4power4 - Replacing old broken electronics - but with what?

[Larsanjus]

Hi.

I've ended up being a powerchair mechanic for my mother, who has been driving a goverment-paid unit for the last 10 or so years. Her latest chair is ottobock b400 (or something like that?), but there is full upkeep and prohibition on self-handed repairs or attachents. That one is ok - let that be the case for that unit.

Last summer I happened to find a amazingly cheap second hand 4wd powerchair called 4power4 v1, manufacturing year seems to be 2009. It only needed a fresh set of batteries and was ready to go. That one really made the difference, added unbelievable amount of freedom for her - a person whos life has been limited to quite small local town centre with paved roads etc. During the last 9 months she has driven about 4000km in total with the powerchair. It allowed her to for example drive for the first time to the other end of my backyard, places where she would have gotten stuck instantly with the b400.
Also the long, cold and dark Finnish winter was like a hot summer, she could still go to places without the fear of getting stuck every other minute. A fresh set of knobby tires and some grease on the steering joints was the only thing needed. It also does fit snugly to my parents Vw Caddy low-floor transporter, so they can go together to places (read: my dad can pick her up after driving the batteries empty, 40km/charge has been proved possible). All in all, a real dream-come-true for her.

4power4-v1 chair

But to the point...
Now the chair has stopped running - controller blinks fault codes on "controller fault or general fault". After fiddling with connectors and cables, measuring/replacing all generic electronic parts etc. there has not been any improvements - the controller and/or power unit are not functional. 4power4 doesn't have any distributor in Finland and so far I have not been able to find a repair shop that had the equipment to diagnose those Curtis-made units. Neither my own efforts with DIY diagnose cable have been successfull.

The chair has CURTIS 1720-5012 joystick controller, CURTIS 1705-5084 power unit labeled as "master" and CURTIS 1705-6084 labeled as "slave".
They communicate through MC2-bus, with proprietary curtis Conxall-connectors. I did find a picture on this forum about the pinout of the connector

Conxall pinout

I have now ordered a fdti-based cable that regarding to golf-cart-entusiasts should do the trick with communicating with the units.
Nevertheless, even if I'd succeed to communicate with the units, I'm afraid that spare parts are not available any more. 4power4 is still producing similar chairs, but with some other electronics and they don't have any old equipment on stock any more. Hints of right direction on programmer or spare parts will be highly appreciated.

So that leads us to the actual point of this post...
What would you more experienced suggest for replacement for the whole control system? The chair has 4 motors for driving, one actuator for steering (turns all 4 wheels via a fancy linkage system). There might be an option to convert the chair to 2wd if 4wd is too difficult to handle (not a desired option but better than nothing), but the steering would still need to be actuator-driven.
So "just a generic chair controller" might not be an option? Or are they all able to be programmed to that kind of configuration?

The chair does have lights, indicators and seat adjustments also, but thos can be controlled with something generic. I'm an electrician by profession so that will not be a deal breaker.
The new system should be programmable with PC or something by myself, local workshops don't seem to be very help(or use-)full on this matter.

Any thoughts on the subject? Anyone?

[Burgerman]

With a normal tank steer type powerchair most of the brands can just be swapped out or exchanged. Just change a few connectors.

When it comes to things like his which are really scooters with a modified power module to turn a dual channel tank steer device ito a single channel dual output one, and with an extra custm module to work a seering actuator then its not so simple.

Those are custom units made for the specific manufacturerer and use different firmware etc. So you cant just swap parts.

Unless you find a chair with similar steering system, which are like the preverbial rocking horse excrement and steal its control system. Even then you would need to make sure that it used the same actuators or servos for steering and the same feedback potentiometrs. And then you wold need to program it with an OEM level programmer which is bespoke as well.

So I dont know what to tell you.

[Larsanjus]

I happened to be able to source out quite complete set of electronics from a scrapped Chasswheel Fourx DL that has the same basic principle - four drive motors (2+2 paraller connected) and an actuator for steering (swivel joint in the middle of the frame). So basically it should be possible to retrofit them to the 4p4 chair. Only thing missing is the return-to-center feature on the steering - FourX dos not have position sensor on the actuator. I think that is something we just have to live with for not at least.
A partial cable loom was also included - I'll have to combine that with the current one, shouldn't be an issue.

They are labeled to be PGDT D51194.04 as power module and D50601.02 as controller. And an 50602.02 as actuator controller.
They also appear to have R-net labels and connectors in them.

Powermodule

Controller2

Controller

What do I need to program them? Some official dongle or some DIY lead? I do have a few usb/serial adapters already if they are useful on this matter. Which software to use - and where to get one?

Thanks in advance!

[Burgerman]

Does the existing module say 120 in the bottom corner like the one in the image?
This is very important!

