FrankE
a2c9e575a2
- worked on about everything - grid walker using plugable modules - wifi models - new distributions - worked on geometric data-structures - added typesafe timestamps - worked on grid-building - added sensor-classes - added sensor analysis (step-detection, turn-detection) - offline data reader - many test-cases
140 lines
3.0 KiB
C++
140 lines
3.0 KiB
C++
#ifndef BAROMETER_H
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#define BAROMETER_H
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#include "../../data/Timestamp.h"
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#include "../../math/MovingAVG.h"
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#include "BarometerData.h"
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/**
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* calculates the pressure realtive to a startup-calibration of a barometer
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* hereafter all returned values are relative to the calibration
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*
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*/
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class RelativePressure {
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private:
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/** barometer history entries (timestamp -> value) */
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struct History {
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Timestamp ts;
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BarometerData data;
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History(const Timestamp ts, const BarometerData data) : ts(ts), data(data) {;}
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};
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/** barometer calibration helper */
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struct Calibration {
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Timestamp neededTimeframe = Timestamp::fromMS(5000);
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std::vector<History> history;
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bool isCalibrated = false;
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float baseAvg = 0;
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float sigma = 0;
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// prevent sensor-startup-issues and skip the first 25% of measurement values
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float skipStart = 0.25;
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void tryToCalibrate() {
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// determine the timeframe contained within the history
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const Timestamp timeframe = history.back().ts - history.front().ts;
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// do we have enough values to perform a calibration?
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if (timeframe < neededTimeframe) {return;}
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// we need double as float would lead to huge rounding errors!
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double sum = 0;
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double sum2 = 0;
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int cnt = 0;
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// calculate sum and sum²
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for (int i = (int)(skipStart*history.size()); i < (int)history.size(); ++i) {
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const History& h = history[i];
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sum += h.data.hPa;
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sum2 += ((double)h.data.hPa * (double)h.data.hPa);
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++cnt;
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}
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// calculate E(x) and E(x²)
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double avg = sum / (double)cnt;
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double avg2 = sum2 / (double)cnt;
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// set calibrated values
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this->baseAvg = avg;
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this->sigma = std::sqrt( avg2 - (avg*avg) );
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this->isCalibrated = true;
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}
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void reset() {
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history.clear();
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isCalibrated = false;
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sigma = 0;
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baseAvg = 0;
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}
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} calib;
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float latesthPa;
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public:
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/** ctor */
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RelativePressure() {
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}
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/** set the timeframe used for the startup calibration (e.g. 5 seconds) */
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void setCalibrationTimeframe(const Timestamp timeframe) {
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this->calib.neededTimeframe = timeframe;
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}
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/** add new sensor readings that were received at the given timestamp */
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void add(const Timestamp& ts, const BarometerData& baro) {
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// perform calibration?
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if (!calib.isCalibrated) {
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calib.history.push_back(History(ts, baro));
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calib.tryToCalibrate();
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}
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// most recent pressure reading
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latesthPa = baro.hPa;
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}
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/** get the most recent pressure reading realtive to the startup calibration. returns 0 until the sensor is calibrated */
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float getPressureRealtiveToStart() {
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if (calib.isCalibrated) {
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return latesthPa - calib.baseAvg;
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} else {
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return 0;
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}
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}
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/** reset the sensor's calibration */
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void reset() {
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calib.reset();
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}
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/** get the barometer's calibrated uncertainty determined during the startup calibration */
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float getSigma() {
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return calib.sigma;
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}
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/** get the barometer's calibrated average during the startup calibration */
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float getBaseAvg() {
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return calib.baseAvg;
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}
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private:
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};
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#endif // BAROMETER_H
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