采用C语言编写的PID控制例程
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- 文件大小:6.40KB
- 运行平台:Windows
- 开发工具:C
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- 说明
Ziegler-Nichols方法PID参数整定
在闭环控制系统中,增加积分控制增加了系统的稳态误差精度,由于不断累计误差,能使误差迅速消除,但能使系统产生超调;而在系统中增加微分控制,能够增加系统的阻尼,提高动态响应速度,由于PID控制器能够补偿绝大多数的控制系统,整定方法简单,鲁棒性好,因此是目前应用最广泛的控制器....
这是从网上找来的一个比较典型的PID处理程序,在使用单片机作为控制cpu时,请稍作简化,具体的PID
参数必须由具体对象通过实验确定。由于单片机的处理速度和ram资源的限制,一般不采用浮点数运算,
而将所有参数全部用整数,运算到最后再除以一个2的N次方数据(相当于移位),作类似定点数运算,可
大大提高运算速度,根据控制精度的不同要求,当精度要求很高时,注意保留移位引起的“余数”,做好余
数补偿。这个程序只是一般常用pid算法的基本架构,没有包含输入输出处理部分。
=====================================================================================================*/
#include <string.h>
#include <stdio.h>
/*====================================================================================================
PID Function
The PID (比例、积分、微分) function is used in mainly
control applications. PIDCalc performs one iteration of the PID
algorithm.
While the PID function works, main is just a dummy program showing
a typical usage.
=====================================================================================================*/
.........
#include <stdio.h>
#include<math.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(" m m O O O\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 ;
}
}
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