GP2Y0A02YK0F voltage to cm is not linear

[peterwallhead]

SOLVED

This caught me out.

The datasheet for this SharpIR sensor shows a non-linear mapping between the output voltage and distance, but this package uses an average linear mapping calculation. This causes lines that should be straight to become curved in scan plots.

I solved this by not using this package, but instead by writing 2 semi-linear maps that use data directly from the analogRead() which gives me a lot more accurate results:

int getDistance(int sensorPin, int numberOfSamplesToCollect, int samplingRate) {
  int distance = 0;
  int distancesSum = 0;

  for (int i = 0; i < numberOfSamplesToCollect; i++) {
    int analogSensorReading = analogRead(sensorPin);

    if(analogSensorReading > 200) {
      distance = map(analogSensorReading, 544, 200, 15, 60);
    } else {
      distance = map(analogSensorReading, 175, 81, 70, 150);
    }

    distancesSum += distance;

    delay(samplingRate);
  }

  int averageDistance = distancesSum / numberOfSamplesToCollect;

  return averageDistance;
}