power wheelchair

[professorsites]

Does anyone have any thoughts about the Hoveround power wheelchairs??

[Burgerman]

Not good ones.

[ex-Gooserider]

Four letters... First one's an S, last one's an M, I will leave the middle two as an exercise for the student...

ex-Gooserider

[JoeC]

I was actually considering getting the plastic fenders and seat from Hoveround chair and building a *real* capable chair underneath it, the type I work on for sports, just to see people's reactions when a 'Hoveround' is slamming around on a basketball court. It would be a difficult illusion to achieve, though, since a front wheel drive would never work for the sport.

[Burgerman]

Or pretty much anything else other than curbs very well.

[LROBBINS]

FWD works great for Rachi, who can't go fast anyway, and who lives where there are no curb cuts. Makes fitting lift and tilt with a very low floor-to-seat height easy too. Ciao, Lenny

[Burgerman]

Well there are always exceptions! But try using one at normal speeds day to day and its awful. They feel unstable and hard to control at 4 mph, at 6 they get downright dangerous on grass, leaves on the pavement etc. I have had one get away from me and spin around and face backwards on some wet slippy winter footpath. Banged my toes against a wall... You can fight physics. And in the pub you run the casters over peoples feet behind as you manoever about.

[LROBBINS]

At above walking speeds I wouldn't want to drive one any more than I'd want to fly a tail-wheel airplane (even though it's considered macho and fun to constantly and precisely jiggle the pedals to keep it from swapping ends. There are two kinds of tailwheel pilots: those who've groundlooped and those who will.). At least without some kind of electronic stability augmentation that cut turn rate or speed just before tire breakout. Dynamic has a h--f-assed approach based on essentially programming not-to-exceed g values (and what if the surface is icy?), but these days someone could program a real dynamic stability augmentation system (NOT a closed loop servo) that might tame the beast. I agree, FWD is intrinsically unstable, but for those who can't use speed anyway it can offer some plusses. Ciao, Lenny

[LROBBINS]

John, what's "normal" speeds. Normal for Rachi is very slow for you and many others, but it IS normal for her. The excuse for putting an unusable chair lift into the Siena Synagogue was that Rachi does not have a "normal" wheelchair (meaning a hospital clunker, which can't actually use it either but could be lifted and tilted onto it). None of us denizens of WheeldhairDriver are "normal", I'm surely not nor would I want to be. Ciao, Lenny

[Burgerman]

No, the normals in society have a huge problem. Because they do not, and usually can not think. This site attracts those that do/can!

It affects everything in life, not just powerchairs. Intelligence and logic make everything in life easier. Its a control thing. I like to be in control of everything. Dont do anything on blind faith.

I have no faith at all in most people, or most equipment. And as it turns out I am usually correct!

If you didnt have your ability and capability your daughter would be much worse off!

[rollingcowboy]

my chair is front wheel drive - but the center of gravity is only about 2" behind the drive wheels so it is almost center drive.
I am guessing the chair will go 7 or 8 mph.
I have total control when wide open and can slalmon down my streets and over bumps with no problems.
I have never experienced anything other than total control - other than occasional caster flutter.
my hi speed drive is set to;
80 % response
100% forward speed
15% acceleration
22% turn speed
15% turn acceleration
15% turn deceleration
0% braking

maybe it is because I am close to center drive? - or since my brushless setup has feedback?
my chair is much easier to negotiate indoors than my old rear drive chair.
I would think that when you are near the cog with front or rear the handling would be similar.

[LROBBINS]

maybe it is because I am close to center drive? - or since my brushless setup has feedback?

Probably both. A tailwheel airplane with CG close to the main wheels is much less likely to ground loop, and much more likely to nose over. The motor feedback will control turns better, though it probably won't stop a skid once it's started. One of the reasons I'd like to go LiFePO4 on Rachi's next chair is to be able to get the CG further forward (but not so much that front anti-tips are needed). Your low turn acceleration and deceleration values also probably help stability, but will make steering less snappy than if they were higher. Ciao, Lenny

[Burgerman]

80 % response
100% forward speed
15% acceleration
22% turn speed
15% turn acceleration
15% turn deceleration
0% braking

80 response? No idea what that does. But 100 sounds better!
15% acc??? You have to be kidding. All my chairs are set to 100 and its not enough...

22% turn speed? Mine are all at 45 or 55, How on earth can you steer? I like it to jump and turn fast accurately when needed. You try that in a front drive and it will go anywhere it wants. Which is why its set super low.

15 percent turn acc? Mine are all set to 100. And 80% feels dangerously delayed and innacurate. But even worse. So it will not turn quickly and does it "late" after you wanted it. So you add more and over control.

15 turn dec??? I wouldnt be able to drive it at all. Mine is at 100. So it stops turning when I say so rather than sometime later when it decides.

Braking at 0??? Mines at 100 so it stops when I say so And howls its tyres embarassingly 100s of times a day.

