Study On Control Strategy Of Steer-by-Wire System Based On Fractional Order Calculus

Vehicle Steer-by-wire(SBW) system,which has no mechanical linkage between steeringwheel and front wheels can achieve the driver’s intention through electrical signal to controlthe steering wheels. The basic function of SBW system is to transmit the driver’s steeringintention to vehicle and provide the driver with good sense of road information.Theinstructions issued by controller are used to control steering actuator to ensure that the vehiclehas ideal steering stability under different conditions.Firstly, the design of controller based on the fractional calculus theory is proposed bystudying on the application of fractional calculus in engineering. The design of the controller,parameter setting and the digital realization method are studied.The design and analysis offractional calculus controller is carried out in this paper. The fractional order PIλDμcontrollerhas two more adjustable parameters than the traditional PID controller, the integral order anddifferential order. Influence on the control system is discussed of the five parameters, whichlaid the foundation for the subsequent research on SBW system.Secondly, the dynamics model of SBW system is established by Matlab/Simulinksoftware, mainly including the steering control model and the execution model. The vehiclevirtual test simulated by CarSim and Matlab/Simulink is carried out to verify the accuracy ofthe established model. And this method can provide the theoretical basis and softwaresimulation platform for the subsequent research on SBW system.Finally, in order to achieve reliable steering performance, the front wheel angle controlstrategy and the steering execute motor control strategy are proposed. The new fractionalorder PIλDμcontroller is designed based on the theory of fractional calculus. The controlstrategy and the control effect of fractional order PIλDμcontroller is simulated and analyzedunder typical operating condition. The result shows that the fractional order PIλDμcontroller iseffective to improve the handling performance of the SBW system.