Chief Delphi - Encoders and distance (labview)

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MorbidAngel

23-11-2008 10:11

Encoders and distance (labview)

I'm trying to program for autonomous, using the encoders. However, the formula I'm using for finding the right number of ticks for one inch and such isn't working. Does anyone have a formula, or an input value for a distance of one inch? I'm using LabVIEW. Help me please ^^

Kevin Sevcik

23-11-2008 11:51

Re: Encoders and distance (labview)

If you're using the encoder VIs, then they should be doing 4x decoding. That is, they'll return 4 ticks for every cycle of the encoder. So if your encoder is 1024 pulses/cycles per revolution, the VI will actually read 4096 ticks per revolution. After that, it's just properly figuring how many inches you have per revolution.

billbo911

23-11-2008 11:53

Re: Encoders and distance (labview)

Quote:

Originally Posted by MorbidAngel (Post 777056)

This is difficult to do without more information. Needed is: Ticks/rev of the encoder used, Gear ration in the drive AFTER the encoder has sampled, wheel diameter.

Tom Bottiglieri

23-11-2008 12:18

Re: Encoders and distance (labview)

The formula you are looking for is this

Code:

distance = (ticks) * (Gear Ratio) * (wheel diameter * pi)/(ticks per rev * scale)

Where Gear ratio is amount of times the wheel spins per amount of times the encoder spins, and scale is 4 (per what Kevin said above).

As I last saw them, the WPI Robotics Library encoder VI's had provisioning for real world unit distance feedback. The VI's had setters and getters for the gear ratio and distance travelled, respectively.

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