Velocity measurement from low resolution encoders

Question

Hi, I have 1024 pulse/1rotation encoders. I want to calculate or estimate angular velocity from this low resolution encoders. When I use dx/dt(derivative.vi)  there are high and low readings which obviously seem wrong to me.I want to have a more smooth and accurate reading(and without much delay). Is there an efficient and accurate way of reading velocity measurements from this low resolution encoders? FOr example does Ni/Motion help? Or is there a velocity measurement .vi ?
Thank you.

Answer 1

As far as I remember (*) , the FP-QUAD will measure the velocity by counts during a fixed time slot. The maximum time is (was?) 26.??ms.
Your resolver has 1024 pulses (I assume 2 pulse streams with 90° shift) , the QUAD will count pulse edges, so you get 4096 counts per revolution. Together with the integration time (26.??ms), you get a resolution of 38.15 counts/s (See manual of the FP-QUAD) or an error of +/- 0.559 RPM
Of course you can read the 32bit counter of the QUAD in a user defined time periode and calculate the velocity.
If you have real slow movements, you can measure the time between each pulse. The accuracy will depend on the quality of your resolver and the resolution of your timer, however I think this couldn't be done with the FP-QUAD.
* My last task with FP-QUAD was 4 years ago, maybe new firmware and driver give you more choices now
Greetings from Germany
Henrik
LV since v3.1
“ground” is a convenient fantasy
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