TMGsi

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Circling positionHold
« on: November 05, 2020, 01:23:45 pm »
Circling positionhold.

I am not managing to make the positionhold acceptable.
The drone when I activate the positionhold is circulating. consequently rtb is kind of weird.

I've done the calibration of the compass and the gps naza is only with the auxiliary compass.

I only calibrate the compass, I don't make any adjustments. (all values on the x, y and z axes are at zero. Do I need to have any value to stop circulation?)

I need a tip to be able to end this positionhold circling.
Sometimes the positionhold is good, but there are few.

Thanks.

TMGsi

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Re: Circling positionHold
« Reply #1 on: November 05, 2020, 06:33:45 pm »
I ask the patience of the members of the group.
This problem of mine seems to have been answered in another topic of mine. (about another problem)

The only alternative I have not yet done is to braid the esc power wires. In the meantime, I put a post about 20cm over the fc and the fc about 7 cm from the pdb. That is, the gps is above the engine wires about 27cm.

But both are all in the middle of the drone, (I think that may be the problem)

TMGsi

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Re: Circling positionHold
« Reply #2 on: November 05, 2020, 06:35:21 pm »
Could someone with a well-regulated drone show me a picture of their setup and how the engine wires looked?

jdl

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Re: Circling positionHold
« Reply #3 on: November 05, 2020, 09:54:24 pm »
I guess you're talking about the so-called "toilet bowl", not exactly circling...

MAGs should be really well calibrated, please search the forum and Librepilot documentation; preferred calibration procedures and lot of helpful info / advices there...

In short, best practice is to use Oplink for wireless communication with the PC durung the calibration procedure, not USB cable. Live Oplink telemetry would also help to observe MAG status / alarms during actual flight.

Reset the Home Location before calibration start. Do it outdoors, far away from any metallic objects / structures, including underground pipes, power lines, etc. I have a favourite spot far away from the city, in the fields, where I do always achieve successful MAGs calibrations. Althougt this is a little bit extreme... ;)

27cm separation should be more than enough, at least according my experience. 15-20 cm should already be fine...

Quote
Could someone with a well-regulated drone show me a picture of their setup and how the engine wires looked?

https://forum.librepilot.org/index.php?topic=4889.msg32749#msg32749

The quad flies stable in autonomous modes, incl. PositionHold. The only issue (in all my autonomous quads when doing PH) are the fast tiny oscillations you have mentioned in your other topic, they seem not be MAGs related...

AuxMag is no more than 4-5cm away from power lines, even when current drawn exceeds 80-90A during throttle bursts there are not red MAG alarms in the telemetry log. Twisting the cables does the job!

TMGsi

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Re: Circling positionHold
« Reply #4 on: November 06, 2020, 12:10:32 am »


Quote
Could someone with a well-regulated drone show me a picture of their setup and how the engine wires looked?

https://forum.librepilot.org/index.php?topic=4889.msg32749#msg32749



you chose a GPS without a compass, do you think a compass outside GPS is better?  another question.  does esc dshot protocol work with FC Revolution?  in mine i just had the oneshot to choose from.  does FC revolution store flight information for later viewing?  what a good setup this yours.  good flights.

jdl

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Re: Circling positionHold
« Reply #5 on: November 06, 2020, 07:52:01 am »
Thanks! :)

Separate GPS & Compass are for saving weihgt and space. I've used in the past Beitian BN-880 with great success but it's heavier and bulkier than BN-200 GPS (approx. 5gr) and GY-273 Mag (approx. 1gr.). BN-880 also didn't support Galileo (not that a big deal) once I've used it. And separate setup also allows for more flexible compass positioning.

The 4-in-1 ESC I've used in this particular setup works very well with DSHOT1200. With current "next "Librepilot Revo firmware this is the useable DSHOT speed! Setting to lower speeds (600,300, etc.) intruduces some issues. I believe this is going to be fixed. Beware that DSHOT1200 requires really short wires between FC and ESC, maybe 5-7cm. I would not use DSHOT1200 is ESCs are on the arms of the quad, distance is much longer... Oneshot125 is a pretty good choice.

AFAIK, Revo does not support logginig flight information locally ("blackbox" like). Flight information is viewable and recordable on PC / Android phone through Oplink telemetry.

