Good chair "design" article

[MenCallMeGimpy]

https://sci-bc.ca/wheeled-mobility/

Interesting article on stupid design and the flood of "cool" wheelchairs that either never get made or shouldn't be.

[woodygb]

Good read!

[ex-Gooserider]

Why does it seem like most of those designers stopped by here (and never came back....)

Definitely nailed it....

ex-Gooserider

[Burgerman]

The isue is that they want their wiz bang features. And so dont want to be told the truth. So they go where people are impressed by an arty looking chair or some new stair climbing chair gadget.

They dont want hidden real improvements because those dont impress the masses or media. You cant SEE a tubeless tyre, or a better controller or a lithium pack, or less weight, or better reliability, etc. They must do stuff that is both visible and an "invention" at all costs! Even when we dont want that. They must have "features" and hype it all to impress the dumb masses!

The original iBot did that well. All hype and features. Very wiz bang. But it was a terrible daily chair 90 percent of the time because of it when not doing its tricks.

[eugenech]

It is not that easy. While working on Xceed chair we face a lot of stupid things done in the industry. Non-marking tubeless tires in traditional wheelchair sizes do not exist or I haven't found one yet. Finding split rim wheels is a challenge as well. For small guys making everything yourself is cost prohibitive. I was able to source, manufacture and try brushless motors coupled with good gearbox. They work really well in a wheelchair and provide superior efficiency. It only took two years to find manufacturer.
From design point of view I am trying to incorporate most of the things people ask for, with main focus on convenience and performance. Your comments are very valuable to me and already caused some elements redesign. Hopefully within 6 month I will be able to get it to the market.

Eugene
www.cheelcare.com

[Burgerman]

Please dont take this the wrong way. But one glance and I ran away. I wouldnt want it, or be seen in it. Its everything I dont want in a chair.

Why do you make it look like a plastic kitchen appliance? With skinny tyres, daft colours, (just ordered a black chair at extra cost because I dont want to look like I came from toys'r us. And neither does anyone else!) . And those two slabs either side preventing me getting next to a chair/bed etc for transfers? They have to go!

And I just spent 2 days getting rid of those fragile mobility sized nasty tubed/solid tyres on my latest stock production chair.
download/file.php?id=7648&mode=view

Also moved the seat back, repositioned the controller, sawed off various bits and drilled/moved actuators to allow the centre footplate to work on a rear CG powerchair with centre footplate, reprogrammed so it does as its told, got rid of the nasty weak tubed grey tyres, relocated the lights so they are not in the way, redesigned the swing away so iut works, got rid on most of the inhibits so it lets me do what I choose, etc etc.

[Burgerman]

It is not that easy. While working on Xceed chair we face a lot of stupid things done in the industry. Non-marking tubeless tires in traditional wheelchair sizes do not exist or I haven't found one yet.

The chinese will manufacture any tyre in any colour, style, size, to suit any application in relatively small quantities. They do this for own branded scooters, toys, carts, etc. Many are available as samples or requests. And. Why would you want to use that size anyway? They are too skinny for the weight and sink, and theres many other sized tyres available. Just because the industry use 3.00 x 8 for almost everything doesent mean you should. As for caster tyres, bigger is always better. Those things need to float over soft stuff, and not transfer shocks or bounce off ridges or edges.

Finding split rim wheels is a challenge as well. For small guys making everything yourself is cost prohibitive.

Again. Why would you WANT split rims? I went out of my way to find rims that were NOT split rims, and were proper tubeless rims so as to get over the stupid solid spine jarring tyres, or the tubed pop here we go again ones! Look here: download/file.php?id=7426&mode=view £9 each... One at a time, in 2.5 or 3.5j widths and 8 inch.
Compared download/file.php?id=7646&mode=view
download/file.php?id=7648&mode=view
Fitted with 3.00 or 3.50 x 8. Or the wider one 120/70-8 as I have on my chair.

[Sully]

Might I inject some thoughts? OK so I will anyway; If the seat base is constructed so the user/owner can reposition it to be set either over the center of the axle or a half inch or so behind that to adjust the CG where a user may want that. In other words, adjustable Center of Gravity seating. Not every wheeler wants to go or use their conveyance (Power Chair) in the same exact way, or in the same exact places.

All the other things that John suggested are quite valid, ie; distance from a transfer to object is a key thing for most users .

In trying to see the motors, these appear to be some of the newer brushless motors being produced, supposedly the same wattage as the brushed motors are simply weak. They develop their power/torque through revolutions, the slower a motor develops its power to move the better these chairs perform. So what actually occurs in soft ground, OR wet hard ground, or concrete is they spin and get stuck, with user likely helpless to get themselves moving again. Hard skinny tires bring a lot of dirt into the house, a real problem. The dirt packs into the treads then releases as it becomes drier.

