Cheaps disposable joysticks from China

[martin007]

This motor controllers?

> https://www.cw-industrial.com/en-gb/pro ... management

[Burgerman]

No dual channel complex tank steer ones as fitted to powerchairs like these:

1. Joystick. Top.
2. Motor controller. Right.
3. Seating and lighting module. Left.

Those are the 3 things you need to fully equip a complex rehab powerchair. If you dont need lights, elevating seat, power angle and length adjustable footrests, recline, tilt then you have a basic powerchair. So you then do not need part 3.

Thats everything r-net required for almost any powerchair. All of the electronics.

[martin007]

OK.

[Burgerman]

heres the other side of 3 of my cheap spare 120A R-net power modules. Note labels. So I know which chair I programmed them for ready to swap out in literally 20 seconds!

These 3 cost me under 150 uk pounds together delivered as new. They contain all the programming, and are the brain and the heavy lifting that sends power to the motrs etc.

[Burgerman]

3 complete r-net 120A top of range systems, all basically as goor as brand new, 3 seating and lighting modules, a bunch of extra stuff like cables and programmer, an attedant joystick, an LED joystick, etc. The whole lot cost me less than 1k. Over a 1 year surveylance of ebay, ebay ermany, ebay US, HERE etc.

I am future proof. Also have several sets of brand new or as new motors. 6 and 8mph (they were cheap)... And wheels, tyres, bearings, bolts, upholstery, cushions, and a whole lot more. I like to be able to fix a chair that fails instantly. I cant manage without. And I dont have to rely on idiots.

[slomobile]

Maybe try to understand the need behind a project before calling it pointless, or just don't say dumb hurtful stuff like that at all. You have several times crushed the spirits of people coming here to reveal work they are proud of, in need of, or working on and looking for help, just because you didn't make it, understand it, or it doesn't fit your specific needs or preferences. Then other times you painstakingly hold someone's hand walking them through a problem you do understand. Several smart contributors don't come here any more because they are sick of being shot down by you and the piling on of others that sometimes happens. Many projects have a point that isn't plainly obvious at first. That doesn't make them pointless.

Rnet simply does not allow direct setting of individual wheel speeds. A fwd/rev input and turn input only. It provides no method to say "drive left wheel at 40RPM while driving right wheel at 80PPM". Except maybe the undocumented unicorn encoder module. There are difficult empirical ways to get close to repeatable results, but changing any Rnet drive parameters invalidates those tests and forces you to start over. That makes developing any kind of GPS, autonomous, semi autonomous, or AI driving assistant unnecessarily frustrating. Rnet sucks as a development tool. There is no practical way to have more than 1 Rnet Power module in a single system, no 4 wheel drive with individually controlled wheel speeds. DE Sabertooth and several other general controllers make that possible.

You can choose nearly any joystick you like with a general controller rather than being locked into the one that matches your particular power module. A $2 thumbstick, an industrial crane joystick, a gaming steering wheel, or no joystick at all. Sabertooth accepts 2 0-5v analog signals like my 2 foot pedals for tanklike hands free driving. And RC signals for unloading my chair from the van and bringing it around to drivers door. And a couple different varieties of serial communication for integration with ArduPilot Rover, Robot Operating System, and other advanced control methods.

My eventual goal is to be able to point toward a doorway and have my chair quickly and autonomously navigate through it without hitting anything. To start down a nature trail with a walking friend and have my chair automatically keep pace with them. And other things that ought to be possible with modern technology but are thwarted by Rnet.

The cheap joysticks are a necessary backup until the algorithms are proven. Once the algorithms work, they can be simply adapted to different motor controllers, but Rnet will still present problems.

[Burgerman]

I look forward to seeing it. But I think you are a million miles away from understanding the level of complexity, safety, drivability, output power and safety that you will need. Before it will be useable or practical. That encoder module when added to r-net works. Just like the gyro. And in the same way its useful if you have to drive with digital (on off or suck blow) controls. With a joystick it is also just like the gyro, making the chair drive worse. It removes feedback and the chair drives robotically. Where you have no choice, on an unstable front drive layout theres little option. Everywhere else is best disabled.

[LROBBINS]

Two things seem to have gotten confused together in this thread.

One is the use of inexpensive low power, but conventional, wheelchair controllers. For this, Burgerman is right that they will be inadequate unless the person and chair are light weight and the motor is geared down.

The other is use of simple motor controllers, such as the Sabretooth, to create novel control methods, requiring things like un-mixed speeds of 2 or 4 motors. The 60A controllers may again work out if user and chair are light and the motors are geared down, so are certainly worthwhile for experiments. Whether they will be adequate in the "real" world is another question. Since they can be programmed at a relatively low level, you should be able to implement things like motor compensation, various mixing or non-mixed algorithms, getting turn priority when changing both speed and turn etc. You are quite right that you wouldn't be able to try these things with any dedicated WC controller such as Rnet.

