Parts list for VR2 joystick hacking!

[lordk]

Hi,
I update my schematics. This is what I´m testing right now. It works fine with buttons or with a thumb joystick (like playstation). Code still under heavy work.

I´m still waiting for a switching power to feed my arduino directly from 24V batteries. Now I power my arduino with a 9V battery without noise problem.

Comments and suggestion are welcome as I need to round up this project.

Regards.

[woodygb]

Perhaps we can help with the code.

IF you want ...post your code as a text file ...but rename the extension zip.

[getsiddd]

I request you to attach the arduino code that has been used with it.

[cdb0ewm]

Did the Arduino code ever get posted for this

Thank you

[lordk]

No, sorry! Im still working in hardware and firmware.

[vr2hacker]

I keep getting private messages asking for help to make the VR2 work!

Just to be clear, the info I give at the start of this thread is just for using the JOYSTICK with my own hardware. I put the VR2 and its proprietary hardware in the trash: It was faster to use another (different) motor driver.

D

[kolaf]

I'm sorry for resubmitting such an old thread, but I just want to post a thank you for the information I found here. I used this to RC-enable my sons power chair as a fun gimmick. My joystick had opposing voltages on the two outputs for the same axis had to do a redesign from the schematics posted here.

A few pictures and videos of my success :-)
https://photos.app.goo.gl/8HPiafQUUM8GKwYG6
https://photos.app.goo.gl/AN5HSSE5ySbLPwsY7
https://photos.app.goo.gl/E6bKJYWSQpZBV2SE6

[woodygb]

Nice job.
I use a digipot for my version and they are mostly dual channel in the same direction ..thus bifurcating the output is simple.

Should the required output be opposing I then simply add another digipot piggy backed on top .... then cross over the end supply feeds to each ... this simple addition gives the required 4 opposed outputs.

[kolaf]

That looks great, much more compact than mine. How do you interface with it? And how do you power it? I've been looking for a way to get power out of the chair, but I can't mess with it too much since it's technically government property.

Have you tried to add any autonomy? My next step is to add a raspberry pi with a camera to do object tracking on a aruco code with opencv. With a couple of pid controllers for speed and direction it should be possible to have it follow me while walking. Great for when my kid is too tired to drive himself.

For the record, we also have a factory installed remote to act as an emergency brake.

[woodygb]

I take power from inside the joystick pod and feed it to a Traco 2450...
https://uk.farnell.com/tracopower/tsr-1 ... dp/1696320

The interfacing itself is via the joysticks ribbon cable.

Here's a layout that is similar to what I'm using.

[kolaf]

Thanks, but I'm not sure I understand you. You use the joystick to interface with the joystick replacement controller? Does this mean that the purpose of what you have built is to replace the original joystick? I must admit that I got a bit lost in all the postings, so I might have missed this detail.

I was also planning to power it directly from the on-board mains power, but I am not sure where to find a feed. If there is sufficient power in the 5V that comes from the controller board to feed the joystick I guess I can use this...

[woodygb]

Sorry ... I wasn't clear ...the coding gives the original joystick preference and I interface between the Arduino and the joystick.

From the joystick to the Arduino AND/OR from the R/C to the Arduino ...then depending on coding ...from the Arduino to the joystick pod.

[kolaf]

Ah, that make sense. It sounds similar to what I'm doing. Whenever the joystick is moved it will take control from the RC transmitter. I could flip a switch on the RC to regain control until the joystick is moved again. The system boots with the joystick in control.

I'm currently struggling a bit with steering calibration being a bit off, it seems that the v/2 oh feed to the controller is not exactly the same as the centre frequency of my emulated joystick signals. I'm also struggling a bit with getting the correct output range. I measured what came out of the original joystick, but the maximum extents seem to be outside of what is tolerated by the control box and everything starts beeping. The result is that until I find the exact limit I cannot reach the same speed and steering range as when connecting the joystick directly to the controller as it is supposed to be.

[woodygb]

I have sent you a P.M. ... CHECK THE FORUMS INBOX.

[woodygb]

Kolaf... Do not supply Vs/2 with the Arduino ...instead just leave it alone and allow the joystick / board to do this.
You can however measure / read Vs/2 with the Arduino and use this reading to set the Arduino's center / OFF /Neutral voltage.

Only measure/read the output voltages from the joystick and have the Arduino supply the steering and forward/reverse voltages to the pods board using your own dedicated 5v power supply NOT the pods 5v.

You should consider using JUST the transmitters right stick for driving the chair.

Question ... What is the control system on the chair?

