位置型 增量型pid

------------------------------------------pid.c----------------------------------------------------------------------------
#include "pid.h"

static pid_t gPid = {0};

void Pid_SetGain(float ProportionGain,float IntegralGain,float DerivativeGain)
{
   gPid.ProportionGain = ProportionGain;
   gPid.IntegralGain   = IntegralGain;
   gPid.DerivativeGain = DerivativeGain;
}

void Pid_SetPoint(float SetPoint)
{
   gPid.SetPoint = SetPoint;
}

#ifdef INCREMENT_PID_CONTROL   
void pid_compute(float CurValue)  /* 增量型   */
{
    float thisError = 0;
    float increment = 0;
    float pError,dError,iError;
    thisError       = gPid.SetPoint - CurValue; //得到偏差值
    pError          = thisError - gPid.LastError;
    iError          = thisError;
    dError          = thisError - 2 * (gPid.LastError) + gPid.Preerror;
    increment       = gPid.ProportionGain * pError + gPid.IntegralGain * iError + gPid.DerivativeGain * dError;   //增量计算
    gPid.Preerror   = gPid.LastError;  //存放偏差用于下次运算
    gPid.LastError  = thisError;
    gPid.Result     += increment;
}
#else   
void pid_compute(float CurValue)    /* 位置型 */
{
    float thisError = 0;
    thisError       = Pid.SetPoint - CurValue;
    gPid.Integral  += thisError;
    gPid.Result     = Pid.ProportionGain * thisError \
                    + Pid.IntegralGain * Pid.Integral \
                    + Pid.DerivativeGain * (thisError - Pid.LastError);
    gPid.LastError  = thisError;
}
#endif
-----------------------------------------------------------------pid.h-------------------------------------------
#ifndef __PID_H__
#define __PID_H__

#define INCREMENT_PID_CONTROL

/*定义结构体和公用体*/
typedef struct
{
    float SetPoint;               //设定值
    float ProportionGain;         //比例系数
    float IntegralGain;           //积分系数
    float DerivativeGain;         //微分系数
    float LastError;              //前一拍偏差
    float Result;                 //输出值
#ifdef INCREMENT_PID_CONTROL
    float Integral;               //积分值
    float Preerror;               //前两拍偏差
    float DeadBand;               //死区
#endif 
}pid_t;

extern void Pid_SetGain(float ProportionGain,float IntegralGain,float DerivativeGain);
extern void Pid_SetPoint(float SetPoint);
extern void pid_compute(float CurValue);

#endif /* __PID_H__*/