\n
![](\"http:\/\/www.skippari.net\/projects\/wp-content\/uploads\/diameter_calibration_lut.png\")
<\/a><\/p>\nHere is a second degree polynom fitted to the points to see how accurate results could be had this way.<\/p>\n
For measuring the tree diameter there is a quadrature encoder connected to the track so that the encoder follows the amount of track opening and as a result gives a value relative to the diameter of the tree that is between the tracks. The encoder reading isn’t linear to the track opening so some calibration is needed.<\/p>\n
To get an idea of the relation between the encoder pulse values and the actual diameter some logs were measured and the readings written down.<\/p>\n
Here are the results. The line on top of the measured points is the result of a 10 point look up table fitted over the points. The relation between the pulse reading and actual diameter was more linear than I expected. Certain parts of the curve need some additional data points to verify the behaviour. Here is a second degree polynom fitted to the points to see how accurate results could be had this way.<\/p>\n
\n<\/a><\/p>\n