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Drone control for disabled users
1988 8 2021-4-30
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thalon
lvl.1
Flight distance : 49012 ft
Germany
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Hello everyone!

I don't know if I'm exactly right on this forum, because my question is a bit technical and special. But I'll try it here anyway, if in doubt there might be a hint about where I can find something else.

I have been the proud owner of a DJI Mini 2 since December and have already made the first flights. However, I am physically disabled and therefore cannot use my hands to operate the joysticks on the remote control. I. E. Unfortunately, at the moment I can only use the drone together with my girlfriend. She then operates the joystick for me.

Is there perhaps the possibility of somehow controlling the drone differently? For example, I can operate my smartphone completely by myself and I can also control my PC alone.

Since the smartphone is connected to the remote control anyway, I thought there might be a way to send commands from the smartphone to control the joysticks to the remote control, which are then passed on to the drone via the remote control.

I also read that the protocol is open source. Maybe there is a way to hook one here. Another option would be to use an SDK, if this makes operation possible.

I am a computer scientist myself and have some programming knowledge, so that I could program such a tool myself if the interfaces for it are available.
Of course, I could also just build a piece of hardware into which the remote control is clamped and which moves the joysticks via motors. But that would be the mallet method and maybe it is more elegant.

I would be very happy about any help and advice!

Lovely wishes


2021-4-30
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Jackie-Gan
Second Officer
Flight distance : 457477 ft
Mexico
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Hi, unfortunately, I don't think that's possible. DJI never implements new features for drones older than like 2-3 months. The only DJI camera drone capable of smartphone-only control is the DJI Spark, but that's too old for me to recommend. Also without a controller, the DJI Spark only goes like 50-80 meters max. So I'm sorry to say that there is no other option. There is the DJI FPV, and you can control that with a Joystick, but that's too expensive and it is prone to crashes; also, it can't fly in manual with the joystick and you only get like 15 minutes of real flight time per battery. Also, the DJI FPV is very expensive, 1299 USD for the basic kit with 1 battery, fly more is 299 USD extra, and the joystick I talked about is another 199 USD. So we are talking about 1500 USD for 15 minutes of real flight time (Basic Kit + Joystick) or 1800 USD for 45 minutes of real flight time (Basic Kit + Fly More + Joystick). It is not worth it.
2021-5-21
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Ozzyjim
lvl.2
Australia
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It would be quite nice if the device you used had accelerometers that you could use to achieve the movement and maybe a on screen button you could drag up or down to have some control over the speed that the drone would climb / descend.

I would be a little concerned if motors were used that the delay between user input - processing - motor output to sticks - processing - command sent to drone would be too significant depending on the type of flying of course..


However if you can use a joystick -

Most controllers along the lines of RC aircraft, a number of game consoles etc use resistance (Potentiometers) to tell the position of the sticks... I know a number of PC Joysticks do also..... If the Mini 2 is the same it may be possible to replace the potentiometers in the joystick to match that of the original controller, then it's possible that the internal pcb's that hold buttons etc could have their traces cut and wired through to the mini 2's controller... PC Joysticks are self centering and would cover 3 of the 4 movements needed for control except for ascend / descend, throttle control could be used but they don't normally self center, so even with a lot of care you would probably end up gaining or losing height. I guess  a "hat" switch could be used with fixed value resistors to mimic stick input but you would be limited to a single speed up or down :/..

- fixed value resistors could probably by wired in to a button to simulate the sticks being moved for motor start
- the trigger would make a excellent shutter button
- use of a PC joystick would mean it would probably need it to be placed on a table for stability..

here is a pic from one of the FCC applications for one of DJI's other controllers. I am sure the orange boxes would be potentiometers and the mini 2 would be similar, I just haven't found that FCC application yet...



I would love to have a play with this but unfortunately I can't at the moment, but it would be great if someone has a spare controller hanging around to try out.

2021-5-26
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thalon
lvl.1
Flight distance : 49012 ft
Germany
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Thanks for the valuable hints and suggestions!

A small update: I'm currently working on a software-based solution using the SDK. I'm already making good progress :-) I'll keep you posted.
2021-5-26
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Duane Degn
First Officer
Flight distance : 598415 ft
United States
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Ozzyjim Posted at 5-26 07:57
It would be quite nice if the device you used had accelerometers that you could use to achieve the movement and maybe a on screen button you could drag up or down to have some control over the speed that the drone would climb / descend.

I would be a little concerned if motors were used that the delay between user input - processing - motor output to sticks - processing - command sent to drone would be too significant depending on the type of flying of course..

I don't have a Mini 2 but I do have the FPV drone. The joysticks in the FPV controller all have wired connectors which would make substituting an input signal easier than having to cut traces.

Here's a photo of the inside of the FPV controller.


The joystick connectors are next to the two bottom corners of the large heatsink. Here's a link to a thread with more photos of inside of this particular controller. Here's a link to my Hackaday IO project about the drone.

The Mini 2 controller likely has similar connectors which could be used in inject an external input signal.
2021-5-26
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Ozzyjim
lvl.2
Australia
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Hello thalon,

How is your project going?.

looking forward to hearing updates.

Cheers,

James.
2021-6-12
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thalon
lvl.1
Flight distance : 49012 ft
Germany
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Ozzyjim Posted at 6-12 07:04
Hello thalon,

How is your project going?.

Hi James,

thank you for asking! Indeed, I've made some progress and I was able to control my Mini 2 with my micro joystick - at least as a proof of concept. Watch me in action in this video:

https://youtu.be/vGn_3X2Wn3Q

However, I still have problems with the video feed for preview in the app which seems to come from the lack of official support for the Mini 2 in the DJI mobile SDK. Unfortunally the SDK doesn't send key frames on a regular basis and there is no api call to trigger this manually. So when there is a bit error or something in the video stream, the decoder only shovs black frames. Only workaround is to stop/start video or toggle video mode (video/photo). This is kind of annoying.

Another problem is that the movement is a bit clunky. It could be smoother. You can see this in the video when the drone turns. I still have to find out what causes that problem.
If you like, you can have a lookat the repo on GitHub: https://github.com/cbayerlein/rosettadrone_mini2

Cheers
Chris
2021-6-15
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Ozzyjim
lvl.2
United States
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Hello,

Thanks for the links, I will have a look shortly. Unfortunately I don't do much on the mobile side of things so I don't know how much help I will be there but I will certainly try and spread the word for you

Sorry for the late reply.
James
2021-8-12
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geoman
lvl.1

Ireland
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thalon Posted at 2021-6-15 10:38
Hi James,

thank you for asking! Indeed, I've made some progress and I was able to control my Mini 2 with my micro joystick - at least as a proof of concept. Watch me in action in this video:

Hi thalon,
I'm have a c5 quad Spinal Injury (no hand function). I'm thinking of getting a DJI... I was worried about controlling it in an enjoyable way though until I saw the DJI FPV motion controller.  Im thinking I could strap it to my forearm (or head :-) )... For basic flight, I think all I would have to figure out is controlling the 'trigger/accelerate finger switch.

Did you consider the motion controller?

I researching if I could make a mouth with control a servo to use the trigger/accelerate button...

(I know I wouldn't be able to hit the emergency stop button...)
6-3 08:15
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