crossfall

[Tomkilmore]

I found this on the internet today....

https://www.swincar.fr/

This looks like a better solution than other off roaders I have seen (for paraplegics?), it got me thinking, are there any powerchairs that combat crossfall mechanically? I am aware of a couple that try to do it via programming (i think) but none that use mechanical means?

[Burgerman]

Its the same size as a normal car. and there are literally hundreds of off road buggies. I wish I understood the facination of driving about in mud and crap. Why bother with batteries if its only any use outdoors?

Crossfall?

How do you get a thing as big as a car, but without the range or road legality as a car to the place where you want to get stuck in mud? What do you do with all the trailers, wheelchairs, vans etc? Just doesent make much sense unless you live on a farm and then any number of petrol powered machines are better and cheaper!

[MichaelB]

Its the same size as a normal car. and there are literally hundreds of off road buggies. I wish I understood the facination of driving about in mud and crap. Why bother with batteries if its only any use outdoors?

Crossfall?

Because you can't use a petrol powered vehicle on footpaths and bridleways legally nor will one go through a standard national park gate. You could use it on a county road but that requires a driving licence and I can't see the DVLA giving me one. I've spent the last 30 years mountain biking, live in the Lakes for that reason, losing the use of my body was bad enough not being able to get out in the countryside that I love made it worse, having an off road wheelchair changed that. If you can be bothered there is an article in a cycling mag and their website on what it meant to me to get out https://www.cyclinguk.org/cycle/michael-bonneys-boma-7

Totally agree on machines that are too big to transport, mine had to fit in my van. Too big and you can't go anywhere without checking how wide the gates are. There is a place for battery power off road wheelchair/buggies but they need to be within a certain size or you might as well buy an atv/quad

[Burgerman]

Because you can't use a petrol powered vehicle on footpaths and bridleways legally

Wrong. The law does not specify power source here or in the US.

There is a place for battery power off road wheelchair/buggies but they need to be within a certain size or you might as well buy an atv/quad

Size is not determined by power source. And yes you may as well buy any of the thousands of off road buggies with ic power as they are more capable and cheaper!

[Tomkilmore]

I think you missed the point, i'm wondering if there are any powerchairs that keep the user level on a sloped path, I have had a good google but can'y see any.
There are loads of people who love the great outdoors with all it's mud and nature and can't get to it anymore, this is capable of getting them there, it also keeps them level if they don't have much/any muscle support, look at the terrain it takes on in the videos,, spectacular, a quad bike would stuggle and throw the occupant all over the place. It's quiet too, pertol engines are not and this detracts from being in the countryside. Its expensive though at 12500 euros. You would need a trailer etc but it ticks some big boxes.
I want to plunder the knowlege on here for powerchairs that counteract crossfall or sideways sloping hills.....but can't think of the correct terminology.

[Tomkilmore]

case in point

[foghornleghorn]

I would find the self levelling on that a lot more comfortable to sit in on a cross slope but wonder if it would take away the feeling you get that stops you from doing something stupid and tipping over.

[Tomkilmore]

watching the videos. i don't think there is anything stupid you can do! other that drive off a cliff

[Burgerman]

Maybe because they dont show the vids where it failed... And fell over or got stuck.

The problem with a powerchair is that it will never do the stuff off roader buggies or cars like this one do, because wheelchairs must be around 25 to 27 wide to fit through doors, vans etc,. And short so they can turn around without demolishing your house or killing someone in a bar. So we are left with a seated person on wheels. A barstool with power and a too high CG. So any serious angles, and it falls over sideways or backwards or both. So allowing it to lean sideways (tilt seat) is of dubious benefit.

[Tomkilmore]

yes, i suppose. but c'mon you have to admit it's got alot more to it for wheelchair users than any petrol quad or atv.
I remember reading something about wheelchair programming that span one wheel faster than the other to compensate for sloping pavements but can't find it anywhere. I'm looking into mechanical means like actuators, gyros and pendulum type arrangements but want to keep it as simple as possible.

[LROBBINS]

Tom,

Motor compensation that increases voltage to a more heavily loaded motor is nearly universal, and goes a large way toward counteracting the tendency of the casters to slide downhill on a cross slope. It doesn't actually speed up the motor, but keeps its speed nearly constant instead of having it "lug" under load. It isn't perfect because "perfect" motor compensation (which is positive feedback) in one situation will lead to runaway in others - so it always has to be set a bit sub-optimally.

