On Wednesday

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On Wednesday

Postby Burgerman » 04 Feb 2020, 10:57

I will get off this bed to try a bunch of chairs from a freind (a dealer) inc the front drive permobil F5 and some mid drive chairs. He will let me program them so they steer. Partly because bored. Partly because people that use them tell me that they handle great. From memory some years ago, I would have to disagree. But its hard to tell with stock programming at a show or 3 mins in a hospital meeting (spinal injuries unit) as its so slow to respond that you cant "feel" whats really happening. And theres no wet leaves, angld pavements, grass etc. And the programming prevents you from throwing it around as I usually do. Its like driving a slug that only goes fast in straight lines on good surfaces.

I already know that I hate the rear swinging about behind me indoors. I tried front drive before. It feels like you have a huge tail. And it makes manoevering and changing position in a kitchen or at a computer or something very unweildy. I take out furniture and people feet with them at the bar. Or I did when testing a front drive sunrise chair.
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Re: On Wednesday

Postby Irving » 04 Feb 2020, 12:12

We have 2 x Salsa M and a TDX2 in the lab (part of the CrowdBot and ADAPT 'intelligent' wheelchair' projects) and having tried them out I'd never have a MWD chair myself. Not tried a FWD, but the physics of one is enough to put me of.f.
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Re: On Wednesday

Postby Burgerman » 04 Feb 2020, 16:58

We have 2 x Salsa M and a TDX2 in the lab (part of the CrowdBot and ADAPT 'intelligent' wheelchair' projects) and having tried them out I'd never have a MWD chair myself.


Ditto. I hate them. Horid harsh ride, and wheels sticking out in every direction. Dont even like them indoors - the place they should be better.

The last time I tried front drive on wet grass (my park across the road with dog) it swapped ends at about 6mph when I tried to change direction. Gyros only work if theres enough tyre grip for it to stop the thing from getting out of shape. There wasnt. It didnt. It ended facing the wrong way but didnt spit me out, but almost...

But on normal dry surfaces you can feel the gyro taking away your steer ability as you try to control it at speed. Try to steer an accurate path and it wont let you. It runs out of overhead. All the motor power is being used to stop it spin out and it slows you down. So you cant just point it where you want. And this gets way, way worse if you remove all that turn acceleration and deceleration so hat it should steer properly. Its no longer hidden by all the delay. Thats when it is real problematic for me. But some still tell me its OK. And that things have improved. Dont see how, but will try. I think its that they are driving it like my grandma and cant tell... We will see. Again...
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Re: On Wednesday

Postby Burgerman » 05 Feb 2020, 02:51

This is exactly why I tell people to run away from front drive and permobil especially.

What happens if you turn off the stability module, and/or the gyro in the OEM software? Unlke every other chair, where theres no problem, they do not use the PG stbility/gyro modules. They use a home grown one. And thats whats screwing you up.

You dont WANT to increase turn speeds, (turn rates). You want to set turn acceleration, and minimum turn acceleration, and turn deceleration, and minimum turn deceleration, all 4, to 100. But with the gyros/stability/accelerometers that makes them undrivable. And with the gyro/accelerometers disabled, no front drive cair can go beyond about 3 mph without being unstable. fishtailing, or swapping ends...

So theres no way to make one steer properly. Theres no way on earth I could live with the stock setup, I couldnt hit a barn door. How do I know? I already saw the stock R-Net settings on an F5. :lol:

hey burgerman! so ive found the permobil chairs - the newer ones specifically - don't allow much tuning with the ESP modules installed.. if you turn up the turn rates (even in OEM) the gyro module starts to fight you and surges as you try to accelerate into, or out of a turn. the 5 series chairs specifically are VERY tricky to program..


