LibrePilot Forum
General Category => General Discussion => Topic started by: Pertti on November 20, 2016, 01:33:53 pm
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Does VelocityRoam need also GPSAssist?
My flight mode switch settings:
-Flight mode: VelocityRoam
-Assisted control: None
-If Assisted control is "GPSAssist", what different does it make?
I managed to hold my drone in position hold very well, but then next day something happened and it started drifting. Also arming is impossible if Assisted control is "GPSAssist" togerther with VelocityRoam or PositionHold .
I use internal mag and UBlox GPS. Health boxes are green.
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Does VelocityRoam need also GPSAssist?
No,
GPSAssist make sense only for primary stabilization modes like Attitude.
Why add a GPSAssist tag to a flight mode already using GPS ?
https://librepilot.atlassian.net/wiki/display/LPDOC/Gps+assist
Be sure the Mag alarm still ok while motors are running and drawn current.
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No, GPS Assist just turns on "GPS PositionHold" if the sticks are centered. VelocityRoam already does exactly that.
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Ok, GPSAssist is now clear to me, thank's for that.
But when switching to VelocityRoam the drone starts moving and must be immediately switched back to Stabilized. As if REVO had a different board levelling parameter set for roaming and stabilized modes. Board levelling calibration has no effect. Should I change board rotation parameters?
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Board rotation or board leveling should be the same, while flying using a primary stabilized mode or gps modes.
What do you mean with "starts moving" ?
Most common issue is magnetometer disturbed with high motors currents around that causes a wrong heading measurement.
With wrong heading the position error is corrected in a wrong direction and result in a "toilet bowling", a increasing circular trajectory around the expected position.
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Do your mags stay green even when hovering?
Did you make strange adjustments to mag orientation? Generally (at least to start with) this should always be multiples of 90 degrees.
Did you wait 15 minutes before first takeoff for GPS to download almanac?
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I have not measured mags when hovering, only in the house. It's winter here...maybe I try when it's warmer.
- GPS fix is ok, more than 7 satellites,it takes usually 10-15 minutes
- "starts moving" means a sudden increase in pitch when switching to VelocityRoam and the following increasing speed. Not enough control to stop the moving.
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Are you using aux mag only (Mag Usage: AuxOnly) (that works best).
What is your AuxMagSettings.BoardRotation / Attitude->Magnetometer->AuxiliaryMagnetometerOrientation
for OP GPSv9 and DJI/Naza GPS/mag it should be 0,0,0
for PixHawk and APM GPS/mag if should be 0,180,0 (or 180,0,180 which is the same thing)
Are you using INS13 (Attitude->Settings->AttitudeEstimationAlgorithm).
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...I use internal mag and UBlox GPS....
Unless you have a large quadcopter like a 450 or larger an internal mag is unlikely to work well. On smaller quads it's almost impossible to avoid the magnetic field from the power wires. That's why the external mags were created.
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@ theothercliff
I had to set my naza gps 0 , 0 , 180 to get all zeros.
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Sounds like you have it mounted with the arrow pointing backwards. :) In that case, the 180 yaw is fine.
It is confusing that the cable comes out the front of this GPS.
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I had several frames, this frame weights 34 grams and the whole drone 410 grams. The actioncam Sjcam M20 is placed in the front because it makes the onboard mag go crazy. Also the powerwires are drawn ast far from the fc as possible.
This configuration seems to work properly.
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Are you flying in the house with a GPS mode? I have never tried that because I assume it does not work. I would try it outdoors to see if that helps.
I see an antenna (FPV) close to the GPS. Switch that off. Switch off telemetry. Leave the camera unpowered. Try to fly outdoors. If that works, then you just narrow it down to what causes the problem.
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I have not tried to fly GPS in the house yet. How to switch off telemetry? I will test it but now it is - 10 ºC outdoors.
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Telemetry is off by default. If you don't have an OpLink on your GCS, you don't have telemetry.
