GPS LOST : FLYAWAY

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Everyone is nice to be still with you. With the last flight I returned from a terrible cliff. I take off with 10 satellites as it was all right. I gave the command to go back to the solo because of the 40% battery and the risk of approaching cloud and the angle of sight falling. On his way home control also "LOST GPS" warning with the way everything turned out. 0 on the application screen and a fast drift with a terrible hdop value. I do not know how to analyze the logs. I have a hard time recognizing what caused Flyaway. I do not know if it could be an effect of being in the cloud. High vibration, imu error ...

Obviously a very blurry photo. Maybe somebody's diagnosed right. 3DR Solo Rev B Gps Gopro

Hero 4 Black M.A.S Propeller

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log file: Uploadfiles.io - sololog.rar
 
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I agree with BillHally101. What you experienced was not a "flyaway". According to your video, at the moment that your Solo realized that its GPS Lock was lost, your Solo did exactly what it's supposed to do, namely, kept doing exactly what it had been doing, which is why it kept flying in more or less the same direction & speed. In a real "flyaway" the drone THINKS that it DOES know where it is, but is wrong, and goes speeding away to get to the "correct" location which is usually determined by Murphy's Law.

Gentle suggestion: Never fly a drone above or through clouds (or fog, which is just a low-flying cloud). It's illegal to fly a manned aircraft without radar into a cloud for obvious reasons, so it makes sense to keep drones far from clouds too. Flying above a cloud is VERY tempting (it's so beautiful up there!) but what goes up must come down, and cloud boundaries change unpredictably, so don't. My brother and I got stuck in a Cessna 150 above a sudddenly-appearing and rapidly-expanding cloud bank just north of Chicago one winter, and we were forced to descend THROUGH it. Illegal and scary as hell. Thank goodness we had good luck and a "carb heat" switch. But I digress. Avoid clouds.
 
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I agree with BillHally101. What you experienced was not a "flyaway". According to your video, at the moment that your Solo realized that its GPS Lock was lost, your Solo did exactly what it's supposed to do, namely, kept doing exactly what it had been doing, which is why it kept flying in more or less the same direction & speed. In a real "flyaway" the drone THINKS that it DOES know where it is, but is wrong, and goes speeding away to get to the "correct" location which is usually determined by Murphy's Law.

Gentle suggestion: Never fly a drone above or through clouds (or fog, which is just a low-flying cloud). It's illegal to fly a manned aircraft without radar into a cloud for obvious reasons, so it makes sense to keep drones far from clouds too. Flying above a cloud is VERY tempting (it's so beautiful up there!) but what goes up must come down, and cloud boundaries change unpredictably, so don't. My brother and I got stuck in a Cessna 150 above a sudddenly-appearing and rapidly-expanding cloud bank just north of Chicago one winter, and we were forced to descend THROUGH it. Illegal and scary as hell. Thank goodness we had good luck and a "carb heat" switch. But I digress. Avoid clouds.


Thank you @Joe Horn.

"and cloud boundaries change unpredictably"

You're right. I did not have that intention. A surprise cloud came and I called the device home. The area I fly is about 2400 meters above sea level. And my flight height is 60 meters. I know that Flyaway is about losing the gps lock, but I do not understand why it is impossible for a cloud cluster to block all gps signals.

Something else is the vibration barometer error etc ... I've already had a lot of flyaway with Dji Naza M and so I vowed with Dji. The first experience with Solo is worrying ...
 
Clouds will interfere with a GPS signal depending on density. It also depends on the GPS you have installed in the drone. Rev A? Rev B? Stock gps shield or new gps shielding? The design of the drones body and the amount of carbon contained within will also block GPS signal depending on the angle of the drone. This is why people like to upgrade to the HERE system. It's a much better GPS system than the stock systems, the mast also lifts the GPS up and away from the body of the drone which also improves reception. It's also got flashy lights which appeals to those grown ups here who are impressed by such things..... now if it only made jangly key noises too....
 
Clouds will interfere with a GPS signal depending on density. It also depends on the GPS you have installed in the drone. Rev A? Rev B? Stock gps shield or new gps shielding? The design of the drones body and the amount of carbon contained within will also block GPS signal depending on the angle of the drone. This is why people like to upgrade to the HERE system. It's a much better GPS system than the stock systems, the mast also lifts the GPS up and away from the body of the drone which also improves reception. It's also got flashy lights which appeals to those grown ups here who are impressed by such things..... now if it only made jangly key noises too....

Thanks @IrishmanPDX.


According to your thesis, a dense cloud can weaken the gps signals. There are those who do not agree with this idea*. And they think that only a few millimeters of solid mass of water can accumulate on the gps antenna's protective plastic. This meant that the incoming signal was going down, but I lost 10 satellites at the same time. And there was nothing but birds, clouds and beautiful air. I do not know what caused it.

I am using the Solo Gps module Rev B. with cardboard modification ...

I ordered a new gps receiver and upgrading it to the M8N is inevitable. My area is full of mountainous and deep valleys. And it's often annoying to have to fly with 7-8 satellites. For this reason I ordered the CUAV's U-Blox M8N Gps receiver. I will upgrade as soon as it comes.

*
The signal loss due to any and all conditions in the troposphere
is no more than 2 dB making it insignificant generally.


