Power wheelchair design
Anybody else wondering whether wheelchair manufacturers bother to have anyone sit in their chairs before putting them into production?
I have sat in and tried many chairs from the basic to the ludicrously top end and they all have faults in my eyes so don't think criticisms are restricted to the two I mention below (they just hapen to be the two I own and use).
So .. take the Quickie Salsa M (my NHS supplied chair) that I use around the house. As a centre drive chair it is marvelously manouevrable and glides through the narrow corridors and doorways of my home with aplomb. But its design and manufacture is beneath crude. I might have been very proud if I'd managed to construct it as a young teenager out of recycled prams but I assume it was designed by adults. Its armrests are attached by crude metal brackets that allow the range of angle adjustment that users might need. Trouble is these brackets are simply a punched metal plate - and their shape means that when set to their normal (mid) position they present themselves as a downward pointing triangle .. just right to catch in the pockets of my jeans, neatly holding me captive in the chair when I try to transfer or, in the case of one pair of fine trousers obviously made of less robust material left me looking at a torn pocket and thoroughly ruined garment.
It doesn't stop there. The footplates are again crude flat punched metal plates. They are thick enough that I couldn't call them sharp as such but by the heck they are well designed to carve slots out of door frames, furniture - or the legs of anyone who makes the mistake of approaching me from the front. My wife now approaches me from the side - the bruises on her shins will heal eventually.
The swing-away controller arm is not just badly designed, it's evil! As a teenager armed with a box of Meccano I'd have been unsatisfied with it. First, it fails in its primary function as it only brings the controller part of the way back - most of the controller still sits forward of the armrest. If I'm lucky, it might sit above a table I'm trying to sit under but most of the time it just stops me getting where I need to be. Its construction - a parallelogram made out of (you guessed it) more punched steel and square tube crudely welded and bolted together is where the evil bit comes in. Put simply, dangle a sleeve (surely an unexpected piece of clothing to find hanging near your wrist) and the thing will eat it or tear it. Ladies with (say) charm bracelets would find themselves cursing the thing many times each day - and probably nursing wounded wrists.
The controller itself needs a cable and is designed for easy replacement (a good thing). But rather than fit say a locking connector to the controller housing itself (like any teenager would sensibly do) the manufacturer has saved some pennies by installing a cheap in-line push in connector - about 8cm along the controller cable ... where it happily obstructs the aforementioned swing-away.
Oh yes, the connector sits in an ideal position to catch on door frames as I pass through ... at the slightest brush falling apart (it doesn't have a locking device) .. neatly turning the chair off. Hence one finds oneself not only wedged against a door frame but unable to move and unable to reach the darned connector to restore connection. Of course I don't mind being trapped in a doorway until my wife comes home.
Of course I don't - I'm disabled and have nothing better to do.
I could go on about the Quickie Salsa M - footplate hangers that don't swing far enough back and are too heavy to remove; the way the back rest uses thumbscrews (that my weakened hands and arms can't operate) to remove; the fact that the device is designed for people less than 5'8" high - and I'm 6'4" ...
But it would be unfair as all wheelchairs I've tried have similar problems.
To illustrate, let me look at the (£9,000 worth of) Otto Bock B600 that is my means of getting out of the house.
Let me say this first - I love my "Bockie". It gives me the means to be independent (ie, the ability to get out and about without a carer); it is comfortable; accommodates my 6'4" frame (just!); shifts along at a respectable speed; has a swing-away that could be used as a model by others and is almost as manouevrable as a rear wheel drive chair can be.
But it has its faults.
First is the controller electronics. This is a complaint against all powered wheelchairs that I have tried. Since the 1970s I've been accustomed to seeing electric motors driven by simple servo-feedback controllers. Take a record deck from the mid-70s say. Its speed can be pretty accurately controlled with a simple bit of electronics that monitors the speed set by the user (33 or 45 rpm in this case) against the speed of the record deck and regulates the amount of Volts/Amps supplied to the motor to ensure that the motor rotates at precisely the speed set regardless of load. In these days of PCs with more processing power than that possessed by a small nation in the 1970s a truly trivial piece of electronics.
Yet no wheelchair I have examined uses such a controller. Instead, the user is given a choice of maximum speed settings which simply limit the maximum velocity you might obtain via a scheme of calculated guesswork. If you happen to be going uphill, you'll go slower .. faced with a downhill slope you had better be strapped in for the ride.
What does this matter in the real world, you ask. Well, get yourself stuck (trying to turn slowly on say a deep pile carpet - no, I'm not joking) and if you have the maximum speed sensibly turned down so that you can safely move about indoors, the motors will simply stall through lack of Volts/Amps. Your choice as a user? Why turn up the maximum speed (the manufacturers are heard to cry) - as this will deliver the extra Volts and Amps you need.