Motor compensation will also not keep a chair upright if the center of mass falls outside its footprint, whether by tilting too far or hitting an obstacle and having inertia take the cg out of bounds. Nothing you can do at the motors is going to fix that, other than moving them out (for sideways stability) or lengthening the wheelbase (for fore-aft stability).

[Burgerman]

I remember reading something about wheelchair programming that span one wheel faster than the other to compensate for sloping pavements but can't find it anywhere.

On your rear drive chairs, the front end is heavy, and the CG is ahead of the two drive wheels. So if a road camber, or footpath has a lateral slope the chair tries to head down it because the frontend has caster. It simply goes where gravity pushes it, downhill. Towards the gutter.

The rear wheels must compensate for this. And they PARTLY do. As you travel along you automatically correct with the joystick to make it go straight. You push the stick fowwards, and slightly away from the gutter and towards the high side as you go along. Then the power module senses that theres much higher current (Amps) in the motor on the low side, and it ASSISTS you by adding the extra power required.

This makes you go straight with only a small correction on the joystick. Both wheels then are rotating at the SAME rpm since you are traveling straight. But the lower motor, will have maybe 30A going through it. And the higher motor, may have 3A going through it. Or it may even be a NEGATIVE figure. This is all caused by Motor Load Compensation. If you dont believe this, set it to zero, and try driving along a road edge!

[sacharlie]

Because you can't use a petrol powered vehicle on footpaths and bridleways legally

Wrong. The law does not specify power source here or in the US.

Incorrect. In the USA each state regulates Disability Mobility Devices. In Texas in can only be battery powered and less than 8mph. The user is considered a pedestrian and as such can travel where foot travel is allowed.

[Burgerman]

Is Texas different? Can you show me the rules?

I can find this, applying to certain mobility devices (meaning not all) https://texas.public.law/statutes/tex._ ... on_542.009

It may be the case, I dont live there!

[Tomkilmore]

I do believe it, I do remember reading about one wheel being braked, so the same as feeding one motor more amps. I also think I'm getting confused with something I read about front wheel drive chairs and programming to make them more stable/responsive
I am finding for many people with little balance it is very hard work to have to constantly adjust the joystick whilst leaning over slightly due to the slope. It's not the crazy angles I want to resolve it's the everyday small ones.

[Burgerman]

Then you need to build mid drive chairs. They dont head down the slope. Or front drive, they always want to climb UP the slope.

You can also fit encoders, that measure motor rpms. Or a gyro and configure that to keep it straight. But those make a chair drive horrible as they remove the need to correct manually, so remove all feel.

[Tomkilmore]

Mid wheel drive chairs can't even get up a standard ramp properly, no chance. i''m sure I can work something out.

[sacharlie]

Is Texas different? Can you show me the rules?

I can find this, applying to certain mobility devices (meaning not all) https://texas.public.law/statutes/tex._ ... on_542.009

It may be the case, I dont live there!

That's the law I am going by. You did a good job finding it. That means the device can be used in areas restricted to only pedestrian traffic as in sidewalks, hiking paths, fishing piers and such.

[Burgerman]

But it doesent mean that its the only description of a mobility device. Or does it?

[sacharlie]

It means that is the only mobility device that is not restricted from foot traffic areas. That is how they restrict bicycles and two wheel scooters off sidewalks, by requiring 3 or4 wheels. The law even restricts Segways although I would think a LEO would look the other way, seeing a lower limb amputee riding one.

[Gnomatic]

I want one of these


youtu.be/MiH8r76ZehA

[Gnomatic]

Mid wheel drive chairs can't even get up a standard ramp properly, no chance.

My Frontier V6 laughs at this!

But I get where you are coming from as most MWD are crap IMO.

[Burgerman]

So sacharlie what about this?

sacharlie wrote:
Petro is convenient but over here limits where you can use it. All the government parks allow only electric mobility aids.

WRONG!!!! Check the ADA rules - definitely apply since you give your location as Texas, and last I heard they haven't managed to secede yet...

