Erratic Behavior

[Sarie]

Yesterday I took my V+ for a small flight with the children in our garden which is reasonably spacious, where it is enough for small children to play a soccer game. The bird powered up normally, calibrated equally good as always, I let it hover for a little while checked all the controls they are all working and the bird was responding accordingly. Although I noticed that it was trying to stay locked on position while hovering but I attributed that to slight wind factor that was around. The problem started when I tried to rotate the bird on its axis then that is when the bird started to drift sharply to the left and no matter what I do it was very difficult to control its direction, needless to say that I crashed to time but the bird in totality was fine, then I recalibrated it again and hovered on a height less than 6 feet, the same happened when I tried to rotate the bird sharp banks to the left where I eventually cut the power and made it drop to the ground. Needless to say that at times it was struggling to maintain a 3 foot hover immediately after launch.

Returned home last night, connected the bird to the computer and recalibrated everything and checked it had all the new firmware, needless to say it did not any calibration, except the IMU. I calibrated that as Basic and Advance, did not fly it since. Anyone has an idea as to what has happened? I am concerned that if I go out and fly it, I might have a flyaway?

Thanks in advance for reading and feedback.

Regards,
Sarie

 

[IrishSights]

It sounds to me that it did not have satellite lock and it then defaults to atti mode where it will drift in the wind. With gps lock it will stay within 1-2m when hovering. Can you confirm led sequence at start up and if it was in Phantom or Naza mode?
EDIT: or lost satellite lock after take off

 

[Sarie]

I did have satellite lock more than 7, the green lights were flashing steady throughout the flight. now according to the software it kept showing as if I do have more than 7 satellites, however, due to the erratic flight I lost focus on the software itself to monitor it as i was visually maintaining contact.

However, even on atti mode it was extremely difficult to control, however, your assumptions could be true since it was floating from side to side.

 

[crash1sttime]

At 6ft it may well have been fighting its own propwash or as irishSights says you didnt have a proper sat lock, i had a similar issue when i was out flying around a stately home, it kept losing sat lock (giving red light on rear) and drifting badly around, at one point i took it up to about 50ft and it settled fine and i had all green lights.

 

[Crazykaktus]

First off, how did you calibrate your compass ? and most importantly... WHERE ? If near aANY metal structures or power lines you have a bad reading and that will cause major issues to get GPS LOCK. Secondly if you have a bad compass reading you will get BAD GPS readings. When you try to get airborne, do you get GPS lock first or do you just go for it.... This can also cause this problem.

I would suggest doing a Compass calibration on an open field. Then go back and doing an ADVANCED IMU calibration as well. That should sort the issue. And ALWAYS ensure that you have at least 6 Satellites locked before going airborne

 

[crash1sttime]

and that will cause major issues to get GPS LOCK. Secondly if you have a bad compass reading you will get BAD GPS readings.

Really ? you can get a good GPS lock irregardless of whether or not the compass is calibrated, all that will happen is the quad wont be sure which way is North and will cause instability in hover (toilet bowl effect) and worst case a flyaway.

Also do an advanced IMU calibration first on a level surface, then go into an open area and let the quad warm (blinking green lights) up for at least 5 minutes, then flick the S1 switch up and down at least 6 times, the rear lights will go yellow, then do the compass calibration, remember its a 2 stage operation, turn 360 degrees until lights go green then point the nose down and turn 360 degrees until the lights flash green

 

[jason]

and that will cause major issues to get GPS LOCK. Secondly if you have a bad compass reading you will get BAD GPS readings.

Really ? you can get a good GPS lock irregardless of whether or not the compass is calibrated, all that will happen is the quad wont be sure which way is North and will cause instability in hover (toilet bowl effect) and worst case a flyaway.

Sorry but I disagree With statement regarding compass calibration. Whether you do the dance or not will not effect or cause instability in hover nor will it be the reason for flyaways. I for one do not calibrate the compass each time I change locations and as videographer I change locations often I do wait till GPS lock for home point but that it. So next time your out for a flight do not calibrate get home lock and switch to ATTI fly out 200m and switch it to FAILSAFE and see what happens next. Oh yes don't forget to clean the toilet bowl.

 

[Ohary]

I've noticed total erratic behavior as well.

I'm noticing instability (quick jogs to one side, then correction) and I'm also noticing a very hard drift whether in ATTI or GPS mode.

Something messing with it. I've tried this indoors as well and same issues. I also tried to calibrate. I'm thinking the NAZA is whack

 

[Buckaye]

and that will cause major issues to get GPS LOCK. Secondly if you have a bad compass reading you will get BAD GPS readings.

Really ? you can get a good GPS lock irregardless of whether or not the compass is calibrated, all that will happen is the quad wont be sure which way is North and will cause instability in hover (toilet bowl effect) and worst case a flyaway.

Sorry but I disagree With statement regarding compass calibration. Whether you do the dance or not will not effect or cause instability in hover nor will it be the reason for flyaways. I for one do not calibrate the compass each time I change locations and as videographer I change locations often I do wait till GPS lock for home point but that it. So next time your out for a flight do not calibrate get home lock and switch to ATTI fly out 200m and switch it to FAILSAFE and see what happens next. Oh yes don't forget to clean the toilet bowl.

