PID控制算法举例之(一)

(1)包含必要头文件

#include
#include

(2)定义PID必要参数

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;
};

//准备必要的数据
struct _pid warm,*pid;
int process_point, set_point,dead_band; 
float p_gain, i_gain, d_gain, integral_val,new_integ;; 

// 初始化PID 当前值和设定值
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; 
} 

// 设置PID参数
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; 
}

// 设置积分项
void pid_setinteg(struct _pid *pid,float new_integ)
{ 
pid->integral = new_integ; 
pid->last_error = 0; 
} 

// 求设定值与新值的差

void pid_bumpless(struct _pid *pid) 
{ 
pid->last_error = (pid->sp)-(pid->pv); 
} 

// 位置式PID计算

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); 
}

// 举例说明PID的用法

int _tmain(int argc, _TCHAR* argv[])
{
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");

// 计算20次
while(count<=20)
{

// 输入当前的处理值
scanf("%d",&process_point);

// PID处理过程
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);


display_value = pid_calc(&warm); 
printf("%f\n", display_value); 

count++; 
}
return 0;
}

/*
内容:PID控制算法举例
作者:罗世洲 QQ370756740  xyy0215@qq.com
欢迎技术交流
*/