huge commit

- 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

sensors/imu/StepDetection.h

@@ -0,0 +1,112 @@
+#ifndef STEPDETECTION_H
+#define STEPDETECTION_H
+
+
+#include "AccelerometerData.h"
+#include "../../data/Timestamp.h"
+
+#include <cmath>
+#include <vector>
+
+#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 "../../Assertions.h"
+
+
+/**
+ * simple step detection based on accelerometer magnitude.
+ * magnitude > threshold? -> step!
+ * block for several msec until detecting the next one
+ */
+class StepDetection {
+
+private:
+
+	/** low pass acc-magnitude */
+	float avg1 = 0;
+
+	/** even-more low-pass acc-magnitude */
+	float avg2 = 0;
+
+private:
+
+	class Stepper {
+
+	private:
+
+		/** block for 300 ms after every step */
+		const Timestamp blockTime = Timestamp::fromMS(300);
+
+		/** the threshold for detecting a spike as step */
+		const float threshold = 0.17;
+
+		/** block until the given timestamp before detecting additional steps */
+		Timestamp blockUntil;
+
+
+	public:
+
+		/** is the given (relative!) magnitude (mag - ~9.81) a step? */
+		bool isStep(const Timestamp ts, const float mag) {
+
+			// still blocking
+			if (ts < blockUntil) {
+				return false;
+			}
+
+			// threshold reached? -> step!
+			if (mag > threshold) {
+
+				// block x milliseconds until detecting the next step
+				blockUntil = ts + blockTime;
+
+				// we have a step
+				return true;
+
+			}
+
+			// no step
+			return false;
+
+		}
+
+
+	};
+
+	Stepper stepper;
+
+public:
+
+	/** does the given data indicate a step? */
+	bool isStep(const Timestamp ts, const AccelerometerData& acc) {
+
+		avg1 = avg1 * 0.91 + acc.magnitude() * 0.09;	// short-time average	[filtered steps]
+		avg2 = avg2 * 0.97 + acc.magnitude() * 0.03;	// long-time average	[gravity]
+
+		// average maginitude must be > 9.0 to be stable enough to proceed
+		if (avg2 > 9) {
+
+			// gravity-free magnitude
+			const float avg = avg1 - avg2;
+
+			// detect steps
+			return stepper.isStep(ts, avg);
+
+		} else {
+
+			return false;
+
+		}
+
+	}
+
+
+};
+
+
+#endif // STEPDETECTION_H