Position measurement problem using encoders
Position measurement problem using encoders
(OP)
Hello,
I am trying to measure the position from 2 linear encoders (XY Plance).
My hardware setup is such as:
2 Encoders (Heidenhain) provide sine wave position signal (signal period 2 µm, frequency appx. 50KHz ). Signal is then digitized and interpolated (Sine wave to TTL, 200 times) using an interpolator box (Heidenhain). Position is then calculated using a counter board.
But I do not getting correct position signal. Encoders are used to trace a circular motion. But recorded motion is an uneven circle with incorrect scale.
What could be the possible reason?
I would be thankful for any suggestion.
Simasa
I am trying to measure the position from 2 linear encoders (XY Plance).
My hardware setup is such as:
2 Encoders (Heidenhain) provide sine wave position signal (signal period 2 µm, frequency appx. 50KHz ). Signal is then digitized and interpolated (Sine wave to TTL, 200 times) using an interpolator box (Heidenhain). Position is then calculated using a counter board.
But I do not getting correct position signal. Encoders are used to trace a circular motion. But recorded motion is an uneven circle with incorrect scale.
What could be the possible reason?
I would be thankful for any suggestion.
Simasa





RE: Position measurement problem using encoders
If the diameter is relatively large, 100 mm or so, the mechanical problems usually are easily mastered. You have to turn to the manufaturer for advice. Those encoders are not known to have any problems.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Position measurement problem using encoders
I just thought about the possibility that the input frequency of 50 KHz might be high for the interpolator (200 times interpolation). May be I should try to reduce the interpolation factor (not sure).
could it be a possible reason?
I would be thankful for some further suggestion.
simasa
RE: Position measurement problem using encoders
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Position measurement problem using encoders
It seems violating the allowable input frequency range.
Would be the reason?
Some extra detail: Position output signal of X and Y motion should appear to be proper sine wave form (As motion along XY-Plane is a circular motion). I am getting a kind of sine wave with sharp edges.
I would be thankful for some further suggestion.
simasa
RE: Position measurement problem using encoders
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Position measurement problem using encoders
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The IBV660B limitation is the output edge speed.
12,500 x 200 x 4 = 10,000,000 edges/sec which is the maximum edge rate out of the IBV660B
The encoder signals are adjusted for amplitude, etc. via Pots in the APE boxes at the end of the encoder read head cable. Heidenhain sells calibration units to use to do this.