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Indoor/sensors/imu/StepDetection2.h

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C++

#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/FIRComplex.h"
#include "../../math/FixedFrequencyInterpolator.h"
#include "../../math/LocalMaxima.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 = 75;
static constexpr int every_ms = 1000 / sRate_hz;
private:
FixedFrequencyInterpolator<AccelerometerData> interpol;
FIRComplex fir;
LocalMaxima locMax;
const float threshold = 0.5;
#ifdef WITH_DEBUG_PLOT
K::Gnuplot gp;
K::GnuplotPlot plot;
K::GnuplotPlotElementLines lineMag;
K::GnuplotPlotElementPoints pointDet;
Timestamp plotRef;
Timestamp lastPlot;
#endif
#ifdef WITH_DEBUG_OUTPUT
std::ofstream outFiltered;
std::ofstream outSteps;
#endif
public:
/** ctor */
StepDetection2() : interpol(Timestamp::fromMS(every_ms)), fir(sRate_hz), locMax(5) {
fir.lowPass(0.66, 40); // allow deviation of +/- 0.66Hz
fir.shiftBy(2); // typical step freq ~2Hz
#ifdef WITH_DEBUG_PLOT
gp << "set autoscale xfix\n";
plot.setTitle("Step Detection");
plot.add(&lineMag); lineMag.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 step = false;
auto onResample = [&] (const Timestamp ts, const AccelerometerData data) {
const float mag = data.magnitude();
const std::complex<float> c = fir.append(mag);
const float real = c.real();
if (real != real) {return;}
const float fMag = real;
LocalMaxima::Res res = locMax.add(fMag);
step = (res.isMax) && (res.val > threshold);
#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);
lineMag.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();};
lineMag.removeIf(remove);
pointDet.removeIf(remove);
gp.draw(plot);
gp.flush();
usleep(100);
}
#endif
};
interpol.add(ts, acc, onResample);
return step;
}
};
#endif // STEPDETECTION2_H