| The electrically operated steering system (Electric Power Steering, hereafter EPS) is one kind of new vehicles steering control system which has better resistance to interference, fuel oil economical performance, the low temperature performance and environmental protection performance compare with the traditional manual steering system and the hydraulic power steering system.Research of EPS system dynamic properties of EPS system is the foundation of the research and development of EPS. The EPS system consists of EPS, the road surface condition, the steering gear rack, the steering operation. The dynamics research of EPS is to discuss the stress mutual function with changes of the performance in the automobile steering system movement and in the movement the relations, mainly discusses the following two aspects of the question:(1) Control of the steering assist electric current provided by the motor (physical system constitution and control strategy) and optimization (influence factors of physical system to steering assist signal).(2) The dynamic characteristics of EPS system in the different operating mode (including straight line steering, normally steering, fast steering, statitc steering and so on), including the steering portability, the frequency response, the time response characteristic and so on.This paper tasked Column-EPS (hereafter C-EPS) as the object and analyzed the input/output relationship of the C-EPS's mechanical parts such as the torque bar, the gear rack and the worm gear and the electrically controlled system parts like torque sensor, the vehicle speed sensor, the motor and so on through experimental and the simulation method, and applied system dynamics principle to established the mathematical models of C-EPS mechanical system and the electrically controlled partial functions module.Through analysis and research to the armature damping and armature rotation inertia which affect the assist steering electric current, the damping compensating and returns compensating mechanism of the assist steering electric current had been determined. The paper studied control method of steering assist power through synthetically applying kinds of controls technology including PD control, phase compensation, feedback control and est. and designed the mathematical mode of EPS control system which is based on straight type steering power assist the curve line. The control goal of the mode is to make the assist electric current to be able accurately to track the expected current value.The paper established synthesis mathematical model of mechanic and electric system based on the relationship of the road surface reaction load as input and the corner change of pinion as output. The findings indicated the PD control enable the EPS system to have the better frequency response and the transient response performance compared to the sole proportional control which can effectively reduce the steering wheel vibration impact come from the road surface impact.This article also applied 3 dimensional modeling software Pro/E to construct C-EPS prototype's entity's model and converted it into the ADAMS to construct a full-scale prosperous model which shuts the car with EPS system from ground to steering wheel. Meanwhile, employ comprehensive simulation technology to combine the ADAMS EPS system model with the control system model under the MATLAB, constructed the simulation model of the system and carried on the simulation of EPS dynamic response under conditions of steering wheel input and road load input. This joint simulation technology is valuable to EPS performance assesses and regulates and...
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