But this does two other things too (by design). First, it reduces the precision you need from the controller joystick - in other words, a smaller joystick movement now leads to a much bigger movement of the chair. Secondly, you may now have the power you need to make the chair move but as soon as it starts to move you very definitely do NOT want all that power. It seems that the human brain (at least mine) can't react fast enough to cut off the juice before (by now travelling at quite some velocity) you collide into the walls, furniture or people foolish enough to stand too close.
If ever a simple servo-feedback controller were called for ...
Next, the tyres - again a complaint against all chairs. What on earth do they make these thing out of? Durable? Yes. Leave no marks? Yes. Able to grip to common roads, pavements, indoor surfaces etc? ABSOLUTELY NOT!
And that's in the dry! In the wet? All bets are off.
On the slightest downward slope, I can lock my drive wheels solid yet continue to skid out of control downhill from less than a crawl. There's a slope outside my GP surgery (designed for wheelchair patients) that gets me every time, rain or shine.
Otherwise I'm pleased with my "Bockie". Until I come to the practicalities of preparing to go out and about. Now I find there is nowhere to hang a bag (to carry wallet, medicines, keys - the praphernalia of life).
Now the B600 is a very attractive chair as these things go. But most definitely a case-study in style over substance. Those attractive lights on the side of the chair severely limit the carrying of any bag - and are perfectly positioned to achieve maximum damage whe you collide with doorways/furniture etc.
If this is sounding like a bit of a rant .... well, it is! But I'm posting it into the "I had this idea ..." section of the site, so what's my idea?
Several, actually:
- First off and coming as no surprise, PLEASE manufacturers do some product testing before foisting your wares on us poor folk. I volunteer to act as a guinea pig for any manufacturer willinmg to test and (if necessary) modify its chairs prior to sale. Consider it a contribution to lowering the number of ripped jeans and bruised shins.
- Servo-controllers please. Their cost would add but a few Pounds to an already high priced product yet the functionality they would add to the device would be enormous.
- A better blend of style and substance please. My "Bockie" shows what can be done with modern plastics to provide attractive moulded components that also provide improved function when compared to a fabricated part made out of steel tube and flat plates crudely welded and bolted together. But more than that, a bit of THOUGHT into the design process please - for example; a couple of slots in those neat translucent modesty panels on my B600 would prove really useful as a place to hang a bag.
- Tyres. Really? Is it beyond the wit of man to devise a compound that might actually provide grip where and when it's needed?
That's enough from me I'm sure. Next time (if you ask nicely) I'll rant about the lack of joined up thinking that makes it almost impossible to transport a powered wheelchair in an ordinary car.
- Attachments:
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SalsaArmBracket.jpg, 96 KB -
SalsaSwingaway.jpg, 143 KB
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SalsaFootplate.jpg, 257 KB
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Replies to This Discussion
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Permalink Reply by Anne Walker on
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Wow, enjoyed reading that and agree wholeheartedly with your sentiments. I have tried a few models without success so far, the manual chair I have from the NHS is a joke, as it was given to me when I still weighed 8 stone it looks like a childs chair, ok I am only 5 foot but the problem is my hubby is 5ft 10in, and the handles are so low down for him to push me it is a total joke, we tried asking for something with handles a bit higher to make it easier for him to push the chair but got told thats how they come, we tried to find handle extenders to make them higher ourselves but with luck. Surely as you say they could try these things out before foisting them on us, and yes even a teenager would have more sense on something as simple as this. Ok like you rant over for now, have just joine dthe site so will have a wee look round
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Permalink Reply by Catherine Rideout on
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Your experience of the Quickie Salsa M is the polar opposite of mine, and I am not by any means short either. In old fashioned measurements I am 6' tall, with legs and arms more in line with someone who would be 6'10" tall (legs are 39" inseam and arm span 6'10") that's how messed up my spine is, and that's what put me in this chair 5+ years ago.
I found the sturdy construction, power management, seating, and arm rests so much better, and safer than my current NHS chair. I do not like plastic cars, I certainly do not like plastic parts on a wheel chair as they would make it look cheap and it isn't. Plus if you think of where a lot of these things are designed, in the US, where they have Real winters the plastic parts would be a big problem. I'm originally from Canada and I have family there who have had to dig out from under 80cms of snow one week (2 weeks ago) and a further 75 cms of snow the week before with temps about -45C (add the windchill to that and you're looking at -50C or colder). Plastic parts in those conditions, and then in summer when it hits +45C, would not stand up at all.
The chair I have atm from the NHS is an archaic Spectra Plus. It is far too slow, when I get stuck in mud outside walking my dogs I have to have help to get out, which is embarrassing if I have to rely on a stranger for help. Gutless 4 wheeled thing I had trouble getting myself into the buses (when I was still forced to use them) as the space for wheel chairs has a bar stuck right in the wrong place. The Quickie Salsa M would manage to get into that space much more easily, effortlessly in fact.
