外文翻译--智能汽车系统控制算法的研究-汽车设计(编辑修改稿)

外文翻译--智能汽车系统控制算法的研究-汽车设计(编辑修改稿)内容摘要：

foundation for taking the near way in the curvy trajectory. After the smart car system records the information of the first circle, it can distinguish the next corner information directly and turn left or right while the smart car is running in the second circle. Then it can cross the curvy trajectory according to a smaller radius, reduce the distance and save the time. Figure 5 is the control strategy for the curvy trajectory. Figure 5. Curvy trajectory control strategy While the smart car is moving along the Stype trajectory, if the speed can not be controlled effectively, it may run out of the runway. Figure 6 and Figure 7 show the Stype control strategy. The smart car system records the digital signal values of the AD module and pares with the number 255, if the values of sensors of the right are less than 255, set A1=1。 if the values of sensors of the central are less than 255, set A2=1。 if the values of sensors of the left are less than 255, set A3=1. If A1, A2 and A3 are all 1, it can be claimed that the sensors have detected the Stype trajectory. 3) The Possible Situation and Its Corresponding 6 Algorithm: Because the smart car is rearwheel drived, if the smart car accelerates when it crosses a curvy trajectory, there may have a oversteering phenomenon. The smart car system need to accurately control the steering gear. If all the 10 photoelectric sensors can not detect the black trajectory, which implies that the smart car run out of the runway. In this case, the smart car system should carry out the following control strategy in Figure 8. Figure 6. The subroutine of judging runway which is curvy trajectory or Stype trajectory If all the 10 photoelectric sensors can not detect the black trajectory, the smart car system can determine the location of the black trajectory through Interrupt Mode. Then the smart car system determines that whether or not the smart car is out of the runway. If it is, the smart car system works under the error handling mechanism. If not, the smart car system continues operating the tracking control algorithm. The error handling mechanism is that the smart car system read the latest historical data from MAP table and sends it to the central 7 processing unit. Then the CPU determines the sensor which is the last one detected the black line and controls the steering gear so that the smart car can turn back. D. PID Control of The Smart Car System The smart car system makes the motor actual velocity close to the given speed according to PID algorithm . In the C/OSII system, digital PID control algorithm is divided into the position form control algorithm and the incremental form control one. In order to reduce the calculated amount and get a stable result, the steering gear control will adopt the incremental form control algorithm. Figure 9 is the flow process of the calculation. 8 Figure 7. The flow chart of Stype trajectory target speed Figure 8. The interrupt program to determine whether or not the smart car ran out of the runway 9 Figure 9. The Control Module of Motor Speed The smart car system can control the steering angle easily by using the coordinate method. For example, when detected the black trajectory, the smart system would set up the corresponding coordinate figure for 17. The lateral sensor is farther from the centerline, there is a bigger coordinate figure corresponding to the sensor. Table 1 show that every photoelectric sensor has a unique coordinate figure. TABLE I. COORDINATES MATCHING WITH THE PHOTOELECTRIC SENSORS We pile the C++ program in CodeWarrior IDE . The following code is the main program code. The definition of PID structure: struct PID { int Proportion。 // Proportional Const int Integral。 // Integral Const int Derivative。 // Derivative Const int LastError。 // Error[1] int PrevError。 // Error[2] int Outlimit。 // Output limiter int Output。 } speed1。 Calculation of PID: double PIDCalc( PID *pp, double NextPoint ,double A, double Pup, double Pdown)。 The initialization of the structure of speed: void init_pid(struct PID *pid。