Research On Control Algorithm And Key Problem Of Tranction Control System On Complicated Working Condition

Traction Control System(TCS)belonging to Electronic Stability Control(ESC)is an important technology of vehicle active safety.It can improve the driving performance effectively.There will be a better acceleration performance and driving stability for vehicle on various complex road conditions with it.However,the core technology of TCS is still held by a few foreign enterprises,which creates a technological barrier.In the complicated and various practical working condition,how to identify the road condition exactly,deal with the adjustments reasonably and improve the adaptability of working condition and the comfort of controlling is a difficulty for the development and application of practical TCS with our own intellectual property rights,which has an important significance.In practical complicated working condition,due to the transient of road condition,the noise of sensing signal,the variation of driving habits and computing power,it is difficult to estimate the key variable which reflects the road conditions precisely and timely with low consumption.A kind of estimation method of road adhesion coefficient based on the believable degree of utilization adhesion is presented in this paper.This method can reduce the computational burden and the accuracy of the estimated road adhesion coefficient can meet the requirements of practical TCS.A kind of estimation method of longitudinal road slope based on longitudinal dynamics and acceleraction sensing signal is proposed in this paper.The estimated longitudinal road slope can reflect the road slope condition timely and accurately,which improves the timeliness and veracity of TCS effectively.A kind of recognition method of split friction road and uniform friction road is presented to distinguish the two kinds of road condition,which makes the relevant TCS algorithm apply exactly.The adjustment of active brake pressure and the adjustment of engine torque are two main regulating measures of TCS.In practical complicated working condition,the exact,efficient and concerted coordination of them is a key point to make a better control effect for TCS in objective and subjective evaluation.A coordinated method of brake pressure and engine torque is showed in this paper to improve the rapidity and comfort of practical TCS.According to their own specialty of the two regulating measures,different control objectives have been set for them to decouple control and exert each advantages.The engine torque controller mainly contains a PID controller with variable parameters,a reference value for PID controller when TCS is about to enter,a compensation value to help PID controller conquer the large change of road adhesion coefficient in order to guarantee the timeliness and veracity of engine torque adjustment.A hierarchical controller is used in the active brake pressure controller.Two different brake pressure targets respectively for the split friction road and the uniform friction road are calculated in the upper brake pressure controller.The calculated brake pressure targets are realized in the under brake pressure controller.A restriction for brake pressure targets is designed to ensure the comfort of brake pressure adjustment.The vehicle test datas show that the purposed coordinated method of brake pressure and engine torque have a better objective and subjective performance in typical working conditions.In practical vehicle test,there are some difficult special working condition for the basic TCS.In this paper,for two difficult special working conditions which are the uneven and low-friction road and the split friction and slope road,two compensation methods containing brake pressure and engine torque and utilizing the fuzzy logical algorithm are presented.The vehicle test datas show that the purposed compensation methods can assist the basic TCS to reach the control targets in the two difficult special working conditions and improve the adaptablility of the basic TCS.