machines/components/pid-controller/reference-impl/osPID-Firmware/PID_AutoTune_v0.cpp

/**********************************************************************************************
 * Arduino PID AutoTune Library - Version 0.0.0
 * by Brett Beauregard <br3ttb@gmail.com> brettbeauregard.com
 *
 * This Library is ported from the AutotunerPID Toolkit by William Spinelli
 * (http://www.mathworks.com/matlabcentral/fileexchange/4652) 
 * Copyright (c) 2004
 *
 * This Library is licensed under the BSD License:
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are 
 * met:
 * 
 *     * Redistributions of source code must retain the above copyright 
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright 
 *       notice, this list of conditions and the following disclaimer in 
 *       the documentation and/or other materials provided with the distribution
 *       
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 **********************************************************************************************/

#if ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

#include "PID_AutoTune_v0_local.h" //renamed to avoid conflict if Autotune library is installed on IDE

PID_ATune::PID_ATune(double *Input, double *Output)
{
	input = Input;
	output = Output;
	controlType = 0; //default to PI
	noiseBand = 0.5;
	running = false;
	oStep = 30;
	SetLookbackSec(10);
	lastTime = millis();
}

void PID_ATune::Cancel()
{
	running = false;
}

int PID_ATune::Runtime()
{
	justevaled = false;
	if (peakCount > 9 && running)
	{
		running = false;
		FinishUp();
		return 1;
	}
	unsigned long now = millis();

	if ((now - lastTime) < (unsigned long)sampleTime)
		return false;
	lastTime = now;
	double refVal = *input;
	justevaled = true;
	if (!running)
	{ //initialize working variables the first time around
		peakType = 0;
		peakCount = 0;
		justchanged = false;
		absMax = refVal;
		absMin = refVal;
		setpoint = refVal;
		running = true;
		initCount = 0;
		outputStart = *output;
		*output = outputStart + oStep;
	}
	else
	{
		if (refVal > absMax)
			absMax = refVal;
		if (refVal < absMin)
			absMin = refVal;
	}

	//oscillate the output base on the input's relation to the setpoint

	if (refVal > setpoint + noiseBand)
		*output = outputStart - oStep;
	else if (refVal < setpoint - noiseBand)
		*output = outputStart + oStep;

	//bool isMax=true, isMin=true;
	isMax = true;
	isMin = true;
	//id peaks
	for (int i = nLookBack - 1; i >= 0; i--)
	{
		double val = lastInputs[i];
		if (isMax)
			isMax = refVal > val;
		if (isMin)
			isMin = refVal < val;
		lastInputs[i + 1] = lastInputs[i];
	}
	lastInputs[0] = refVal;
	if (nLookBack < 9)
	{ //we don't want to trust the maxes or mins until the inputs array has been filled
		initCount++;
		return 0;
	}

	if (isMax)
	{
		if (peakType == 0)
			peakType = 1;
		if (peakType == -1)
		{
			peakType = 1;
			justchanged = true;
			peak2 = peak1;
		}
		peak1 = now;
		peaks[peakCount] = refVal;
	}
	else if (isMin)
	{
		if (peakType == 0)
			peakType = -1;
		if (peakType == 1)
		{
			peakType = -1;
			peakCount++;
			justchanged = true;
		}

		if (peakCount < 10)
			peaks[peakCount] = refVal;
	}

	if (justchanged && peakCount > 2)
	{ //we've transitioned.  check if we can autotune based on the last peaks
		double avgSeparation = (abs(peaks[peakCount - 1] - peaks[peakCount - 2]) + abs(peaks[peakCount - 2] - peaks[peakCount - 3])) / 2;
		if (avgSeparation < 0.05 * (absMax - absMin))
		{
			FinishUp();
			running = false;
			return 1;
		}
	}
	justchanged = false;
	return 0;
}
void PID_ATune::FinishUp()
{
	*output = outputStart;
	//we can generate tuning parameters!
	Ku = 4 * oStep / ((absMax - absMin) * 3.14159);
	Pu = (double)(peak1 - peak2) / 1000;
}

double PID_ATune::GetKp()
{
	return controlType == 1 ? 0.6 * Ku : 0.4 * Ku;
}

double PID_ATune::GetKi()
{
	return controlType == 1 ? 1.2 * Ku / Pu : 0.48 * Ku / Pu; // Ki = Kc/Ti
}

double PID_ATune::GetKd()
{
	return controlType == 1 ? 0.075 * Ku * Pu : 0; //Kd = Kc * Td
}

void PID_ATune::SetOutputStep(double Step)
{
	oStep = Step;
}

double PID_ATune::GetOutputStep()
{
	return oStep;
}

void PID_ATune::SetControlType(int Type) //0=PI, 1=PID
{
	controlType = Type;
}
int PID_ATune::GetControlType()
{
	return controlType;
}

void PID_ATune::SetNoiseBand(double Band)
{
	noiseBand = Band;
}

double PID_ATune::GetNoiseBand()
{
	return noiseBand;
}

void PID_ATune::SetLookbackSec(int value)
{
	if (value < 1)
		value = 1;

	if (value < 25)
	{
		nLookBack = value * 4;
		sampleTime = 250;
	}
	else
	{
		nLookBack = 100;
		sampleTime = value * 10;
	}
}

int PID_ATune::GetLookbackSec()
{
	return nLookBack * sampleTime / 1000;
}