Weight! (A continuation, sort of, of my Storm 4 review.)

[Burgerman]

I doubt you even know what you are looking for.

I have great eyes. And a very deep understanding of physics. And powerchairs.

Which is why I build my own. Because bought ones are frankly useless. In a great number of ways. Been there, got the T shirt, wore it out, and moved on 15 years ago. Been fixing other peoples, and testing everything available, at shows, spinal injuries units, friends (other guys with spinal injuries etc from my unit) ever since. And I know WHY they are useless.

This is ONE way. Take a look at this script here. THIS code runs on my own BM3 powerchair. Was written by Lenny, and tested and developed by the three of us. (Will, myself, Lenny over a few years now) to allow the use of a higher voltage and more powerful controllers because the powerchair ones are too weedy and too inefficient. (wasteful of power) and don't give adequate torque (Amps). Precisely because we do understand all this stuff. http://www.wheelchairdriver.com/BM3-con ... %203.0.txt

Theres a similar sort of ADJUSTABLE code (via a programmer) lives inside your controller written by Dynamic, common to all their powerchair controllers. As fitted to many chairs inc yours. That's where your turn acc / dec delay lives. Its a bit of code. It has nothing to do with user weight. In fact there's some more code, called motor compensation that actually CORRECTS motor response so that different motor loads (or user weights) are automatically compensated for. To make the chair follow the chosen command + any delays etc accurately. Would you like to know how that works? Didn't think so.

This took 3 years and 73 pages of technical discussion, and 1450 posts to develop. All of which goes totally over your head, and the heads of the powerchair manufacturers. They don't make controllers themselves. The only people that would understand any of this would be the control system manufacturers such as Dynamic or PG drives or Curtis that sell the controllers to the various powerchair "designers"... And even then only a few of their experts.

What I am trying to explain to you seems beyond your ability to understand. No matter what way I try. You just seem to ignore everything and keep asking the same things I already answered. And even others that have posted here that KNOW the difference - because they tested it themselves - don't sway you. You make all kinds of silly claims that go against the physics and logic. Not to mention the stuff many of us already know through testing as well as theory and in some cases training.

I KNOW how your chair works! You quite obviously don't. And no amount of "laughing" changes this.

HAHAHAHA! You are sooooooooooooooooo funny!

These sorts of comments just make your posts look desperate. Everything I wrote was correct, and factual, and I even did a vid to attempt to explain the issue. You plainly do not get it. I watched the 2 vids you made again. And can clearly see the turn acc in the 2nd one in several places - even though you are barely moving - where the stick moves and the chair accelerates to turn afterwards. Its push and wait to see what happens.

Remember its not how SENSITIVE. Its not how SOON it turns. Its how quickly it reaches you chosen turn rate. In other words how linear it is. And it isn't!

[robnnorthaustin]

Sakima nothing wrong with my eyes and I say Bm has made his point so clearly that I suspect you are more concerned about finding any way to justify your rambling posts that you are blinded by the light...so to speak. Open your eyes and ears and remove foot from your mouth and you might have an ah-ha moment LOL.

[fuzzy logic]

Invoking Newtons first law for controller reaction times is not really helping http://en.wikipedia.org/wiki/Inertia taking us back to Aristotle. Einstein really only enters this at speeds beyond any powerchair available at present so for brevity can we ignore this and quantum physics also -please

[Burgerman]

What's more, Newton was wrong, as shown very clearly by Einstein, with E=MC2 and yes I absolutely understand relativity and have been studying physics since school.

[Step]

the effort wasted on discussing a worthless chair baffles me.

as this thread is on weight:
I tested the storm 4 and scratched it off the list when I saw it weighs 170kg!
empty it weighs more then my you-q Alex with me in it and probably even more then BM's F55 with his 20 stone in it.

no physics around that

[sakima]

YOU NEED TO CHANGE THE SUSPENSION FOR A HEAVIER USER AND ADJUST THE SETTINGS FOR A HEAVIER USER.

[sakima]

Sakima nothing wrong with my eyes and I say Bm has made his point so clearly that I suspect you are more concerned about finding any way to justify your rambling posts that you are blinded by the light...so to speak. Open your eyes and ears and remove foot from your mouth and you might have an ah-ha moment LOL.

I am not blinded by any light. Everything BM has written is not based on fact, just based on his findings.

[Burgerman]

Its based on both. And much experience with other users and other chairs too.

>>> YOU NEED TO CHANGE THE SUSPENSION FOR A HEAVIER USER AND ADJUST THE SETTINGS FOR A HEAVIER USER.