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Now I moved the antenna forward and removed the camera. That improved the GPS hold performance.
Howering was accurate, vertically less than 0.3 meters and horizontally less than 1 meter.
Now the telemetry is on. If I put 0 mW power to the transmitter , does it switch it off? I don't want to destroy the transmitter by removing the antenna.
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Yes if you put 0w to the transmitter its off. But save first and then power off your board. I think its still powered on if you only hit save without restarting the board...
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Sounds like you have it mounted with the arrow pointing backwards. :) In that case, the 180 yaw is fine.
It is confusing that the cable comes out the front of this GPS.
Is this also the case with the Ubox? I couldn't get mine to calibrate until I set the offsets to 180,0,180. The drone now hovers precisely over the same spot but seems to vary altitude allot. I have only had three test flights. On two of them the drone veered off violently after about 10 minutes of stable flight in hover. Could this be a voltage issue (Approx 10.5 volts 3S battery)?
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I couldn't get mine to calibrate until I set the offsets to 180,0,180.
There is no relation between AuxMag orientation and correct calibration.
When you do the Mag calibration you need to need to cover all the 3D space while rotating the frame, whatever the AuxMag orientation.
Can you post your config file ? File > Export UAV Settings
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I couldn't get mine to calibrate until I set the offsets to 180,0,180.
There is no relation between AuxMag orientation and correct calibration.
When you do the Mag calibration you need to need to cover all the 3D space while rotating the frame, whatever the AuxMag orientation.
Can you post your config file ? File > Export UAV Settings
Thank you for helping out, are these the data you requested?
Regards,
Robert
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Your settings looks good.
Maybe a GPS glitch occurred.
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Thank you for taking a look, I'm hoping to fly again tomorrow. Hopefully we won't crash.
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Take a look here (https://forum.librepilot.org/index.php?topic=1202.msg15524#msg15524)
And change the GPSSettings > UbxDynamicModel to AirBorne4G using UAVOBrowser
Save settings using the button with a red arrow.
(https://forum.librepilot.org/index.php?action=dlattach;topic=2649.0;attach=6916)
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OP Platinum GPS (the one with mag included) and DJI both use aux mag orientation = 0,0,0 if the arrow on the GPS is correctly pointing forward. Note that the arrow does not always match where the cable comes out of the GPS. For instance, authentic DJI GPS has arrow on same side as cable which seems backwards, but is actually a good thing if you think about it.
uBlox GPS with aux mag usually needs aux mag orientation = 180,0,180 = 0,180,0 if the arrow on the GPS is correctly pointing forward.
If arrow on GPS points some other way, you need to adjust orientation numbers (only the last number of the 3).
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Take a look here (https://forum.librepilot.org/index.php?topic=1202.msg15524#msg15524)
And change the GPSSettings > UbxDynamicModel to AirBorne4G using UAVOBrowser
Save settings using the button with a red arrow.
(https://forum.librepilot.org/index.php?action=dlattach;topic=2649.0;attach=6916)
That is really interesting as both times that I experienced the issue I was in the proximity of buildings. The first time was in front of a large metal barn and the second was in my enclosed back garden. The time i didn't have an issue was in an open field. I will experiment with the settings and report back
Thanks again,
Rob
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OP Platinum GPS (the one with mag included) and DJI both use aux mag orientation = 0,0,0 if the arrow on the GPS is correctly pointing forward. Note that the arrow does not always match where the cable comes out of the GPS. For instance, authentic DJI GPS has arrow on same side as cable which seems backwards, but is actually a good thing if you think about it.
uBlox GPS with aux mag usually needs aux mag orientation = 180,0,180 = 0,180,0 if the arrow on the GPS is correctly pointing forward.
If arrow on GPS points some other way, you need to adjust orientation numbers (only the last number of the 3).
Thank you cliff,
You have confirmed my configuration so one less thing to worry about.
