My Phantom likes to randomly descend fast, information here and elsewhere has lead me to believe it's an IMU issue.

It's been generally random, however increasing levels of frequency may have made it worse as I've read that not only firmware but also impacts are when the IMU should be recalibrated.

I've recalibrated the IMU 2-3 times over the last year-ish, however I'm uneasy about why it would have suddenly failed before the first impact?

I'm asking here in hopes for affirmation, thoughts, other ideas for cause, etc...

Recent glitches during two very short flights yesterday (day before had an unevetful and full flight)



First falling event


When unintended descents begin I've always countered with full vertical throttle, such events have began anywhere from 5 seconds, to 5 minutes into flight.

Also I'm presuming the flight controller must be replaced if the IMU has gone bad. My phatom is still under warranty but after I've read so many people have waited months for warranty work (of which I've only about a month and a half remaining) it's feels worth it to just pay for/install it myself.

Have you tried opening the Phantom and taking out the Naza unit and smacking it on the table? Sounds  unconventional but it does work. It unsticks a sensor in the IMU. If that is the issue it will work, if it is not the issue then it will not do anything. Worth a try in my opinion.


Dave

DJI-Dave Posted at 2015-10-16 14:42
Have you tried opening the Phantom and taking out the Naza unit and smacking it on the table? Sounds ...

I definitely understand how smacking hardware can fix things. However with the issue being random where I've had full flights, or where it will only glitch partway through a flight, I don't think the sensor is just sticking. (still not even certain it is the IMU but I don't know what else it could be)

Glitch Posted at 2015-10-16 14:01
I definitely understand how smacking hardware can fix things. However with the issue being random  ...

True. Random issus are very hard to track down. I am not sure what it could be. You might have to send it in. I know you don't want to do that but I can say our turnaround times are getting much better.

Dave

Have you tried a cold IMU calibration?

This is where you put your Phantom in the refrigerator for 30 min take it out and immediately do a advanced IMU cal.

DJI-Dave Posted at 2015-10-16 15:16
Have you tried a cold IMU calibration?

This is where you put your Phantom in the refrigerator for  ...

I've only recently read about the cold calibrations, and was waiting on more input before trying it because of fearing a temporary patch rather than a more permanent fix. I'm certainly going to try it, but I didn't want to complicate things if someone came back with a better idea.

Also it's good to know that turnaround times are improving, however despite my many issues, I don't fault DJI. I know I bought a cheap (for what it can do, it's cheap) aerial video platform from a company that's exploded in popularity in the last two years. I've not expected reliability (I know the Phantom is consumer not pro grade) or fast turn around times, and the few times I've felt things were worth the effort to contact customer service, the actual interaction has been amazing. I genuinely intend this as a compliment since in addition to the random descent issue (now up to 6 times) I'm also expecting my 5th replacement H3-3D (I did buy a second one), my AVL58 Tx needed replaced, and all of this in ~10months. When everything works, it makes it all worth it.

Good to know, thanks for the reply.

Although you bought a consumer grade you should expect and get the same quality with you Phantom. I have been flying my two Phantoms for over a year and have hundreds of flights. The only time I have had random decent is with the battery going bad and it tells its to auto land. It will do that automatically when the battery hits critical level.  Problems with the IMU is most likely going to give you drift issues and some up and down drifting but not normally decent issues like you are having, especially if you are giving t full throttle and it still descends. Time to send it in for repair. Keep going and your next issue will be with crashing it. Better 8 weeks at repair than months on the shelf.