About beginners luck and compass error

[hurtigpelikan]

Hi,

I am new to this forum having just acquired my very own P3S after having flown the Hubsan X4 for a year.

Yesterday I was out flying for the first time in my backyard. I had previously calibrated the compass on the P3 indoors (yeah i know - read the manual! - stupid thing to do).

Temperatures were just above freezing and the was a mild wind with some very heavy gusts.

The flying started great - nothing unusual until I was about 3 minutes in and got 3 "compass error - Exit P-GPS" in rapid succession. These errors happened just as i began to climb and rotate, was at about 15m altitude when the errors occurred. During the last error a heavy gust accelerated the P3 away from me at a speed of roughly 30 kph. I tried to steer it in ATTI mode but the wind was to strong. The flight stopped after about 50m as the compass came to its senses again and the P3 reentered GPS mode. (During the drift, the P3 missed a tree by 10cm and a propeller clipped a branch.

I managed to land the P3 in the snow - no harm done. Took it up for a quick spin afterwards to verify that everything was okay.

Now to the question. I presume the compass errors most likely was caused by the faulty calibration i made. Another reason could be that the compass is faulty and I should return it for a new (which I am able to do for the next week or so). I am not likely to fly it again for the next week due to work and bad weather.

What would You do?

Long story short - I behaved stupidly and had incredible luck, it could have gone allot worse than it did.

I appreciate any comment!

Brgds!

 

[msinger]

What would You do?

Calibrate the compass again outside in a location where there are no magnetic metal objects. Then, take another flight and see if you experience the same issue.

 

[Meta4]

Now to the question. I presume the compass errors most likely was caused by the faulty calibration i made. Another reason could be that the compass is faulty and I should return it for a new
What would You do?

The cause is almost certainly calibrating in a bad location with a distorted magnetic field.
The Phantom needs a good compass calibration to be able to fly straight and prevent forcing the Phantom into atti mode because of compass error.
Get a good calibration in a good area and stick with it.

 

[Waylander]

Hi
Yes do what msinger says, in addition I would advise you that once you are happy flying, landing and doing recovery of control after a RTH (practice this a lot),
you should learn to fly in ATTI mode, in this mode the Phantom software does allow more power to the motors, so can overcome wind problems more readily, however it is more difficult to fly as you have to compensate more for wind,
Regards
Waylander

 

[BillW50]

I am glad to hear that you have flown the Hubsan X4 for a year. I too have a bunch of them since 2013. I have also been RC flying since the 70's. And if you can handle the Hubsan, you should have no problems flying the Phantom in ATTI mode. Yeah calibrating the compass in a bad area is a bad idea unless you just want to fly in ATTI mode. Once you calibrate the compass in a good location, you shouldn't have to do it again unless you fly somewhere else many miles away. Well now go out and have fun and keep the GPS side up.

 

[hurtigpelikan]

Thank You for all your help!

My checklist for the next flight is:
- Calibrate compass at a suitable location
- Keep the P3 low and check for any problems
- Avoid hitting trees and trimming bushes (There are other more suitable and inexpensive tools for this)
- Practice flying in ATTI
- Practice flying in ATTI a bit more...

If the problems persists I will get the quad exchanged for a new one. By reading on this forum you could get the impression that the compass error is a common fault with the P3S - but people without problems seldom posts on forums.

I am actually quite good at flying the Hubsan in full manual mode, but the problems caught me completely of guard - which it off course should not have.
But I think that for a newbie a scare like this actually is good thing in the long run...

 

[solentlife]

Calibration .... do it properly and judging by the first flight - all indicates should be fine. The model itself seems to have performed OK. Your learning to fly the lesser quad also helped you in a bad situation ... forgive me for saying ... of your own making by calibrating INDOORS !!

Now go out there .... calibrate properly .... and ENJOY !!

Cheers
Nigel

 

[hurtigpelikan]

of your own making by calibrating INDOORS !!

Yeah about that... Not one of my proudest moments

 

[Raeq]

I just learnt about calibrating the compass properly before a flight is a must! I thought I had the calibration right, see I had multiple calibration errors and it told me that there was too much magnetic interferrance or something of that sort - but I kept calibrating it around the same area, till I saw the GPS turn green for flight. Quickly got the drone up and away, my goal was to check the tennis courts if there were players 400m plus away. It flew toward the area without problems, it was when I did RTH... I had a notification if I wanted to exit landing! This caught me by surprise at that juncture I lost contact with my P3 4k, there was no video feed as well. I found out that it landed on a roof of a house. After retrieving the drone... recalibrate properly, flew it 300m and it did RTH okay... calibrate properly!

 

[hurtigpelikan]

Hi again!

Sitrep: I drove out in the sticks today to try again. The nearest structure was a powerline about 200m away. Calibrated it away from any metals and took off. Hovering at a height of about 1,5m at a distance of 20m I started rotating the P3 and the exact same error occurred when facing east causing it to drift in the wind again. I sat it down, tried calibrating again - same error. In this area there should be no soil or rock causing any magnetic disturbance (I know this because I am a geotechnical engineer).

I even tried picking it up and rotating it. Each time the front was towards east the drone would exit GPS mode and not be able to reenter GPS mode until I turned it away from east.

I packed the drone and drove to the shop for an exchange. Unfortunately they were sold out of P3S so I received a refund.

Is the compass error a common problem with the P3S?

The odd thing is that I have a feeling that the P3S i bought had been used before and returned as defective. The stickers were loose on it and the P3 threw a IMU calibration error at me the first time i started it.

Thank you again for your time!

 

[Waylander]

Hi HP

Just a thought..... I think I have seen what you described on my old Phantom 2, and in the end it was not a problem with the compass, but a problem with the IMU calibration.
Now back then I was not as familiar with the Phantom's so I did the IMU cal even though the software told me the bird was too hot, and when I took her out she flew OK until I tried to Yaw her 360 Deg's. then she began to drift and oscillate from side to side, and eventually dropped from a height of around 10 feet lucky I was over deep moorland heather so no damage.

Did my research, then next IMU cal got my level surface set up outside with everything ready to go, and put the Phantom in a plastic bag in the fridge ( yes I know some say don't do that..!)
non the less.. did the IMU calibration, and a compass cal when I got out on the moor and hey presto, no drifting or dropping during Yaw manoeuvres. Job Done.

Hope this helps you or some other OP, IMU calibration applies across the range of DJI Phantoms, and the colder you do the calibration the better the outcome. ( as agreed by other OP's)
Waylander

 

[BigR1979]

Yeah definitely sounds like you bought a defective one to me, at least you got a refund and can buy another elsewhere if need be. Don't let that put you off once you get a none faulty one I'm sure you will love it.