| Electric power steering system is the inevitable developing direction forautomobile power steering, which is much superior to hydraulic power steeringsystem. The digital electric power steering system is accomplished, which meet withhigher stability, reliability, and excellent dynamic and stationary performance.Physical and mathematics model of electric power steering system is analyzedand studied, and three types of controls is presented, which is assist control, returncontrol and damp control. Further more, the feasible method of realization of threetypes of control is designed.Based on Motorola DSP56F805 as the central control unit and the integratedcontrol software on PC as the communication software between PC and ECU, thedigital electric power steering system is successfully accomplished, in which discretenonlinear assist character curve is used. Assist control is used at low speed and dampcontrol is used at high speed. Applying this digital system, steering is comfortable,steady and reliable in full speed range.Neural network is put forward in this subject to describe assist characteristic,while assist characteristic is realized based on discrete nonlinear assist character curve.Neural network is trained off line, and the training result accord with the target value.Making use of the training result, it is realized in the practical system. The experimentresult in experimentation platform which applied neural network assist characteristicis superior to the experiment result that used discrete nonlinear assist character curve.The ability of advanced theory in the practical system is perfectly validated in thissubject.Finally, the theory of MicroC/OS-II is analyzed and studied in this paper, whichis an embedded real time operating system(RTOS). It is perfectly transplanted toMotorola DSP56F805, and the digital electric power steering system is able to runsuccessfully in this real time operating system. The return ability using RTOS issuperior to the ability without it.
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