Solo Transmitter Sanity Check via Solex app

[k4kfh]

Some of you may have seen my thread from a few days ago about my Solo crashing on takeoff. As it turns out, the crash was due to the controller sending bad data. Even though the sticks were in the center, it was telling the Solo to pitch backwards wildly. The Solo did exactly that immediately after lifting off the ground, causing a nice crash in which I broke all four props.

Luckily some disconnecting/reconnecting pots inside the controller and a software reset seemed to fix the problem, but what surprised me is that there is no way I could have detected the problem and prevented the crash (at least not with some substantial testing beforehand using Mission Planner).

So I used DroneKit to make a Python script that will sanity check all the RC channels. You run the script, then flail the sticks around wildly for 10 seconds. As long as every channel exhibits sufficient change over that 10sec, it'll tell you it's safe to arm. If any one channel fails, you'll get a very large message telling you not to arm the copter, because armageddon will likely follow.

It's surprisingly convenient to use thanks to the remote commands feature inside the Solex app. All I have to do is push "Quick Stick Test" under the "Commands" panel in Solex, and move the sticks around. Then after 10 seconds, assuming all goes according to plan, I get a nice "SAFE TO ARM!" message on Solex, and a goodly dose of peace of mind.

I've open-sourced all the software behind this (only 2 python scripts) so if you'd like to install it on your Solo, it's very easy, and you can find more detailed instructions here. If you have questions about installing it, feel free to reply to this post and I'll help you out.

StickEmUp - Sanity Check for 3DR Solo Transmitter

 

[Maddog]

Do you have any idea why this happened to begin with?
I can't remember anyone else having this problem- unless they had it but never figured out the cause.

 

[k4kfh]

Do you have any idea why this happened to begin with?
I can't remember anyone else having this problem- unless they had it but never figured out the cause.

It was one of two things:
- A software issue caused by Mission Planner (I had started to set up a joystick in MP, but wasn't using it at the time, so it is possible that channel override could've been "stuck" and screwing things up)
- A bad electrical connection inside the transmitter. I didn't find any disconnected pots when I opened it up to check, and ultimately I doubt this was the problem, but it is possible.

I found it extremely odd myself and couldn't find anyone else who'd had a similar problem, but the fact that it could go totally unnoticed like that made me a little nervous. I'd much rather sacrifice 30 seconds to run the test every time than nearly $30 in props on the off chance this happens again.

 

[Maddog]

It was one of two things:
- A software issue caused by Mission Planner (I had started to set up a joystick in MP, but wasn't using it at the time, so it is possible that channel override could've been "stuck" and screwing things up)
- A bad electrical connection inside the transmitter. I didn't find any disconnected pots when I opened it up to check, and ultimately I doubt this was the problem, but it is possible.

I found it extremely odd myself and couldn't find anyone else who'd had a similar problem, but the fact that it could go totally unnoticed like that made me a little nervous. I'd much rather sacrifice 30 seconds to run the test every time than nearly $30 in props on the off chance this happens again.

Great idea with your test!

 

[RichWest]

I applaud you for creating the test script. But like MD, I'm unaware of anyone having an issue with the controller losing stick calibration and being able to fly as stock. I assume Solo has a self test on boot to confirm all systems normal, as you'd receive a controller calibration required warning and not be able to arm the bird. Again assuming a stock bird...which you likely do not have at this point...

 

[Pedals2Paddles]

I'm guessing the RC override or some parameter change is what actually caused this.

 

[yt lee]

I am trying to figure what caused your problem.

Did you send a mission thru MP.
Did you manually take off.

 

[k4kfh]

I am trying to figure what caused your problem.

Did you send a mission thru MP.
Did you manually take off.

I'm fairly certain, in hindsight, it was either something going wrong with MP at the time, or that MP had set a channel override intentionally in the past and somehow it hadn't cleared the override. Ultimately I don't think it was entirely Solo's fault, I was just a little surprised it's so smart and still dumb enough to let me take off with the pitch set so strong lol