Re: [mowbot] Bumper switches

Paul Jurczak (pauljurczak nospam at
Mon, 25 May 1998 15:43:10 -0700 (PDT)

---Doug Smith <dsmith nospam at> wrote:
> Another possibility for bumpers are the piezo film elements made by
Amp. I
> recently ordered information from their web site at
> <>.

I was doing some experiments with these sensors a year ago. I would
definately use Tapeswitch ribbon rather than AMP piezoelectric film.
First of all ribbon switch is much cheaper, easier to interface
(on/off versus volatage spikes) and ready to use out of the box
(piezo-film would require some protective layer). You have to realize
that bumping the sensor would generate short voltage pulse, so its
senses transitions between different states rather than states
themselves (voltage is generated temporarily when sensor is
compressed/decompressed). I found that the easiest form of this sensor
to work with as a bumper switch is coaxial cable mounted on foam base.
If you are still interested in experimenting with it I can send you a
foot or two of coaxial cable (I had to buy 8 meters to meet their
minimum order quantity). Actually, recalling that I paid about $100
for it, coaxial cable is probably in the same price range as ribbon
switch. One more difficulty with piezo-sensor: it is very sensitive to
vibrations - you will pick up motion vibrations of your robot easily.


Paul Jurczak
<pauljurczak nospam at>

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