ABS has been more and more widely as the vehicle speed is faster and faster. As the core technology, control algorithm is practically important for the improvement braking efficiency.In this dissertation, the domestic and overseas development and tendency of ABS are introduced. Basic principle of sliding variable structure is deeply analyzed. And sliding-mode controller (SMC) is established.With the method of manual graphical modeling, the corresponding vehicle simulation model based on the principle of vehicle dynamic is built .It include quarter vehicle system model, tyer model and brake system model.Then the ABS based on slide mode control algorithm is simulated. In the aspect of before and after eliminating chattering, chattering is eliminated through saturation function take place of typical signum function.The simulation result shows that sliding-mode controller after eliminating chattering is able to track the exact optimal slip ratio changes excellently, make the brake torque changes more stability and meet the requirements of brake performance.The control algorithms of Bang-Bang control and logic threshold control have been simulated.The ABS braking efficiency of these three algorithms is discussed, analyzed and researched. The ultimate conclusion is that slide mode control is simple and practical, and the braking efficiency is good. It has better precision, adaptability and robustnessFinally, the simple ABS test stand have been debugged. The experimental result is expected to provide reference for real vehicle ABS, and hence is of applicative value.