GY-63_MS5611/libraries/AverageAngle

AverageAngle

Arduino library to calculate correctly the average of multiple angles.

Description

AverageAngle is a class to calculate the average of angles.

This is especially useful when angles are around 0 degrees, e.g. from a compass sensor or the resultant of a track. Example, the average angle of 359 and 1 is 0, not 179 (most of the time)

Furthermore the AverageAngle can also include the length (weight) of the angle as if it is a vector. Default this length is set to 1 so all angles are by default of equal weight.

Example: The average angle of 359 (length = 2) and 1 (length = 1) is 359.something not zero.

The average angle is calculated by converting the added angle (in DEGREES, etc) to polar coordinates. These (x,y) are added to a (sumX, sumY) and divided by the number of angles added so far.

Related to

• https://github.com/RobTillaart/Angle
• https://github.com/RobTillaart/AngleConvertor
• https://github.com/RobTillaart/runningAngle

AngleType

• enum AngleType { DEGREES, RADIANS, GRADIANS } idem.

value	name	range
0	DEGREES	0 .. 360
1	RADIANS	0 .. 2PI
2	GRADIANS	0 .. 400

Interface

• AverageAngle(AngleType type = DEGREES) constructor defaults to degrees.
• uint32_t add(float alpha, float length = 1.0) add a new angle, optional with length other than 1. Returns the number of elements (count).
• void reset() clears internal counters.
• uint32_t count() the amount of angles added. If count == 0, there is no average.
• float getAverage() returns the average, unless count == 0 or the internal sums == (0,0) in which case we have a singularity ==> NAN (not a number)
• float getTotalLength() the length of the resulting 'angle' when we see them as vectors. If count == 0 ==> total length = 0.
• float getAverageLength() returns the average length of the angles added. If count == 0 ==> average length = 0.
• AngleType type() returns DEGREES, RADIANS or GRADIANS.
• void setType(AngleType type) changes type DEGREES, RADIANS or GRADIANS. Type can be changed run time and still continue to add.

Gradians

Gradians a.k.a. gon, is a less often used unit for angles. There are 100 gradians in a right angle. A full circle = 400 gradians.

https://en.wikipedia.org/wiki/Gradian

Operation

If you want to average 5 compass readings you can just add the angles and do not use the length parameter.

  AA.reset();
  for (int i = 0; i < 5; i++)
  {
    AA.add(compass.readHeading());
    delay(100);    // e.g. compass read needs some time
  }
  Serial.println(AA.getAverage());

If you want to average a track, e.g. 5 steps North, 3 steps west etc, you need to include the length of each step.

  AA.reset();
  AA.add(90, 5);     // 5 steps north
  AA.add(180, 3);    // 3 steps west
  Serial.println(AA.getAverage());
  Serial.println(AA.getTotalLength());

If you want to average an angle in DEGREES and an angle in RADIANS, just change the type runtime.

  AA.reset();
  AA.setType(DEGREES);
  AA.add(90);
  AA.setType(RADIANS);
  AA.add(PI/3);
  AA.setType(DEGREES);
  Serial.println(AA.getAverage());

Warning

As the internal representation has a limited resolution (float) it can occur that when the internal values are large, one cannot add a very small angle any more. Did not encounter it yet myself.

Future

Must

Should

Could

• add a USER AngleType, in which the user can map 0..360 degrees to any range.
  • float userFactor = 1.0; (default)
  • can even be negative?
  • use cases? e.g 0..4 quadrant?