In the end, however, you might have to go to a more powerful and expensive controller such as the Roboteq HDC2460 to get both the programmability you want and the power that a faster, heavier chair needs. How much of your code would transfer from one to the other I don't know, probably not much, but the logic of whatever you develop should work on both even if the coding details are different.

[Burgerman]

Thats what I am saying all along. Ultimately a waste of time on that small controller. But as an interesting experiment/project maybe great fun. And probably years of work/testing etc as per the roboteq project.

The R-Net stuff was a reply or two for martin007.

>>>Maybe try to understand the need behind a project before calling it pointless, or just don't say dumb hurtful stuff like that at all.

Wasnt to say the project was pointless but that wasting time doing that stuff on a tiny weedy controller was. It may be "able" to do high peak currents intermittently just as my RC heli ones do. And yet I have a draw full of those that only lasted several flights that went nowhere near their rated 125A capability... You can set a current limit anywhere the reliability/marketing decides. Those tiny controllers are nowhere near adequate driving a heavy powerchair if you expect it to be a reliable useful controller. They are cheap hobby grade chinesium stuff. Thats why there are 16 mosfets and 32 mosfets in the R-net or the Roboteq respectively. So they can lose heat fast, and share a conservative safe current rating of 120 and 150A. Even then they still roll back current due to heat. At least te r-net one does. Never managed that on the roboteq.

[slomobile]

For some 4x4 designs, 2 cheap low power wheelchair drives can get it done. Because the driving work is distributed among 4 wheels instead of 2 the peak current required on any one wheel isn't as high. It isn't cut in half because of unequal loading. However, consider a simple 'hay wagon" design. This is where the front wheels are on an axle that pivots in the center and the rear are fixed in place. It does work if you give front and rear controllers the same turning signal, but there is a lot of wasted current trying to get it to start turning. It can be very efficient if you split the turn into 2 phases. First operate the front controller to position the front axle to the commanded turn radius, next operate both front and rear controllers together with each wheel now consuming much lower and more even amounts of current. It is what we did to implement "swerve" omnidirectional drive in FIRST. The 2 sequences can happen in very rapid succession so the driver barely notices and be calculated by a microcontroller so the operator does not need to make any inputs other than he normally would. It should be trivial to allow the microcontroller to operate with mixed(wheelchair) controllers, or unmixed(general like sabertooth) controllers provided there is a precompiler switch and a steering angle sensor. However the problem of getting screwed up every parameter change would continue.

The wheelchair market does have a nice wide selection of joysticks with displays and buttons which is lacking in the robotics market unless you DIY or pay a ton for industrial controls. It would be nice to document how these joystick modules communicate. So that they may be used with robotic projects as well as swapped onto other chairs with something like an Arduino based protocol adapter. VSI is dead simple. What are some other wheelchair joysticks that may have an easy to decipher output? All the better if we can figure out screen display inputs as well, so we can display our own images. Or blank out the screen for better visibility at night. I only have PJSM and Omni 1 available here. But I know the Omni 1 screen seperates from the rest of the unit at a 0.1" dual row header. So that might be hackable at least. I see that as a potential new direction for the cheap Chinese joystick market. Making them open, modular, and modifiable. Fingers crossed.

[martin007]

Thats what I am saying all along. Ultimately a waste of time on that small controller. But as an interesting experiment/project maybe great fun. And probably years of work/testing etc as per the roboteq project.

The R-Net stuff was a reply or two for martin007.

>>>Maybe try to understand the need behind a project before calling it pointless, or just don't say dumb hurtful stuff like that at all.

Wasnt to say the project was pointless but that wasting time doing that stuff on a tiny weedy controller was. It may be "able" to do high peak currents intermittently just as my RC heli ones do. And yet I have a draw full of those that only lasted several flights that went nowhere near their rated 125A capability... You can set a current limit anywhere the reliability/marketing decides. Those tiny controllers are nowhere near adequate driving a heavy powerchair if you expect it to be a reliable useful controller. They are cheap hobby grade chinesium stuff. Thats why there are 16 mosfets and 32 mosfets in the R-net or the Roboteq respectively. So they can lose heat fast, and share a conservative safe current rating of 120 and 150A. Even then they still roll back current due to heat. At least te r-net one does. Never managed that on the roboteq.

I didn't say that...

[Burgerman]

I know. You were asking what controller.

This motor controllers?

> https://www.cw-industrial.com/en-gb/pro ... management

[martin007]

heres the other side of 3 of my cheap spare 120A R-net power modules. Note labels. So I know which chair I programmed them for ready to swap out in literally 20 seconds!

These 3 cost me under 150 uk pounds together delivered as new. They contain all the programming, and are the brain and the heavy lifting that sends power to the motrs etc.

Did you buy those sets so cheap on Ebay?

[Burgerman]

On eBay, on here, from a dealer, etc. Mostly ebay. German US, and UK, ireland etc ebay. When something comes up cheap, its gone in minutes, so you dont get to see it. Some people have alerts set up. So when they appear I make a daft offer and see what happens, or buy very fast. Mostly from unused or demo chairs or brand new chairs stripped for parts. Everything is either new, factory refurb, or as new.