L1 and L2 Navigation satellite Signal Power Budget

Parameter L1 P-Code L1 C/A-Code L2 P-Code
-----------------------------------------------------------------------
User minimum received power -163.0 dBw -160.0 dBw -166.0 dBw
Users linear antenna gain 3.0 dB 3.0 dB 3.0 dB
Free-space propagation loss 184.4 dB 184.4 dB 182.3 dB
Total atmospheric loss 2.0 dB 2.0 dB 2.0 dB
Polarization mismatch loss 3.4 dB 3.4 dB 4.4 dB
Required satellite EIRP +23.8 dBw +26.8 dBw +19.7 dBw
Satellite Antenna gain at 14.3° 13.5 dB 13.4 dB 11.5 dB
worst case Block II off-axis angle
Required minimum satellite antenna +10.3 dBw +13.4 dBw +8.2 dBw
input power 10.72W 21.88W 6.61W
 
User minimum received power -163.0 dBw -160.0 dBw -166.0 dBw
Users linear antenna gain 3.0 dB 3.0 dB 3.0 dB
Free-space propagation loss 184.4 dB 184.4 dB 182.3 dB
Total atmospheric loss 2.0 dB 2.0 dB 2.0 dB
Polarization mismatch loss 3.4 dB 3.4 dB 4.4 dB
Required satellite EIRP +23.8 dBw +26.8 dBw +19.7 dBw
Satellite Antenna gain at 14.3° 13.5 dB 13.4 dB 11.5 dB
worst case Block II off-axis angle
Required minimum satellite antenna +10.3 dBw +13.4 dBw +8.2 dBw
input power 10.72W 21.88W 6.61W
Huh? Is this in the Solo Manual if so I missed it?...
 
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You are aware that the cardboard mod is frowned upon? The reason being is cardboard can collect humidity/moisture and could potentially cause more issues than it helps...Plastic is better..But the best scenario would be a HERE type GPS which sits on a mast moving it away from the noise of the Solo. It really makes a big difference.
 
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I'm no expert, I'm self taught, and I'm still learning, but from what I see the number of satellites or HDop had nothing to do with this incident. You are VERY lucky that you did not lose the drone though because it was in Fly:Manual while it was out of your site.

10 satellites during flight except for just a moment when the count was 9:
upload_2018-7-2_10-56-45.png


HDop under 1 during flight:
upload_2018-7-2_10-59-58.png


The IMUs had variances with the Z axis - I think that this might be what caused the switch to Fly:Manual:
upload_2018-7-2_11-4-11.png
upload_2018-7-2_11-4-24.png


Perhaps someone with more experience can explain further?
 
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Thanks @jimloss


A vicious cycle!

I'm not quite sure of the origin of the high stress on the Z-axis. Across the high hold in the Alt Hold mode, the Solo muffled the vibration, or the abnormal vibration in the Z axis went into the Alt Hold mode.

According to the log information, the gps and hdop values were positive, but during the escape, the controller and the screen were writing 0 gps.

There is a major problem here: This is a mistake that causes GPS loss. This is how a mistake that falls in the gps log records to "fly away" because of the loss of gps software while at normal level.

It's a pity to see that this is not taken seriously enough.

There must be an explanation of this nightmare that begins without an abnormal vibration and without entering into a cloud when everything is on its way and ending when inside!
 
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Mission Planner automatic log analysis result:


Vehicletype ArduCopter
Firmware Version solo-1.3.1
Firmware Hash 7e9206cc
Hardware Type
Free Mem 0
Skipped Lines 0

Test: Autotune = UNKNOWN - No ATUN log data

Test: Brownout = GOOD -

Test: Compass = GOOD - mag_field interference within limits (10.44%)

Test: Dupe Log Data = GOOD -

Test: Empty = GOOD -

Test: Event/Failsafe = FAIL - ERR found: FLT_MODE

Test: GPS = FAIL - Min satellites: 0, Max HDop: 99.99

Test: IMU Mismatch = WARN - Check vibration or accelerometer calibration. (Mismatch: 1.14, WARN: 0.75, FAIL: 1.50)

Test: Motor Balance = GOOD - Motor channel averages = [1503, 1467, 1528, 1454]
Average motor output = 1488
Difference between min and max motor averages = 74

Test: NaNs = GOOD -

Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = GOOD -

Test: PM = FAIL - 73 slow loop lines found, max 13.12% on line 178054

Test: Pitch/Roll = GOOD -

Test: Thrust = GOOD -

Test: VCC = GOOD -
 
"Test: Event/Failsafe = FAIL - ERR found: FLT_MODE" - I believe this was caused by the IMU mismatch - the problem I graphed earlier.

"Test: GPS = FAIL - Min satellites: 0, Max HDop: 99.99" - The log doesn't show that this was a problem during the flight - these numbers (0 and 99.9 ) are from before/after the flight - not during

"Test: PM = FAIL - 73 slow loop lines found, max 13.12% on line 178054" - this is reported frequently when looking at Solo logs (even with successful flights. This was going to be looked into by the Arducopter guys, but I never saw anything more on it.

"Test: IMU Mismatch = WARN - Check vibration or accelerometer calibration. (Mismatch: 1.14, WARN: 0.75, FAIL: 1.50)" - I believe this problem is related to what I graphed earlier and is what caused the automatic change from Fly to Fly:Manual
 
Get Satellite TV for a year and then tell me it works through heavy clouds.

The two issues are different. There must be a mathematical difference between the TV broadcast from a single satellite and the letters sent by two dozen GPS satellites. Yeah; heavy rain and snow are breaking satellite TV broadcasts. But I know that there are a lot of boats in stormy seas helping with gps.
 
Have you ever tried an external gps tracker? kind of worked for me when I had the same experience. I know there's already a built in but you know I was just trying to be sure.
 

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