Easily programmable to assure the user can make it function how they wish it to. Nothing is more irritating to me for instance, is hesitation while operating somewhere. That causes me, unintended actions, and accidents.

[eugenech]

It is not that easy. While working on Xceed chair we face a lot of stupid things done in the industry. Non-marking tubeless tires in traditional wheelchair sizes do not exist or I haven't found one yet.

The chinese will manufacture any tyre in any colour, style, size, to suit any application in relatively small quantities. They do this for own branded scooters, toys, carts, etc. Many are available as samples or requests. And. Why would you want to use that size anyway? They are too skinny for the weight and sink, and theres many other sized tyres available. Just because the industry use 3.00 x 8 for almost everything doesent mean you should. As for caster tyres, bigger is always better. Those things need to float over soft stuff, and not transfer shocks or bounce off ridges or edges.

Finding split rim wheels is a challenge as well. For small guys making everything yourself is cost prohibitive.

Again. Why would you WANT split rims? I went out of my way to find rims that were NOT split rims, and were proper tubeless rims so as to get over the stupid solid spine jarring tyres, or the tubed pop here we go again ones! Look here: download/file.php?id=7426&mode=view £9 each... One at a time, in 2.5 or 3.5j widths and 8 inch.
Compared download/file.php?id=7646&mode=view
download/file.php?id=7648&mode=view
Fitted with 3.00 or 3.50 x 8. Or the wider one 120/70-8 as I have on my chair.

You wheels and tyres are awesome. Do they come in indoor variety (non-marking)? It should be no problem to fit them into our wheelchair.

Some people we spoke to like the safety of foam filled tyres and will require split rims to accommodate. Lately we switched motors and gearbox and now can put different size of tyres based on need.

New motors

We also have to drive in different circumstances. Snow tyres are typically narrower than summer tyres. Here is a video driving in 3" of snow on skinny tyres.

youtu.be/1XrebAsEnfk

[Burgerman]

That chair in the vid needs bigger and lighter loaded casters to deal with real snow. Anything works on fresh, soft, 3 inch thick stuff. You are just driving on the ground and pushing it away. What happens when its broken/frozen or on mud/sand? And the best tyres for snow are wider high floatation low pressure ones as on my chair shown in the link for that very reason. The chair in the vid wouldnt get near this one in snow. Or sand. Along with 3 inch wide and 10 diameter lightly loaded castors.

http://www.wheelchairdriver.com/images- ... mp-car.jpg Yes, tubeless... Look at the type of valve. And yes they are available in red, blue, camoflage colours, etc and yellow, and non marking.

Also you WONT NEED solid/foam filled tyres with TUBELESS tyres and one part rims. Thats the whole point. They are just as "safe" and better ride/wear/range They can be either puncture proof (K sheild) tyres as on my BM3, or just add some proper off road sealer as this WORKS garanteed on tubeless tyres. Once you get rid of tubes the sealer is 100 percent foolproof. You can stab a tyre with a screwdriver 100 times and its just fine. And no battery sapping, spine damaging foam filled flat free tyres required. So no split rims wanted!

No they dont make these in institution grey. But as already mentioned you can get some made in batches. Although why you want grey beats me it looks terrible.

This looks way better! And its not a problem with marks unless wet. download/file.php?id=7743&mode=view
Whats more the tyres are tubeless, and the puncture seal actually works! It doesent work on tubes... And the tyre is tougher anyway so far less likely to ever get a puncture.
As are these download/file.php?id=4326&mode=view

I like the new brushless motors, provided theres a decent system like r-net for eg to match them. Not a recently developed one off specifically for your chair for a number of reasons. Also in the vid seating is too high up, Legs too far forwards. And it looks unstable. So climb a steep ramp or drive off a curb at speed and you look like you will end up the wrong way up. CG too high.

Also in your vid I see the user/seating sway side to side, like its not rigid enough as all the extending wheel arms etc flex. Couldnt live with that. And lift up arms are the same. Too long, introduces flexibilirt making accurate control impossible once programmed to respond properly so I can use it. I just paid extra to dump a set of those and have very solid single post arms instead, and threw away the swingaway joystick mount for the same reason. If it moves/wobbles its unusable.

Also dont shoot the messenger but presumably you need people to buy this? Well even with powerchairs people like style, simplicity, and good looks. However you have made it look like a pram. And people will not go for that look. I know you see this as all negative, but you did ask. And it must be said. But I dont mean to be negative. Just pointing it out how I see it.

[LROBBINS]

John,

Is there an r-net for brushless motors?

[Burgerman]

No. And theres none from Dynamic other than the one we cant get as its built specifically for Invacare, and non from curtis instruments, curtiss wright etc either. And as it stands the R-net system with its extremely well evolved drive software, and masses of different modules and options is about as good as it gets.

