/********************************************************
* PID Adaptive Tuning Example
* One of the benefits of the PID library is that you can
* change the tuning parameters at any time.  this can be
* helpful if we want the controller to be agressive at some
* times, and conservative at others.   in the example below
* we set the controller to use Conservative Tuning Parameters
* when we're near setpoint and more agressive Tuning
* Parameters when we're farther away.
********************************************************/

#include "PID_v1.h"

// 被控量 控制量 IO口
#define PIN_INPUT 0
#define PIN_OUTPUT 3

//Define Variables we'll be connecting to
double Setpoint, Input, Output;

//Define the aggressive and conservative Tuning Parameters
// 两组PID控制参数
double aggKp = 4, aggKi = 0.2, aggKd = 1;
double consKp = 1, consKi = 0.05, consKd = 0.25;

//Specify the links and initial tuning parameters
PID myPID(&Input, &Output, &Setpoint, consKp, consKi, consKd, DIRECT);

void setup()
{
	//initialize the variables we're linked to
	Input = analogRead(PIN_INPUT);
	Setpoint = 100;

	//turn the PID on
	myPID.SetMode(AUTOMATIC);
}

void loop()
{
	Input = analogRead(PIN_INPUT);

	// 求设定值和被控量绝对差
	double gap = abs(Setpoint - Input); //distance away from setpoint
	// 如果两者接近了，采用稳健控制参数
	if (gap < 10)
	{  //we're close to setpoint, use conservative tuning parameters
		myPID.SetTunings(consKp, consKi, consKd);
	}
	// 否则采用激进控制参数
	else
	{
		//we're far from setpoint, use aggressive tuning parameters
		myPID.SetTunings(aggKp, aggKi, aggKd);
	}

	myPID.Compute();
	analogWrite(PIN_OUTPUT, Output);
}