Subject:
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Re: super cheap tilt sensor?
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 23 May 2002 12:27:01 GMT
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Original-From:
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PeterBalch <peterbalch@compuserve.SAYNOTOSPAMcom>
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Viewed:
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681 times
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A polaroid filter attached to a pendulum works very well indeed.
You need a lightbulb, a piece of polaroid attached to a pendulum, a fixed
piece of polaroid then a photoresistor. I've made tilt-sensors like that
and they're reliable but, of course, still have problems with inertia and
momentum.
Decades ago, I used to attach sensors to each joint of a crab's leg to
investigate how they swam. Everything had to be tiny and immune to
seawater. I used a "grain of wheat" lightbulb on one side of the joint and
a photo-transistor on the other. As the distance between them varied, you
got a measure of the angle of the joint. You could do the same with a
pendulum.
I recall once glueing a 1mm dia glass tube onto a Selenium solar-cell so as
to measure the level of a (dark) liquid in the tube. In your case, the tube
could be half of a U-tube to measure tilt. It didn't work very well but a
Cadmium-sulphide photoresistor or a photodiode would probably work far
better (photoresistors have a more linear response).
Peter
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