help me

[q700m]

I was going up a slope
first at 10% of maximum speed, then I switched to maximum speed, but immediately the chair spun quickly on itself and fell on its side
what will happen?

[Burgerman]

What will happen?

How do you mean?

Do you mean the chair fell on its side, why?

Have you been messing about with motor compensation? If you set it too high it runs away. Sees a load, then the wheel that sees the most load, accelerates out of control. Its a positive feedback loop. This is what the manufacturers are afraid of. Thats why they hide the OEM level tools from those that dont understand what they are doing.

If thats not it, then I need a lot more information.

[q700m]

What will happen?

How do you mean?

Do you mean the chair fell on its side, why?

Have you been messing about with motor compensation? If you set it too high it runs away. Sees a load, then the wheel that sees the most load, accelerates out of control. Its a positive feedback loop. This is what the manufacturers are afraid of. Thats why they hide the OEM level tools from those that dont understand what they are doing.

If thats not it, then I need a lot more information.

Yes, the chair fell on its side, but I didn't lift the motor compensation.
I dropped it from 40 to 30 mohm a day ago
on the slope should he stop or not?

[Burgerman]

Question too vague.

It should climb a 10 degree slope easily enough. And shouldnt stop.
It should DECEND a 10 degree slope and it should stop when you tell it to do so.

Provided you have motor compensation set correctly. If its too low it will not perform properly up, or down the slope. It will behave like "weak" motors.
If set too high it will behave the opposite way. And be jumpy and will accelerate when climbing a slope. And may stop suddenly if you try to decend a slope.

But the problem here is that your translations and descriptive powers are inadequate and this may be nothing to do with motor compensation Not even really sure what you are asking.

[q700m]

Question too vague.

It should climb a 10 degree slope easily enough. And shouldnt stop.
It should DECEND a 10 degree slope and it should stop when you tell it to do so.

Provided you have motor compensation set correctly. If its too low it will not perform properly up, or down the slope. It will behave like "weak" motors.
If set too high it will behave the opposite way. And be jumpy and will accelerate when climbing a slope. And may stop suddenly if you try to decend a slope.

But the problem here is that your translations and descriptive powers are inadequate and this may be nothing to do with motor compensation Not even really sure what you are asking.

one day ago I lowered the compensation from 40 to 30 mohm
I did this because the chair was too snappy for me.
I tried it on the flat and on small slopes, everything was fine.
Today on a bigger slope I started at minimum speed, then when I raised the speed the chair turned quickly on itself and fell on its side.
what happened?
i'm afraid it might happen again

[Burgerman]

one day ago I lowered the compensation from 40 to 30 mohm
I did this because the chair was too snappy for me.

Thats not what motor compensation is for. It has far reaching effects. You must put it back and then reduce turn speed, min turn speed, increase turn acceleration/turn deceleration. And minimum turn acceleration/deceleration.

I tried it on the flat and on small slopes, everything was fine.
Today on a bigger slope I started at minimum speed, then when I raised the speed the chair turned quickly on itself and fell on its side.
what happened?

No idea.

[q700m]

one day ago I lowered the compensation from 40 to 30 mohm
I did this because the chair was too snappy for me.

Thats not what motor compensation is for. It has far reaching effects. You must put it back and then reduce turn speed, min turn speed, increase turn acceleration/turn deceleration. And minimum turn acceleration/deceleration.

I can only control the chair well by lowering the motor compensation
what happens?

[LROBBINS]

Is this a rear wheel drive chair or a front wheel drive chair? If it's front wheel drive it will have a strong over-steering tendency that gets worse as speed increases. In that case you may have just had what in airplanes would be called a "ground loop". The only way to avoid this tendency with front wheel drive is to slow down if on ground that's at all uneven and make sure to not start a turn when going fast.

[LROBBINS]

Oh, I see from your moniker that this must be a q700m so its steering stability should be pretty neutral as long as your center of gravity isn't behind those drive wheels.

[q700m]

according to me one engine was running and the other stopped, but I didn't understand why

[Burgerman]

If thats actually the case:
Bad motor connection.
Bad motor brush.
Bad motor rubber cush drive connection.
Bad gearbox.
Bad armature.
Bad (broken) magnet.
You ran over a strap of belt fastened to your chair.
Bad power module (unlikely).

Lowering motor compensation is still the wrong way to make a chair "drivable"... Bad idea.

[Pierro]

according to me one engine was running and the other stopped, but I didn't understand why

Was your chair fully loaded when the tipping happened? Some chairs have overcharge protection and they will stop erratically when you go downhill with full batteries. Otherwise the batteries would be overcharged. Charging the battery when driving downhill = recuperation process.

Is just an idea.

[Burgerman]

Cannot be overvoltage stop, because that stops both motors.

[Pierro]

Cannot be overvoltage stop, because that stops both motors.

with the Alber Adventure, the motors stop independently of one another. This could be due to the strange betterie supply. I speak from experience. I've lost my way several times.