Best regards
Rob
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That is really interesting as both times that I experienced the issue I was in the proximity of buildings. The first time was in front of a large metal barn and the second was in my enclosed back garden. The time i didn't have an issue was in an open field. I will experiment with the settings and report back
It is a known issue that GPS's have problems in situations like that. It helps somewhat to let the GPS "warm up" (download almanac) out in the open for 15 minutes before the first flight of the day. After that, you can get away with a much shorter (3 minutes?) warm up.
It's far better to avoid flying near buildings, especially those with metal roofs. I fly in my back yard (non-metal roof). I generally don't get so close to a building that the (non-metal) roof top is 45 degrees or higher above the horizon. Between two buildings I would avoid places where the roofs were more than 30 degrees above the horizon. I completely avoid metal roofs (100m away from a typical metal barn roof).
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That is really interesting as both times that I experienced the issue I was in the proximity of buildings. The first time was in front of a large metal barn and the second was in my enclosed back garden. The time i didn't have an issue was in an open field. I will experiment with the settings and report back
It is a known issue that GPS's have problems in situations like that. It helps somewhat to let the GPS "warm up" (download almanac) out in the open for 15 minutes before the first flight of the day. After that, you can get away with a much shorter (3 minutes?) warm up.
It's far better to avoid flying near buildings, especially those with metal roofs. I fly in my back yard (non-metal roof). I generally don't get so close to a building that the (non-metal) roof top is 45 degrees or higher above the horizon. Between two buildings I would avoid places where the roofs were more than 30 degrees above the horizon. I completely avoid metal roofs (100m away from a typical metal barn roof).
I took it out yesterday but there was an issue with the GPS being recognised. I stripped everything down tonight and checked the connections. I couldn't find any issues but its working OK now. I probably won't get to fly until the weekend, weather permitting.
Thanks again for all the help.
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Thanks for your help everyone, I flew today and no issues.
I am getting some strange behaviour when the 3S lipo gets down to around 10v but no uncontrolled fly aways.
Thanks again.
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Two things:
#1 and most important, don't fly a 3S lipo down to 10 volts. 3.5 per cell on the lowest cell is bare minimum and that is only if you have an alarm that reads individual cell voltages, not just total voltage. If you over discharge a lipo a few times it gets bad, then worse and worse.
#2 is that when a multicopter gets close to "barely able to stay in the air" it does bad things because it cannot stabilize if all motors must run 100% just to stay in the air.
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Two things:
#1 and most important, don't fly a 3S lipo down to 10 volts. 3.5 per cell on the lowest cell is bare minimum and that is only if you have an alarm that reads individual cell voltages, not just total voltage. If you over discharge a lipo a few times it gets bad, then worse and worse.
#2 is that when a multicopter gets close to "barely able to stay in the air" it does bad things because it cannot stabilize if all motors must run 100% just to stay in the air.
Thanks Cliff,
I appreciate your advice. I do have a balance plug alarm which is set at 3.6v/cell load voltage (first cell to hit 3.6). Off load is about 4.0v. I keep an eye on the voltage monitor on my transmitter which monitors the total cell voltage,this is 10.x as I'm just using it as a guide of the rate of discharge and don't regard it to be accurate. What minimum load voltage/cell do you fly too?
I did some research before setting the alarm but there is alot of conflicting information. I guess its prudent to err on the side of caution.
Thanks again for your help,
Rob
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What minimum load voltage/cell do you fly to?
Generally 3.6v alarm under load.
It depends on the battery and load (old battery or high load = more voltage drop with load, so maybe alarm at 3.5v), the time of day (last flight I fly down to storage voltage, other flights I may discharge more) and even whether the battery gives so much flight time that I don't want to squeeze the most out (then it is only down to storage voltage).
Generally after voltage recovery after the flight I like to see at least 3.6v and usually 3.7v
For a very light load like fixed wing FPV cruising locally I may set it higher to 3.7v
Battery specs usually say never go below 3.3v and I take that to mean under load.
ESCs that have Low Voltage Cutoff the highest voltage is usually 3.3v which I consider to be about useless.