This project aimed for the derivation of an output function for SHARP IR sensor (GP2Y0A21YK0F) in order to convert the raw value to meaningful distance.

SHARP IR sensor (GP2Y0A21YK0F) outputs a raw value which is not linearly correlated with the distance. So, a non-linear function is needed to output the distance from raw value.

The distance measureing characteristics (output) of GP2Y0A21YK0F is shown below:

The experiment is designed with a fixed opaque obstacle, a ruler for distance measurement and the sharp IR sensor. Matlab Arduino Support Package and Curve Fitting Toolbox was used respectively for Arduino Nano-Matlab connectivity and curve fitting.

• Total 25 distance data of the obstacle and the sensor was recorded from the physical scale to the Matlab input prompt.
• The corresponding sensor raw ADC value was recorded simultaneously.
• Curve Fitting Toolbox was used on the recorded ADC value and measured distance following the settings.

Fitting Characteristics= Rational
Numerator degree= 0
Denominator degree= -1

General model Rat01:
     f(x) = (p1) / (x + q1)
Coefficients (with 95% confidence bounds):
       p1 =        4835  (4723, 4948)
       q1 =      -28.76  (-33.52, -24)

Goodness of fit:
  SSE: 1.701
  R-square: 0.9987
  Adjusted R-square: 0.9986
  RMSE: 0.272

Derived output function:

The output function resembles the output characteristics of the sensor within 10-80 cm distance.