Research On Steering-by-wire System Of A Certain Car

With the development of electronic technology and information technology, every industry began to realize intelligent. The wave of technology extends permeating into the automotive industry, the pure electric vehicles of new energy and intelligent vehicles with networking became the two most important direction of development. Steering-By-Wire(SBW) technology of automobile is the key technology of the development of pure electric vehicles and intelligent vehicle.SBW can not only improve the car’s handling stability, but also improve integrated control combining with other control systems in the car. It makes the car more intelligent as well.In this paper, steering.by.wire system of automotive were studied. In terms of traditional car with a driver, the variable gear ratio is designed rationally, in order to reduce the burden on the driver and improve handling stability. In terms of unmanned cars, the algorithm of tracking the target path is studied to get the target steering wheel angle. Then, appropriate control algorithm of the steering motor is designed so that the execution module of steering.by.wire system can perform better to track the target steering wheel angle. For the above mentioned problems, this article specifically complete the following works:(1) Study the variable gear ratio of the steering.by.wire system, optimize the yaw rate gain based on the Drosophila algorithm and design the variable gear ratio based on the constant yaw rate gain. Meanwhile, in order to prevent the execution motor from the effects of the mutative gear ratio, the ideal ratio is fitted with the appropriate correction curve. Results of Matlab/Simulink and Carsim co.simulation platform show that the design of variable gear ratio is feasible.(2) Based on model.free adaptive control, the control algorithm of tracking target path of unmanned car is designed. Comparing the simulation results of traditional PID control and model.free adaptive control on Matlab/Simulink co-simulation platform and Carsim, the results show that the design of path tracking control algorithm in this paper can track the target path well, and it is better than the PID control.(3) Based on a certain car, automotive steering system modification program and steering controller design method is introduced. And the transformation of automotive steering systems, steering control strategy design and controller hardware design is completed. Fuzzy PID algorithm is designed to control the current of execution motor. Then carry on simulation on the Matlab/Simulink and Carsim co.simulation platform. Finally, contact the real vehicle tests on the test car modified before. The simulation and experimental results show that the design of the steering.by.wire controller and control algorithms in this paper meet the requirements of unmanned vehicle steering and it perform accurately, fast, steadily.