VR2 Programming problem - Q500R

[Burgerman]

What impedance are they because thats what matters. Watts = meaningless.

[faico_26]

What impedance are they because thats what matters. Watts = meaningless.

Hi BM, how can check the impedance?

[Burgerman]

Well several ways.

1. My fluke meter has a LOW scale for measuring such things.
2. My chinese impedance meter is designed to do that.
3. You look inside the software and see what the manufactrer choose in motor compensation for that specific motor.
4. If you dont HAVE a manufacturers settings file: You configure compensation by starting low and testing to find the best value by increasing it a little at a time until the chair starts to be jumpy. Which happens quite rapidly as you increase beyond a certain point. Go back one step and read what it says on the screen.

[faico_26]

In my settings is indicated: Motor Compensation (milli-Ohms) 40

[LROBBINS]

But you don't know if that's the best setting for your motors. If you don't have an impedance meter, do number 4 of Burgerman's list. DO MAKE ONLY SMALL INCREASES IN THE MotorCompensation SETING (e.g. increase by just 5 milliOhm at a time) and back off from the last increase as soon as the chair gets at all "jumpy". Don't be surprised if the correct value for your chair is a good bit more than 40; for example, 60 mOhm.

[Burgerman]

I should have said,
3. Bla bla, is often a good starting point. But usually a little lower than the correct figure. In some cases, its completely wrong!

[Burgerman]

THIS is how PG suggest its done.

This matches the Power Module to the motors used on the wheelchair. This is necessary to achieve optimal performance and control, especially on a gradient.

The programmable range is 0mOhms to 500mOhms in steps of 5mOhms.

PGDT recommend this value is initially set to 70% of the total resistance of the motor’s armature, and all the connectors and cables between the motor and the Power Module motor output. Motor manufacturers should be able to supply a figure the motor’s armature resistance and typical connector and cables may be around 40mOhm.

Example: The motor has a specified armature resistance of 100mOhms, and cables and connectors between the motor and the Power Module are estimated to be 40mOhm. This gives a total value of 140mOhm. The value of Compensation should therefore be set to 70% of 140mOhm = 100mOhm.
Once this value has been programmed, some drive testing should be carried out.

First of all, check that the wheelchair is controllable and comfortable to drive on a smooth, level surface. If it is not, then the value of Compensation may be too high and should be reduced.

Then drive the wheelchair towards a gradient at a very low speed, perhaps 10%. There should be no reduction in speed as the wheelchair climbs the gradient. If the speed drops or the wheelchair stops, then the value of Compensation may be too low and should be increased.

As a final check, drive the wheelchair up a gradient at full speed and release the joystick. The wheelchair should come to a smooth, complete stop and should not rollback before the brakes are applied. If the wheelchair does roll-back, then try increasing the value of Compensation slightly. If the wheelchair appears to drive slightly up the gradient before the brakes are applied, then the value of Compensation should be reduced slightly.

All these tests should be conducted when the motors are cold and hot.

WARNING:

These tests should be conducted in an open space and a restraining device such as a set belt should always be used. PGDT accepts no liability for losses of any kind arising from failure to comply with this condition.

The wheelchair manufacturer is responsible for ensuring that the value of Compensation is correctly set for the motors being used on the wheelchair. This is particularly important if replacement motors are being sent out to upgrade a wheelchair already in the field. Failure to comply with this requirement may result in poor control characteristics, which in extreme instances can make a wheelchair uncontrollable and potentially unsafe. PGDT accepts no liability for losses of any kind arising from failure to comply with this condition.

The wheelchair manufacturer is responsible for always ensuring that any replacement motors supplied as spare parts are fully compatible with the originals that the system was programmed to match. Failure to comply with this requirement may result in poor control characteristics, which in extreme instances can make a wheelchair uncontrollable and potentially unsafe. PGDT accepts no liability for losses of any kind arising from failure to comply with this condition.

A control system must not be moved from one wheelchair type to another without first ensuring that the system is correctly programmed for the wheelchair it is intended to fit it to. Even if control systems have the same PGDT part number, they may not be programmed the same. Failure to ensure the system is correctly programmed for the wheelchair may result in a hazardous condition. PGDT accepts no liability for losses of any kind arising from failure to comply with this condition.

I dont do that.
I set it low, like 30. And drive it. I increase in steps of 5mOhm and test. Over and over until I begin to detect that its beginning to turn in place, set off, climb a threshold, stop when expected, etc. In stages. At some point it starts to get much better and is obvous. Go further, and it starts to be snatchy and jerks. And thats obvious too. So now you can set the best setting by the seat of your pants.

[Potty]

In my settings is indicated: Motor Compensation (milli-Ohms) 40

By the way, from reading BM talk about VR2 settings in another thread, some of the rough feeling you get, could be from having "Torque" set to 100?

So it may be worth testing that, before trying to work out motor compensation, else you maybe wont feel when it gets "jumpy" from the motor compensation being out.

torque (%) 55 This adds extra motor compensation at small stick movements. Helps start a turn or climb a threshold. adding a little more may help if you have that problem, but will make the chair jumpy.

[Burgerman]

Remember that I had all these exact same descriptions from John with his Q300R.

In the end I just configured a set of settings from my bed, by email, never saw the chair and sent the file to him.

And he said:

Apologies for long delays I've been struggling with my gammy leg over the last few weeks.

