Indoor/sensors/imu/StepDetection3.h

/*
 * © Copyright 2014 – Urheberrechtshinweis
 * Alle Rechte vorbehalten / All Rights Reserved
 *
 * Programmcode ist urheberrechtlich geschuetzt.
 * Das Urheberrecht liegt, soweit nicht ausdruecklich anders gekennzeichnet, bei Frank Ebner.
 * Keine Verwendung ohne explizite Genehmigung.
 * (vgl. § 106 ff UrhG / § 97 UrhG)
 */

#ifndef STEPDETECTION3_H
#define STEPDETECTION3_H


#include "AccelerometerData.h"
#include "../../data/Timestamp.h"

#include <cmath>
#include <vector>

#ifdef WITH_DEBUG_PLOT
	#include <KLib/misc/gnuplot/Gnuplot.h>
	#include <KLib/misc/gnuplot/GnuplotSplot.h>
	#include <KLib/misc/gnuplot/GnuplotSplotElementLines.h>
	#include <KLib/misc/gnuplot/GnuplotPlot.h>
	#include <KLib/misc/gnuplot/GnuplotPlotElementLines.h>
	#include <KLib/misc/gnuplot/GnuplotPlotElementPoints.h>
#endif

#ifdef WITH_DEBUG_OUTPUT
	#include <fstream>
#endif

#include "../../Assertions.h"
#include "../../math/dsp/iir/BiQuadStack.h"
#include "../../math/FixedFrequencyInterpolator.h"
#include "../../math/DelayBuffer.h"


/**
 * simple step detection based on accelerometer magnitude.
 * interpolated to a fixed frequency
 * passed through IIR filter
 * searching for zero crossings that follow a peak value
 * that is above a certain threshold
 */
class StepDetection3 {

	static constexpr float gravity = 9.81;
	static constexpr float stepRate_hz = 2.0;
	static constexpr float cutOff_hz = 3.0;
	static constexpr float iirQ = 0.70;

	static constexpr int sRate_hz = 100;
	static constexpr int every_ms = 1000 / sRate_hz;
	float threshold = 0.8;

	float max = 0;
	Timestamp maxTS;

private:

	FixedFrequencyInterpolator<AccelerometerData> interpol;
	IIR::BiQuadStack<float> biquad;
	DelayBuffer<float> lookBehind;



	#ifdef WITH_DEBUG_PLOT
		K::Gnuplot gp;
		K::GnuplotPlot plot;
		K::GnuplotPlotElementLines lineRaw;
		K::GnuplotPlotElementLines lineFiltered;
		K::GnuplotPlotElementPoints pointDet;
		Timestamp plotRef;
		Timestamp lastPlot;
	#endif

	#ifdef WITH_DEBUG_OUTPUT
		std::ofstream outFiltered;
		std::ofstream outSteps;
	#endif


public:

	/** ctor */
	StepDetection3(bool useBandPass) : interpol(Timestamp::fromMS(every_ms)), lookBehind(5) {

		//biquad.setBandPass(stepRate_hz, 1.5, sRate_hz);
		//biquad.preFill(gravity);

		if (useBandPass) {
			biquad.resize(3);
			biquad[0].setHighPass(1, 0.7, sRate_hz);
			biquad[1].setLowPass(3.0, 0.7, sRate_hz);
			biquad[2].setLowPass(3.0, 1.0, sRate_hz);
			//biquad.setBandPass(2, 3.0, sRate_hz);
			threshold = 0.6;	// needs a little reduction
		} else {
			threshold = 0.8;
			biquad.resize(1);
			biquad[0].setLowPass(3, 0.7, sRate_hz);
		}

		#ifdef WITH_DEBUG_PLOT
			gp << "set autoscale xfix\n";
			plot.setTitle("Step Detection");
			plot.add(&lineRaw); lineRaw.getStroke().getColor().setHexStr("#0000FF");
			plot.add(&lineFiltered); lineFiltered.getStroke().getColor().setHexStr("#000000");
			plot.add(&pointDet); pointDet.setPointSize(2); pointDet.setPointType(7);
		#endif

		#ifdef WITH_DEBUG_OUTPUT
			outFiltered = std::ofstream("/tmp/sd2_filtered.dat");
			outSteps = std::ofstream("/tmp/sd2_steps.dat");
		#endif

	}

	/** does the given data indicate a step? */
	bool add(const Timestamp ts, const AccelerometerData& acc) {

		bool gotStep = false;

		// accel-data incoming on a fixed sampling rate (needed for FIR to work)
		// NOTE!!!! MIGHT TRIGGER MORE THAN ONCE PER add() !!!
		auto onResample = [&] (const Timestamp ts, const AccelerometerData data) {

			bool step = false;
			const float mag = data.magnitude();

			// apply filter
			const float fMag = biquad.filter(mag - 9.81);	// remove gravity

			// history buffer
			float fMagOld = lookBehind.add(fMag);

			// zero crossing?
			float tmp = max;
			if (fMagOld > 0 && fMag < 0) {
				if (max > threshold) {
					step = true;
					gotStep = true;
				}
				lookBehind.setAll(0);
				max = 0;
			}



			// track maximum value
			if (fMag > max) {max = fMag; maxTS = ts;}

			#ifdef WITH_DEBUG_OUTPUT
				if (step) {

//					// track delay due to zero crossing
//					const float tsDelay = ts.ms() - maxTS.ms();
//					std::cout << "step at " << ts.ms() << ". delay due to zero crossing: " << tsDelay << std::endl;

					outSteps << maxTS.ms() << " " << tmp << "\n";
					outSteps.flush();
				}
				outFiltered << ts.ms() << " " << fMag << "\n";
			#endif

			#ifdef WITH_DEBUG_PLOT

				if (plotRef.isZero()) {plotRef = ts;}
				const Timestamp tsPlot = (ts-plotRef);
				const Timestamp tsOldest = tsPlot - Timestamp::fromMS(5000);

				lineRaw.add( K::GnuplotPoint2(tsPlot.ms(), mag) );
				lineFiltered.add( K::GnuplotPoint2(tsPlot.ms(), fMag) );

				if (step) {
					pointDet.add( K::GnuplotPoint2((maxTS-plotRef).ms(), tmp) );
				}

				if (lastPlot + Timestamp::fromMS(50) < tsPlot) {

					lastPlot = tsPlot;
					auto remove = [tsOldest] (const K::GnuplotPoint2 pt) {return pt.x < tsOldest.ms();};
					lineRaw.removeIf(remove);
					lineFiltered.removeIf(remove);
					pointDet.removeIf(remove);

					gp.draw(plot);
					gp.flush();
					usleep(100);

				}

			#endif

		};

		// ensure fixed sampling rate for FIR freq filters to work!
		interpol.add(ts, acc, onResample);

		return gotStep;


	}

};


#endif // STEPDETECTION3_H