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*============================
这是一个比较典型的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.
=========================================*/
typedef struct PID {
double SetPoint; // 设定目标Desired value
double Proportion; // 比例常数Proportional Const
double Integral; // 积分常数Integral Const
double Derivative; // 微分常数Derivative Const
double LastError; // Error[-1]
double PrevError; // Error[-2]
double SumError; // Sums of Errors
} PID;
/*===============================
PID计算部分
========================================*/
double PIDCalc( PID *pp, double NextPoint )
{
double dError,
Error;
Error = pp->SetPoint - NextPoint; // 偏差
pp->SumError += Error; // 积分
dError = pp->LastError - pp->PrevError; // 当前微分
pp->PrevError = pp->LastError;
pp->LastError = Error;
return (pp->Proportion * Error // 比例项
+ pp->Integral * pp->SumError // 积分项
+ pp->Derivative * dError // 微分项
);
}
/*====================================
Initialize PID Structure
=========================================*/
void PIDInit (PID *pp)
{
memset ( pp,0,sizeof(PID));
}
/*=================================
Main Program
========================================*
double sensor (void) // Dummy Sensor Function
{
return 100.0;
}
void actuator(double rDelta) // Dummy Actuator Function
{}
void main(void)
{
PID sPID; // PID Control Structure
double rOut; // PID Response (Output)
double rIn; // PID Feedback (Input)
PIDInit ( &sPID ); // Initialize Structure
sPID.Proportion = 0.5; // Set PID Coefficients
sPID.Integral = 0.5;
sPID.Derivative = 0.0;
sPID.SetPoint = 100.0; // Set PID Setpoint
for (;;) { // Mock Up of PID Processing
rIn = sensor (); // Read Input
rOut = PIDCalc ( &sPID,rIn ); // Perform PID Interation
actuator ( rOut ); // Effect Needed Changes
}
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