Have a very good slow careful read here: http://www.wheelchairdriver.com/powerch ... amming.htm

Because your chair is programmed even worse than most pride stuff. To prevent fishtailing by removing most of the control. You would be amazed how instantly and accurately it really could be. You are on a different planet to me. I honestly couldnt even use your chair and would find it unsteerable unless I slowed right down for everything and prayed.

The reason it doesent obviously fishtale is probably the mild delayed slow steering response. And likely its that way for this very reason.

But seriously unless your figures are somehow reversed from what we are used to seeing, you need to get hold of a low level programmer fast! Then you will FEEL the real control, and the instability it induces in the front drive layout with proper steering. Prepare to be amazed and horrified!

[rollingcowboy]

there appears to be a great difference between your (BM) set up for gearmotors and what works for brushless.

here is my drive 1 setup;
for ref see
http://www.invacare.ca/doc_files/1141471.pdf
start on page 24
response 80%
forward speed 60
forward accel 15
turn speed 35
turn accel 30
turn decel 15
brake 0

I have spent a considerable amount of time testing the settings.

when I try to approach your (BM) settings the chair turns and stops violently!
if I stayed on BM settings the chair would tear itself apart.

[Burgerman]

Well I never tested them on brushless but I know a man that did. He has no problems with it set up with all turn acc or dec set to max. But it could be that your setup is somehow different. Would need to test to be sure. But delays (acc/dec on turn) always make steering worse. If it turns too fast reduce turn rate rather than add delays.

Or its possible you really would be shocked if you tested my chair. I dont know how skilled your control fingers are!

Try reducing turn rate to 1. Then set turn acc and dec to 100. That will give a super slow turn rate but it will do it when YOU CHOOSE by the exact amount you input. Not "time based" as your 30 setting is giving you. Not turning enough? Add turn RATE (TURN SPEED). A bit at a time.

>>>> when I try to approach your (BM) settings the chair turns and stops violently!

So does mine. Thats a good thing. The joystik is PROPORTIONAL so says exactly HOW violently. But if turn rate (turn speed) set too high it will be too violent. But turn acc/dec should still be 100.

[LROBBINS]

Without knowing which brushless motors Rowlingcowboy has, and even then perhaps not knowing their characteristics, it's hard to know for sure that reduced turn accel/decel isn't appropriate for them. Our geared, brushed motors have a lot of spin-up inertia built in, so don't respond well until turn accel/decel is at or near 100%. I can imagine, but don't know never having had the chance to work with one, that a multi-pole gearless brushless motor with a light rotor and almost all of its weight in the stator might have so little inertia that it needs some taming. It's also possible that Rowlingcowboy also has a controller with less intrinsic ramping than we're used to - again, if it has fewer time delays (before the programming), it may need different settings. I know that in the Dynamic DX series, just the filtering on the CAN data lines adds time delay, so much so that on one product where the engineer got carried away with noise filtering, they actual got erratically outside the allowed CAN-frame time slot and had to re-design, and after CAN, there's all the computer processing and the time delays of the rest of the electronics too. Newer controllers may have less of this parasitic delay as the frequency response of semiconductors keeps on improving. Ciao, Lenny

[Burgerman]

The thing is, delay is still delay. It adds to the lag in response. Thats always a bad thing. All my cars and motorcycles, turn the instant I tell them to by the amount I say. My RC stuff, helis, jet planes etc are the same, we pay much money for superfast servos and low latency RC systems so theres no perceptable delay. If thers any they become hard to control.

So too much turn rate can be a problem. Too fast and too instant response isnt ever a problem. It always takes a finite time to actually move the stick, and for the electronics to catch up, even with everything set to have no delay whatsoever.

[JoeC]

I've done some adjustments on Invacare chairs with the handheld programmer, and it's definitely true that some of the controllers have programming options and percentages that are not similar to what we've seen with Pilot+, R-net, and Dynamic DX. The percentages Rollingcowboy listed for an Invacare brushless will not drive the way you'd expect a Pilot+ to drive if you gave it those values.

It's definitely confused me when I've had to adjust these chairs for people. I know what I want to change to help them play a sport, but some of the things the handheld programmer does are really counter intuitive. It's not just that they're brushless, it's that Invacare has a different structure of control for some of their chairs. It's bizarre, and I'm glad I don't have to deal with it often. If I had some lower level programmer for the invacare chairs it would be interesting- but I have *never* heard of anybody who had one. They must keep them under lock and key.

[JoeC]

The thing is, delay is still delay. It adds to the lag in response. Thats always a bad thing. All my cars and motorcycles, turn the instant I tell them to by the amount I say. My RC stuff, helis, jet planes etc are the same, we pay much money for superfast servos and low latency RC systems so theres no perceptable delay. If thers any they become hard to control.

So too much turn rate can be a problem. Too fast and too instant response isnt ever a problem. It always takes a finite time to actually move the stick, and for the electronics to catch up, even with everything set to have no delay whatsoever.

