Problem found see last part of thread, Pixhawk switched flight modes by itself...

Any help would be greatly appreciated. I'm just getting started with the Pixhawk on a XAircraft 650-X8 frame. With Cobra 2217 motors and Afro 20A ESCs using Genfan 11x4.7 props to lift a NEX-5 camera. I made several auto test flights with the equivalent weight of of the camera. Everything was fine. Made several auto test flights with the camera again worked fine (took off, flew to waypoints, landed). Then yesterday I had trouble arming it due to high HDOP but finally it went down enough to arm and hit the auto mode. It flew to the first waypoints properly but then it started rising in elevation (from 150ft which was planned to 200+). it then switch to stabilize mode by itself, Since I had the throttle position low it dropped like a rock (about 50 ft) then switched back to auto mode by itself and climbed back to 200+ ft. It did this twice the second time is when I saw it happen and I switched it to RTL and it came back and landed. Looking thru the logs I can see where it happened but can't determine why. This is a false assumption. ( I'm guessing since I didn't have the Kalman filter on it was getting a bad reading from the barometer.) Turns out it is VCC look at a lower reply. And that somehow triggered the flight mode switch. Today I turned on Kalman filtering and put it in Loiter mode for ~9 min. about all my 3S can handle. it Loitered properly. I then planned a mission to take 45 photos at 50 meters. It flew the mission fine with no problems. Could someone take a look at these logs and let me know what happened? The flight doesn't start until about 60% into the tlog.

Thanks.

Robert

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@Robert,

An auto analysis of your 31.bin file revealed the following:
Size (kb) 5359.5205078125
No of lines 71376
Duration 0:05:04
Vehicletype ArduCopter
Firmware Version V3.2.1
Firmware Hash 36b405fb
Hardware Type
Free Mem 0
Skipped Lines 0

Test: Autotune = UNKNOWN - No ATUN log data
Test: Balance/Twist = GOOD -
Test: Brownout = GOOD -
Test: Compass = FAIL - Large compass off params (X:218.00, Y:107.00, Z:89.00)
Large compass offset in MAG data:
X: 218.00
mag_field interference within limits (14.72%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: FS_BATT
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.31, WARN: 0.75, FAIL: 1.50)
Test: Parameters = GOOD -
Test: PM = FAIL - 29 slow loop lines found, max 11.68% on line 1608
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = WARN - VCC min/max diff 0.308v, should be <0.3v

As you can see you have a compass issue, a Battery Fail Safe event occurred, there was a PM failure, and your VCC appears to have varied more than 0.3vdc.

Regards,

TCIII AVD

Yes I ran the auto analysis, but it doesn't tell me what caused the flight mode to switch from auto to stabilize, then back to auto, then back to stabilize, then back to auto by itself.

Regards,

Robert

I meant to say thank you Thomas (first) in my previous post. I can find the place in the log file where it switches from auto mode to stabilize but I can't determine why. This is due to my lack of understanding on how to interpret a log file. Are there any threads on how to read a log file and what the different entries mean?

Thanks,

Robert 

Auto Analysis on my laptop says the compass is GOOD

Log File C:/Users/rgraham/AppData/Local/Temp/tmp8382.tmp.log
Size (kb) 5359.5205078125
No of lines 71376
Duration 0:05:04
Vehicletype ArduCopter
Firmware Version V3.2.1
Firmware Hash 36b405fb
Hardware Type
Free Mem 0
Skipped Lines 0

Test: Autotune = UNKNOWN - No ATUN log data
Test: Balance/Twist = GOOD -
Test: Brownout = GOOD -
Test: Compass = GOOD - mag_field interference within limits (14.72%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: FS_BATT
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.31, WARN: 0.75, FAIL: 1.50)
Test: Parameters = GOOD -
Test: PM = FAIL - 29 slow loop lines found, max 11.68% on line 1608
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = WARN - VCC min/max diff 0.308v, should be <0.3v

Regards,

Robert

Looks like VCC is the problem. Here is my interpretation... when it dropped to 4.91 volts the mode switched to stabilize. Since the throttle position was low this allowed the voltage to rise above 5 volts it switched back to auto mode and continued the mission until the same thing occurred again. I don't know what caused this. I'm using the 3dr power supply and a new 3S 35C 5300 mAh battery. After looking at some APM 2.5 threads I'm assuming the VCC should be a straight a line as possible when graphed. I am powering the Pixhawk straight from the 3dr power supply. I'm using a separate Castle 10 amp BEC to power a older 2 axis gimbal from XAircraft. This is wired in before the connection to the 3dr power supply. Is it possible that gimbal caused the drop in VCC at these two points? There was zero wind that day. 

Regards,

Robert

Ok I thought the VCC bouncing around was being caused by the 2 axis gimbal being powered before the 3dr power supply but this doesn't appear to be the case. Below is a VCC graph of a test flight just taken without the gimbal being powered. So what gives? Shouldn't the VCC be a steady line on the graph for the Pixhawk?

Regards,

Robert

Your problem is most likely with your RC RX or Tx. If you plot your RCIN for channel 5 (the channel that changes the Pixhawk's flight mode) you'll see that the PWM values seen by the Pixhawk changes. Thus the Pixhawk switched flight modes....because that's what it thought you were telling it to do. The signal it was seeing from your RC receiver was changing.

I don't think the issue has anything to do with Vcc. When the Pixhawk switched to Stabilize your throttle stick must have been up a bit because it went to a high throttle level with a resultant high current. That probably caused the voltage to sag just a little bit.

You didn't say what sort of RC Tx or Rx you are using, but I think that's your problem. It could just be something as simple as PWM drifting on channel 5, with the dividing line between Auto and Stabilize very close.

Thank's Tom. I'm using a Hitec Aurora 9 Tx and a Hitec Optima 9 Rx with the 3DR PPM encoder. So what I saw was the X-8 falling without power during the mode switch, then when it hit the stabilize mode (because of the throttle setting it climbed) causing the Vcc to drop. Then it switched back to auto mode. Is the Vcc supposed to bounce around this much on the Pixhawk vs. the straight line graphs I saw for the AMP 2.5? So if I make the dividing line higher between the flight modes should that prevent it from occurring?

Regards,

Robert

I have an Aurora too, check your PWM values that aren't near limits http://copter.ardupilot.com/wiki/initial-setup/configuring-hardware/

 

Vcc will move around a bit and I'd say your's is OK. It looks within normal limits. Maybe tweak your transmitter's flight mode settings a bit, if possible, so you are more centered in the ranges, as Cala suggested below.

The isuue you had has nothing to do with Vcc, which by the way looks totally normal on your graphs (stays between the limits 4,6V to 5,6V).

Your issue is like Tom said a PWM instability on your channel5. Check your radio and receiver.

Thanks for the help everyone. Newbee learning curve here. I'll give this a shot and report back.

Regards,

Robert

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