Study On Acquisition And Processing Of Wheel Speed And Wheel Angular Acceleration For Commercial Vehicle

Owing to the legal requirements and market demands, active safety technique of domestic commercial vehicle develops rapidly in the last few years. However, converse exploit instrumentality is mainly used for the most inland automotive active safety productions, which means most of them imitate the same production of abroad, and the developing tools do not follow up to the times. The production which is made by this way has its own faultiness and does not match the whole vehicle in largely. Comparing with the productions abroad, there is still long way to go for inland manufacturers. So the independent exploiting of the safety technique for the commercial vehicle should be reinforced in the future.The signal of wheel speed has been set up as the main input in the active safety system, which is common feature in the safety control system. The problem involved in both the research and design departs is how to acquire and analyze the wheel speed signal. The control performance and reliability of the active safety controller depends on the quality of wheel speed signal.The acquiring and processing of controlled variable has been deemed as the key technology in the automobile active safe production, and the acquiring and processing signal of wheel speed are the mostly important ones, which could affect the control performance of the active safety products. It has been years of the algorithm research of wheel speed abroad. Up to now, abundant product experience has been accumulated in the corporations abroad and good algorithm has beenpresented in the processing of wheel speed signal. However, the modules about processing wheel speed signal have been protected by the special chips or circuits, the information about the product is not introduced in their specify. Many questions exist in the processing wheel speed signal such as bad reliability and high threshold of sensing wheel speed (it could not identify the wheel speed when it draws to 10km/h ) etc. Therefore, the research on the processing of wheel speed is the key steps and also is the only way to research own patents in electronic controlled system.Independent development ABS for commercial vehicle is set up for theme in this article. Gathering the signals from sensors and processing these signals are the main research subjects of the ABS for the commercial vehicle. Six chapters are presented in this paper.The reason for gathering and processing signal from wheel speed, the intention and the main subjects about this paper are introduced in the first part.The system analysis of gathering wheel speed is the main content in the second chapter. Gear ring, sensors about wheel speed and circuit of gathering wheel speed signal constitute the system. Firstly, the structure of the system is introduced in brief; secondly, the working principle and characteristics about the output signal of the magnetic wheel speed sensor. Ring radius, the gap between sensor and ring and wheel speed are the main factors that affects the output voltage of the sensors. The gear ring and how to fix the ring on the vehicle are also discussed in this part. Design formulas are listed in order to calculate the range of tooth for the gear ring. Using these formulas could decide the 100 teeth in this paper. Thirdly, the functions of circuit for processing signals are described and the functional block diagram is also presented in this parts.Wheel speed sensor is the only sensing component in ABS for commercial vehicle, so, accurately recognizing and counting the signal are the key technologiesin the active safety system. Two aspects must be considered when processing the wheel speed signal: the first one is how to recognize and eliminate the parasitic errors in the originality signal; the second one is how to deal with the measure errors in the system. The parasitic errors is caused by highly electromagnetism outside and rough road surface, and the measure errors is caused by manufacture errors and wrong trigger of the shipping circuit and counting errors etc. The method about processing wheel speed for the commercial vehicle is designed, which includes the method of recognition and elimination the parasitic errors , data filter technology ,the strategy of the adjustment by itself for wheel speed and acceleration of angle etc. All of these works are helpful to the simulation of processing wheel speed.Simulation models have been built on the foundation of chapter 3. In this chapter, there are five segments including recognize the signals and time interval, eliminate abnormal spot, calculate the originality wheel speed, data filter, calculate the acceleration and speed etc. Simulation models about processing wheel speed have been validated by simulation results, so the foundation is built for the road test.The algorithm of processing wheel speed has been verified by road test. Three different tests have been made in order to verify the algorithm of the processing wheel speed. The road test includes without main control logic of ABS, with simple control logic and with the whole algorithm of ABS. It could be proved by the road test that the algorithm of processing wheel speed could work normally in every driving situation and have good performance, especially, it works normally in low speed , meet the demands about ABS for commercial vehicle and the algorithm could adjust itself according to the different situation.. It establishes the foundation for researching ABSIn conclusion, acquiring and processing the wheel speed has been studied in this article. A lot of technology methods which could handle with the wheel speed are put forward. The algorithm has been verified by simulation and road test. Thus the stability foundation has been built for the future research about ABS,TCS,ESC etc.