Subject:
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Re: measure motor torque with a light sensor
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 29 Jan 1999 13:46:09 GMT
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Viewed:
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860 times
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Ben Erwin writes:
> If you hook the motor to an input and then set up the input to read
> light sensor - you can measure the retarding torque on the motor (100 is
>
> stopped, 0 is free) (this from Chris Rogers)
>
> -Ben
Actually you are measuring the speed of the motor. For DC motors the current
is linear with torque and the speed is linear with voltage. If you just hook
the motor to the input, you made a tachometer. It will only work in one
rotation direction. The RCX doesn't read negative voltages.
I assume you didn't hook a powered motor to the input. I suppose this is
possible without hurting anything, but at any output power level but full, the
results will be very mixed readings. The PWM and the input measurement are
synchronized as discovered by Paul Haas. At times the Light level would be 100
(0V) and other times the actual motor voltage.
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Message is in Reply To:
 | | measure motor torque with a light sensor
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| If you hook the motor to an input and then set up the input to read light sensor - you can measure the retarding torque on the motor (100 is stopped, 0 is free) (this from Chris Rogers) -Ben (26 years ago, 28-Jan-99, to lugnet.robotics)
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