Board logo

标题: 哪位有详细pid控制程序 [打印本页]

作者: 梦想的天空    时间: 2008-2-13 09:11     标题: 哪位有详细pid控制程序

哪位有详细pid控制程序,网上的倒是可以找到几篇,但是pid这块都是分开说的 ,看不明白
作者: zhv2008    时间: 2008-3-12 15:56

pid的差分方程为
U(n)=U(n-1)+Kp(En-E(n-1)+Ki*En+Kd(En-2E(n-1)+E(n-2)))
Un为输出
En为输入
简单些就是
u(k)=u(k-1)+a*e(k)-b*e(k-1)+c*e(k-2)
u(k)是当前要输出的duty cycle
e(k)是当前误差。
a b c是控制参数,
其实可以用查表法,这样就不用耗时的乘法了,查表一加就得下一个dutycycle的值。

  #i nclude <stdio.h>
  struct _pid {
   int pv; /*integer that contains the process value*/
   int sp; /*integer that contains the set point*/
   float integral;
   float pgain;
   float igain;
   float dgain;
   int deadband;
   int last_error;
  };
  
  struct _pid warm,*pid;
  int process_point, set_point,dead_band;
  float p_gain, i_gain, d_gain, integral_val,new_integ;;
  
  
  
  /*------------------------------------------------------------------------
  pid_init
  
  DESCRIPTION This function initializes the pointers in the _pid structure
  to the process variable and the setpoint. *pv and *sp are
  integer pointers.
  ------------------------------------------------------------------------*/
  void pid_init(struct _pid *warm, int process_point, int set_point)
  {
   struct _pid *pid;
  
   pid = warm;
   pid->pv = process_point;
   pid->sp = set_point;
  }
  
  
  /*------------------------------------------------------------------------
  pid_tune
  
  DESCRIPTION Sets the proportional gain (p_gain), integral gain (i_gain),
  derivitive gain (d_gain), and the dead band (dead_band) of
  a pid control structure _pid.
  ------------------------------------------------------------------------*/
  
  void pid_tune(struct _pid *pid, float p_gain, float i_gain, float d_gain, int dead_band)
  {
   pid->pgain = p_gain;
   pid->igain = i_gain;
   pid->dgain = d_gain;
   pid->deadband = dead_band;
   pid->integral= integral_val;
   pid->last_error=0;
  }
  
  /*------------------------------------------------------------------------
  pid_setinteg
  
  DESCRIPTION Set a new value for the integral term of the pid equation.
  This is useful for setting the initial output of the
  pid controller at start up.
  ------------------------------------------------------------------------*/
  void pid_setinteg(struct _pid *pid,float new_integ)
  {
   pid->integral = new_integ;
   pid->last_error = 0;
  }
  
  /*------------------------------------------------------------------------
  pid_bumpless
  
  DESCRIPTION Bumpless transfer algorithim. When suddenly changing
  setpoints, or when restarting the PID equation after an
  extended pause, the derivative of the equation can cause
  a bump in the controller output. This function will help
  smooth out that bump. The process value in *pv should
  be the updated just before this function is used.
  ------------------------------------------------------------------------*/
  void pid_bumpless(struct _pid *pid)
  {
  
   pid->last_error = (pid->sp)-(pid->pv);
  
  }
  
  /*------------------------------------------------------------------------
  pid_calc
  
  DESCRIPTION Performs PID calculations for the _pid structure *a. This function uses the positional form of the pid equation, and incorporates an integral windup prevention algorithim. Rectangular integration is used, so this function must be repeated on a consistent time basis for accurate control.
  
  RETURN VALUE The new output value for the pid loop.
  
  USAGE #include "control.h"*/
  
  
  float pid_calc(struct _pid *pid)
  {
   int err;
   float pterm, dterm, result, ferror;
  
   err = (pid->sp) - (pid->pv);
   if (abs(err) > pid->deadband)
   {
   ferror = (float) err; /*do integer to float conversion only once*/
   pterm = pid->pgain * ferror;
   if (pterm > 100 || pterm < -100)
   {
   pid->integral = 0.0;
   }
   else
   {
   pid->integral += pid->igain * ferror;
   if (pid->integral > 100.0)
   {
   pid->integral = 100.0;
   }
   else if (pid->integral < 0.0) pid->integral = 0.0;
   }
   dterm = ((float)(err - pid->last_error)) * pid->dgain;
   result = pterm + pid->integral + dterm;
   }
   else result = pid->integral;
   pid->last_error = err;
   return (result);
  }
  
  
  void main(void)
  {
   float display_value;
   int count=0;
  
   pid = &warm;
  
  // printf("Enter the values of Process point, Set point, P gain, I gain, D gain \n");
  // scanf("%d%d%f%f%f", &process_point, &set_point, &p_gain, &i_gain, &d_gain);
  
  
  
   process_point = 30;
   set_point = 40;
   p_gain = (float)(5.2);
   i_gain = (float)(0.77);
   d_gain = (float)(0.18);
  
  
  
   dead_band = 2;
   integral_val =(float)(0.01);
  
  
   printf("The values of Process point, Set point, P gain, I gain, D gain \n");
   printf(" %6d %6d %4f %4f %4f\n", process_point, set_point, p_gain, i_gain, d_gain);
  
   printf("Enter the values of Process point\n");
  
   while(count<=20)
   {
  
  
  
   scanf("%d",&process_point);
  
   pid_init(&warm, process_point, set_point);
   pid_tune(&warm, p_gain,i_gain,d_gain,dead_band);
   pid_setinteg(&warm,0.0); //pid_setinteg(&warm,30.0);
  
   //Get input value for process point
   pid_bumpless(&warm);
  
   // how to display output
   display_value = pid_calc(&warm);
   printf("%f\n", display_value);
   //printf("\n%f%f%f%f",warm.pv,warm.sp,warm.igain,warm.dgain);
   count++;
  
   }
  
  }

自己调试过,希望你能看得明白






欢迎光临 电子技术论坛_中国专业的电子工程师学习交流社区-中电网技术论坛 (http://bbs.eccn.com/) Powered by Discuz! 7.0.0