Wow... I hate to say it... But you've just been blind lucky.

GPS provides the position on the planet
Compass provides orientation

Both are needed for successful navigation

Even DJI suggests if you see the toilet bowl behavior...to recalibrate.

I would suggest everyone defer to what the manual says about calibration rather than personal preference or even experience.

The instability in hover can happen if the phantom reads that you're drifting from a GPS position but doesn't know the correct orientation of the phantom.

The ONLY time GPS can determine orientation is if you are moving...

That said... In most cases... A calibration only needs to be done in rare circumstances.

DJI suggests doing a calibration when you travel to a completely different flying area... Some have suggested 50 miles (like me) some have suggested 100 miles.

 

[crash1sttime]

Im with you on that Buckaye

 

[jason]

Im with you on that Buckaye

Nothing ventured nothing gained. Just word in parting don't forget to clean that toilet bowl. LOL

 

[Mako79]

At 3 ft, you are suffering from what is called ground effects from its own propwash. At that height you will be suffering from gps loss especially if you have buildings and mountains blocking the horizon sats.

Before i did the foil mod, my phantom would try and drift with the wind everytime i tried to catch land. I wasnt looking at the screen to notice the phantom droppping sats and switching to atti.

 

[Ohary]

I've been flying Phantom 1 for about a year and Phantom 2 for about 6 months. Definitely a change in character which couldn't be explained by prop wash, trust me.

But I just noticed I'm having trouble calibrating. It won't lock. Any advice?

 

[Mako79]

I've been flying Phantom 1 for about a year and Phantom 2 for about 6 months. Definitely a change in character which couldn't be explained by prop wash, trust me.

But I just noticed I'm having trouble calibrating. It won't lock. Any advice?

After any bumps or crashes, it requires an adv imu. Make sure you this when the phantom has been resting for more than 30minutes. You need to do the calibration immediately when plugged in so the temp warning does NOT appear. Also do it on a surface that is levelled with the horizon.

 

[Ohary]

got a successful compass calib. Took her out for a test flight and all seemed normal! 90% sure it was the compass (although I did swap out my props back to stock.)

Still very difficult to calibrate compared to my P1 (takes about 5 tries).

Thanks for the help folks, and sorry to hijack this thread, just thought my experiences might help.

 

[ianwood]

GPS mode requires both a GPS fix (it's a fix, not a lock) and a working and well calibrated compass. A well calibrated IMU is required for both GPS and ATTI modes.

 

[jason]

GPS mode requires both a GPS fix (it's a fix, not a lock) and a working and well calibrated compass. A well calibrated IMU is required for both GPS and ATTI modes.

I check my setup weekly and recalibrate IMU once a month or after a crash when one occurs. Compass calibration is checked each time I discharge a battery but I do not do a dance each time fly nor when changing location which could several times in a day.

 

[Buckaye]

GPS mode requires both a GPS fix (it's a fix, not a lock) and a working and well calibrated compass. A well calibrated IMU is required for both GPS and ATTI modes.

I check my setup weekly and recalibrate IMU once a month or after a crash when one occurs. Compass calibration is checked each time I discharge a battery but I do not do a dance each time fly nor when changing location which could several times in a day.

To be clear... I don't think anyone is telling you you have to calibrate every time you change location.... DJI has a comment that they suggest you calibrate when in a completely different flying location which seems to mean if you suspect a big magnetic difference in the situation or based on being quite a distance away (some suggest 50 or mores some suggest 100 or more miles).

I think what we're all saying is that you need both a good GPS position and good compass orientation to get the best flight result.

The fact that you are getting great results in the way your working with the Phantom is great... And probably nothing wrong with it. But...if your start seeing erratic behavior (which this thread is about) a compass calibration may help clear that up.

 

[jason]

GPS mode requires both a GPS fix (it's a fix, not a lock) and a working and well calibrated compass. A well calibrated IMU is required for both GPS and ATTI modes.

I check my setup weekly and recalibrate IMU once a month or after a crash when one occurs. Compass calibration is checked each time I discharge a battery but I do not do a dance each time fly nor when changing location which could several times in a day.

To be clear... I don't think anyone is telling you you have to calibrate every time you change location.... DJI has a comment that they suggest you calibrate when in a completely different flying location which seems to mean if you suspect a big magnetic difference in the situation or based on being quite a distance away (some suggest 50 or mores some suggest 100 or more miles).

I think what we're all saying is that you need both a good GPS position and good compass orientation to get the best flight result.

The fact that you are getting great results in the way your working with the Phantom is great... And probably nothing wrong with it. But...if your start seeing erratic behavior (which this thread is about) a compass calibration may help clear that up.

While removing, checking antenna for damage, rerouting cable under copper shield and testing the GPS module I noticed a diamond shaped icon flashing at the bottom of my monitor. That flashing icon is a warning to calibrate the compass and is function of the mini iOSD module. Now it's the first time that warning in all the months of flying and changing locations has come on indicating a need to re-calibrate. Once that was done to be on the safe side I also re-calibrated the IMU.