Development Of And Resrarch On The Test Bench For Recirculating Ball-type EPS Of Commerical Vehicle

The EPS improves the steering portability when the vehicle speed is low and the controllability and stability when the vehicle is in high speed, the EPS and other electronic control systems can be combined to improve vehicle safety and driving comfort. The EPS has several advantages, such as, energy conversion and environmental protection, small space, good steering feel, and convenient installation and maintenance, its range of application has grown from the original mini-cars to high-class cars, sports cars, SUV and commercial vehicles and passenger cars. Therefore, the EPS has broad prospect, and is one of the hot spots of automotive technology currently.Firstly, this paper introduces the development of steering system simply, summaries the status of the EPS domestic and foreign. Then introduces the EPS in detail, including: EPS classification, EPS advantages and disadvantages, operation principle of a typical EPS structure and key components. And then compares the curvers of assist characteristic of all the three kinds, which provides the theoretical basis for the establishment of the real-time simulation model, then presents the evaluation methods of the EPS performance, introduces the control strategy of the EPS. The introduction of the EPS system by chapter one and two lays the foundation for the establishment of the test bench for recirculating ball-type EPS.In the third chapter, this paper firstly explains the necessity of building test bench, then compares the test bench plan, and ultimately by comparing the electro-hydraulic servo system and electro-hydraulic proportional system, and in accordance with the requirements of the test bench, selects the electro-hydraulic proportional system as the resistance loading plan. Then presents the operation principle of the test bench for recirculating ball-type EPS and plans and designs the overall layout of the test bench. Finally, presents the main technical indicators of the test bench and the basic functions which should be realized and the useage of the bench.The fourth chapter designs and selects the components of the hardware system, the emphasis of this chaper is the design of the components of resistance loading system, in the selection of the components, introduces the structure, characteristics and operation principle of certain parts, and gives the fundamental parameters of the determined components. Then introducs the data acquisition system of the test bench, which is consisted of data acquisition card and industrial computer.Chapter five were introduces the xPC Target, and presents the method of the building real-time simulation system based on the xPC Target, and describes the the signal acquisition step of the xPC Target. Then establishes the eight degrees of vehicle model and Unitire1.0 steady-state model, which can fully meet the needs of real-time, and in addition establishes the tire vertical load model and the front wheel side slip angle model. In the steering system model, establishes recirculating ball-type steering model, motor model which current uses PID control, and controller model which uses straight-line type assist characteristic. The man-machine interface is designed based on Visual C++ 6.0, and the serial communication which connects the host PC and target PC is introduced, and then introduces the components and function of each module of the man-machine interface.