[q700m]

specific question
when climbing a slope with the motor compensation lowered, what happens?

[Scragger7]

You didn't accidently push the joystick hard left/right when you upped the speed (presuming you change speed while driving) and cause it to roll.

[q700m]

You didn't accidently push the joystick hard left/right when you upped the speed (presuming you change speed while driving) and cause it to roll.

no , straight forward joystick , but the chair turned quickly to one side

[Burgerman]

specific question
when climbing a slope with the motor compensation lowered, what happens?

If you choose say speed 2, and climb the slope te chair will slow. If you choose a too high compensation it may even speed up or run away. The CORRECT level is where it invisibly assists turns, slowing, climbing a threshold etc. It is not intended to make controls feel "weaker" because that then affects many other things that its intended to do properly. Use other settings like turn speed, minimum turn speed, and forward and reverse accelleration for that.

DONT reduce turn acceleration, min turn acceleration, or turn deceleration or min turn deceleration, as these should alsways be set to a high figure for accuate linear control. On my chairs these 4 are all set to 100.

[q700m]

this Switched Input Smoothing parameter
can you help me?

[Burgerman]

You are driving with SWITCHES (NO JOYSTICK?) ???

So no proportional input just on/off switches?

[q700m]

specific question
when climbing a slope with the motor compensation lowered, what happens?

If you choose say speed 2, and climb the slope te chair will slow. If you choose a too high compensation it may even speed up or run away. The CORRECT level is where it invisibly assists turns, slowing, climbing a threshold etc. It is not intended to make controls feel "weaker" because that then affects many other things that its intended to do properly. Use other settings like turn speed, minimum turn speed, and forward and reverse accelleration for that.

DONT reduce turn acceleration, min turn acceleration, or turn deceleration or min turn deceleration, as these should alsways be set to a high figure for accuate linear control. On my chairs these 4 are all set to 100.

how do you find the correct motor compensation level?

[Burgerman]

By first of all setting all 4 turn acceleration settings and turn deceleration settings to 100.
Forward acceleration to 100 too but most people wouldnt like that! So say 70.

Then by assessing it in several ways.
Start by driving forwards and backwards with speed set to low, like speed 1 or 2. And see if it does so reliably and the same speed on a ramp, a turn in place and a threshhold.

Then turn it to 0. Or the lowest it can be set to on your specific chair. And then try driving in the same way. On the same obstacles. The same speeds. Try turn in place. THIS s an essential step because then you will feel the exact thing it actually does! It probably wont start rolling. Or rolls too far without slowing down properly. It likely will not turn in place unless you set speed to a higher setting like 4 or 5. This allows you to feel what it is doing.

Then set max speed to 1 or 2. THEN try driving up a slope or long ramp. If compensation is too LOW then it will stop. Or will slow severely.
Then try a turn in place on a nice thick carpet. It may refuse to turn. Or may only turn unreliably or need to move forwards or backwards befor a turn will begin.
Then try running it up to a threshold. Stop. Then try and drive forwards. It will stop and not climb it. It will feel like the battery is dead, or that you are driving in glue.

Now return the chair to the manufacturers "recommended" setting. And try those same things again.
When set CORRECTLY, when set to speed 2 for e.g and you arrive at a ramp, slope, it will not slow very much at all. Maybe very very slightly.
Try all the other things above. It should turn in place reliably etc.

Now you know what it does. So now start with the manufacturers base setting. And try adding 5mOhm. Then do your tests again. It will probably start, climb thresholds, and slow less on a ramp. Will turn in place more easily. But the chair may begin to feel "jumpy". Too responsive. If not, try adding another 5mOhm. And do the same tests again. It will perform better still. If you add more 5mOhm increments it will sonner or later start to be very jumpy and harder to move around smoothly. At this point it is becoming dangerous. If you were to add yet more, the chair MAY decide to run away and be unstoppable, or spin out of control no matter what you do.

So its a compromise between great control and a step too far. But now that you can FEEL what it does you can easily use the chair and fine tune it. I can feel the difference of a 5mOhm change very easily if its already close to correct. I cant tell the difference if I add or remove 20mOhm if its already too low.

If you have no base setting (say an uknown set of motors, start at 30mOhm. Then increase in 5mOhm steps - not more - and test carefully. As above. Then you wil find the sweet spot. You cannot feel this sweet spot UNLESS you set the turn accelarations and decelerations to 100 first. And forward acceleration to say 60 or so. And obviously you need normal hands/control skills. Without that dont try any of this.

[Burgerman]

You should read lennys post here https://www.wheelchairdriver.com/board/ ... 73#p194021


When motor compensation is working properly (and you are at a low speed or a low speed setting) the chair itself does all the work. Motor LOAD compensation helps you behind the scenes. By which I mean for e.g. where it needs extra power when turning in place, or as you begin to climb a ramp, the chair ADDS just the right amount of extra power AUTOMATICALLY in order to make the chairs speed stay the same. So it will not slow on a ramp. refuse a threshold. It will turn just the same on a tiled floor and empty chair or on a heavy carpet fully overloaded. Or on a ramp. The joystick doesent need to be pushed "further" to begin a turn. To climb a ramp. It all happens automagically in the background hidden from view.

