Research On Controller Of Automotive Electro-hydraulic Power Steering System

With the renovation of new vehicle technology, the demands for driver comfort, flexibility, and security are getting higher and higher. One of most the key performances is steering, and directly affects vehicles'handling and stability. It plays more than important role of insuring for safely steering, decreasing road traffic accident, safeguarding drivers'safeties and improving drivers'work conditions. In order to improve steering performance, many vehicles have been equipped active steering system. Hydraulic Power Steering is pioneer form of active steering. Steering system has being greatly renovated as for adopting electric technologies.Electro-Hydraulic Power Steering system, compared with traditional Hydraulic Power Steering system, has much more advantages that make driving easy, such as saving energy, providing variably steering power and so on.The contents of this paper mostly research and design controller of EHPS. First, Steering characteristic curve of EHPS provided by TRW is obtained. The motor speed that is corresponding to vehicle speed and the steering speed is get collected. And steering characteristic curve of EHPS is analyzed by OringinLab8.0. It can provide theoretical basis for design characteristic curve of my controller though identifying EHPS'characteristic.Second, the control tactic and control method that are researched and employed in BLDCM of EHPS system are researched. BLDCM is significant in Electro-Hydraulic Power Steering system. It is critical to motor finishing its function that BLDCM well run. The paper analyzed superiority of control tactic that is motor current loop and speed loop. Two-closed-loop control policy also is well analyzed. What's more, PID algorithm that is classical control theory is made clear.The core of EHPS system is the controller which is a part to collect and process the signals, control the BLDCM and communicate with other systems, realize the algorithm and output control signals and so on. The thesis deeply research DSP and design EHPS'controller. Hardware module comprises power supply module, DSP system, SCI module, JTAG interface module and so on. At the same time, control software is compiled by CCStudio3.1 platform after ASM program is deeply researched.Finally, the EHPS system experimentation platform is established to test the assist character and the performance of controller. Though experiment is analyzed, this controller can provide transmutability steering power that can follow different vehicle speed and steering speed.