Or in the case of the joysticks they were refurbished by PG Drives ones and there were lots floating about on here and ebay and basically the same as new. £125. Even the externals and screens wih screen protectors still fitted were new.

I paid 125, 125, and £150 for 3 different ones. I have 5 total inc the ones fitted to chairs.

[martin007]

Why are these ultra-cheapest prices?
You have bought at less than half the market price.

[Burgerman]

Dont understand the question. They are cheap because I watched ebay, like a hawk, and so on for a year and only bought if the price and condition was right. Ie new or as close to that as makes no difference...

[martin007]

I rephrase the question.
What makes a person sale at half the price?

[Burgerman]

Maybe they bought a large batch of refurb joysticks rom PG and paid very little. They are literally as new but technically used. So to get rid of hundreds in a limited market they sell them cheap! Beats me.

Same as 120A power modules. They go "used" as new with no dust, no marks, for £45 regularly. So I bought 3. One was USA, one germany, one UK. And one came with a bunch of cables and battery loom too! I got the seller to throw them in.

[Burgerman]

Slowmobile

THIS is a light rear dive chair, not a nose heavy chair, no seating options.
It has a 100A controller.
I have the clamp meter over just 1 extended motor wire.
All tyres are at 40psi.
https://www.wheelchairdriver.com/gopro/motoramps.mp4

Watch the amps. It hits 100A so often that the power module overheats and rolls back in summer even though I increased that point to 70C. With 6mph motors 100A is just enough. It hesitates, reaches 100A and then the turn starts. Watch the last one slowed down. On a slope or cambered road 100A isnt enough.

With a heavy chair like the salsa with 80kg of added weight, 120A isnt really enough at times.
With 8mph motors 120A is not enough and the chair frequently stalls out or doesent begin to turn without adding some forward stick too.

[martin007]

Maybe they bought a large batch of refurb joysticks rom PG and paid very little. They are literally as new but technically used. So to get rid of hundreds in a limited market they sell them cheap! Beats me.

Same as 120A power modules. They go "used" as new with no dust, no marks, for £45 regularly. So I bought 3. One was USA, one germany, one UK. And one came with a bunch of cables and battery loom too! I got the seller to throw them in.

I understand.
You also talk about cheap dealers.
How to locate them?

[slomobile]

Those are very good data points to keep in mind.

My prone position is very nose heavy, so having drive wheels under that weight makes sense. My body position is long, so I may as well take advantage of that with a long wheelbase 4 x 4. It will probably be a long trail front axle several inches behind the pivot point. Still working out the steering geometry.

If you can figure out how to add 2 Rnet power modules at once, I'll give it a try. I bought a whole bunch of Rnet stuff specifically to try that. But AFAIK that is not really an option.

Probably, what I will do while waiting to save up for 2x60 and Kangaroo is to use Rnet 120 with Omni 1 for the back wheels and Sabertooth 2x25 on front wheels, I'll use the Fanatec CSL Elite foot pedals for input, with a modification to the arduino sketch I already posted, to send signals to both the Sabertooth for steering front wheels w/steering angle pot, and also to rear Omni using https://bobparadiso.com/2018/10/09/cust ... -controls/.

If that isn't enough, I can try the 2x60. If I go with a 2nd Rnet, then I also need a 2nd Omni unless someone figures out how to run an Rnet PM without an Rnet Joystick. That work is also under way BTW. Not by just me.

[Burgerman]

Joysticks? I bought one from tom who tried to clone my chairs. One from a local place made of bricks, and one on ebay. The rest all came from ebay I think.

I understand.
You also talk about cheap dealers.
How to locate them?

There were some on here 2 years ago too. From hungary I think. All factory refurbs so basically new but brown box...

What are you looking for? All of it? Or just joystick? I watch all the time. If things crop up at a good price I buy... Just di that with a camera from HK and saved £1300...

[Burgerman]

For e.g. A UNUSED CJSM joystick and cable just appeared. I would make a daft offer. Its already too cheap. But he might bite. It will be gone in a blink. https://www.ebay.com/itm/256028419049

[shirley_hkg]

Is it ok to pair it with a PM from a PERMOBIL chair ?
Want to put a Rnet system on an Otto Bock .

[11ydy]

Is it ok to pair it with a PM from a PERMOBIL chair ?
Want to put a Rnet system on an Otto Bock .

可以的朋友，我在EBAY上面买的120A PM和 PJSM CJSM2都可以使用，需要有编程器

[shirley_hkg]

Thanks fellow .

[steves1977uk]

Yes Shirley, I have a few 120A R-net PM's off Permobils. They work fine with generic joystick pods from Curtiss-Wright (PGDT).

Steve

[shirley_hkg]

would like you to point me to get Rnet programming software please .

[steves1977uk]

PM sent Shirley.

Steve

[shirley_hkg]

work fine with generic joystick pods from Curtiss-Wright (PGDT).

Steve

Do you recommend a pod from Permobil too ?