pid算法应该算是所以算法中最稳定最可靠最简单的算法，在库函数中添加这种算法对实际控制的时延有非常大的帮助。

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  C语言PID算法.doc

PID算法(c语言)(来自老外)

#include

#include

//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;;

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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.

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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

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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;

}

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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

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void pid_setinteg(struct _pid *pid,float new_integ)

{

pid->integral = new_integ;

pid->last_error = 0;

}

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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

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void pid_bumpless(struct _pid *pid)

{

pid->last_error = (pid->sp)-(pid->pv);  //设定值与反馈值偏差

}

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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

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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);

}

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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,warm.dgain);

count++;

}

}

增量式PID算法

#include

#include

struct _pid

{ double set;

double actual;

double err;

double err_one;

double err_two;

double Kp,Ki,Kd;

}pid;

void PID_init()

{ pid.set=0.0;

pid.actual=0.0;

pid.err=0.0;

pid.err_one=0.0;

pid.err_two=0.0;

pid.Kp=0.2;

pid.Ki=0.02;

pid.Kd=0.2;

}

double PID_real(double speed)

{ double increment;

pid.set=speed;

pid.err=pid.set-pid.actual;

increment=pid.Kp*(pid.err-pid.err_one)+pid.Ki*pid.err+pid.Kd*(pid.err-2*pid.err_one+pid.err_two); pid.actual+=increment;

pid.err_two=pid.err_one;

pid.err_one=pid.err;

return pid.actual;

}

main()

{   int i;

PID_init();

for(i=0;i<1200;i++)

{ double speed=PID_real(100.0);

printf("%f\n",speed);

}system("pause");

}