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Tilt sensor

Discussion in 'Electronic Design' started by [email protected], Apr 10, 2006.

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  1. Guest

    Hi,

    Some of my students need to use a tilt sensor for their project.
    Unfortunatley they need a sensor with a continuous output to measure
    the angle of tile over a wide range ( +/- 60).

    Can anybody suggest a sensor that measure tilt yet it is still cost
    effective or maybe a homebrewed method that gives similar results.
    Accuracy is not an issue here, 2 degrees tolerance is allowed.

    Any idea will help!

    Thanks

    Regards

    Joseph
     
  2. Slurp

    Slurp Guest

    Have you considered a pot with a weight hanging from the spindle?
     
  3. Nico Coesel

    Nico Coesel Guest

    How about a joystick with potmeters? Remove the springs. Mount it with
    the stick facing the earth and attach a small wheight to the stick.
    Now the stick will always point to the earth.
     
  4. Sjouke Burry

    Sjouke Burry Guest

    Use an incremental pulse potentiometer,with a small
    weight hung onto the shaft.
    (example:SHARP GP-1R52C 360 pulses/rotation)
     
  5. John Larkin

    John Larkin Guest


    As mentioned, a pot with a weight would be cheap and easy to signal
    condition.

    These are electrolytic:

    http://www.frederickscom.com/products/tilt_overview.html


    Or I suppose you could use mems accelerometers, Analog Devices maybe.

    John

    John
     
  6. John_H

    John_H Guest

  7. Roy L. Fuchs

    Roy L. Fuchs Guest

    You used to cook your soup with a plumbed pot? Hehehhe... just
    kidding.

    Most pots have a fair amount of resistance to turning.

    A round slit wheel, and optical sensor array would work. Those found
    in old mice might work, but probably don't resolve well enough. The
    slit wheel from the back of an old industrial motor (surplus) will
    resolve to single or half degrees usually. Some have a dual,
    staggered sensor so the wheel slit resolution gets doubled.

    An analog version might be the tried and true pinball machine tilt
    mechanism with a capacitive sensor in the ring section. That will
    sense any tilt in any direction, but without sectoring it, you would
    only know the amount of tilt, not the direction. With a sectored ring,
    and quite a bit more circuitry, you could detect tilt amount and
    direction.
     
  8. Roy L. Fuchs

    Roy L. Fuchs Guest

    Great transducer as long as all resistance (damping) to movement and
    any return to center springs are removed. Then, the problem of the
    read circuitry comes into it. Probably only a slight variant of the
    calibration applets old joysticke used to come with. Most of those
    gave coordinate readout. One would have to read all four pots at all
    times, and extrapolate tilt value and direction from the four
    readings. Also, it would likely only work with a fairly big (heavy)
    bob on a fairly long rod. His package size requisite wasn't
    mentioned.
     
  9. Roy L. Fuchs

    Roy L. Fuchs Guest

    If the weight could turn the damped shaft, the sensor would only
    give answers in one plane. Do pulse pots have sub two degree
    signaling?
     
  10. Sjouke Burry

    Sjouke Burry Guest

    No ,just use two perpendicular pots,if you want,
    however I dont see a request for a 2 directional
    tilt measurement.
     
  11. Christopher

    Christopher Guest


    Hello Joseph,
    I could never match the talent of all these engineers but as a garage
    hack and homebred tinkerer your singing my song. :)

    Take a 2.5" (6.25 cm) clear plastic bottle, fill halfway with water.
    Make yourself a calibrated strip to stick on the side, zero would be
    at the exact point of level water. Tilt it to 60 degrees either way
    and mark it. I would imagine the scale and the rest of the markings
    would be linear. You could also use a 1" or larger pvc pipe glued in
    the center vented for water flow to force the water to stabilize
    quicker. Electronically you could do fancy things to monitor the
    water's angle relative to the walls. A larger diameter bottle will
    give you a greater sweep distance per tilt angle.

    It's 3am, I will wake up tomorrow and go "what was I thinking"

    Just a thought,



    * * *
    Christopher

    Temecula CA.USA
    http://www.oldtemecula.com
     
  12. Tom

    Tom Guest

    schreef:
    You can use a dual-axis accelerometer, e.g. ADXL311 from Analog
    Devices: accuracy to 0.1 degree of inclination, available from Digikey
    for $8.5 in ones.

    greetings,
    Tom
     
  13. Zak

    Zak Guest


    I'd go for pins from the top and a strip at teh bottom. The strip at the
    bottom is ground; measure teh conductifity from the two other pins that
    are more-or-less inserted in water (or other liquid).


    Thomas
     
  14. Nico Coesel

    Nico Coesel Guest

    Calibration is easy. Hold the entire contraption in the 'zero'
    position and hit 'zero' on the read-out device/application. Besides,
    PC style joysticks have 2 potmeters which are directly to the PC.
     
  15. Nico Coesel

    Nico Coesel Guest

    I think you will run into huge errors with this method when the angles
    are small due to noise and inaccuracies in the accelerometers.
     
  16. John_H

    John_H Guest

    Which is why appropriate noise filtering is required in an
    accelerometer-based system.

    The Analog Devices accelerometers have noise specified 320 ?g/rtHz or less.
    I can't find noise data on the ST parts but a 3-axis accelerometer with
    digital output has settable decimation values for bandwidths down to 10 Hz.
     
  17. John_H

    John_H Guest

    sorry... 300 ug/rtHz (micro-g)
     
  18. Roy L. Fuchs

    Roy L. Fuchs Guest

    What makes you think a PC is being used? I was talking about using
    the calibration software as a primer for the software he would need to
    write to do the job.
     
  19. Roy L. Fuchs

    Roy L. Fuchs Guest

    He merely said "tilt". On a pinball machine, that is any direction.
    In industry, it likely refers to any direction as well.

    Two pots would require two swing bobs, and would have to be
    separated, and both would have to be read to extrapolate the answer.

    This suggestion is very similar to the joystick suggestion, but much
    more obtrusive.
     
  20. Roy L. Fuchs

    Roy L. Fuchs Guest

    Nice item, but it also requires a lot of support circuitry, as well
    as software. Hell a G force resolver would work, if you want to get
    into advanced technical solutions.
     
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