Btw, you should also check if your Auxmag (mounted on the mast) is well aligned with the Revo FC, and not rotating during flight! Even relatively small misalignments can lead to the "toilet bowl" behavior.


Re: Circling positionHold
« Reply #6 on: November 06, 2020, 09:17:20 am »
16.09 supports OneShot* MultiShot

Next adds DShot, but there appears to be issues with it and I recommend you avoid it.
https://forum.librepilot.org/index.php?topic=4883.msg32723#msg32723

I use PwmSync or [email protected] and there is very little reason to bother with the highest speed protocols.

"Toilet bowl" is often caused by mag problems such as poorly routed poorly twisted motor cables, bad mag calibration, using USB for mag calibration without degaussing the USB plug, putting the drone down on ground or metal between the 6 mag cal steps, etc.

TMGsi

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Re: Circling positionHold
« Reply #7 on: November 06, 2020, 10:58:30 am »
Thanks! :)

Btw, you should also check if your Auxmag (mounted on the mast) is well aligned with the Revo FC, and not rotating during flight! Even relatively small misalignments can lead to the "toilet bowl" behavior.

How to check if it is aligned? Only visually? (I think it's aligned, but visually)

Or check in another way? do not know.

(I had given up on having the compass on my osd, but when you see your video, you have no crazy compass problem on osd. What did you do?) You have the same micro minimosd as me. What is your osd firmware?

TMGsi

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Re: Circling positionHold
« Reply #8 on: November 06, 2020, 11:08:55 am »

"Toilet bowl" is often caused by mag problems such as poorly routed poorly twisted motor cables, bad mag calibration, using USB for mag calibration without degaussing the USB plug, putting the drone down on ground or metal between the 6 mag cal steps, etc.

I have a physical compass, with it I can see where I have trouble with the compass.

On the drone, I calibrate the compass on a wooden table, and my physical compass revealed that there is nothing interfering there.
(but it is inside the house) I will change places for a test, I will calibrate outside the house and also find a place where the physical compass shows a place without disturbance.

If you don't stop with this "toilet bowl", I'll rewire the engine. Leave them WELL wrapped up.

Re: Circling positionHold
« Reply #9 on: November 08, 2020, 04:39:40 am »
Mag calibrations are probably good if running INS13 mag health is green and compass heading in GCS matches correct direction of north and health stays green (or yellow) with flight power to motors (props on).

TMGsi

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Re: Circling positionHold
« Reply #10 on: November 08, 2020, 10:23:04 am »
I'm not able to do the thermal calibration.
  I've tried it several times and it doesn't end successfully. 

what can i be doing wrong? 
this calibration I never did.

TMGsi

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Re: Circling positionHold
« Reply #11 on: November 08, 2020, 10:30:31 am »
a doubt.

 I don't have the oplink, so if the flying compass turns red, the osd will show "critical compass"?

  before, did this message appear before starting the engines, but in flight?

 this message never came up again after I am doing the calibration correctly.

TMGsi

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Re: Circling positionHold
« Reply #12 on: November 08, 2020, 11:00:01 am »
I have more doubts.

 when the rtb is triggered ( by the radio switch or by loss of signal) it starts the rtb normally, but the direction of the drone does not change, that is, it flies backwards (I know I could give the yaw command at that moment  to turn it around) would there be a way to change that, so when entering the rtb he turns himself to where the gps marked his takeoff point before going to his destination? 

and the other doubts. 

would it be possible to calibrate the compass with the radio stick command?  without usb cable or oplink?

Re: Circling positionHold
« Reply #13 on: November 09, 2020, 01:23:59 am »
I'm not able to do the thermal calibration.
  I've tried it several times and it doesn't end successfully. 
what can i be doing wrong? 
this calibration I never did.
Remove FC from drone.  Put it in plastic baggie in freezer for 5-10 minutes, not longer.  Remove from freezer but leave FC in baggie.  Plug in USB cable, place baggie, then some folded cloth and small weight (not metal) on table (not metal) on top of baggie and quickly begin the thermal calibration.  Weight holds it so it does not move during long (many minutes maybe) calibration.  Do not bump table or make shaking foot steps during calibration.