What I'm saying is that some of the Invacare handheld adjustments are able to be set from 0% to +100%..... or -100%, or some other range! It's odd. So without some trial and error with his controller and programmer, we don't have a great idea of what setting causes the least delay.

[malamar]

Well company, I was having a ball changing prog.parameters and testing them in the corridor, when PC screen said it better cnanged me something: after that comms never has been any longer "active" no matter the hunndred of drivers tried: seems,for a conspiralcohlic like me, a typical "factory job" AS TO VERBOTEN popular OEM usage At least before stopping working i had the time to strike in controller a bit "bronco" set of numbers and with those i drive actually, before deciding to revert to genuine cable and dealer soft. porca miseria!!!!! Then some wild obvously wong parameter ejected me from the chair to the gtound (teethhing inconvenients), but i can't stand up by myself and had to wait many hoursfor bombers to rescue me and a neighbour with the door key; last i discovered that my chair is only 50 A hence the yawing,i suppose......I've not entered here for two days, a bit saturated by chair never ending problems...
Best

[Burgerman]

Then some wild obvously wong parameter ejected me from the chair to the gtound (teethhing inconvenients)

Yep this is part of the fun! And how you learn.

[Burgerman]

Malamar, uninstall EVERY driver, all software, and plug in cable. Look in device manager, and remove and choose DELETE DRIVER anything related to your USB SERIAL driver.

REBOOT.

Install ONLY OEM Software.
Install ONLY the one single driver that works.

Choose same port as worked before IN DEVICE MANAGER even if it says it is "in use".
Choose this too in PG software.

Now it will work again.

[DREW]

OK I limped home yesterday (second time this month) with only two red bars showing battery life left. I didn't go far, maybe 6 miles roundtrip. On straight, smooth, black-top, trails. The unit was charged over night and went from a full charge (all light bars lit) to two red bars lit in less then 30 minutes on the way home. The company that leases me the chair did a load test about 3 weeks ago and said "everything" is in good condition. Bulls@#t! Now they are saying that the batteries passed the load test and therefore, can not be replaced (paid for) at this time. Is it normal for batteries to act like this?

[DREW]

Important part ... the chair and batteries are 6 months old

[DREW]

OK I limped home yesterday (second time this month) with only two red bars showing battery life left. I didn't go far, maybe 6 miles roundtrip. On straight, smooth, black-top, trails. The unit was charged over night and went from a full charge (all light bars lit) to two red bars lit in less then 30 minutes on the way home. The company that leases me the chair did a load test about 3 weeks ago and said "everything" is in good condition. Bulls@#t! Now they are saying that the batteries passed the load test and therefore, can not be replaced (paid for) at this time. Is it normal for batteries to act like this?

[Burgerman]

A load test means almost nothing unless its a car starter battery. And even then unless you really know what you are doing it doesent mean much.
At best it shows up a bad cell.

To test properly you need the full battery specs, and to do a proper capacity test. This MEASURES actual Ah that the battery can do. It measures the stored power and you can then compare it to manufacturers spec. EG on abother thread I posted a test of a 2 year old Odyssey battery. It did almost exactly the same as a brand new battery. I measured 65Ah taken out. This shows it is literally as good as new.

The other thing is that there is no "pass" or "fail" in either a load or capacity test. All batteries deteriorate over time, and deteriorate due to discharge. Its entirely possible to be unhappy with a battery after 6 months use, if it no longer has the capacity left to do what you normally do. But give that same battery to an old lady, and she may be happy with it for years to come.

Its like this.
Discharge your battery deeply every day, use a nasty mobility charger, and get 6 months use before it feels as if your battery has reached end of life.

Or use a better charger, top up as often as possible during the day, to keep average discharge level down, and it will easily see two or more years. As it will if you dont use the chair for big distances. 8 miles IS a big distance. Regardless of manufacturer claims of 20 miles.

[Burgerman]

Remember that batteries are the weekest part of any electric vehicle. And mobility devices use the worst type of batteries. Lead.

If you want batteries to be able to cope without problems you need to do all you can to put everything in their favour.
Mobility chargers are usually pretty crap, and too small and slow (cheap) and charge at less than optimum voltage in some cases.
And they cut off too early, so the user doesent complain about charge time.

So your batteries are likely 99 percent charged every day when you see the green ready light. But that last tiny bit is important.It typically doubles service life by converting the sulphates back to usable sulphuric acid before it hardens forever on the battery plates.

The other thing that shortens battery life id deep discharges. The less you discharge them the greater number of cycles you get. So topping up some when time allows during the day will make them live much longer.

As such, I now only use Odyssey batteries (not cheap) and I charge while sat at my PC, while I eat, in my van as I drive, as well as overnight via an advanced computer controlled charger every day that lets me choose the exact correct parameters for the odyssey batteries. I now get about 2 to 3 times the service life from my batteries that I user to do.

Worst case: Cheap batteries (only MK or Odyssey are worth fitting) charge overnight with a low power mobility charger (not optimised for batteries) and travel a long way daily. Then get 6 to 12 months a set of batteries.