This just proves you have no grasp of physics or any clue what we are talking about here.
How exactly does this suspension adjustment or suspension in any way at all affect the electronic programming delay??? That's like saying your car does more to the gallon if you vacuum the house.

What possible affect will this suspension have on a smooth floor? When just turning on the spot? You obviously haven't got any clue about physics or chair dynamics. In this case the suspension doesn't even move and may as well not exist... And even if it does, it has zero affect on the TIMED delay that is turn acc, turn dec that we are discussing.

Wheres your promised video? I am expecting something to match this: http://www.wheelchairdriver.com/gopro/control.mp4

Except yours should reach its full rotation speed, and stop rotating when released, very slightly more quickly than mine since as you say you are much lighter. Less mass to accelerate or decelerate. Your claim.

To rotate the chair from a standstill a full 180 degrees, and completely stop rotating takes mine just 0.9 of a second. (see last part when set to 100% turn acc/dec) Use a stopwatch.

But you cant make this vid. Yours will be way slower. And importantly much harder to predict where and when it will end. So you cant gun it till you find out...
And my turn rate is set reasonably slow at only 45%. But this still isn't the whole point. We are really talking about the TIME TAKEN to reach full rotation speed, and then the time taken to decelerate to a stop upon release of the stick - that is actually the question.

Either way you cant do it. Your programming will try to smooth it out and not do as you tell it.

I am not trying to make you look like a liar, or stupid. As you claimed. You are doing that quite well. What you should do is listen and think. Admit you could be wrong, and try out what I say. And take advantage of this information to make your own chair better. Seriously you will not want it put back how it is now! More easy to steer naturally with a greater confidence level as it will be linear. You just need to get hold of someone with a suitable programmer.

All the first 2 vids showed really was that you were moving and steering so slowly and steadily that you wouldn't be able to detect anything much about the programming at all... I was waiting for some kind of action. To show the turn capability.

[steves1977uk]

It's people like sakima who blindly accepts the default programming of his chair which is why all factory built chairs come with the same settings for the average user who has never tried anything else.

I bet if the majority of power chair users knew that their chair could be made better via programming, most would want it as best as it could be. I have been a power chair user since I was about 4, so I speak from experience.

Sure there are exceptions where a user doesn't have great control of however it is set up for them to drive it and need some delays set, but even they would prefer theirs to be the best programmed for them.

All what BM and others (myself included) are trying to make you realise your chair could be made better, but you are refusing to even try it out if you can get access to a programmer and actually try it for yourself.

Steve

[greybeard]

BM, I admire your patience. I'm losing mine just reading this thread, never mind contributing. There are some people who just refuse to be helped. I am in awe of the time you have taken trying to help this one.

[Burgerman]

What I would like to do is, program it to steer - no turn acc, dec or minimum turn acc or dec, and reduce the turn speed so its not as sensitive.

Then watch his face after a few minutes testing. I have done this so many times I lost count. Every time the user was very pleasantly surprised. I have done a good few for members of this forum as well. They were surprised how much easier and more accurate it was. But as you say, some cant be helped.

[sakima]

http://www.timsstroke.co.uk/#/proof-is-in-the-pudding/4587264903

[Burgerman]

That shows the turn acceleration, and turn deceleration reasonably clearly.
EXACTLY what I am talking about!

That was what I expected to see. I have seen enough of the things!

Why can you not see how long its taking to accelerate to full turn rate AFTER you push the stick to full travel?

Or to decelerate to a stop after you tell it by releasing to the centre? Once in the centre the chair isn't supposed to be turning. It should stop as the stick hits the centre in an ideal world. It actually stops turning smoothly, over about 1 second period even when you release the stick to the centre. Why do you suppose that is? That is called TURN DECELERATION - its a delay. It causes me to crash because the chair doesn't end up pointing where the stick tells it to and hello doorframe - or I have to go slow.

We are not talking about how long it takes to "respond" to the stick here.
We are talking about the time it takes for a turn command to *reach* the chosen (max) turn rate and its taking about 2/3rds of a second or so after your stick hits the side. Its therefor not linear.

And to finally stop turning upon release. Should be instant. The same time you let go. And its slow to do that! At least 4 times slower than my own chair set to 100 at around 1 second.

That's why its not linear when you steer when moving forwards.

It must be easy to feel this since you are sat in it. I am bewildered that you can watch the same vid, and sit in it, and not grasp this. Watch how fast my chair start/stops and more importantly how fast it achieves its full turn rate and how fast it STOPS turning. At setting 100 at the end.

http://www.wheelchairdriver.com/gopro/control.mp4 This turns, stops turning, and goes at least 3x sharper and more accurately. It doesn't start turning gently. It doesn't stop turning gently. As yours does in the vid. It just follows the stick even with 20 stone sat in it. The difference is simply the programming.

