| There is more and more attention to the vehicle active safety with the fast evolution oftransportation industry in recent years. The safety problem especially for commercial vehicles used totransport goods and passengers，is very great significance, and the performance of braking systemserves as an important index for evaluating the safety capability. Since the braking system acts as animportant part for vehicle safety， its technical innovation possesses a significant impact on theimprovement of safety and comfort for vehicle. Along with unceasing progress of electronic controland integrated algorithm， the active safety system for vehicle has witnessed new development.However, the traditional mechanical system has not fully resolved the safety requirements formodern vehicle, and multiform electronic systems for vehicle safety have already become theresearch focus for the automotive enterprises and the scholar, with a stage of rapid development.Electronic braking system （EBS） for commercial vehicle are mainly developed to improvethe braking performance on the basis of anti-lock braking system in recent years. In additional, itcompensates for the disadvantages of conventional pneumatic braking system greatly, and improvesthe performance of braking system such as braking comfort and safety with braking-by-wire. Theelectronic-controlled braking system based on X-by-wire has become a powerful appliance to evenfurther improve the performance of braking system for commercial vehicle, and it will be the mainresearch and development direction for the following commercial vehicle braking system.But now, because the commercial vehicle adopts the pneumatic braking system with inherentproperty of pneumatic transmission in general, the delay and hysteresis characteristic of pneumaticEBS became the bottle neck for enhancing its performance. Meanwhile, controlling pneumatic delayand hysteresis will be the focus of attention both for the modern pneumatic EBS technology and the future technology of pneumatic braking system, which is of great significance in progress ofpneumatic braking system technology.This paper is supported by National Natural Science Foundation of China “Research onmulti-targets control for heavy-duty semitrailer dynamic stability based on modelprediction”(identifier:51075176). On the basis of the research achievements and application ofelectronic braking system theory for commercial vehicle from domestic to abroad, a hysteresiscompensation control strategy of EBS critical components are developed, which can improve theresponse time and the control accuracy and offer the theoretical support for independent development,aimed at improving the braking stability and safety.The main research works of this paper are summarized as followed：(1) On the basis of the comprehensive analysis on the hysteresis characteristic of pneumaticEBS for commercial vehicle, the hysteresis characteristic of EBS key components is researched. First,the influence of hysteresis characteristics on the braking performance for commercial vehicle isanalyzed. And then a mathematic model of proportional relay valve acted as the key component ofEBS is built by AMESim with simulation of hysteresis characteristic, and the model accuracy isverified by open-loop test. Finally, the impact of parameters of proportional relay valve on theresponse and the hysteresis characteristic is analyzed via this mathematical model, which offers thetheoretical substratum for further improvement of proportional relay valve.(2) Based on an total technical scheme for commercial vehicle EBS，a dynamic model ofpneumatic EBS for commercial vehicle is developed by AMESim, including proportional relay valve,axle modulator, ABS solenoid valve, pipeline and other key components, etc. And then the modelaccuracy is verified by hardware-in-the-loop test bench, which provides the foundation fordeveloping the control strategy and mending the pneumatic EBS for commercial vehicle.(3) The control framework of EBS system is established, and the control strategies of normalbraking and emergency braking for commercial vehicle EBS are developed, with the development ofsome valve control methods such as proportional relay valve, axle modulator, ABS solenoid valveand etc. The developed control methods of normal braking involve deceleration control, brakingforce distribution and differential brake, etc. The emergency braking control strategies relates to ABScontrol strategy and braking assist control algorithm based on hysteresis compensation. Combined with the analysis on the hysteresis characteristic of proportional relay valve, the PID control strategyintegrated feed-forward compensation is presented, which offers a good basis on the off-line and HILtest bench simulation for EBS control strategy.(4) The off-line dynamics simulation platform of EBS for commercial vehicle is built, and theoff-line co-simulation of the developed compensation strategy for delay and hysteresis is conductedon vehicle dynamic model built by Simulink, combined with the AMESim model of EBS system.The results indicate that the developed compensation strategy can work well under variousconditions, and get the expected control effectiveness, which is able to improve the braking stabilityand braking performance for commercial vehicle.(5) The pneumatic EBS control strategy based on hysteresis compensation is experimentallyverified on the developed HIL test bench for commercial vehicle EBS，in consideration of thehardware of EBS system. And the HIL test has further proven the developed control strategies, and itcan effectively improve the braking stability and the braking performance for commercial vehicle,which offers the basis for the vehicle test.In summary, this dissertation has made innovative achievements as followed：(1) A dynamic model of proportional relay valve of pneumatic EBS for commercial vehicle isestablished, and the hysteresis characteristic and its sources is detailed analyzed on the basis of thesimulation on the dynamic characteristic of proportional relay valve, which lays the foundation oftheoretical basis for hysteresis compensation control.(2) The physical models of the key components and the whole system for pneumatic EBS areestablished by AMESim, the influence of main parameters of components and system on pressureresponse characteristics of EBS components and system is analyzed by simulation, which lays thetheoretical foundation for designing and controlling the key components of EBS system.(3) The control method of EBS system based on the hysteresis compensation control isdeveloped, and the results of the simulation and HIL tests indicate that the developed controlstrategies effectively improve the braking stability, the braking performance and active safety ofcommercial vehicle. |
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