Take a look at the programming software for eg.

See PM.

If there was a well developed system I would already be using brushless geared motors. Probably. But heres the thing. The BRUSHED motors work almost as well in efficiency terms. Most of the losses are actually in the gearbox. So in range terms theres not a lot in it. And brushed ones with motor load compensation offer a better feel and user feedback than a locked system that sensored brushless motors give. You can fine tune it probably but unless they are gearless too theres only a tiny gain in efficiency. Although it all helps.

[eugenech]

I like the new brushless motors, provided theres a decent system like r-net for eg to match them. Not a recently developed one off specifically for your chair for a number of reasons. Also in the vid seating is too high up, Legs too far forwards. And it looks unstable. So climb a steep ramp or drive off a curb at speed and you look like you will end up the wrong way up. CG too high.

Also in your vid I see the user/seating sway side to side, like its not rigid enough as all the extending wheel arms etc flex. Couldnt live with that. And lift up arms are the same. Too long, introduces flexibilirt making accurate control impossible once programmed to respond properly so I can use it. I just paid extra to dump a set of those and have very solid single post arms instead, and threw away the swingaway joystick mount for the same reason. If it moves/wobbles its unusable.

Also dont shoot the messenger but presumably you need people to buy this? Well even with powerchairs people like style, simplicity, and good looks. However you have made it look like a pram. And people will not go for that look. I know you see this as all negative, but you did ask. And it must be said. But I dont mean to be negative. Just pointing it out how I see it.

No offence taken. I am asking to make a better chair. And I am incorporating your feedback, when it makes sense.
Now back to video. Hight of the ride is personal preference. He likes it high. I know a lady who drives her TDX at 10" elevation 100% of the time. Beauty of this design is that you get to choose how high you want to ride depending on circumstance (low cruising, high in the pub). Chair is very stable. You can see more videos on YouTube. I will try to make mode videos going through broken/frozen staff, if it doesn't melt soon. Suspension allows wheels to move around 5cm. Keep in mind that chair can shift CG which makes it less likely to get stack with the proper tyres

I asked Dynamic and PG about brushless controllers. Only Dynamic makes them and only for Invacare.

[eugenech]

No. And theres none from Dynamic other than the one we cant get as its built specifically for Invacare, and non from curtis instruments, curtiss wright etc either. And as it stands the R-net system with its extremely well evolved drive software, and masses of different modules and options is about as good as it gets.

Take a look at the programming software for eg.

See PM.

If there was a well developed system I would already be using brushless geared motors. Probably. But heres the thing. The BRUSHED motors work almost as well in efficiency terms. Most of the losses are actually in the gearbox. So in range terms theres not a lot in it. And brushed ones with motor load compensation offer a better feel and user feedback than a locked system that sensored brushless motors give. You can fine tune it probably but unless they are gearless too theres only a tiny gain in efficiency. Although it all helps.

I build two identical chairs. One uses M300 brushed motors( see attached) and the other brushless (see the picture in a previous post). So far, about 10 different people drove them and they are unanimous that brushless feel and drive much better. Both use Roboteq controllers and same script for motor compensation. Efficiency gain is around 10-15%.

Xceed with brushed motors.

[Burgerman]

Both use Roboteq controllers and same script for motor compensation.

Hopefully with current sensors on the brushed system? Or it wont work properly. But I like the idea of brushless motors. Its the rest that defeats me. Too high, too complex and too "flexi" to give confidence or stability. What would it do if acceleration is set high as I like it? You are sitting several inches too high up. And with no heavy battery down low to compensate. And the battery is too small for weight needed dow low or sensible range.

I dont see the advantage of the complicated legs over stock seating setups. Other than lateral leaning but if its not stuck too high up to begin with do we need it? That is of debatable benefit, and it would need to predict which way I was going to turn before I do to be useful. And be very fast! But thats too slow to respond to be really useful for anything? Also wheelbase needs to increase as you get higher, wheras this gets shorter further reducing stability if you were to accelerate suddenly? Or one wheel ran down a pot hole? I know you dont want to hear it, and you may sell a few based on percieved suspension clever legs, but the mainstream users looking for solidity, performance, range, programability, cool build/looks will not look at it. The very look of it will put them off checking it out any further. Dont be shocked when you think its great, but nobody wants one! Read the title of this thread and the peice that it linked to. https://sci-bc.ca/wheeled-mobility/

We do need many incremental improvements in powerchairs of conventional design. But a new set of legs/suspension that does tricks really isnt it. At least for most serious users. Like most of these new innovations it will likely vanish without trace. Have you considered what happens when roboteq goes broke? Thats not a sustainable business model. For eg Invacare bought Dynamic, so that they are never in that situation. Same with a few other manufacturers. But at least if for eg Permobil can no longer get PG controls they can use one of 3 or 4 other manufacturers systems off the shelf.

