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Unread 14-04-2005, 07:49
Dave Garnett Dave Garnett is offline
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Re: How to measure low velocity

The first thing you need to do is establish wether the sensor will actually give a valid reading at these low levels - the specs do not give any values for 'hysteresis' which might be an issue.

So, set up an op amp with some gain (eg x 20) and look at the amplified readings - don't worry about the reduced range at this point. This should show you if the sensor actually registers the motion. [Watch out for noise and drift - alternate readings for stationary, clockwise and counterclock] You could do all this with a quality voltage meter instead, of course.

If the sensor actually works at these levels, then you could implement a dual channel readback - in parallel with your normal +- 150 deg channel, add a channel with some gain centered about the null position. In operation this channel will saturate at high turn rates, but you have the readings from the other channel. Of course you will need a strategy to select which reading to use, as well as thinking about compensating for zero offset and drift.

good luck !