Hi Jeremy.
I have come across V4 micro switches that behaved oddly, sometimes not
working, sometimes making contact, and it all depended how tightly the nuts
and bolts holding the switch in place were done up! This was in a
commercially manufactured switch.
We requested a custom version from the manufacturers that used a higher
quality sealed version u-switch and had no further problems.
The other possibility is contamination. It would be worth investigating the
resistance required to initiate the switching function on the omni+. is it
100 ohms, 1k, 10k, 1M? Has the "forwards" input got a different
sensitivity? The higher the resistance the greater the chance of body fluids
or incomplete insulation etc causing unwanted switching.
Hope this helps.
Geoff.
-----Original Message-----
From: Jeremy Linskell [mailto:[log in to unmask]]
Sent: 13 February 2004 11:28
To: [log in to unmask]
Subject: Light Touch j/s with Omni+
Hi All
I have come across a strange problem, which I wondered if any of you
had come across or had any idea about. It concerns the relationship
between a Dudley Light Touch Joystick and an P&G Omni+ wheelchair
controller.
We had reports of a wheelchair switch joystick sticking in the forward
position. We could find no obvious fault with the joystick (it was a new
one), but we bought another new one anyway ... and the same thing
happened again! We brought the wheelchair into the Dept and tried to
replicate the fault, which we eventually managed to do after much playing,
although we could not consistently reproduce it.
I have tested the joystick through various toys and a switch tester and
cannot reproduce a pure joystick fault. Dudley have since investigated the
problem and again can find no fault. I have also tried other switch inputs
with the Omni+ and again I cannot reproduce the fault. Dudley said that
they would check with the micro switch manufaturer, but have not
uncovered anything as yet. It appears to be the combination that is the
problem, but why?
All useful comments will be gratefully accepted.
regards
Jeremy
Jeremy Linskell CEng,MIPEM,SRCS
Clinical Engineer
Co-ordinator, Electronic Assistive Technology Service
Tayside Orthopaedic and Rehabilitation Technology Centre
Ninewells Hospital, Dundee, DD1 9SY, Scotland
tel +1382-496286, fax +1382-496322
email: [log in to unmask]
(backup email: [log in to unmask])
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