Thats because as you begin a turn, the unstable configuration, (Front drive) means the rear tries to swing ever further, so the stability system, tries to stop that by adding OPPOSITE turn. And it overules your turn command. Its exactly this that makes me so frustrated with all front drives. YOU lose control authority, and the gyro/accelerometers take away your control. And it wont go where you tell it. So to stop that happening you are basically stuck with delayed, slow and inaccurate stock programming that they come with. If you try to reprogram to get some linear accurate control, Or even some high forward acceleration, then it is VERY noticable. It makes no difference what the brand is, you cannot defeat physics with a stability control system! (your ESP).
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Re: On Wednesday

Postby Burgerman » 05 Feb 2020, 03:05

ive tried removing the ESP modules - BUT the firmware on the 5 series permobils will freak out if its not connected - and i haven't been able to find a compatible profile/firmware/system software(whatever) to flash onto them that allow the power base to move AND still preserve all the seating functionalities.

And you wont. They use specially modded settings files, to work with their OWN seating modules. Instead of using the standard ISM6 or the 8 channel one with positional feedback that all the other manufacturers do for advanced seating. As well as their own stability modules. It basically makes it impossible to do anything with, hard to fix, impossible to program properly unless you have the OEM permobil version because many things will be missing... Dont buy permobil! Overpriced and locked down.
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Re: On Wednesday

Postby Burgerman » 05 Feb 2020, 04:30

Try that with front drive...

For my own amusement, and your testing, I can add a small file here.
Its not a full settings file. It changes only the profiles. And only the settings in SPEEDS. And removes some walls.
It has just 2 profiles:

-Profile 1 is just for an empty chair and is only one speed. SLOW! And it has 90% of the load compensation of your usual setting.
-Profile 2 is for slow, right up to max speed. Its the ONLY profile you should need all day.

This file only changes these files, it leaves all other files, seating, settings etc alone. They will all stay as they are.
It isnt a r-net file. It is loaded from inside the OEM software, and can be written to the chair. It has a different file extention. file.rnss - It will not change any other settings other than what you see.

You can write your old (saved) settings back later if you dont like it. But you will. NOT for the F5 or anything with stability/gyro control...
Attachments
Drive settings.zip
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Re: On Wednesday

Postby snaker » 05 Feb 2020, 08:55

danpayton wrote:but same is true for my rear wheel drive bounder..

You forgot bounder is double faster than permobil. What would happen if you had driven a FWD down hill with the bounder's speed?
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Re: On Wednesday

Postby foghornleghorn » 05 Feb 2020, 09:51

@Dan

I'm reluctant to post this as it will just descend into an argument but you need to ignore the expert on things they've never done.

Having seen your videos and knowing you are out and about on all sorts of surfaces I respect your opinion on chairs far more than some others on here. Don't back down - you are not wrong about FWD.
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Re: On Wednesday

Postby greybeard » 05 Feb 2020, 10:32

foghornleghorn wrote:@Dan

I'm reluctant to post this as it will just descend into an argument but you need to ignore the expert on things they've never done.

Having seen your videos and knowing you are out and about on all sorts of surfaces I respect your opinion on chairs far more than some others on here. Don't back down - you are not wrong about FWD.


Good points. The ONLY issue I have with the front drive I LIVE IN is occasional caster shake at 6mph that I haven't been able to fix, and which may be nothing at all to do with FWD. There is no way I could navigate in my home with RWD even with BM's programming and JSM positioning etc - I've tried!
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Re: On Wednesday

Postby rover220 » 05 Feb 2020, 10:45

danpayton wrote:but i suppose front wheel drive chairs are TERRIBLE and they should be illegal...
and mid wheel drive chairs too...
for that matter ALL mainstream wheelchairs are bad..

can anyone recommend a chair THEY didnt build themselves?

or is EVERYTHING trash?

all i know is its NOT possible to maneuver in my house with a rear wheel drive chair. and very difficult with a mid-wheel drive. Front wheel drive works great however.

i can see that there's displeasure and frustration with a lot of the stuff out there.. but MOST people don't have a choice...
i personally own 23 power chairs, and 4 manual ones. ranging many brands and drive types - a good representation of everything that the general population uses.

