Hi! Some time ago I made a project for a friend with limited mobility where I used joystick I got from her old electric wheelchair, It was a 4 axis joystick with 6 wires. Turns out this joystick was a little damaged, and it hardly turns to some directions, so she got a replacement. This new joystick looks exactly the same, however it only has 3 wires (red, white and black) and I just can't figure out how it works.
I tried to measure the resistance with a multimeter between the 3 wires, but the values never change no matter the combination.
I should mention that this joystick was connected to a box with an electronic board, although I believe this board is probably used to transform the joystick values for the wheelchair main circuit.
Could someone help me figure out how does this joystick work?
Hard to say what it does without spec sheet or manual etc. Maybe 1 wire is ground, while other two could be control signals of some sort. If you need to get a replacement joystick etc, you normally need to make sure that it's going to be compatible.
Southpark:
Hard to say what it does without spec sheet or manual etc. Maybe 1 wire is ground, while other two could be control signals of some sort. If you need to get a replacement joystick etc, you normally need to make sure that it's going to be compatible.
Hi, I couldn't find any datasheet online. These kind of joystick are really specific, the only way we have to ask the maintenance company to send a replacement for the wheelchair joystick. They send the whole joystick thing with the box that goes to the wheelchair controls, but I only need the joystick itself as it the only kind of joystick she can move. The joystick wont be connected to the chair but to a computer, so she can control the computer with the joystick.
I see! Yeah....... it's hard to say whether it's compatible with your old joystick. Maybe not compatible due to the huge difference in number of wires.
Your new joystick might be more advanced internally .... such as black and red could possibly be for power and ground, while the white may be digital data signals or something.
Hi, you could be right. I opened the Joystick and I found out that it doesnt have potentiometers, apparently it gets the position of the joystick with an inductive sensor?
In this case I imagine that red and black are power, and white is the value output. I will try to get some readings with arduino and try to figure it out.
I tried to read the white wire as a pulse signal, but I only got 0 as result. I would gladly take guidelines or how to get an usable digital read from the white wire (assuming that red and black are power).
Can you intercept the joystick signal after it passes through the control box? With just power+ground+data you have absolutely no chance of working out the data format by guessing.
There's a chance that this is a published format. Try the joystick manufacturer's website.
MorganS:
Can you intercept the joystick signal after it passes through the control box? With just power+ground+data you have absolutely no chance of working out the data format by guessing.
There's a chance that this is a published format. Try the joystick manufacturer's website.
The control box has a 7 pin exit, but I think it works a 25V and I don't have a way to power the box with 25V here. I can't connect it to a wheelchair either as this model uses a different connection that my friend's current wheelchair.
Anyway the joystick would had to work with the power that arduino can supply, using another power source wouldn't be viable.
The manufacturer website just have a short description of what the joystick can do
That number didn't help, but the fact the joystick end is a magnet suggests the 8 chips are possibly hall sensors.
These will act either as discrete switches or will combine to provide a polar output depending upon joystick position and the gauss value each chip is 'seeing'
jackrae:
That number didn't help, but the fact the joystick end is a magnet suggests the 8 chips are possibly hall sensors.
These will act either as discrete switches or will combine to provide a polar output depending upon joystick position and the gauss value each chip is 'seeing'
Im pretty sure that's the last one, as electric wheelchairs move a different speed according to the joystick position. How would this work? Each chip sends the value to a chip that does the conversion and sends the data? If so, do you think it would possible to read this data from the joystick without the box?
It would only be possible if the digital data format is published.
If I was doing it, I would consider making my own PCB with similar hall-effect sensors and an Arduino chip on the other side, which will fit into the existing housing.
Some wheelchair systems use a variation of Canbus data comms, so minimal numbers of wires involved but without the protocol information you are running blind.
I imagine there may be a 'collection' chip that takes in information from all eight sensors and outputs a data stream that defines joystick position.
If you have access to an oscilloscope you could apply power (red/black ?) and observe data (white/black ?) as you move the joystick. If you can see data then you need to set up defined joystick positions N,S, E, W etc and see what changes are made to the data stream. You might then manage to make sense of what's being sent.
