Re: Automatic Wheelchair Turntable

["Robert L Bass" <robertlbass@xxxxxxxxxxx>]

At first I hadn't noticed that this is a scooter rather than a wheelchair.
The first thing you should do IMO is find a way to ensure that the chair
cannot be shifted into reverse unless it is in the lowest speed mode.  A
sensor on the tiller could also kill the power if the tiller is moved too
far L or R at a speed that could result in tipping during a tight turn.

You could rig visible strips on the ramp to warn of proximity to the edges
as you mentioned.  You may wish to consider rigging a reflective strip and a
pair of photoelectric beams on the back of the scooter.  A loud alarm and/or
application of a brake could be triggered if the chair crosses the line in
reverse.

By limiting automatic braking and/or motor kill functions to low speed,
reverse motion you can avoid the possibility of a false trigger messing him
up while traversing a puddle or some other reflective surface while
traveling along the sidewalk or crossing the road.

If you would like to experiment with a photo beam for this sort of project
I'd be happy to provide one at cost.

--

Regards,
Robert L Bass

=============================>
Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
941-925-9747 Sales & Tech Support
http://www.bassburglaralarms.com
=============================>


"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote in message
news:_9mdneHCU76Ch6DeRVn-hA@xxxxxxxxxx
> "Robert L Bass" <robertlbass@xxxxxxxxxxx> wrote in
>
> <stuff snipped>
>
>> > I believe it might be possible to do if I can figure out some way of
>> > insuring he doesn't back himself off the ramp while entering.
>>
>> That one should be easy enough.  Add a 3" lip on each side of the ramp
>> (unless there already is one).
>
> There is already a lip, and it can't be extended because of the way the
> device deploys and refolds itself.
>
> http://www.entervan.com
>
>> He won't back over that.
>
> You would be surprised at what a fully charged 24V scooter or powerchair
> can
> mount when they're angry!  In a worst case scenario (already happened)
> where
> Dad's got the speed control set to 10 and he's now in close maneuvering
> space (where it SHOULD be set to 1 or 2, but usually isn't), you can bend
> a
> fairly stout metal cane in half if the conditions are right.  These
> puppies
> have plenty of low-end torque.  At the 10 setting, you're thrown back in
> the
> seat, hard, from the acceleration.  It's something you don't even feel in
> a
> Shelby Cobra - well, maybe a little! :-)
>
>> It might make him more comfortable backing up the
>> ramp if you were to add a bicycle mirror to one
>> armrest.
>
> I've been thinking about both mirrors and/or a tiny, onboard camera system
> with a small LCD TV mounted in the tiller to handle reversing and a number
> of other status functions.  You can get pretty amazing pinhole cams that
> draw next to nothing in current and can see in near darkness.  Plus, these
> cameras could serve to relay status information via cell phone, a project
> still floating around in my head.
>
> Tiny "curb feelers" on the rear chassis could beep if the chair was going
> off-center.  While a powerchair could be controlled remotely via such a
> function, and, in theory be steered up the ramp by external microprocessor
> control, a scooter could not remotely controlled.  They have a single
> motor
> and are steered by a tiller.  Powerchairs have independent motion and were
> the chair to drift left, the proper reduction in power to the right motor
> would correct the course.
>
>> This could be angled down so that he can see how he's lining
>> up with the ramp as he moves.
>
> Yes - easy confirmation of "fair or foul" reversal is going to be
> essential.
> Most likely it will be visual, but I'd sure like it to be robotic as well.
> I could, I believe mount some sort of reflective strip to the ramp deck's
> two halves.  Then, a phototransistor and an IR LED mounted on the rear of
> the scooter could easily relay when the scooter had gone off the mark.
> Three such devices would even tell me which way the scooter had drifted.
> The question is, what do I do with that information?
>
> My first inclination is to look toward avionics controls.  This is an
> application where a small display of a two lines can be shown converging
> or
> diverging might make up for head turning and ramp edge tracking.  I am
> thinking the ramp center AND edges need reflective tape in any event.  The
> ramp is painted flat black and even *I* have a hard time seeing it with my
> much younger eyes than Dad's.
>
> Might need to have some of those little, incredibly bright yet power
> stingy
> white LEDs mounted to illuminate the wheel-ramp edge contact zone.
>
>> > I'm still mad at myself for not realizing that a swing-arm type scooter
>> > lift
>> > would have solved this problem, as well as the problem of people
>> > parking
>> > so
>> > close to the van that the ramp can't deploy or can't be boarded because
>> > it's
>> > too close to an adjacent car.
>>
>> There's a solution to people who do that.  Operate the ramp several
>> times,
>> leaving a "reminder" on the roof of their car.  :^)
>
> Damp ramp HW costs way too much for that.  The real solution is to park in
> the far corners of parking lots across two spaces diagonally.  At the
> mostly
> empty edges you can find spots where no one can park you in.
>
> Next time you're out and about, look at the far edges of mall lots.  I'll
> bet you'll eventually find an  Entervan parked as described.  Since Dad's
> got the scooter, even an added 1/4 mile to the van isn't going to make
> much
> difference in trip time. It does mean a longer ride through the parking
> lot,
> which can be pretty dangerous, but getting parked in by a dodo, on the
> other
> hand, is both dangerous AND time consuming.
>
> I was in a Home Depot the other day and one of their new scooters has a
> tall
> mast and a rotating yellow light at the top.  I'll bet that's a good thing
> to add to Dad's chair to make in more visible as he drives the scooter to
> the lot fringes.  I also bet that there have been some serious or at least
> near-miss collisions in the store aisles driving that decision.  Expensive
> modifications don't sprout on these things without a driving force.
>
> --
> Bobby G.
>
>
>
>