strange behaviour of pixhawk-request help to understand

Hi

I am building a 1300mm octocopter with 30AH lipo. I want to be using a tegra tx1 for onboard visual processing coming from a sony a6000. 

I have built the drone and assembled it. I have configured it as usual. I was using the external compass on the m8n gps. and when the compass calibration happened both of them had similar reading all under 150. I have also done a compass motor calibration for the offset.

however when I took it to the field and wanted to test it in autonomous mode, it started behaving weirdly. below is the auto diagnosis of the data log and also please find attached the flight log.

I fail to understand what could have gone wrong. I would appreciate any help solving it. I wish to fly the machine and then work the tegra part.

Size (kb) 856.1298828125
No of lines 10433
Duration 0:00:28
Vehicletype ArduCopter
Firmware Version V3.5.3
Firmware Hash 1a85c237
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = UNKNOWN - No ATUN log data
Test: Brownout = GOOD -
Test: Compass = FAIL - Large change in mag_field (257.75%)
Max mag field length (1112.76) > recommended (550.00)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERRs found: CRASH GPS_GLITCH
Test: GPS = UNKNOWN - join() takes exactly one argument (2 given)
Test: IMU Mismatch = WARN - Check vibration or accelerometer calibration. (Mismatch: 0.81, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = FAIL - Motor channel averages = [1722, 1684, 1360, 1314, 1480, 1441, 1754, 1650]
Average motor output = 1550
Difference between min and max motor averages = 440
Test: NaNs = GOOD -
Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = UNKNOWN - 'BarAlt'
Test: Thrust = GOOD -
Test: VCC = WARN - VCC min/max diff 0.563965v, should be <0.3v

thanks in advance 

Views: 656

Attachments:

Replies to This Discussion

I have thoroughly reviewed your log. You have major magnetic interference from your power wiring being too close to your magnetometer. That's why it couldn't fly. I get the felling that this is the first time this machine has flown, so it should never have been put into Auto mode at all,, irresponsible and dangerous considering that it is a large machine hovering at 60 amps. That's a big expensive aircraft.

OK enough of that. Your primary magnetometer in the GPS module needs to be at least 20 cm from induced magnetic fields from high current conductors. That's why you always see them mounted on a mast. Its not for the GPS, it's for the mag. 

I don't know what's going on with your power system, but power to your flight controller was marginal and close to a fatal brownout reset. The voltage dropped when the motors spun up. That should not happen.

Vibration levels looked very good until the props started beating the ground.

Looked like a very short and scary flight. I hoop you learned a lesson. Drones are hard. A lot of things must be right for it to fly, but only one thing wrong can bring it down.

You should first fly in stabilize mode with a new machine. It is safer to get some manual flight experience on a less lethal machine.

If stabilize works then try althold mode. When that is working well and tune you can try loiter mode. If that works, then you can try an auto mission.

Good Luck!

1200 watts to hover , wow !

What is your AUW ?

moriati, please do not attempt to fly this machine until it is fixed. I noticed something. You are using a Pixhawk power module on a big copter and totally overloading it. You are lucky not to have a total power failure. The standard power module is only rated for a 4 cell and only measures up to 60 amps. The data shows you were above 60 amps(flat line at 60). That also explains the vcc drop when the copter stars flying. That is the problem that didn't yet cause a crash. The other is the magnatometer interference. When the current increases the mag readings change before the copter moves. That is the cause of the crash.

The current sensor is a shunt resistor that has a maximum rating of 100 amps. If your machine hovers near 60 amps it will easily exceed 100 amps often during windy or fast flight. You really must redo your power power monitor. And get the mag/gps away from current conductors and your current indication can't go above 60 amps.

Hi Greg

thank you so much for the support. I have actually tested the drone yesterday again. I have moved the compass away from the battery, I have put the battery below the drone and the compass on a mast. and yet it had the same result although I was lucky this time not to have a crash.

regarding the power module, can you suggest any power module I shoud buy. plz find the flight log from yesterdays flight

Attachments:

my AWP now is about 9 Kilograms

Luc Maximilien said:

1200 watts to hover , wow !

What is your AUW ?

I looked at your latest log. There is still a strong magnetic influence that follows current on both mags, one more than the other. there is also a large motor imbalance like one of the motors is not working or loosing sync.

Regarding the power module, you could use this one, from 3DR:

https://store.3dr.com/products/10s-power-module

Hi Greg,

thank you so much for the support through out. I apologise for the late reply. I have recently changed my autopilot, Compass, shifted the battery a little further down and moved the autopilot also a little above its previous position. I have performed a bench test tying the drone down to ensure everything is alright before flight, Also as you suggested I have purchased the attopilot 180 Amp current sensor, and coupled it with a BEC to make a power module.I will be bench testing it with the power module changed and uploading the flight log later in the day.