This makes the chair easy to drive as every movement only depends on the joystick position, not the load, or terrain or slope. If compensation is say just 5mOhms too low then you feel this as a chair that doesent reliably follow the joystick reliably in the same way.

And the chair may wander off course if a wheel encounters some resistance or a bit of grass. Or a caster happens to be pointed in the "wrong" direction. It makes the chair go where YOU decide. Without you having to make any corrections.

Never use motor compensation set too low on purpose to try and make up for a bad hand control or incorrect joystick position so that it makes a chair "smoother". Or less responsive. There are other setting designed to do this. Because you will destroy much of what is needed to make the chair work reliably under every condition. Correctly set motor load compensation is absolutely essential. Get that wrong and every other control setting is a waste of time. Since it changes the effect of EVERYTHING else in a way that isnt stable. So everything else cannot be correctly set.

[fishinjunky]

By first of all setting all 4 turn acceleration settings and turn deceleration settings to 100.
Forward acceleration to 100 too but most people wouldnt like that! So say 70.

Then by assessing it in several ways.
Start by driving forwards and backwards with speed set to low, like speed 1 or 2. And see if it does so reliably and the same speed on a ramp, a turn in place and a threshhold.

Then turn it to 0. Or the lowest it can be set to on your specific chair. And then try driving in the same way. On the same obstacles. The same speeds. Try turn in place. THIS s an essential step because then you will feel the exact thing it actually does! It probably wont start rolling. Or rolls too far without slowing down properly. It likely will not turn in place unless you set speed to a higher setting like 4 or 5. This allows you to feel what it is doing.

Then set max speed to 1 or 2. THEN try driving up a slope or long ramp. If compensation is too LOW then it will stop. Or will slow severely.
Then try a turn in place on a nice thick carpet. It may refuse to turn. Or may only turn unreliably or need to move forwards or backwards befor a turn will begin.
Then try running it up to a threshold. Stop. Then try and drive forwards. It will stop and not climb it. It will feel like the battery is dead, or that you are driving in glue.

Now return the chair to the manufacturers "recommended" setting. And try those same things again.
When set CORRECTLY, when set to speed 2 for e.g and you arrive at a ramp, slope, it will not slow very much at all. Maybe very very slightly.
Try all the other things above. It should turn in place reliably etc.

Now you know what it does. So now start with the manufacturers base setting. And try adding 5mOhm. Then do your tests again. It will probably start, climb thresholds, and slow less on a ramp. Will turn in place more easily. But the chair may begin to feel "jumpy". Too responsive. If not, try adding another 5mOhm. And do the same tests again. It will perform better still. If you add more 5mOhm increments it will sonner or later start to be very jumpy and harder to move around smoothly. At this point it is becoming dangerous. If you were to add yet more, the chair MAY decide to run away and be unstoppable, or spin out of control no matter what you do.

So its a compromise between great control and a step too far. But now that you can FEEL what it does you can easily use the chair and fine tune it. I can feel the difference of a 5mOhm change very easily if its already close to correct. I cant tell the difference if I add or remove 20mOhm if its already too low.

If you have no base setting (say an uknown set of motors, start at 30mOhm. Then increase in 5mOhm steps - not more - and test carefully. As above. Then you wil find the sweet spot. You cannot feel this sweet spot UNLESS you set the turn accelarations and decelerations to 100 first. And forward acceleration to say 60 or so. And obviously you need normal hands/control skills. Without that dont try any of this.

great explanation on motor compensation BM

[Burgerman]

Its about the 100th time! So getting quite good at it by now!

[q700m]

one day ago I lowered the compensation from 40 to 30 mohm
I did this because the chair was too snappy for me.

Thats not what motor compensation is for. It has far reaching effects. You must put it back and then reduce turn speed, min turn speed, increase turn acceleration/turn deceleration. And minimum turn acceleration/deceleration.

I tried it on the flat and on small slopes, everything was fine.
Today on a bigger slope I started at minimum speed, then when I raised the speed the chair turned quickly on itself and fell on its side.
what happened?

No idea.

is there no log?

[Burgerman]

Not that will help. Its a mechanical or electrical issue.

[Dan]

I hope you download the chairs settings before making changes? Or maybe you have made physical changes to the chair? If not Sunrise medical maybe able to help. Or if you bought the chair from a dealer they might be able to help get the original settings.

If you are not using a normal joystick then you may need someone who knows about your customized system to help.

Name all the components.
R-Net, Controller, joystick, etcetera.

[q700m]

Not that will help. Its a mechanical or electrical issue.

could it be the low motor compensation, which made the chair go crazy?

[Burgerman]

Nope.