New spark - calibration question

[tvon]

Hey all - Got my new Spark this week and went out for my first test flight. All went well, I kept it low and slow. But one curious thing, was never prompted to calibrate my IMU or Compass. This is brand new out of the box Spark.. I did get prompted for firmware updates however. It seemed to work fine but is there any reason to force any of these calibrations? Seems like the rule of thumb is to not calibrate unless prompted. Thanks

 

[DesertWindAero]

I didn't calibrate either out of the box. I haven't been prompted to perform either calibration yet. Hundreds of flights, no problems.

 

[kentlim26]

when you spark near to metal object and sense it. it will automatically prom you to do compass calibration .which my always ask me to do so

 

[msinger]

But one curious thing, was never prompted to calibrate my IMU or Compass.

That's normal.

is there any reason to force any of these calibrations?

The majority of Spark owners are probably not calibrating the compass before their first flight. I always calibrate the compass when unboxing any new DJI drone -- just so I know for sure the calibration is good.

Seems like the rule of thumb is to not calibrate unless prompted.

The Spark will rarely prompt you to calibrate when it's really needed. Check out the Compass Calibration Guide for the best advice on when you should and should not calibrate the compass.

 

[VETTE198620002000]

I was prompted once on my spark to calibrate my compass once, but on my mavic i forced the calibration of the "imu" because it was drifting and it fixed the issue.

 

[tvon]

Thanks for the replies. As you can see, this is why i'm asking. Several different schools of thought here. Will check out the guide and probably do both

 

[sdharris]

when you spark near to metal object and sense it. it will automatically prom you to do compass calibration .which my always ask me to do so

Important point there is to move away from the metal object and retry. Calibrating near a metal object will simply lead to a bad calibration and potential flight problems.

If it helps the original poster I have not calibrated the IMU or compass on my Spark since receiving it and I have travelled from the UK to Spain with it. Back a couple of years ago DJI products needed more frequent calibrations but now that they are more sophisticated its not required unless prompted by the app or you notice flight issues.

Calibrating often just raises the risk of a bad calibration.

 

[msinger]

Calibrating near a metal object will simply lead to a bad calibration and potential flight problems.

Calibrating near a magnetic metal object should only lead to a failed compass calibration (not a bad stored compass calibration). Taking off near a magnetic metal object often leads to erratic flight behavior.

 

[sdharris]

Calibrating near a magnetic metal object should only lead to a failed compass calibration (not a bad stored compass calibration). Taking off near a magnetic metal object often leads to erratic flight behavior.

No, not always, I calibrated a P3 Pro once because it prompted, got it up in the air and it had compass issues and was a real wild wide to bring down and land. Turned out there was rebar in the concrete I was standing on which led to a poor calibration. Hence my advice to always look around the area if you get a compass warning rather than calibrate as you could save yourself some white knuckles.

I think a single compass craft is always vulnerable to problems like this so don't overdo it, there is a reason the manuals say to stand well away from metal objects as the software is only so good.

 

[msinger]

No, not always, I calibrated a P3 Pro once because it prompted, got it up in the air and it had compass issues and was a real wild wide to bring down and land. Turned out there was rebar in the concrete I was standing on which led to a poor calibration. Hence my advice to always look around the area if you get a compass warning rather than calibrate as you could save yourself some white knuckles.

Your issue was most likely only caused by taking off near the rebar (not the compass calibration itself). I reviewed hundreds of flight logs over at Phantom Pilots. Nobody has ever posted a flight log that showed a compass calibration successfully performed near a magnetic metal object. If you still have that DAT flight log, you should post it over there. You'll be an absolute star for sharing that data (if what you say is true).

 

[sdharris]

Your issue was most likely only caused by taking off near the rebar (not the compass calibration itself). I reviewed hundreds of flight logs over at Phantom Pilots. Nobody has ever posted a flight log that showed a compass calibration successfully performed near a magnetic metal object. If you still have that DAT flight log, you should post it over there. You'll be an absolute star for sharing that data (if what you say is true).

Unfortunately I don't have the P3 anymore, wish I did it was a great craft.

But it is true, and don't really need to prove it, I mean running a site does not make a person an expert ;-) and I am not saying it flew away or crashed and its all DJIs fault. I am saying when a craft takes off fine near rebar, then gets 50 foot in the air and loses compass it means the crafts compass calibration was influenced by the rebar and what was normal, was no longer normal when it moved far enough away from the rebar.

