Re: measuring tilt

Gordon McComb <NOSPAMgmccomb@xxxxxxxxxxxxxxxxx> wrote in
news:42C4C04B.3746@xxxxxxxxxxxxxxxxx:

> Michael Noone wrote:
>>
>> Hi - in a machine I'm working on I need to be able to measure tilt -
>> as in what angel the robot is at with respect to the earth. I've seen
>> those sensors that have a conductive fluid in them (mercury maybe?) -
>> but I don't think those would work well as this machine will be
>> moving around quite a bit. So - does anybody have any suggestions?
>> Thanks!
>
> Sharp makes some indexpensive tilt switches (about $2 each from
> Digikey) that you can mount on an arc to measure discrete tilt from,
> say, 0 to 90 degrees. The extents depend on the number and angle of
> the switches you mount. These switches are really optical slotted
> switches, with a ball in the slot. They're pretty cool.
>
> If you need more accuracy, there's always an accellerometer, like the
> Memsic units ($29 from Parallax), or the slighly more expensive
> ADXL202 module that lots of folks sell. You can still get the surface
> mount version of these directly from Analog, I believe, on a samples
> request.
>
> -- Gordon
>

The sharp sensor would be fairly sensitive to vibrations and sudden
movement, correct?

An accellerometer sounds like it might be a good idea. Correct me if I'm
wrong - but I'll need a 3 axis accelerometer chip, right? It's
unfortunate there seem to be so few 3 axis chips on the market -
Analog's only one is delayed till september apparently - which is too
long of a wait for me. Kionix makes a very nice looking chip:
http://www.kionix.com/Product%20Sheets/KXP74%20Series.pdf - seems the
primary challenge will be finding a distributor for the bugger. (already
e-mailed all the ones listed on their website - here's to hoping I
actually get a response from one of them) It even uses SPI which is
perfect for me as my whole machine is wired for SPI communication
between everything, so it'll fit in quite nicely.

How sensitive would an accellerometer be to vibrations and sudden
movements?

Thanks Gordon,



-Michael J. Noone
.

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