| With the development of Automobile Electronic Technology, automobile steering system has been improved from traditional Mechanical Steering System to Hydraulic Power Steering and Electronic Power Steering,which are widely used for solving the conflict between steering handiness and steering agility existed in traditional mechanical steering system. But those three steering systems remain mechanical connections which causes changes of steering response characteristics when the speed changes. Therefore, it's necessary for drivers to modify the angle of steering to some extent according to their experience in order to make the car drive in the pre-selected orbit. While it may be heavy burden for drivers to a large extent, and lessen the vehicle handing stability. Therefore, how to design steering system, improve manipulation stability, then make more and more easily non-professional drivers to drive safely, is very important. Taking a light vehicle as the research object, the paper designed variable transmission algorithm of steering by wire and steering control algorithm, and established the steering executive motor model by the Matlab/Simulink, designed the controller hardware of the steering by wire, the off-line simulation and hardware in the loop test was done to validate and analysis steering by wire control algorithm in TESIS veDYNA environment. Main contents of thesis include:(1)The model and control Steering executive motorThe physical structure of steering executive motor was analyzed and reasonably simplified, on this basis ,the transfer function model of steering executive motor was deduced, and the paper has established its simulation model in Matlab/Simulink environment; In order to establish a more accurate motor simulation model ,the test of steering executive motor was done, and getting the parameters of the modeling; Finally the paper puts forward to the double loop control algorithm of the steering executive motor, and doing simulation experiment, Simulation result shows that the proposed control algorithm can well follow the target goal of motor speed and position, then lays a foundation for the control and development to steering executive system control by wire.(2)The change ratio algorithm of SBW and steering control algorithm This paper analyzes the relationship between vehicle steering system ratio and handing stability, and proposes the calculation method of variable transmission in this foundation; Getting the parameters of variable transmission, Ks was calibrated by neutral steer test in veDYNA environments; To ensure the stability of vehicle yaw-rate under variable transmission, the steering by wire control algorithm was designed based on the feedback yaw-rate, and the off-line simulation tests for two typical working conditions-step inputs to steering wheel and steady-state circular driving was done , proving the effectiveness of the proposed steering by wire control algorithm. Off-line simulation results show that the proposed variable transmission algorithm can guarantee the proportional relationship between vehicle steering curvature and steering wheel Angle, steering control algorithm can guarantee the stability of the vehicle yaw-rate, and making vehicle handling stability is good.(3) Design the controller of the implementation of the SBWBased on the request of the implementation's work, we got the design plan of the controller, then completed the selection of MPU, and designed the drive circuit of the implementation motor, completed the design of the controller hardware, at last designed the software of the controller. It is helpful for the hardware in the loop simulation.(4) Hardware in the loop simulation studyBased on dSPACE real time platform, the paper built SBW hardware in the loop test bed, and used it to complete the step steering and steady-state circular test. The results show that the variable transmission algorithm and steering control algorithm have better control effect, and they can effectively ensure the vehicle handling and stability.
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