You need a hard to buy expensive dongle. In order to program.

[Larsanjus]

Yes, they are the actual modules on my hand, 120 is indeed marked on the bottom corner. I assume that is the current rating?

[Burgerman]

Because of tthe way yours steers, via actuator? it may be that it uses a vary scarce 210A version. That has a single siamesed output that requires a completely different programmer for anything to make any sense. Its a single channel variant. So is that 120A unit the same as the one already on the chair?

If they are the same, 120, then all good. I feel that they should not be!

[Larsanjus]

These PGDT units on the pictures are the ones I got from a scrapped FourX DL, it is a chair with similar 4motors+steering actuator setup but without the steer centering option (no potentiometer on actuator).
https://www.invacare.eu.com/sites/eu/fi ... ochure.pdf

Originally the 4power4 chair had some weird Curtis controllers in it.

Old Joystick

Old joystick type

So, that "120" would be a better alternative in regards of programming possibilites?

[Burgerman]

I see.
Well you will probably find that your chair has a SINGLE channel controller like a scooter, and a special steering type module, to work an actuator? A tank steer dual channel would seem wrong for that chair?

Are you sure it steers via actuator?


Which or if a programmer is even available depends on how it steers.

I would have expected it to steer via tank steer, no actuator, like a wheelchar. If thats true, then any r-net programming dongle will work.

[Larsanjus]

Now that you mentioned the steering, I need to take back my assumptions on it. Looks like there in fact is none and steering is done with kind of tank steer thingy. The axles are connected to each others with a rod and turn freely together.
Found also a service manual that explains it a bit more clearly than me.

https://drive.google.com/file/d/1xl-8iS ... p=drivesdk

So that would lead me to a situation where I can just release the current steering actuator and let the axles turn on their own. Nice.
Looks like a quick "temporary" wire harness needs to be made to test the theory.

[tettralytic]

The actuator module you have purchased identifies as a standard ISM. So unless they're using a seating channel to drive the actuator that won't be doing the steering (would be rather neat though).
Connected in parallel 2+2 implies each PM channel has two motors hanging on it, one pair left and one pair right? (not necessarily a fact). That would give you some sort of tank steer, the fact that one actuator has feedback and one doesn't shows there's a big difference. Could mean that one system uses a pot like a servo, the other is centre zero, or something completely different.
It is ambitious to assume one system is connected and works the same as the other.
Good luck though I would be delighted to hear you got it working.

[Larsanjus]

The motors are linked across, so rear left and fromt right are driven synchronized, that makes the axles turn to desired direction of travel with tanksteer, instead of trying to do actual tanksteer and force wheels to slip. Quite smart actually..

I'll try tomorrow to get it tested and definitely tell the results.

[Burgerman]

So no actuator for steering then! Thats what I expected. And what confused me.

You will need a programmer. A dealer or OE level R-Net dongle.

[Larsanjus]

Got the controllers temporarily wired up to 4p4 wirings. Theoretically it works and does what it is supposed to.
In practise it is impossible to drive. Steering takes a week to react(adjust the direction) and even with 4wd and knobby tires you can get stuck on even gravel due to axles "castering" on their own. So totally useless like that.
I'll need at better time to try rearranging the motors to proper tanksteer and lock the axles straight. Wont be good that way either. Might be that I'll give up with it and use the hardware to something more useful, just have to figure out what..

Good thing is that I was able to find an old Permobil Trax for my mom to use - just needed a few new transistors and fusibles to get joystick and powermodule to negotiate with eachothers again. It actually might be even a better fit to her needs, rides easier straight with only front wheels steering, still being able to drive comfortable and long distances on gravel roads with large wheels and rear wheel drive.
These are both only outdoor use, she'll use manual chair at home/indoors.

[Burgerman]

Got the controllers temporarily wired up to 4p4 wirings. Theoretically it works and does what it is supposed to.
In practise it is impossible to drive. Steering takes a week to react(adjust the direction) and even with 4wd and knobby tires you can get stuck on even gravel due to axles "castering" on their own. So totally useless like that.

Yep as expected!

I'll need at better time to try rearranging the motors to proper tanksteer and lock the axles straight. Wont be good that way either.

You will need 400 Amp to turn like that... So not a chance wheels too far apart.


Might be that I'll give up with it and use the hardware to something more useful, just have to figure out what..

Good thing is that I was able to find an old Permobil Trax for my mom to use - just needed a few new transistors and fusibles to get joystick and powermodule to negotiate with eachothers again. It actually might be even a better fit to her needs, rides easier straight with only front wheels steering, still being able to drive comfortable and long distances on gravel roads with large wheels and rear wheel drive.
These are both only outdoor use, she'll use manual chair at home/indoors.

These are all basically scooters, with joystick steering.
Maybe a scooter is a better solution.