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Unread 27-12-2007, 12:47
Steve_Alaniz Steve_Alaniz is offline
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Re: Gear Tooth Sensor

Quote:
Originally Posted by Bomberofdoom View Post

I think I might have a question about the "two sensors" thing. I belive the GTS has those "two sensors" (as in Phase A and Phase B) inside them, is that correct?
NO... the Gear Tooth sensor only give ONE signal. The Quadrature output refers to a device that can give two signals with one being 90 degrees from the other. IF you could use TWO GTS sensors and align one so that it peaks 90 degrees after the other then you could use the Quad scheme for direction.
Single GTS is intended to give you theoretical distance traveled on a wheel but you keep track of direction by knowing WHICH direction you are driving the motor.
IN other words if my PWM is > 127 and I get a signal I add to my counter... < 127 and I get a signal then I subtract from the count. Same with a relay driving a motor. if the forward direction is set and the interrupt occurs you add to the count...well you get the idea.
Rotary optical encoder have two sensors built in at 90 degree offsets so they are very accurate and directional information comes from knowing what the previous state was... or in hardware by using a simple flipflop. clocked by the A phase. (See the banebot encoder schematic for their divider page 5 of the manual http://banebots.com/pc/ELECTRONICS/EN-A0001-KT )
Now ALL this tells you how much the motor and wheel have rotated but do not take into account slippage of the wheel to the ground, so one more "fly in the ointment" ( Where do we get these old sayings anyway? )

OK that's my piece for now

Steve