Research Of The Electric Power Four-Wheel Steering System Based On Fuzzy Neural Network

As we make the transition to the information era, people demand for cars no longer just used as a transport, but also demand computer could determine whether the driver is in the best condition or not, and according to the feedback information to take a reasonable measures timely. Traditional front wheel steering system has been unable to meet people’s requirements due to its inflexible and poor steering stability at high speeds, therefore we need a high-performance steering system to replace the traditional one. Electric four-wheel steering system is developed in the field of automotive engineering as a high-technology. The steering system collect the all kinds of information by smart sensors, And pass the information to the controller, allocation by the controller reasonably. This system greatly improved the maneuverability, stability, safety and comfort.This thesis will describe a steering system dynamics model based on the electric control targets of four-wheel drive vehicle steering system. List the advantage of four-wheel steering system in flexibility, stability, precision and steering performance area by contrast with traditional front wheel steering system. Then describe the operating principle of electric four-wheel steering control system in detail, and introduced control strategy according to the requirements of the speed, features and steering control. In addition, Fuzzy-Neural Network control system has been proposed for this system due to its multi-variable and nonlinear characteristics. The advantage of this control system is that with the "direction of propagation principle " or "mixing principle" calculated fuzzy rules and parameters, instead of manually summarized according to intuitive or experience. By using MATLAB/Simulink to analyze electric four-wheel steering system both in low speed and mid-high speed cases, the simulation results show that the FNN can make electric four-wheel steering system run stably under different speed. It successfully overcomes the uncertainty of the nonlinear system and proves its mobility and stability.In this thesis, hardware circuit design of electric four-wheel drive vehicle chooses IfmCR0020 type outdoor controller as the core component. This control system adopts CAN bus data communication protocol. Meanwhile, the power of this system provided by battery,the braking power provided by four ac frequency conversion motors. The strength by using four-wheel steering system is that synchronization, wireless control, simple operation, zero emissions, low investment with high efficiency, strong pull, steering flexibility, mobility, etc.