141 lines
3.0 KiB
C++
141 lines
3.0 KiB
C++
/*
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* pid_auto_tune.cpp
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*
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* Created on: Sep 13, 2017
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* @author Andrey Belomutskiy, (c) 2012-2018
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*/
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#include "pid_auto_tune.h"
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#include "efilib.h"
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PID_AutoTune::PID_AutoTune() {
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running = false;
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nLookBack = 50;
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oStep = 10;
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noiseBand = 0.5;
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Ku = NAN;
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Pu = NAN;
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}
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void PID_AutoTune::FinishUp() {
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Ku = 4 * (2 * oStep) / ((absMax - absMin) * 3.14159);
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Pu = (float) (currentPeakTime - prevPeakTime) / 1000.0; // converting ms to seconds
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}
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int PID_AutoTune::Runtime(Logging *logging) {
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justevaled = false;
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if (peakCount > 9 && running) {
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running = false;
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FinishUp();
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return 1;
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}
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justevaled = true;
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if (!running) {
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//initialize working variables the first time around
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peakType = 0;
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peakCount = 0;
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absMax = input;
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absMin = input;
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setpoint = input;
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running = true;
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dataPointsCount = 0;
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outputStart = output;
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output = outputStart + oStep;
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for (int i = nLookBack - 1; i >= 0; i--) {
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// default values for history array
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lastInputs[i] = input;
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}
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} else {
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if (input > absMax)
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absMax = input;
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if (input < absMin)
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absMin = input;
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dataPointsCount++;
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}
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//oscillate the output base on the input's relation to the setpoint
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float prevOutput = output;
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if (input > setpoint + noiseBand)
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output = outputStart - oStep;
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else if (input < setpoint - noiseBand)
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output = outputStart + oStep;
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if (output != prevOutput) {
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scheduleMsg(logging, "direction change %.2f", output);
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}
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bool isMax = true; // is current input max value for the known input history?
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bool isMin = true; // is current input min value for the known input history?
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//identify peaks
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for (int i = nLookBack - 1; i >= 0; i--) {
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float val = lastInputs[i];
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if (isMax)
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isMax = input >= val;
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if (isMin)
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isMin = input <= val;
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lastInputs[i + 1] = lastInputs[i];
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}
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lastInputs[0] = input;
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if (dataPointsCount < 9) { //we don't want to trust the maxes or mins until the inputs array has been filled
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return 0;
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}
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if (isMax || isMin) {
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scheduleMsg(logging, "min %d max %d %.2f peakType=%d", isMin, isMax, input, peakType);
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}
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bool directionJustChanged = false;
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if (isMax) {
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if (peakType == 0)
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peakType = 1;
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if (peakType == -1) {
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peakType = 1;
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directionJustChanged = true;
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}
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// peaks[peakCount] = input; we are not using max peak values
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} else if (isMin) {
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if (peakType == 0)
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peakType = -1;
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if (peakType == 1) {
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peakType = -1;
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prevPeakTime = currentPeakTime;
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currentPeakTime = currentTimeMillis();
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directionJustChanged = true;
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if (peakCount < 10) {
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peakCount++;
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peaks[peakCount] = input;
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} else {
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// todo: reset peak counter maybe?
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}
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}
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}
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if (directionJustChanged && peakCount > 2) { //we've transitioned. check if we can autotune based on the last peaks
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float avgSeparation = (absF(peaks[peakCount - 0] - peaks[peakCount - 1])
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+ absF(peaks[peakCount - 1] - peaks[peakCount - 2])) / 2;
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if (avgSeparation < 0.05 * (absMax - absMin)) {
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FinishUp();
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running = false;
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return 1;
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}
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}
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return 0;
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}
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