Read this slowly and stop trying to prove something that most of the rest of us already know is correct, and have tested for about 17 years!
http://www.wheelchairdriver.com/powerch ... amming.htm

[sakima]

You want it to STOP TURNING right NOW. You do not want a further 4 seconds of turning that begins to reduce then gradually decreases until it goes straight.

4 seconds!!! More like .5.

And what about "it drives like a drunken sailor?"

[Burgerman]

With all that acc and dec it absolutely will.

I was timing how long it took from you hitting the stick, to a 90 degree rotation and total stop. 4 seconds. Mine took 0.9 seconds. that's FOUR TIMES more delayed.

If it takes even half a second to FULLY respond to a given command - that's forever in a control system! For more, less turn, or opposite turn - (and looking at your vid its MUCH longer than .5 second to full effect) - then control is simply not linear or proportional. Its hard to know where exactly it will go. How much control to add when correcting. It causes over-control (as it didn't respond enough at first, so you give it more and then cant be stopped turning fast enough due to the turn deceleration so panic sets in. And you learn to go slower. Mine takes under .2 of a second to reach full turn rate. Or to stop turning upon full release to a complete stop. 0.2 is too slow, but the best possible with mobility equipment. The Roboteq robotic controller on my BM3 chair is much faster.

I make adjustments and corrections at high speed that need to be absolute, in exact proportion to the amount of stick movement. Not increasing over time depending how long I hold it in. Exact and instantly by the amount I choose. Much more quickly that that delay level all of the time. If my car took that long to stop swerving left or right I would take out a lamp post.

Here's the thing. Why don't you try it? Then tell me I am wrong. I just know you wont be able to do so, unless you lie...
I have done this to far too many chairs and users. Never had anyone wanted the delay (acc/dec) back yet, apart from one user that simply didn't have enough hand dexterity or technique to cope. He needed it as a "push wait" switch that starts turning slowly then speeds up, (and the opposite) as yours does, rather than the direct steering as most cars, PC mice, your own hands, or a knife and fork etc do.

I like my chair as direct and predictable as a knife or fork... And if you tried eating with a knife and fork controlled by your chairs accelerated and decelerated controller - so would you!

Its the difference between controlling the chair via some vague stretchy rubber bands and solid accurate direct linked control. This will eventually begin to sink in I am sure...

[sakima]

the effort wasted on discussing a worthless chair baffles me.

as this thread is on weight:
I tested the storm 4 and scratched it off the list when I saw it weighs 170kg!
empty it weighs more then my you-q Alex with me in it and probably even more then BM's F55 with his 20 stone in it.

no physics around that

I had an Alex that I used for about 3 days in the summer!

I go out in my wheelchair most days in the summer and it is very, very hilly around here. I go shopping and hook bags on the back. The Alex didn't like that, as everytime I went up a hill or kerb slope, it did a wheelie!
Getting on and off trains was a complete nightmare, because of the extra suspension, the c of g would go back when going up the ramp and the chair would do a weelie and then going down the ramp the c of g would move right forward and the drive wheels would go up.
That's why I got the Storm. It is a lot, lot heavier keeping the c of g much lower and it is a lwb chair. The Alex is a swb chair at about 4" shorter than the Storm.

As for your other comment regarding this thread, I have to agree with you.
I submitted a reviewhttp://www.wheelchairdriver.com/board/viewtopic.php?f=6&t=4585 why bm felt it necessary to, at first, pick holes in my driving control and then insinuate that I was simple by saying "I know no better." I just don't understand.
I had already stated that it was my review and my opinion, based on my weight and terrain and that the settings would not be ideal for some.

[sakima]

You do not want a further 4 seconds of turning that begins to reduce then gradually decreases until it goes straight.

[sakima]

Does it steer like an oil tanker?

Is it super delayed, taking 4 seconds to stop turning?

Does it drive like a drunken sailor?

[Burgerman]

Absolutely.

Re read this that you have *ignored* viewtopic.php?f=2&t=4591&p=62271#p62265

ALL chairs with STOCK industry standard programming from the mainstream manufacturers do so. Every last one.

It all depends what YOU consider good.
To me (& everyone else that has removed the acc and dec that causes this problem) then yes it seriously does steer like a drunken sailor. Its a liability at speed in areas where you need accurate control.
(In comparison to what is easily possible on any powerchair if sorted out).

