pid auto-tune

firmware/controllers/math/pid_auto_tune.cpp

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+/*
+ * pid_auto_tune.cpp
+ *
+ *  Created on: Sep 13, 2017
+ * @author Andrey Belomutskiy, (c) 2012-2017
+ */
+
+#include "pid_auto_tune.h"
+
+PID_AutoTune::PID_AutoTune() {
+	running = false;
+	nLookBack = 50;
+	oStep = 10;
+	noiseBand = 0.5;
+}
+
+int PID_AutoTune::Runtime() {
+	justevaled = false;
+	if (peakCount > 9 && running) {
+		running = false;
+		FinishUp();
+		return 1;
+	}
+
+	justevaled = true;
+	if (!running) {
+		//initialize working variables the first time around
+		peakType = 0;
+		peakCount = 0;
+		justchanged = false;
+		absMax = input;
+		absMin = input;
+		setpoint = input;
+		running = true;
+		outputStart = output;
+		output = outputStart + oStep;
+
+		for (int i = nLookBack - 1; i >= 0; i--) {
+			// default values for history array
+			lastInputs[i] = input;
+		}
+
+	} else {
+		if (input > absMax)
+			absMax = input;
+		if (input < absMin)
+			absMin = input;
+	}
+
+	//oscillate the output base on the input's relation to the setpoint
+
+	if (input > setpoint + noiseBand)
+		output = outputStart - oStep;
+	else if (input < setpoint - noiseBand)
+		output = outputStart + oStep;
+
+	return 0;
+}
+

firmware/controllers/math/pid_auto_tune.h

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+/*
+ * pid_auto_tune.h
+ *
+ * http://brettbeauregard.com/blog/2012/01/arduino-pid-autotune-library/
+ *
+ *
+ *  Created on: Sep 13, 2017
+ * @author Andrey Belomutskiy, (c) 2012-2017
+ */
+
+#ifndef CONTROLLERS_MATH_PID_AUTO_TUNE_H_
+#define CONTROLLERS_MATH_PID_AUTO_TUNE_H_
+
+class PID_AutoTune {
+public:
+	PID_AutoTune();
+	void reset();
+	void FinishUp();
+	int Runtime();
+	bool isMax, isMin;
+	/**
+	 * sensor position
+	 */
+	float input;
+	/**
+	 * actuator duty cycle
+	 */
+	float output;
+	/**
+	 * trigger line
+	 */
+	float setpoint;
+	float noiseBand;
+	//int controlType = 1;
+	bool running;
+	unsigned int peak1, peak2, lastTime;
+	//int sampleTime;
+	int nLookBack;
+	int peakType; // todo: convert to enum
+	float lastInputs[101];
+	float peaks[10];
+	int peakCount;
+	bool justchanged;
+	bool justevaled;
+	float absMax, absMin;
+	float oStep;
+	float outputStart;
+	float Ku, Pu;
+};
+
+#endif /* CONTROLLERS_MATH_PID_AUTO_TUNE_H_ */