Abnormal Compass Data just before Take Off

A

Ash_K

Member
Hi,

We are trying to fly the S1000 on A2 using 14SG on manual mode. The A2 LED does three violet flashes in repetition which we recently learnt is normal.
Now as the throttle is increased, the motors rev up nicely. And just as it seems it is about to take off, a continuous yellow/green (abnormal compass data) LED flashes.

We did the recalibration successfully and tried again - same result - (did that twice). The IMU is very firmly stuck to the platform.

Any advice would be greatly appreciated.

Thanks,
Ash
 

F

frozentobacco

Member
Most likely interference from your environment. What is the location you are flying in? Any reinforced concrete nearby? Large metal structures etc?
 

A

Ash_K

Member
We are trying to fly it in clear space (grass) with a nearby building (20m away). Will give it a go in the open field - but the 'Green/Yellow' flashing only comes when throttle is increased. It goes away after powering down and back up again. And comes back again, when throttle is increased to the point of take-off.

What are the settings for the IMU and GPS mount offset for the S1000 (Mounting tab in the Basic setting for A2 PC Software assistant) - if the IMU is mounted in the recommended position? It looks like something needs to be altered.

Thanks.
 

F

frozentobacco

Member
You need to measure the distances and input the offset. Tape measure will do it - nearest centimetre will suffice. If it occurs only in power up - you compass maybe too close to the electronics etc - there is interference. Have you done the compass calibration?
 


A

Ash_K

Member
Thanks for the advice - will measure the offset and enter it.

In order to minimise interference, we are using the longest stick (out of the 3) to support the compass/GPS module.
Yes we did the compass calibration (chicken dance) successfully - before each attempt.

I will enter the offset and see what effect that has.
 


Benjamin Kenobi

Benjamin Kenobi

Easy? You call that easy?
Ash_K said:
Hi,

We are trying to fly the S1000 on A2 using 14SG on manual mode. The A2 LED does three violet flashes in repetition which we recently learnt is normal.
Now as the throttle is increased, the motors rev up nicely. And just as it seems it is about to take off, a continuous yellow/green (abnormal compass data) LED flashes.

We did the recalibration successfully and tried again - same result - (did that twice). The IMU is very firmly stuck to the platform.

Any advice would be greatly appreciated.

Thanks,
Ash
Click to expand...

Hmm, odd behaviour. If it only happens when you throttle up it could be vibrations getting through to the IMU. Do you notice any shakes in the frame/arms when you throttle up? ANd as above, check your IMU/GPS position in the assistant and make sure the figures are correct (it's chinese so everything is backwards).
 

A

Ash_K

Member
frozentobacco - thanks for the hint. I have had a look at the video, moved the battery to be more central and entered the figures in the A2 soft. It looks pretty centred now - not completely. I have not mounted the gimbal or camera (which could act as a counter-weight to the battery). The IMU offset is at -10cm along X and the GPS offset is -20cm along Z as I have used the longest stick which comes with the A2.

Benjamin Kenobi - indeed there seems to be a fair amount of vibration in the arms when throttling up. I have tried tightening the arms screw (within reason) with no effect. The IMU is firmly attached (i mean really firmly!) to the frame. Is there something I can do to reduce the vibration in the arms/frame?

We will try to fly it again during lunch and will post an update. Thanks a lot guys!
 
Last edited by a moderator:

A

Ash_K

Member
A quick addition - I have the following led sequence on the A2 IMU (the small LED) - '1 green, 2 red, 6 green, pause' (repeatedly) - no error reported on A2 software. Any clue as to what that indicates - I could not find anything on the A2 IMU LED sequences.
 

A

Ash_K

Member
Success!! Thanks guys!

The changes made to the setup (battery to be more central hanging off the battery tray on Velcro) and the configuration of the offset helped. The alert went away.

1. On manual, it was still behaving oddly - i.e. tipping over
2. On ATTI and GPS ATTI, we got it to take off and hover.

As it was very sensitive to joysticks, we did not venture into flying it away. We used an 80/20 config for Exp and Throttle gain.

Any suggestions about Throttle Gain/Exp curve on the 14SG would be appreciated to make the controls less sensitive?
 

F

frozentobacco

Member
Well done. Sensitivity can also be adjusted by tweaking the attitude settings in the DJI configuration panel. Try different levels of expo - start low and increase until you prefer the response.
 

A

Ash_K

Member
Thanks frozentobacco - I have mapped K1 and K2 onto the Attitude 'Pitch and Yaw' so I can experiment with the sensitivity. It's a bit windy today - will give it a go when things settle down.
 

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