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Topic: Distance values from rangefinder output (Read 333 times) previous topic - next topic

CarstenT

Hej All

I've tried to convert Sharp Rangefiner measurements to distance values.
I read
http://www.acroname.com/robotics/info/articles/irlinear/irlinear.html
but didn't really get it, so, I went my own way. The outcome turns out to be ever so good, so I'll share it with you.

The graph  y = 1/x passes (1,1) with a dx/dy of -1
I've assumed that a scaled graph that the rangefinder should conform to could tell something importent at the point on the graph, where dx/dy = -1.
I find the point at x,y = (108,113) and plotting the graph
y = (108*113)/x    ...   is almost BULLSEYE  ...

https://skydrive.live.com/?cid=382e99b169b58267#cid=382E99B169B58267&id=382E99B169B58267%21201

Measured points are green
Calculated points are red
dx/dy are blue

The topmost measuremets are a bit off, so I decided to fiddle a little and changed it to 108 * 113 / (x + 2000 / (x * x))
And my jaw dropped when I saw that the curve turns around at the top point and follows the steep line down to (0,0) .. appearantly showing the all to close points (2-15 cm) conform to the curve too.
I cannot download pictured curve to show the amazing fit, and this editor doesn't work properly either, so you'll just have to try it out yourself

CarstenT

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