The Research On Steering-by-wire System And Control Strategy Based On Driver Model

Steering system is the important system of the driver to achieve the steerableintention and control the stability of the vehicle. Compared with the traditional steeringsystem, Steering-by-wire(SBW) system is a new concept of the steering system, whichcancels the mechanical linkage between the steering wheel and the steerable wheel, usessensors and electronic controller to control the system, casts off the default of thetransmission ratio in bondage to mechanical performance, realizes the transmission ratiofreely design depend on the driving state, makes it have the both trait of steeringportability and operating stability. So in the SBW system the road sense must besimulated to provide to the driver to sense the road information but not use themechanical component.Firstly, this paper with reasonably simplifying the structure principle of the SBWsystem and researching the dynamics of the system, establish the steering dynamics andthe Simulink model of the steer by wire system, use the virtual prototype model of theCarsim, and finally establish the vehicle model to research on the control strategy of theSteering-by-wire system. Propose the fuzzy immune PID of front wheel angle controlstrategy based on ideal transmission ratio and constant yaw velocity gain, research on thecontrol effect of the virtual prototype model. Simulation results finally show that:compared with the PID and the fuzzy PID control strategy, the fuzzy immune PIDcontrol strategy can trace the yaw velocity more precisely, it can not only acquire thedriving portability and operating stability, relieve the diver's burden.Secondly, considering traditional steering system the road sense use the mechanicallinkage to response to the driver, but in the SBW it needs to analysis the system dependon simulated road sense produced by electronic control system. Through establishingmodel to the self-aligning torque and the wheel module of the SBW, acquiremathematical model of the target torque and the wheel module, establish ideal road sensebased on the variable transmission ratio and compared to the traditional road sensesimulation, Simulation results finally show that: ideal road sense not only make thesystem more light and sensitive in low speed more clear and stable in high speed.Lastly, adjust parameter to change the feedback steering wheel torque according tothe need to the different driver, which can coincide with driver's customer and drivingstyle. Establishing human-vehicle-road closed loop system based on adaptive fuzzy PID, simulation results show that: the model can precisely trace the road information andcontrol the car in time not directly depends on the transfer function of the vehicle model.