I try to offer my thoughts and help on things that are out there in the world..

seems like im usually met with negativity, and am told "thats a terrible chair" when i bring something up...

can we get past the past the "fact" that EVERYTHING is horrible, and have a discussion?

i DO in fact know how to tune the permobil chairs so theyre usable - and the whole reason i posted in this thread was to help out with with my experience with permobil. and their "strange" control systems

sorry if i offended anyone by talking about a wheelchair on a wheelchair messageboard!

-Dan


the reality is most uses in your situation get by perfectly well with FWD and MWD. not all of these chairs are trash at all, some on fact are actually very good and rather more capable than some give them credit for.
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Re: On Wednesday

Postby Burgerman » 05 Feb 2020, 10:48

Do you know why?

Your swing away footrests, and the seat position being well forwards because those footrests must go ahead of the caster wheels, make it way too nose heavy. And way too long. And instead of sitting on the drive wheels, they are behind you meaning you swing around in front of it. And the swing away footrests prevent you turning into doorways etc as they form corners stuck out ahead of you.

In that configuration I cant use rear drive either! They are like unsteerable oil tankers. You must configure all those things correctly, or rear drive is useless. And right now theres ONLY the old salsa, still made, that you can do that with. All the rest have the caster forks too close together. Inc the new Q700 Rear drive. All the other rear drives on the market.
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Re: On Wednesday

Postby greybeard » 05 Feb 2020, 13:04

Burgerman wrote:Do you know why?

Your swing away footrests, and the seat position being well forwards because those footrests must go ahead of the caster wheels, make it way too nose heavy. And way too long. And instead of sitting on the drive wheels, they are behind you meaning you swing around in front of it. And the swing away footrests prevent you turning into doorways etc as they form corners stuck out ahead of you.

In that configuration I cant use rear drive either! They are like unsteerable oil tankers. You must configure all those things correctly, or rear drive is useless. And right now theres ONLY the old salsa, still made, that you can do that with. All the rest have the caster forks too close together. Inc the new Q700 Rear drive. All the other rear drives on the market.


If that is a response to my post, yes, I know why. But I'm perfectly content to use a FWD that suits my needs well with minor tweaking, rather than re-engineer a RWD just so I can conform to your opinion of the perfect chair. Not everyone has your skills or the compulsion to seek perfection in all things. As your perfect chair is not commercially available I have to accept compromise. Many have to.
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Re: On Wednesday

Postby Burgerman » 05 Feb 2020, 13:32

The salsa still is available. But I am not trying to make you use one! Just trying to explain why people think rear drive chairs are generally worse indoors. As you said.

Its not the fact that they are rear drive. But the way they are configured and the swing away footrests they are usually lumbered with.
A few configuration factors that turn what could be a good chair into one that has made the USA move to mid or even front drive because of the "well known" benefits. The reason is that they are all configured incorrectly. Why? Partly because of regulations regarding tipping back on a slope or ramp if you accelerate. So they fix that by sitting you way too far forwards. Loading up casters, swinging you around from the drive wheels behind you, making the thing drive like an oil tanker. With the wrong footrests...

They finally decided to fit a centre footplate on the new quickie chairs. See below. Whoohoo! No special builds needed. And then went and shot themselves in the foot by moving the casters closer together at the same time, making it impossible for your heels to go back between the casters... So you cant move the seat back banghead They are retarded.

https://solentmobility.co.uk/product/sunrise-q700r/

For me to use one of these, I would need to modify the front caster arms so that they are the same distance apart as the Salsa, of my redesigned F55 frames. They made it worse.
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Re: On Wednesday

Postby Burgerman » 05 Feb 2020, 14:24

And now I am not able to test. Because he isnt coming. At least not today. Flue. Hopefully not that chinese one.
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