Discussions

IMU Mid-Air Reset

Posted by David B on September 14, 2011 at 8:49am

I'm getting closer and closer to being ready to test my UAV, but I still have one failure case nagging the back of my mind: what to do if the board resets in mid-air and clears the DCM matrix? I mean, I don't plan on having mid-air resets, but what if it happens?

I've played with the idea of writing the position to the EEPROM every once in a while, but it would have to be very often given how much orientation can change in a second. And given certain instabilities in the flight characteristics, I don't trust it not to crash while the accelerometers slowly sort out the gyroscopes if it resets in, say, a 45 degree bank.

What methods have some of you employed to deal with a mid-air reset of your IMU variables?

Thanks!

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Replies

DaveyWaveyBunsenBurner September 14, 2011 at 9:18am

Assuming we are talking actual IMU resetting, and not autopilot, I would imagine you could, you have no idea what the actual attitude is so level is as good as any guess :) have you had a peek at the existing code for clues??
DaveyWaveyBunsenBurner September 14, 2011 at 9:04am

Sorry, thought we were talking fixed wing!!
3D Robotics

Chris Anderson September 14, 2011 at 8:59am

I think answer is the same for all multicopters: if the controller board crashes, the copter will too. Unlike planes, which can revert to manual control while the board restarts, multicopters aren't controllable without the IMU. Even a one-second reboot time is probably too long to regain control unless you're flying pretty high.
DaveyWaveyBunsenBurner September 14, 2011 at 8:57am

Mid-air resets are covered in thhe code but need to be enabled i believe. The APM sees ground speed via GPS and doesnt reinitialise the IMU. Im on a crappy phone with a tiny screen at the momont but seem to remember enable_air_restart can be set??

Sorry if i misunderstood your question.

D