| Electric power steering system is the inevitable developing direction for automobile power steering, which is much superior to hydraulic power steering system. The control theory and control system design are particularly studied in this paper. The integrated developing & experimentation platform is made. And, based on it, the system core — electric control unit (controller) is developed. The combination of modern electric driving & computer control with mechanism and automobile project is fully showed in this subject.The dynamic mathematics model is established from the actual physics objects in this paper. The basic steering system equations are gained. The control theory of three types of controls and two types of compensations are discussed, which are based on the analysis of the system model. And, the general structure of complex control strategies of current forward feedback is constructed. In this paper, EPS system' key —the assist characteristic is analyzed and studied. Based on the mathematics model and the assist characteristic, the arithmetic to calculate the nonlinear relationship between steering wheel torque and motor torque at any vehicle speed is worked out. Considering the nonlinear assist characteristic in electric power steering system, such as steering dead zone, steering assist zone, steering saturation zone, and the blind zone caused by discrete vehicle speed, a new method to describe assist characteristic which utilizes neural network is presented. The experiment is carried out. The analysis results coincide with experiment results quite well. The nonlinear steering assist in full speed range is realized and the blind zone is eliminated. The effect is verified.The control system includes Motorola DSP 56F8XX as the central control unit, the DC motor in EPS system as the actuator. The hardware and software of electric control unit are designed and the full solution of embedded EPS control system is presented. The development and experiments are all accomplished on the D&E platform, and the experiment results are given which verify that the scheme above is valid and its dynamic and stationary performance is very good. To ensure developing and experimenting, the integrated developing & experimentation platform for EPS system is designed alone in this subject. The experiment equipment is set up, the signal process module is made and the integrated control software on PC is developed. They are the necessary factors to carry through EPS system, which promote the development most.Finally, the project engineering notion is proposed in this paper to link the laboratory fruit and productivity up and to employ the research into practice. The system engineering and the electromagnetism compatibility are realized. The performance requirement is met with higher stability, reliability, and anti-jamming, which satisfies the automotive industrial level.
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