Things I do, but not really necessary:
Because my FC has seen 75C in summer time in dome on pavement, I extend my calibration to hot temperature by putting FC and cloth and weight in a cardboard shoe box with a hot light bulb (like 60W incandescent) underneath.  When calibration says it gets up above 60C or so I unplug the hot light and a few minutes later the calibration sees that it is not getting hotter and stops automatically.

a doubt.
 I don't have the oplink, so if the flying compass turns red, the osd will show "critical compass"?
  before, did this message appear before starting the engines, but in flight?
 this message never came up again after I am doing the calibration correctly.
I have no idea about OSD showing "critical compass".  Big problem is when it is OK on ground, but mag health goes red with the high current of flight power.  Second bit problem is when mag cal is not done well for reasons listed elsewhere in this post.

I have more doubts.
 when the rtb is triggered ( by the radio switch or by loss of signal) it starts the rtb normally, but the direction of the drone does not change, that is, it flies backwards (I know I could give the yaw command at that moment  to turn it around) would there be a way to change that, so when entering the rtb he turns himself to where the gps marked his takeoff point before going to his destination? 
This is by design so that when flying to Base or some Waypoint, you can turn it and look with FPV.
There is a setting in System->Settings->VtolPathFollowerSettings called YawControl which you can change to PathDirection.  I think this changes what you want.

and the other doubts. 
would it be possible to calibrate the compass with the radio stick command?  without usb cable or oplink?
No.  Not without someone writing code to do this; but here are some thoughts.

Mag calibration, you should:
- do calibration outdoors, away from metal (buildings, tanks, cars, etc.) but I have done it inside wooden home...
- never put model down on ground or metal anything once you have started because it is actually always recording.

I have done it with USB cable, but I degaussed (demagnetized) the USB cable end and used flight battery / ESC power at 5.5 to 6 volts (more than USB power) to make sure it used ESC power and not USB power and used a 3 meter USB cable with a laptop all outdoors.

An interesting experiment for someone who has OpLink telemetry would be:
- with model and FC clamped firmly to table and using flight battery power and no USB plugged in
- use OpLink telemetry to view mag scope and compass
- plug in USB cable to USB charger, not computer so telemetry does not change from OpLink to USB
- plug in other end of USB cable to FC, then look at mag scopes and compass to see how much it changed

jdl

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Re: Circling positionHold
« Reply #14 on: November 09, 2020, 10:51:47 am »

How to check if it is aligned? Only visually? (I think it's aligned, but visually)

Or check in another way? do not know.

(I had given up on having the compass on my osd, but when you see your video, you have no crazy compass problem on osd. What did you do?) You have the same micro minimosd as me. What is your osd firmware?

Visual alignment should be enough. But you might also want to check how is the mag chip (L883 / DA5883 markings) on the PCB inside the GPS/MAG plastic enclosure positioned (oriented).

I'm using a modified MinimOpOsd firmware. Some features were discarded to free space and I've coded new ones that I felt being more useful. I've always intended to make it available to LP community, and I plan to do this in near future. What stopped me till now was that the default OSD Config Tool 2.1.3.0 is not really compatible with it. Charset differs, some fields have totally different layout and meanings.
I've recently had some free time and dedicated it to match the OSD Config Tool to my firmware. I'm almost at the final, and hope in a week or two to upload the new config tool, charset file and MinimOpOSD hex files (for RevoFC) for quadcopter and plane use. There is also a version dedicated to quadcopter (w/ CC3D) use, with voltage sensor connected to MinimOSD.


Quote
a doubt.

 I don't have the oplink, so if the flying compass turns red, the osd will show "critical compass"?

  before, did this message appear before starting the engines, but in flight?

 this message never came up again after I am doing the calibration correctly.

If I recall right, the original MinimOpOsd firmware shows "MAG CRITICAL" only while FC is not armed. Not in flight. My version does the same. This could be easily changed but I feel having MAG alarms during fligh to be impractical.

If you don't have an Oplink, you may probably use a separate HC-05/HC-06 Bluetooth module onboard and route the telemetry through it.

https://librepilot.atlassian.net/wiki/spaces/LPDOC/pages/10354702/Setup+a+bluetooth+for+telemetry