The chair is has been transformed from an unpredictable, undriveable pile of crap into a precise and controllable chair that's safe to drive and fun. I've had the Q300 getting on for 3 months and it's done 1.6 miles, it was left in the corner with my other chairs doing a better job. I've been in the chair all day, it drives great and definitely meets my needs.

I've had 3 WCS engineers (of varying pay grades) inspect and 'fiddle' with the chair making it worse every time. Each of them were happy to leave the chair with me in that state, I honestly think they believe they do a good job. What you produced in an hour or so was truly brilliant ... and you said those changes would break their rules. That's crazy.

Been hearing this from many dozens of chair owners that I programmed, some that travelled from other countries in desperation. For 30 years...
Theres a how to here!
https://www.wheelchairdriver.com/board/ ... =2&t=12707

[faico_26]

Remember that I had all these exact same descriptions from John with his Q300R.

In the end I just configured a set of settings from my bed, by email, never saw the chair and sent the file to him.

And he said:

Apologies for long delays I've been struggling with my gammy leg over the last few weeks.

The chair is has been transformed from an unpredictable, undriveable pile of crap into a precise and controllable chair that's safe to drive and fun. I've had the Q300 getting on for 3 months and it's done 1.6 miles, it was left in the corner with my other chairs doing a better job. I've been in the chair all day, it drives great and definitely meets my needs.

I've had 3 WCS engineers (of varying pay grades) inspect and 'fiddle' with the chair making it worse every time. Each of them were happy to leave the chair with me in that state, I honestly think they believe they do a good job. What you produced in an hour or so was truly brilliant ... and you said those changes would break their rules. That's crazy.

Been hearing this from many dozens of chair owners that I programmed, some that travelled from other countries in desperation. For 30 years...
Theres a how to here!
https://www.wheelchairdriver.com/board/ ... =2&t=12707

Hi BM,
Do you think you could send me the settings file of John’s Q300R? Did he use VR2? Or maybe could you send me the pdf or text with the settings? I’m sorry to disturb you with this! Many many thanks!

[faico_26]

Remember that I had all these exact same descriptions from John with his Q300R.

In the end I just configured a set of settings from my bed, by email, never saw the chair and sent the file to him.

And he said:

Apologies for long delays I've been struggling with my gammy leg over the last few weeks.

The chair is has been transformed from an unpredictable, undriveable pile of crap into a precise and controllable chair that's safe to drive and fun. I've had the Q300 getting on for 3 months and it's done 1.6 miles, it was left in the corner with my other chairs doing a better job. I've been in the chair all day, it drives great and definitely meets my needs.

I've had 3 WCS engineers (of varying pay grades) inspect and 'fiddle' with the chair making it worse every time. Each of them were happy to leave the chair with me in that state, I honestly think they believe they do a good job. What you produced in an hour or so was truly brilliant ... and you said those changes would break their rules. That's crazy.

Been hearing this from many dozens of chair owners that I programmed, some that travelled from other countries in desperation. For 30 years...
Theres a how to here!
https://www.wheelchairdriver.com/board/ ... =2&t=12707

Hi BM,
Do you think you could send me the settings file of John’s Q300R? Did he use VR2? Or maybe could you send me the pdf or text with the settings? I’m sorry to disturb you with this! Many many thanks!

Or could I send you my current settings file and you modify it? That would be really helpful!!!! Many many thanks BM!

[Burgerman]

Well I never owned VR2 so while I think that I can match it, it might not! Johns was R-NET. Basically the same settings though. Like all chairs.

[Potty]

You can also check the data cable and even the gym ball, which may be dirty or have poor contact. Sometimes we see the problem there, replace those components, and it's solved.

Hi again,

Just wanted to let you know after chaning out the data cable and gimbal, the problem has totally gone, thank you (luckily I had spares from an old chair)

I suspect it was probably the data cable, after it was removed, it looked like it may have been pinched at some point before I bought it.

[martin007]

Hi.

What connector do you use to communicate the powerchair with the computer?
Have you made it yourself?

[Potty]

Hi.

What connector do you use to communicate the powerchair with the computer?
Have you made it yourself?

I made a cable to this spec:

I bought this cable( https://www.amazon.co.uk/dp/B08Y8DQ4NX? ... title&th=1 ), cut the end off, soldered the the 47k resistor, soldered the 1N5711 Schottky Diode(make sure it's the correct way around), used some heat shrink and soldered it to a XLR plug.

Works fine with regualr VR2 controllers (I think pre 2023 ish), but does not work with the new ones that read "VR2 2" like in this picture:

[martin007]

Works fine with regualr VR2 controllers (I think pre 2023 ish), but does not work with the new ones that read "VR2 2"

That's what I wanted to hear.
The industry has modified the new VR2...
They want to prevent us from programming VR2 in a cheap way.

Thank you very much.

[Potty]

Works fine with regualr VR2 controllers (I think pre 2023 ish), but does not work with the new ones that read "VR2 2"

That's what I wanted to hear.
The industry has modified the new VR2...
They want to prevent us from programming VR2 in a cheap way.

Thank you very much.

It would seem that way.

There may be a way to make a DIY cable for the new controllers, but it is beyond me and sadly Woody is no longer with us to ask.

[martin007]

It would seem that way.

There may be a way to make a DIY cable for the new controllers, but it is beyond me and sadly Woody is no longer with us to ask.

True.