Why don't you actually try it?
Once you try a properly programmed chair *THEN* you will get it!

[sakima]

Drunken sailors move from aide to side!

Erm, as you can see, my Storm does not!
If you think it does, try and illustrate that.

How does .5 of a second become 4 in your eyes?

[sakima]

You do not want a further 4 seconds of turning that begins to reduce then gradually decreases until it goes straight.

?

[Burgerman]

Because that's how long it took from your initial stick movement "left" to when its wheels stop moving when you did a 180 turn.

And about how long it feels when you are trying to get it to hit a small gap at speed after a steering correction. Because first you need to DO the correction, and wait for some affect, and hope it doesn't overshoot and then release it at the correct moment.
Only you cant...
Because it keeps on turning after you decided you were aimed correctly or overshoots (overcontrols) because you gave it "some more" in response to a slow turn acc as not enough was happening. The net result of all this is about 4 seconds of over controlling and correcting.

Its the reason I (or anyone else) cannot drive a powerchair with steer acc or dec in any kind of spirited fashion without crapping yourself with a near miss or hitting a wall or tree or whatever and having to slow down in future. Its dangerous. If your car did this it would be banned from the road the first time it killed someone.

Have you ever used an old very slow computer. Where everything you do legs behind your mouse inputs and clicks? You don't know if that first click did anything. So you click again. Nothing happens so you do it a third time. Now you give up, and try something else. Now the first window from click one opens... And as you try to close that another opens. and another. etc./ And all of this makes the damned computer as frustrating and hard to use as possible... But for someone that uses it S L O W L Y they would never see the problem. Because it keeps up with them.

Same thing. You drive your chair like my grandma drives her car. So you cannot see any problem. Added to the fact that you do not know any better having never tried anything that is any different. But if it was more direct you would find it much more intuitive and controllable all the same.

[fuzzy logic]

Invacare instructions state:

When on the move do not attempt turns at full speed, especially while travelling downhill. Before changing from forward to reverse, and vice versa, you must stop. Failure to do so will cause severe damage to the electronics. Do not use your powered wheelchair beyond its limitations.

Taken from the owners instructions (missed out the parts about checking the tires were not flat before starting trying to stay on topic) a hint at why the control is set the way it is, going beyond the limitations would be a really clever trick if you could with standard settings on the controller.

[sakima]

I AM JUST WASTING MY TIME HERE!

This is what you said;

You do not want a further 4 seconds of turning that begins to reduce then gradually decreases until it goes straight.
[url]
https://www.youtube.com/watch?v=BQ33CFyWFKo[/url]
Thats drunk!
Can you explain the similarity between that and the Storm
and
you havent really indicated where in the video that it steers like an oiltanker.

[sakima]

You drive your chair like my grandma drives her car.

AGAIN!!!
I have written many, many times that I drive fast.
In the video I SLOW DOWN to about 5mph to turn into my drive. ANYONE can see that!

Now you ARE being insulting.

[Burgerman]

You are delusional. I saw your vids. You move that chair about like its sat in glue indoors. Your idea of fast is totally different to mine.

By fast I don't mean in straight lines or in open spaces (your forward acc is set to "gradual" too!). I mean full speed in confined areas, between cars, indoors, without ever letting go of the throttle. Even a tiny delay of half a second (.5) is enough to totally miss a doorway and break your feet/legs at speed, but worse it induces user over control oscillation. As the thing doesn't respond when you do... And that rapidly gets out of hand.

I couldn't possibly do that stuff with all the steer acc/dec yours has programmed in. And neither could you, or anyone else. Been there, tried that in countless different chairs. NON of them steer properly until you get rid of that delayed action programming. Having any less than 90% set for TurnACC or TurnDEC (and MinTurnACC/DEC) makes them all steer like a pig on stilts. 100 is better.

Its ok if all you want to do is creep about slowly inside like my granny, but some of us like some control and some feel, and safety at speed in confined areas. Its like trying to explain how it feels to wheelie a big Japanese bike past a line of cars at 150mph to your mum, who never exceeded 30mph on the way to the shops... She wouldn't get it either.

Anyway its clear that you are only interested in winning some stupid argument. You are plain wrong, and even though I have gone out of my way to explain this, and show in as many ways as I could possibly think of, you still don't "get it"... Or you do but are only interested in trying to win some silly argument.

[Burgerman]

I also fly very fast model planes. I use a very low "latency" radio control system. Latency is how fast the changes in the joystick position results in the servo or control surface doing the same thing. They are however still linear. Its quite similar to "adding" acc/dec to a control. The last thing you would want.

