Replacement of Joystick for wheel chair with RC remote

Other Hardware Device Hacking
1

Hello guys,
I am working on a project where i want to control motors using a RC remote instead of the wheel chair joystick provided as i want to control the motors remotely.

However, there is no datasheet regarding the output of the joystick.

Tests for output signal so far:

  1. Analog - Checked with a multimeter to see if the output was analog. However the voltage didnt change with any corresponding movement of joystick
  2. PWM - checked with an oscilloscope. I placed the signal and ground into an oscilloscope to see the output. The signal looked like a PWM sort of signal but when i change the position of the joystick, the duty cycle or amplitude does not change but the motors move.

As a result, i am finding it difficult reenacting the output of the joystick. Anyone know any other output options I havent checked?

Thanks for the cooperation

2

I guess I would use the "eyeball" test. What is the joystick lever connected to ? Potentiometers? How many wires coming from the joystick?

Are you looking at the actual joystick mechanism? Or are you looking at wires coming out of a controller the joystick is connected to?

Have you talked to a service center that repairs wheel chairs?

Paul

3

Thanks Paul for the response.

The internal joystick connection is in the picture attached

The number of wires coming from the joystick are 4.
Red(assuming for power)
Black(GND)
Green (Signal?)
Blue(Signal?)

The joystick mechanism is not really of importance at the moment. I just need to know the nature of the signals so i can produce them using an Arduino instead of the provided joystick.

IMG_1825.JPG
IMG_1825.JPG1512×2016 653 KB

4

Have you looked at this web site? https://www.ez-robot.com/Community/Forum/posts.aspx?threadId=4157

Paul

5

They make a board that you can bypass all of that, and use arduino, and the wheelchair batteries, with the motor.

You can also use stanard rc controller with it, if you want.

Sabertooth 2x32

6

i have a desire to do this as well. I've successfully used the sabertooth 2x32 on my jazzy w/ brushed motors. However I have a heavy duty invacare chair which has brushless motors rated to push around 400lbs and should be much more fun! however, brushless controllers cost way too much. I'd like to figure out the signals as well to hack in RC control. the above references website was left unfinished although led to some nice conversation on how impossible it was. looks like Im leaning on the servo joystick control route. I'll take it i can't use a quadcopter esc rated at 30amps for each brushless motor :slight_smile:

7

I don't understand that either. How is it a tiny d-cell sized quadcopter motor can claim 30 amps and stall with my fingers? My wheelchair motors push me and someone else around, also use 30 amps. It takes 15 amps to drive a 1.5 horsepower treadmill motor, and you can't drive a treadmill on a 30 amp quadcopter motor, that's for certain.

I think those r/c brushless drivers are cheap enough just to buy one and hook up to a motor to see what happens. If it makes noise or gets hot, just shut it off. Half of the fun in doing all of this is trying different things to see what works.

You can find brushless motor drivers for cheap, just scan ebay you will find them. They are simular to stepper motors (which also are brushless). It's signal that rotates around the poles of the motor. The faster the signal, the faster the motor.

The Arduino can interpret r/c signal from r/c receiver easily. Then you can process the data, and output whatever signals you want - attached to whatever motor drivers you pick out. I think they even make long range 2.4ghz r/c boards for Arduino, so you can just make your own joysticks and own receivers.