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Unread 10-02-2012, 14:13
twiggzee twiggzee is offline
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Re: Hall Effect Latch as an encoder/counter?

Our team is considering using this as an encoder/counter as well. my concern is that it might not work as well at high speeds.

if, for example, a wheel was rotating at 5000 rpm = 83 rps = 0.083 rp(ms) and the teleop loop runs every 20 ms, then that would mean that the wheel would have spun 1.67 times before the next cycle in the teleop loop. wouldn't that mean that we will miss a revolution every now and then?

by those calculations, the max speed of a wheel that the sensor could measure is 1/20 rp(ms) = 50 rps = 3000 rpm???

on top of that, the hall effect sensor we have is latching meaning it turns on when a north pole passes it and turns off when a south pole passes it (i might have that backwards). so that means it actually has to count twice as fast and max speed of the wheel is only half of that 3000 rpm.

is this the right thinking? i'm kind of new with coding sensors so excuse me if this is totally wrong.

we're using a banebots motor with an enclosed cim-u-later gearbox so we can't mount it anywhere else other than the wheel. we're trying to avoid having another auxiliary gear system just for the sensor (that's why we can't use an encoder).

any ideas on how to get around this in the code? or perhaps a different sensor (other than an encoder)?
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