Both use Roboteq controllers and same script for motor compensation. Efficiency gain is around 10-15%.

Then you fitted a 20Ah battery! Totally throwing away any advantage gained and then some...

E.g. my 3 lithium chairs each have 3.1, 3.1, and 3.24 kwh batteries. You have 48V x 20Ah = so less than 1KWH (960watt hours if run to 100 percent dead) so actually worse than some group 24 lead. So with your 10 to 15% range gain you have approx ONE THIRD of the range of my own chairs. Its inadequate. That wont last me a full day. Its the very reason I fitted lithium, to get MORE range. It also means you are working the battery 3x harder, and charging more frequently, increasing C rate loads by 3x per cell and discharging more deeply by 3x every day.

So they wont last anywhere near as long since thats all the stuff lithium hates. The space needed for batteries is all used for that strange suspension setup that I have yet to understand the advantage of, making it impossible to fit a big enough battery low enough. And the bigger lower battery is whats required better stability and with lower seating. So better stability for performance like fast acceleration and other more extreme settings active users want, or on uneven terrain, lateral slopes, ramps, etc that I and many full time users are looking for. So interesting project but I just dont see the positives, so not for me. The problem is that others wont either and your sales will likely point this out in the future when its all too late.

The other thing I can clearly see in the vid above is that you turn left, it leans right. Even at the slow speeds and low turn rates shown. Thats due to tyres, high CG, etc. Or flexibility of everything. I would turn it over in minutes. Thats got to stop! Its a consequence ofhigh CG, small light high up seating and battery. And flexibility. Its like driving a barstool. As a consequence of this the anti tips are far too long. They would take out everything in a confined space like my bedroom, van, loo, workshop.

What does it look like with all that plastic taken away? Because thats the first thing that shouts "run away" to me.

[Burgerman]

What I am saying is that if you have quality frame/mechanicals built well, you dont hide it under some plastic mouldings!

An example. Below 2 bikes. One is proud of its frame, its quality build, its mechanicals and is a piece of art/engineering. Its also 300bhp, turbocharged 1200cc handles like a razor, and is light low and compact. Its brakes alone are worth more than the other bike in its entirety. As are its front forks. So you want to see at its engineering. Every part is well engineered and finished. Form that follows function done properly at the engineering level is good to look at! Even the frame and rear suspension.

The other bike is a plastic coated mass produced 600cc thing thing with ugly 90bhp engine and silver painted cheap steel frame and steel bolts that was hidden under some plastic covers to hide it. Remove the fairing and it looks terrible. One bike's engineering alone is desirable as art, a thing of beauty, the other is a mass produced sluggish vaccuum cleaner where you need to cover up its innards to hide the ugly internals.

Do you see where I am coming from? Good engineering should be seen and admired. Not hidden behind plastic! If it is in fact good. A non biker will not see or understand the difference here though.

I can't see any of your chair. Its all hidden. And the plastic I can see is not exactly pretty.

[eugenech]

Beauty is in the eyes of the beholder!

We come from different worlds. Bikes vs cars. In car world we cover up as much as possible. It does not take away from engineering, in my view it adds.

all exposed

OR

real beauty

jaguar.jpg (8.86 KiB) Viewed 4187 times

or

DB-11

[Burgerman]

We come from different worlds. Bikes vs cars. In car world we cover up as much as possible. It does not take away from engineering, in my view it adds.

For streamlining and to cover up the cheap mass produced rusty dirty bits. Wheelchairs are not cars. Worse yours makes it look like a pram! I know you wont listen to me. But dont be surprised when it gets ignored by the majority of users.

[eugenech]

Just for the fun of it. Love learning new staff. I read up on "covered" Honda bike picture you posted. It is considered classic and was made for over 20 years. Between 1987 and 2000 54% of all 600 Supersport championship races were won by riders on this bike making it the winningest 600 in a history of AMA racing.

HONDA CBR600

[Burgerman]

The specific year I posted an image of had the plastic covering the frame rails and many other parts to disguise the fact that it was cheap silver painted steel. As such it was nicknamed the jelly mould 600. Subsequently they learned that people didnt want that via sales...

The following models used a better lighter alloy frame that they were not ashamed of, and the plastic covering over the frame was removed making the frame and now prettier engine and stainless exhaust visible. It was still faired, but now looked like a quality item. And still does 20 years later with every subsequent model.

[eugenech]

In our case we are covering good looking stainless steel (to avoid rust, reduce weight) and some clever engineering.

[Burgerman]

Well dont!

[steves1977uk]

Any chair I buy I REMOVE all plastic covering as power chair is not a fashion accessory! An open frame looks better!

Steve