Can "IMU is initializing" and drifting be connected?

[Mastiff]

I was going to fly a photo waypoint mission yesterday on Litchi, but when I took off, the bird started to drift a lot more than I'm used to in P-GPS, both sideways and up/down. I decided against flying since most of the mission is above water (it's actually to show the owner of a small island close to my cabin how much I have cut of the top of the trees to make my view better). Anyway, today I drove to a big, open area and tested a litle bit. It still drifted a lot in P-GPS, and it still had a lot of drift up and down. Flying fast back and forth made it sink lower and lower for each turn, much more than I've seen before on warm-up flights. I tried to replace two of the propellers (I have only replaced two before, on maybe 50 missions) to see if that could be the problem. Then, when I was going to start up again it just didn't run the propellers when I moved the joysticks down and out. Litchi didn't say anything was wrong, and after a few minutes of testing (power cycling both the drone, the remote and the Acer 8" tablet I use to fly with) I finally tried DJI Go. And there I saw the message about "IMU is initializing" and I had to wait until it had finished. Of course it never dit. After ten minutes or so I gave up and drove home. I'm guessing that it will work again next time I try it, if not I'll just leave it out for an hour in the evening. Since it's still early spring that means about the same temperature as the frides I read about people using for this IMU thing.

But I'm wondering if the two problems can be related. Is that possible?

 

[Richard R]

The IMU is reading the gyros, compass and barometer, so, yes, if it isn't fully up to speed you could be having the type of problem that you described. I'd do a recalibration before i tried anything else. Find a cool, quiet and level spot (I have a spot on my basement floor) , let it set for 25-30 min so that the temp is stabilized. then do the cal. Have everything ready to go as soon as you turn on the bird. The IMU immediately starts warming up and you want to start the cal when it is a cool as possible. The cool cal temp extends the range over which your calibration is good and reduces the time it takes to bring the IMU up into the calibration range.

 

[John Locke]

I'm surprised Litchi didn't report an IMU issue. Hmm.

IMU is definitely a mandatory component for sound drone navigation and stability. Without it working 100%, you will have issues. The P3 you has only one IMU and one compass, which increases the risk of going into ATTI mode. If compass, GPS or IMU fail, you will be flying in ATTI mode. In ATTI your craft will float around with the direction of the wind.

 

[RodPad]

Hum, on my P3S Litchi tells me it waiting for the aircraft to warm up.
I would think if something is wrong, it would maybe error or never warm up?

Litchi did not tell me the batteries were to cold, I was having intermittent results was driving me nuts.

I would down load the mission and press go, Litchi would instantly say mission ended.

Rod

 

[Mastiff]

I put the P3 outside in 3-4 degrees C yesterday morning for half an hour and then ran the calibration. Seems to have worked, when I tested it today it hovered very nicely where I left it and didn't loose much height on flying fast back and forth. So I think it's healed. Thanks for the help!