PID算法（c 语言)（来自老外） (2010-02-17 00:18:24) 转载 #include <stdio.h> #include<math.h> //定义PID 的结构体 struct _pid { int pv; //integer that contains the process value 过 程量 int sp; //＊integer that contains the set point   设 定值 float integral; // 积分值 －－ 偏差累计值 float pgain; float igain; float dgain; int deadband;    //死区 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.    设定PID参数 －－－－ P,I,D,死区 //－－－－－－－－－－－－－－－－－－－－－－－－ －－－－－－－－－－－－－－－－－－－－－－  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.  设定输出初始值 //－－－－－－－－－－－－－－－－－－－－－－－－ －－－－－－－－－－－－－－－－－－－－－－  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.  pid_bumpless 实现无扰切换 当突然改变设定值时，或重新启动后，将引起扰动输出。这 个函数将能实现平顺扰动， 在调用该函数之前需要先更新 PV值 //－－－－－－－－－－－－－－－－－－－－－－－－ －－－－－－－－－－－－－－－－－－－－－－  void pid_bumpless(struct _pid *pid) { pid->last_error = (pid->sp)-(pid->pv);  //设定值与反馈值偏差 }  //－－－－－－－－－－－－－－－－－－－－－－－－ －－－－－－－－－－－－－－－－－－－－－－ 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" 本函数使用位置式PID计算方式，并且采取了积分饱和限制运算 PID计算 //－－－－－－－－－－－－－－－－－－－－－－－－ －－－－－－－－－－－－－－－－－－－－－－  float pid_calc(struct _pid *pid) {· int err; float pterm, dterm, result, ferror;  // 计算偏差 err = (pid->sp) - (pid->pv); // 判断是否大于死区 if (abs(err) > pid->deadband) { ferror = (float) err;   //do integer to float conversion only once 数据类型转换  // 比例项 pterm = pid->pgain * ferror;  if (pterm > 100 || pterm < -100) { pid->integral = 0.0; } else { // 积分项 pid->integral += pid->igain * ferror;  // 输出为0－－100% // 如果计算结果大于100，则等于100 if (pid->integral > 100.0) { pid->integral = 100.0; } // 如果计算结果小于0.0，则等于0 else if (pid->integral < 0.0) pid->integral = 0.0;  }  // 微分项 dterm  =  ((float)(err  -  pid->last_error))  *  pid->dgain;  result = pterm + pid->integral + dterm; } else result = pid->integral; // 在死区范围内，保持现有输出  // 保存上次偏差 pid->last_error = err;  // 输出PID值(0-100) 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);  // 初始化参数 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);  // 设定PV,SP 值 pid_init(&warm, process_point, set_point);  // 初始化PID 参数值 pid_tune(&warm, p_gain,i_gain,d_gain,dead_band);  // 初始化PID 输出值 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,wa rm.dgain);  count++; } }