Thanks everyone. I didn't think I'd seen it before. I don't think the
principle is unsafe - if the ball stops spinning the chair stops moving.
If you're going to integrate a pulse train to produce an analogue
voltage then you'd introduce a delay, but that could be kept within
realistic limits. If we had a commercial system that would get around
some of the safety issues. As it is we might have to produce some
electronics tied to one of the roller balls used for positioning cranes.
Barry
Barry Taylor, Clinical Scientist
Medical Physics Service
Tulley Medical Physics Building, Hull Royal Infirmary
Anlaby Road, Hull HU3 2JZ
Tel: 01482 675928, Fax: 01482 675750
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-----Original Message-----
From: A discussion list for Assistive Technology professionals.
[mailto:[log in to unmask]] On Behalf Of Harbach Geoff
Sent: 07 August 2008 12:49
To: [log in to unmask]
Subject: Re: roller ball input to wheelchair
The only way I would consider doing it would be to limit the distance
travelled as a ratio of the rotation of the ball. Without a mechanical
self
centralisation of the ball I think it would be unsafe. It could be quite
good for manoeuvring it tight spaces, but if you had that much dexterity
why
not use an ordinary joystick.
In terms of how, you could count the pulses from the relevant axes and
generate an analogue signal to feed into the control system?
Geoff.
-----Original Message-----
From: A discussion list for Assistive Technology professionals.
[mailto:[log in to unmask]] On Behalf Of Simon Judge
Sent: 07 August 2008 12:18
To: [log in to unmask]
Subject: Re: roller ball input to wheelchair
Simple?!!!!! I think that'd be hard (but doable) - especially to do it
safely. Quite a cute idea and a meaty project for an Electronics
Engineer.
I've seen an eye gaze/computer/AAC integrated interface, made in the
Netherlands, but have forgotten the name of the company, it might come
back to me but probably not before your (or my) holiday... But it's not
really 'direct mouse input' that way anyway...
S
-----Original Message-----
From: A discussion list for Assistive Technology professionals.
[mailto:[log in to unmask]] On Behalf Of Taylor, Barry
Sent: Thursday, August 07, 2008 12:04 PM
To: [log in to unmask]
Subject: roller ball input to wheelchair
Dear all
Has anyone seen a tracker ball/mouse input to powered wheelchair? It
would
be fairly simple to make but I wonder whether any of the more modern
systems
might have a mouse interface?
No, I'm not sure how the user will operate it & this brings up lots of
questions, but at the moment I'm just being asked about how it could be
achieved if needed.
PS I'm only at work today before 10 days hol, so I'm after a quick
answer!
Barry
Barry Taylor, Clinical Scientist
Medical Physics Service
Tulley Medical Physics Building, Hull Royal Infirmary Anlaby Road, Hull
HU3
2JZ
Tel: 01482 675928, Fax: 01482 675750
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