[Burgerman]

My right stick has a throttle, for helis, no ratchet. And I drive with main steer axis on that right stick, (aileron in a 4 axis heli or aircraft) And use the left stick which spring centres on all axis, for forward and reverse. So split stick.

I COULD use left stick for both axix, but thats not how I fly planes/helis so feels unatural. On my TX I have mixed BOTH sticks to do left/right, with all trims completely disabled. So can drive on left stick if needed. Or split sticks if doing anything more serious, that requires accuracy. But I know what you mean... I also rates. So that I can leave the joystick on max. And flick a switch to go from indoors/inside vans etc. To outdoor speed. And servo throw is limited to 100% even if both steer sticks are used together.

I also use an elecctronic mix circular joystick limiter. As used on swash plates on a helicopter. So that the joystick responds like a round wheelchair joystick rather than a square RC joystick. Because that gives the same response and feel as a wheelchair.

[woodygb]

Additional info.....DO NOT connect the 5v supply from the board to the Arduino or the joystick pod.....instead supply the joystick with 5v from the Traco 2450 .

[woodygb]

My right stick has a throttle, for helis, no ratchet. And I drive with main steer axis on that right stick, (aileron in a 4 axis heli or aircraft) And use the left stick which spring centres on all axis, for forward and reverse. So split stick.

Kolaf's video shows that he is using the LEFT throttle channel WITH RATCHET for forwards/reverse .

[kolaf]

Thanks for the tips. Let me take this offline with you, I'll send you an email tonight with my schematics.

[Burgerman]

Kolaf's video shows that he is using the LEFT throttle channel WITH RATCHET for forwards/reverse .

Oh dear. That would be quite exiting if it ever starts up to begin with.

[kolaf]

I have flown both helis and planes, so I'm used to throttle/rudder on the left stick and aileron/elevator on the right stick. It's great to have a non-centring stick for throttle, this allows me to set a constant speed when out walking and I only have to touch the right stick whenever I need to correct the travel direction.

To deal with the lack of self centring I have set up an easily accessible switch on the transmitter to act as a throttle hold. This also doubles as an emergency brake :-). Note that my main motivation for doing this is to bring my kid along for walks which means we mostly travel at a constant speed for quite some time :-). Using only the right stick would make sense for more high precision driving.

[Burgerman]

That makes sense. Suggest that you program the chair with all 4 turn acceleration and turn deceleration settings set to 100. To remove all the turn delay and to make it stop turning when told.

[kolaf]

Since more people are following this, I'll post my schematic here. It is heavily based on something I found a few pages earlier. The controller is fed with its own voltage through a voltage divider to create v/2. This is why I am having trouble finding the exact centre since v/2 seems to be 2.54 V when I measure it, but setting this as my centre output voltage does not seem to be the exact centre. The Arduino is currently powered by a separate battery, and the chair's joystick is connected only to the arduino. For joystick control I read the joystick output and convert this using the same DACs as I use for RC control.

The power through the ribbon cable from the chair is not used for anything except for the return v/2. I have connect the ground from the chair and from my power supply.

The chair is a Permobil X850.

[LROBBINS]

I have connect the ground from the chair and from my power supply.

Just in case you are not aware of this, the chair FRAME should never have a direct (low impedance) connection to ground, so do make sure that your ground interconnects don't also connect to the frame (except by a capacitor if you want to reduce noise).

[kolaf]

No, I'm connecting to the ground in the joystick ribbon.

A disclaimer: I'm a software person, not a hardware person

[woodygb]

Downloaded ...Just trying to get my head around your drawing ....
Question ...Where does VDD 5v come from?

[kolaf]

Vdd comes from the Arduino.

The two connectors to the right are the DACs.

The two square connectors FromJoystick and ToControlle the ribbon connectors for interfacing with the chair and joystick.

The thing to the bottom left is two opamps.

The four three pin connectors at the top are pwm interfaces for the RC receiver.

The remaining four vertical connectors with 6 to 8 pins represent the four blocks of connectors on the Arduino UNO.

[woodygb]

Try this modification.

[kolaf]

I see what you mean, but will I not still have the same problem of calibrating my idle output voltage to that provided by the joystick? To me that looks like the same problem that I am having now, calibrating my idle output to whatever my voltage divider produces.

[woodygb]

I simply match the neutral output of my digipot to equal Vs/2 using a 20 turn trim pot .

Vs/2 can be measured with a pin of the Arduino and a bit of coding can be used to flash an led if the readings do not match or to be permanently ON if they do.

Not sure how you would do this with your DAC.

I also measure and calibrate my R/C signal using the Arduino , a push button and some code ... thus I measure the RC Neutral ,High and Low values and save them to Eeprom. ... then map them to the output voltages.