Indoor/sensors/imu/StepDetection2.h

#ifndef STEPDETECTION2_H
#define STEPDETECTION2_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/dsp/fir/Real.h"
//#include "../../math/dsp/fir/RealFactory.h"
#include "../../math/FixedFrequencyInterpolator.h"
#include "../../math/LocalMaxima.h"
#include "../../math/MovingAverageTS.h"


/**
 * simple step detection based on accelerometer magnitude.
 * magnitude > threshold? -> step!
 * block for several msec until detecting the next one
 */
class StepDetection2 {

	static constexpr int sRate_hz = 100;
	static constexpr int every_ms = 1000 / sRate_hz;

private:

	FixedFrequencyInterpolator<AccelerometerData> interpol;
	//FIR::Real::Filter fir;
	IIR::BiQuadStack<float> biquad;
	LocalMaxima locMax;

	// longterm average to center around zero
	MovingAverageTS<float> avg = MovingAverageTS<float>(Timestamp::fromMS(2000), 0);

	float threshold = 0.50;

	float curFiltered = 0;

	#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 */
	StepDetection2(bool useBandPass) : interpol(Timestamp::fromMS(every_ms)), locMax(8) {

		//fir.lowPass(0.66, 40);	// allow deviation of +/- 0.66Hz
		//fir.shiftBy(2.00);			// typical step freq ~2Hz

		//fir.lowPass(3.5, 25);		// everything up to 3 HZ

		//FIR::Real::Factory fac(sRate_hz);
		//fir.setKernel(fac.getBandpass(0.66, 2.0, 40));

		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

	}

	float getCurFiltered() const {
		return curFiltered;
	}

	/** 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)
		auto onResample = [&] (const Timestamp ts, const AccelerometerData data) {

			const float mag = data.magnitude();
			Assert::isNotNaN(mag, "detected NaN magnitude");

			// use long-term average to center around zero
			avg.add(ts, mag);
			const float mag0 = mag - avg.get();


//			const float f = fir.append(mag0);
//			if (f != f) {return;}
			const float f = biquad.filter(mag0);
			const float fMag = f;
			curFiltered = fMag;
			Assert::isNotNaN(fMag, "detected NaN filtered magnitude");

			const bool isMax = locMax.add(fMag);

			const bool step = (isMax) && (locMax.get() > threshold);
			if (step) {gotStep = true;}

			#ifdef WITH_DEBUG_OUTPUT
				if (step) {
					outSteps << ts.ms() << " " << fMag << "\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(tsPlot.ms(), fMag) );
				}

				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

		};

		//qDebug() << ts.ms() << " ---" << acc.x << " " << acc.y << " " << acc.z;

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

		return gotStep;


	}

};


#endif // STEPDETECTION2_H