Research On μAnalysis And Synthesis Of Electric Power Steering System And Test

Steering system is an important component for ensuring running safety.Compared with hydraulic power steering system(HPS),electric power steering system(EPS)has many excellences.For example,its energy-saving,environment protection,its compact configuration and more excellent performance.So it becomes a hotspot of modem steering system research both at home and abroad.The predecessors have made great progress in modeling the EPS dynamics system,rules of assist torque,control theories for EPS and methods for testing the EPS controllers.In recent years,all kinds of EPS products have been manufactured and equipped on some kinds of micro-vehicles and the super heavy vehicles.Some new problems rise when electric power steering system is used in the super heavy vehicle.This paper does some research on control methods and tests of electric power steering system.First,based on analysis of affection of the assistance character,the model for steering torque of vehicle was built up.The relation between steering torque and load of vehicle was ensured through dynamic simulation and electric power steering test bed. The new assistance character of electric power steering system was built up under the effection of load of vehicle,speed and steering torque.The experiments showed that the character of controller designed under new assistance character was much better.Then,on the basis of analyzing control theories of electric power steering system, the author has made a definition for steering motion.The steering motion has been divided into three basic actions:turn steering wheel,slew steering wheel,retain steering wheel.According to the different intentions,Multi-objects Control Stratagems which based on expert system is put forward.By using logic judgments ability of expert system to judge different steering state for executing control aims which correspond to steering states,the stability of EPS is advanced.At the same time,according to control aim in different steering state,simulation research is preceded.Results show that using this control method can obtain excellent steering ability.Third,Based on the dynamics model of electrical power steering system(EPS),the design of electric power steering control system by usingμanalyses and synthesis is first presented.The effects of high frequency from all kinds of roads and disturbances of sensors noises are considered during designing theμcontroller.Based on the requirement of electric power steering performance and system specifications,the EPS control system architecture and the weighting functions are selected.Theμcontroller of the EPS system was computed through D -K method in Matlab.Simulation shows that the designed controller performs satisfactorily and inherits the imposed robustness and performance sections.Fourth,the hardware that adopted ARM S3C44BOX as its microprocessor is designed.The control unit was able to realize real-time data/signal acquisition and system control.At the same time,the software program,which was divided into the realization of control strategy and the acquisition & control of data/signal,was developed in modular after the circuit design was completed.The last,Based on analyze about abilities of electric power steering system,a new pattern test-bed which contains tire and suspension can reflect steering system more verity.This test-bed can simulate the effects of speed and load of a vehicle and road status.The designing of this test-bed is very usefully to electric power steering system research.This ECU is tested on the test-bed,and the designing way and control strategy in this paper are proved to be feasible.The result indicates that using the proposed ECU of electric power steering system,the steering wheel is easy,and return quickly with good steering feel.