Even the slowest responding RC system is far, far faster than any powerchair control system even set to 100%. So latency is at best, very, very much worse on a chair than any cheap and nasty RC system. These are typically under 20ms delay worst case behind the joystick. usually under 8ms which "looks" instantaneous. Especially compared to the clock watching we do with powerchairs. Especially with stock programmed ones, such as yours with turn acc/dec set to less than 100.

People that fly RC already know that the less latency the better. Many of us have spent 3 figure sums to get fast almost instant systems. In any control system these delays cause control issues. Setting a powerchair to 100 turn acc and turn dec (in 4 places), tries to speed this up as much as practical but its still too slow compared to say your car. That is instant. Or your PC mouse, almost instant. Latency is extremely similar to turn acc. Only acc/dec isn't just a delay it is even worse, because the delay isn't a fixed time - is starts slow and speeds up. So its not even linear!

Have a read about the control issues it can cause in models for eg here. And remember we are talking about a few measly ms only here. A RC helicopter or plane would be completely un-flyable with the truly massive powerchair level of delay that we suffer. http://www.rcmodelreviews.com/what_is_latency.shtml

This is far, far more pronounced in a powerchair even set to 100%. And so pronounced if set lower like 40, that I find it plain dangerous in use. And turn deceleration is worse still. It means we cant reduce the over control once we see/feel it happening. Hence the oscillations and panic if we don't slow down as it gets out of shape.

[LROBBINS]

Perhaps a fairer description of how stock wheelchairs handle is an analogy to an American car of the 1960s - say a full-size buick. Rear-wheel drive with 80-90% of weight on the front wheels when braking, 2-speed automatic transmission so there's plenty of latency in the pedal, and massive amounts of understeer. So, not quite an ocean liner, and not extraordinarily unsafe if driven conservatively - fast only in straight lines and slowly if turning, but not exactly sporty handling, nor even pleasant to drive, though Americans swore by these behemoths for decades (and then started to buy anything but).

Another comparison, from light airplanes would be:

Grumman-American Tiger; delightful aelerons, a pleasure to fly in any normal maneuvers, with a tendency toward pilot-induced-oscillation if flown a little too fast on final approach - BM2 behavior, nimble but a bit tipsy. Close second would be Cessna 177 Cardinal, though most variants of that were woefully under-powered and the last model with 180hp and constant speed prop was just too expensive for what it offered, but I liked the handling. Not quite as nimble as the Grumman, but not bad. Turn accel/decel = 100% for the Grumman, 90% for the C177.

Cessna 152/172 and ilk: more sedate. Much less powerful aelerons, so rolls harder to start and harder to stop, so turns have to be planned further ahead (angle of roll determines turn rate, the faster you can roll in and out of a given angle the faster you can start and stop turns). An easier plane to fly for the casual or novice pilot, about the right balance for many, but I liked the Grumman better. ??? Quicky or Invacare chair?? Chair programmed with turn accel/decel of 70 or more and CG not too far forward (in a RWD).

Piper Cherokee series, especially the 6-place Cherokee Six with the original non-tapered wings. Workhorse and safe aircraft, but the Six really took greater piloting skills than the C172 type because it was slow to respond in both pitch and roll. It seemed so "safely" sedate, but one really had to work to stay ahead of it, or anything unusual could turn it into an ungainly beast. ??Pride products?? Turn accel/decel = 40, CG too far forward etc.

I put all the ?? judgements around commercial WC marks because I've not myself used them. I've not used a BM2 or BM3 either, but Rachi's chair, though FWD and much slower, was re-programmed with the quickest accelerations Dynamic will allow for a FWD (turn deceleration can't be set higher than 70%) and the difference between its behavior after changing it from what the factory sent was like night and day! For Rachi, who drives with an array of head operated switches, the difference is even more extreme. Imagine trying to compensate for turns continuing after you say "stop" when the only thing you can do is hit the opposite turn switch (hopefully for just the amount of time that it will take to do what you want, though it'll be a guess because the effect won't happen until you've already come off that switch too). Before re-programming, I'd added optical sensors on the casters to force straightening when coming out of a turn - they applied reverse turn power long enough to stop the turn, which Rachi could never herself do. After re-programming, and new, higher-torque, lower-impedance motors, I threw them away; turns stop (almost) right away when her head moves off a switch.

Ciao,
Lenny

Ciao,
Lenny

[Burgerman]

He will still come back and tell us his is different...
Sometimes you just cant help people.

[sakima]

When you tested the Storm 4, was the suspension adjusted for your weight?
And were the settings adjusted fr your weight?
Actually, the same questions for all your tests?