Re: Automatic Wheelchair Turntable

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"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.