 

[msinger]

I am saying when a craft takes off fine near rebar, then gets 50 foot in the air and loses compass it means the crafts compass calibration was influenced by the rebar and what was normal, was no longer normal when it moved far enough away from the rebar.

It really just means the compass was influenced by the magnetic metal object. The problem itself has nothing to do with a bad stored compass calibration. I would never dare to say something is impossible -- but, such an event has never been proven with data before.

Claiming something extraordinary happened without proof is not very credible. Unless you can prove it happened, it's probably not a good idea to promote incorrect information.

 

[sdharris]

Claiming something extraordinary happened without proof is not very credible. Unless you can prove it happened, it's probably not a good idea to promote incorrect information.

Sorry, but you do the same. For example...

The Spark will rarely prompt you to calibrate when it's really needed. Check out the Compass Calibration Guide for the best advice on when you should and should not calibrate the compass.

When the manual clearly states:-

Calibrating the Compass

Only calibrate the compass when the DJI GO 4 app or the status indicator prompt you to do so. Observe

the following rules when calibrating your compass:

DO NOT calibrate your compass where there is a chance of strong magnetic interference, such

as near magnetite, parking structures, or steel reinforcements underground.

DO NOT carry ferromagnetic materials with you during calibration such as cellular phones.


The DJI GO 4 app will notify you if the compass is afected by strong interference after calibration is

complete. Follow the prompts to resolve the compass issue ​

So you need to be careful here. I gave an example of when I calibrated a compass near a strong source of magnetic interference and that it actually resulted in poor flight characteristics, a fact supported by the manual from DJI and in an earlier comment that you should not calibrate a compass unless prompted, again supported by the manufacturer. You disagree which is fine, its a forum, if you want facts go read the manual and the FAQ. People want experiences right?

Sorry fella, but don't say I am quoting incorrect information when I am actually quoting from the manual and real life experience. Lets draw a line under this one.

 

[BudWalker]

.....

But it is true, and don't really need to prove it,

This is a common perspective when people are making the argument that calibrating in a bad spot will yield a calibration valid for that location but then invalid away from that spot. Some have even stated that it's true because that's what causes these incidents. This perspective has been repeated so many times that pilots believe that it just has to be true. It's then re-repeated, often with capital letters, causing even more pilots to assume that it has to be true.

I am saying when a craft takes off fine near rebar, then gets 50 foot in the air and loses compass it means the crafts compass calibration was influenced by the rebar and what was normal, was no longer normal when it moved far enough away from the rebar.

A calibration can only detect and then compensate for magnetic effects that rotate with the AC. A calibration does not and can not compensate for magnetic effects external to the AC. It's mathematically impossible. Although external magnetic effects can be sensed the data from them is effectively ambiguous - this is the reason compensating for external effects is impossible.

I've looked in depth at literally dozens of incidents like what you've described. By in depth I mean data, i.e. actual numbers. In every case the cause of the incident was launching from a geomagnetically distorted site - not a flawed compass calibration.
If you're interested here are a couple of incidents where this happened.

Compass error
Looking for Trouble ??

I've also attempted to get data, or at least some compelling evidence, about incidents where it's claimed that calibrating in a geomagnetically distorted location was the cause of the incident. In some of these incidents the .DAT was available - in a few the .DAT for several previous flights were also available. In each of these the last calibration was many flights prior demonstrating the calibration was not the issue.

I think part of the reason for the bad-calibration-causes-incident misconception is that it's easy to confuse the symptoms with what happens when the AC is launched from a geomagnetically distorted site. There is one crucial difference though. In a launch-from-a-geomagnetically-distorted-site incident the Yaw value is incorrect at launch. That would not be the case with a bad-calibration-causes-incident if you believe the compass is OK at launch because it's been calibrated at the launch site. You don't need the .DAT for this - the .txt and the pilots recollection can determine if YAW was incorrect.

@msinger

 

[tvon]

I ended up calibrating both. Did the IMU indoors on level ground, and the compass out in the middle of a large field. Checked the levels in the menu, all seem solid in green territory. No erratic behavior so far. Did a flight from a field made out of astro turf as well. Was worried about possible metal under the field but no issues.

 

[VETTE198620002000]

Cool the "imu" normally is the first thing i would have done before messing with the stick calibration. glad it worked out for you

 

[enri68]

when you spark near to metal object and sense it. it will automatically prom you to do compass calibration .which my always ask me to do so

move the aircraft to another spot...couple of meters are enough usually