From your pictures you do not have the options I had on the review unit I had from Quickie though, maybe that's part of it. The chair I had to review was so versatile, could be easily tweaked to fit just about any size person (even me with my overly long legs felt comfy) within reason (I also weigh about 93 KGS so no skinny mini here).
I had a really updated power controller from what yours looks like as well, had the Tilt in Space and other options that really made life much better, I could even reach the top shelf items in the CoOp shop near me and that was a blessing!
The only thing I wish is that it didn't have plastic mud guards, they would not stay off the tyre! Then again that's plastic, cheap.
Here's the review I did, on my site, with pictures of the one I had for that time.
http://www.iama-network.com/sunrise-medical-and-the-quickie-salsa-m...
and in my research before doing that article I found out they do have disabled people testing, but everyone is different.
Cj
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Permalink Reply by Angela Cavill-burch on
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Every wheelchair my Hubby has tried has had problems, his Ti-Lite had sharp edges on it which I as his carer have gashed my legs on. When his spasms were bad his chair front castors used to bang his heels. His NHS supplied IBIS - XP does not tilt back far enough, we have tried other chairs where the headrest has had a piece sticking out at the back just at the right height to wind me while I am pushing it, electric controllers designed to nip fingers off, sticky up bits of seat design that cause possible pressure points. You can get the right wheelchair for you for at a cost that most ordinary users just do not have.
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Permalink Reply by George Perfect on
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Hello Angela,
I fully agree with you - and that's my point. The design and manufacturing "quality" of most power wheelchairs is both appallingly bad - and almost Victorian in nature ... as if the 20th Century never happened.
Lead acid batteries? Please - you'd find them in Faraday's workshop!
The controllers are nothing but simple "power taps" - no use of technology that's been available for 40+ years to actually *control* the darn things.
And yes, my Quickie Salsa bites my fingers (with its uselessly designed controller swing-away), tears my clothes with its stupidly placed metal brackets, carves chunks out of the walls and door-frames of my home whenever I miss (I sympathise with your husband - I spasm too) and is "fitted" to me with the aid of a 6 inch thick seat cushion ... that makes the back-rest come only 1/3 way up my back!
Even my Otto Bock B600 (that's £9,500 worth of chair to those who don't follow these things - or the price of a decent small NEW car) leaves plenty to be desired.
I continue to try to get people interested in producing a chair that is modern in design (ie; uses current technologies [lithium batteries, closed-loop speed controllers] and doesn't look like a Dalek) and ... doesn't cost a fortune so people can actually afford them.
It's not rocket science. But there's an entire industry that enjoys making huge profits out of recycling the same old worn-out designs year after year. THAT is the problem.
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hear hear... i despair at times, we got to the moon or so they tell us and yet we can not seem to use modern technology in wheelchair design.
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Permalink Reply by Alex Papanikolaou on
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Hi George and everyone!
I am so excited to find this discussion because it just proves all the points and purpose of why I started a very special project over a year ago now which is set out to once and for all solve the issues us power chair users are forever raising but are continually ignored and stuck with antique wheelchairs!
To save me repeating my story and exactly what we are doing into a massive message, please take a look at this link and let me know what you think!
www.freedomonelife.com/the-freedom-one-wheelchair/
This is an OPEN project and it's about you, the user! So we welcome absolutely all input and anyone who would like to join us in creating something very special!
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Hi Alex,
Welcome to the discussion. I visited your site and watched the video - you are obviously very well experienced in all the shortcomings in current wheelchair design and it looks like you have discovered John Williamson's site (http://wheelchairdriver.com) and the great work he has done in modifying existing designs with new technology,
What I can't see on your site are any proposals from you on how to improve wheelchair design or bring it into the 21st Century and don't currently understand what you are trying to achieve. Are you hoping to formulate a collaborative wheelchair design ("design by committee"), build a pressure group to persuade manufacturers they must do better, build a "proof of concept" prototype that could be taken into manufacture ... or something else? I see you have an idea for a KickStarter campaign. Does that mean you have a product in the works that just needs funding to turn into reality? That's generally what KickStarter is for.
I'd be interested to talk further with you to better understand your plans and goals. Perhaps you could PM me? My contact details are at http://www.biznik.co.uk/about.htm
All the best
George
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Hi George I sent you an email and message on here, did they reach you?
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Hi Alex,
Sorry, I haven't received anything from you. Could you resend your message please? Click the link to my biznik website above, click the "Contact" link at the top of the page then hit the email link to send to "info@..."
Your message will be forwarded to me.
Thanks
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Just sent again from 2nd Oct
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