The ADA guidelines specifically say that ANY form of mobility aid, including petroleum powered, must be allowed unless there are specific reasons not to, i.e. petro isn't allowed indoors for safety reasons. They can also prohibit dual track vehicles (including regular power chairs) on single track trails if the trail would be damaged.... They DO allow "reasonable" rules about use, for instance restricting you to walking speeds in pedestrian areas, etc....

ex-Gooserider
T-5, ASIA-B
Jazzy 1100
Jazzy Select 6
Quickie Q-7
Invacare Mariner
Want to make / get a better chair, ideally one that stands.

[MichaelB]

Because you can't use a petrol powered vehicle on footpaths and bridleways legally

Wrong. The law does not specify power source here or in the US.

There is a place for battery power off road wheelchair/buggies but they need to be within a certain size or you might as well buy an atv/quad

Size is not determined by power source. And yes you may as well buy any of the thousands of off road buggies with ic power as they are more capable and cheaper!

OK, the law says 8 mph so you would need to restrict your petrol powered atv to that, you would then have to drive a reasonable size vehicle on a public road with a top speed of 8mph as it won't fit on a pavement. Add in the complication of how a high level quad can actually drive and control system needed and you are into some serious modifications. Then consider how you transfer if you use a portable hoist and adapt seating with Roho/Jay back. It can be done but you would still get stuck at the first footpath gate. Size isn't determined by power source, intended use is the most important consideration.

[biscuit]

I once (pre-wireless) had a laptop that you could kind of plug into a desktop gadget where the peripherals are conveniently left plugged in, by just basically putting the laptop on top of said gadget, and thereby turn the laptop into a desktop computer.

I'm picturing a "normal" wheelchair that could plug into an off-road carrier so it's something like the one in the video, only with a wc where the seat is.

But, fantasies aside, I'll be using my Salsa R2, strictly on-road, with its tendency to try and drive me down people's driveways if they are sloping. And ignoring my Australian family's call for me to get a chair that can go hiking with them.

[Burgerman]

A freind, T4 paraplegic, Laury Ardito has been using an old leccy start twist and go 125 or 250cc quad with a big disabled badge stuck on it to walk his dog for a decade. Its ideal, small, so he can transfer from his wheelchair on his own by swinging a leg over and grabbing the bars as he sits on a rear plastic mudguard (fender? for our forein freinds). The thing has gears, at least forward/back and easily fixed with a 1 foot metal bar bolted to the gear lever so he can choose reverse by hand. He drives slowly on and off road, and 4mph legally on pavements (and fits fine if wide, road if not) and has his phone mounted as a gps speedometer with a bit of velcro. Been stopped and questioned a couple of times at first. Once they figure out what/why etc they leave him alone as I suppose they also cant understand if its technically legal/illegal or whatever either. And they can see why he is doing it and doing so safely. And they probably cant think of any actual offence to do him for... A potential can of worms. So they just use common sense. And call it a mobility device. Its quiet, its offending nobody, was about 100 quid used, and works on muddy dog walking tracks in winter. And the law leaves him alone. Even used it to come to the pub in summer as we were sitting outside.

[MichaelB]

As BM keeps pointing out off road wheelchairs are usually buggies and whilst using wheelchair parts they don't steer like a chair applying more or less power to the drive wheels. Many use a single motor driving both rear wheels and a servo steering system so before you can predict what will or won't happen you need to know how it operates.

Getting back to the off camber part, my Boma is quite scary when traversing across a steep slope, made worse as with no trunk control you can't move your body up the slope to give any kind of weight compensation.Wider track and longer suspension travel might help but as you increase the width you restrict where it can get to. Lots of compromises and you have to decide what criteria are the most important to you, if you never encounter footpath gates and have a big enough method of transport you have a lot more choice. I'd still rule out a tracked chair for all the reasons BM has pointed out in the past.

[Tomkilmore]

So i'm thinking along these lines...…...

[woodygb]

Doesn't seem that difficult from an engineering point of view ... the electronics to make everything do what you want might be a P.I.T.A.

[MichaelB]

Once they figure out what/why etc they leave him alone as I suppose they also cant understand if its technically legal/illegal or whatever either. And they can see why he is doing it and doing so safely. And they probably cant think of any actual offence to do him for... A potential can of worms. So they just use common sense.

Common sense and Lake District National Park don't go together, you wouldn't need to restrict speed you'd spend your time justifying the use of a petrol powered vehicle on a footpath to visiting walkers who want to "protect the fells".

It is interesting how vague legislation is defining an invalid carriage , plenty of scope to do what you want.