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Indoor/sensors/imu/StepDetection.h
2018-10-25 11:50:12 +02:00

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/*
* © 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 STEPDETECTION_H
#define STEPDETECTION_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
#include "../../Assertions.h"
#include "../../math/MovingAverageTS.h"
//#include "../../math/dsp/fir/RComplex.h"
/**
* simple step detection based on accelerometer magnitude.
* magnitude > threshold? -> step!
* block for several msec until detecting the next one
*/
class StepDetection {
private:
MovingAverageTS<float> avgLong;
MovingAverageTS<float> avgShort;
Timestamp blockUntil;
bool waitForUp = false;
const Timestamp blockTime; // 150-250 looks good
const float upperThreshold = +0.4*0.8f; // + is usually smaller than down (look at graphs)
const float lowerThreshold = -1.5*0.8f; // the 0.8 is for testing!
#ifdef WITH_DEBUG_PLOT
K::Gnuplot gp;
K::GnuplotPlot plot;
K::GnuplotPlotElementLines lineDet;
K::GnuplotPlotElementPoints pointDet;
K::GnuplotPlotElementLines lineX;
K::GnuplotPlotElementLines lineY;
K::GnuplotPlotElementLines lineZ;
Timestamp plotRef;
Timestamp lastPlot;
#endif
public:
/** ctor */
StepDetection(const Timestamp blockTime = Timestamp::fromMS(200)) : blockTime(blockTime), avgLong(Timestamp::fromMS(500), 0), avgShort(Timestamp::fromMS(40), 0) {
#ifdef WITH_DEBUG_PLOT
gp << "set autoscale xfix\n";
plot.setTitle("Step Detection");
plot.add(&lineX); lineX.getStroke().getColor().setHexStr("#ff0000"); lineX.setTitle("accX");
plot.add(&lineY); lineY.getStroke().getColor().setHexStr("#00ff00"); lineY.setTitle("accY");
plot.add(&lineZ); lineZ.getStroke().getColor().setHexStr("#0000ff"); lineZ.setTitle("accZ");
plot.add(&lineDet); lineDet.getStroke().getColor().setHexStr("#000000");
plot.add(&pointDet); pointDet.setPointSize(2); pointDet.setPointType(7);
#endif
}
/** does the given data indicate a step? */
bool add(const Timestamp ts, const AccelerometerData& acc) {
// update averages
avgLong.add(ts, acc.magnitude());
avgShort.add(ts, acc.magnitude());
// difference between long-term-average (gravity) and very-short-time average
const float delta = avgShort.get() - avgLong.get();
bool step = false;
if (blockUntil > ts) {
step = false;
} else {
// wait for a rising edge
if (waitForUp && delta > upperThreshold) {
blockUntil = ts + blockTime; // block some time
waitForUp = false;
}
// wait for a falling edge
if (!waitForUp && delta < lowerThreshold) {
blockUntil = ts + blockTime; // block some time
waitForUp = true;
step = true;
}
}
#ifdef WITH_DEBUG_PLOT
if (plotRef.isZero()) {plotRef = ts;}
const Timestamp tsPlot = (ts-plotRef);
const Timestamp tsOldest = tsPlot - Timestamp::fromMS(5000);
//lines1.add( K::GnuplotPoint2((ts-ref).ms(), _delta) );
lineX.add( K::GnuplotPoint2(tsPlot.ms(), acc.x) );
lineY.add( K::GnuplotPoint2(tsPlot.ms(), acc.y) );
lineZ.add( K::GnuplotPoint2(tsPlot.ms(), acc.z) );
lineDet.add( K::GnuplotPoint2(tsPlot.ms(), delta) );
if (step) {
pointDet.add( K::GnuplotPoint2(tsPlot.ms(), 0) );
}
if (lastPlot + Timestamp::fromMS(50) < tsPlot) {
lastPlot = tsPlot;
auto remove = [tsOldest] (const K::GnuplotPoint2 pt) {return pt.x < tsOldest.ms();};
lineX.removeIf(remove);
lineY.removeIf(remove);
lineZ.removeIf(remove);
lineDet.removeIf(remove);
pointDet.removeIf(remove);
gp.draw(plot);
gp.flush();
usleep(100);
}
#endif
return step;
}
};
#endif // STEPDETECTION_H