However I am uploading the last flight log when I bench tested the drone after I made reasonable changes. whiel I was going thru the log on auto analyse, I found a couple of things that don't seem right right to me:

Test: Parameters = FAIL - 'THR_MIN' not found

also when I try to arm the drone, it always doesn't respond to the command. I found it weird. it arms at times and at times does not respond to the command even if I hold the sticks centred for a while.
Greg Fletcher said:

I looked at your latest log. There is still a strong magnetic influence that follows current on both mags, one more than the other. there is also a large motor imbalance like one of the motors is not working or loosing sync.

Attachments:

Thanks Javier for the suggestion. I found an interesting 180 amp attopilot current sensor on sparkfun and got that instead. 

Javier Cerna said:

Regarding the power module, you could use this one, from 3DR:

https://store.3dr.com/products/10s-power-module

Hi Greg,

Finally I had my attopilot 180amp current sensor delivered. I have bench tested the drone before taking it to field for an actual flight. I also did an auto analyse on the flight log. interference and other parameters seem to be in check. however I found this:

Test: Motor Balance = FAIL - Motor channel averages = [1612, 1653, 1325, 1371, 1224, 1288, 1600, 1663]
Average motor output = 1467
Difference between min and max motor averages = 439

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

Test: Parameters = FAIL - 'THR_MIN' not found

Test: VCC = FAIL - VCC below minimum of 4.6v (4.534277v)

Also please find attached the flight log.

please suggest if the machine is okie for me to go for a flight test on field

Regards



Greg Fletcher said:

moriati, please do not attempt to fly this machine until it is fixed. I noticed something. You are using a Pixhawk power module on a big copter and totally overloading it. You are lucky not to have a total power failure. The standard power module is only rated for a 4 cell and only measures up to 60 amps. The data shows you were above 60 amps(flat line at 60). That also explains the vcc drop when the copter stars flying. That is the problem that didn't yet cause a crash. The other is the magnatometer interference. When the current increases the mag readings change before the copter moves. That is the cause of the crash.

The current sensor is a shunt resistor that has a maximum rating of 100 amps. If your machine hovers near 60 amps it will easily exceed 100 amps often during windy or fast flight. You really must redo your power power monitor. And get the mag/gps away from current conductors and your current indication can't go above 60 amps.

Attachments:

HI all

today I performed my flight after much suggested changes in the power module and other power issues.

FIRST FLIGHT:

Test: Autotune = UNKNOWN - No ATUN log data
Test: Brownout = GOOD -
Test: Compass = FAIL - Large change in mag_field (59.65%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.46, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = FAIL - Motor channel averages = [1768, 1679, 1535, 1441, 1543, 1457, 1736, 1726]
Average motor output = 1610
Difference between min and max motor averages = 327
Test: NaNs = GOOD -
Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = UNKNOWN - 'BarAlt'
Test: Thrust = GOOD -
Test: VCC = WARN - VCC min/max diff 0.338379v, should be <0.3v

SECOND FLIGHT:

No of lines 5584
Duration 0:00:13
Vehicletype ArduCopter
Firmware Version V3.5.4
Firmware Hash 284349c3
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 (1.09%)

Test: Dupe Log Data = GOOD -
Test: Empty = FAIL - Empty log? Throttle never above 20%
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.14, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = WARN - Motor channel averages = [1231, 1229, 1167, 1176, 1220, 1216, 1253, 1201]
Average motor output = 1211
Difference between min and max motor averages = 86
Test: NaNs = GOOD -
Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = GOOD -

THIRD FLIGHT:

No of lines 51355
Duration 0:05:26
Vehicletype ArduCopter
Firmware Version V3.5.4
Firmware Hash 284349c3
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 (9.63%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.19, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = WARN - Motor channel averages = [1196, 1268, 1246, 1289, 1178, 1237, 1179, 1277]
Average motor output = 1233
Difference between min and max motor averages = 111
Test: NaNs = GOOD -
Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = WARN - VCC min/max diff 0.362548v, should be <0.3v

Now firstly all these three flights were on the same machine without changing anything on the machine, except the first flight was where the drone took off and crashed and the following two were flights with the drone tied down(bench tested). I fail to understand the following:

1) The volatility in the vcc when its all the same battery(TATTU 30AH 6S) same current sensor(ATTOPILOT 180AMP).

2) The volatility in the magnetic field.(my last bench tests, to which I uploaded the logs just a while ago, showed the magnetic fields in check when throttled all the way up and down and thru the other channels of roll/pitch/yaw.however today all of them had different values on the exact same setup)

3) the second and the third flights were actually bench tests with the drone tied down. I fail to understand why it has a crash error. further, I had the same issue bench testing the drone the other day, when it was absolutely static and tied down . still  had the same error message. following is a read from that log

No of lines 10375
Duration 0:00:28
Vehicletype ArduCopter
Firmware Version V3.5.4
Firmware Hash 284349c3
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 (1.91%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.18, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = FAIL - Motor channel averages = [1570, 1422, 1558, 1453, 1386, 1209, 1369, 1605]
Average motor output = 1446
Difference between min and max motor averages = 396
Test: NaNs = GOOD -
Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = FAIL - VCC below minimum of 4.6v (4.485938v)

4) I don't understand why all these flights have the following error messages:

a) Test: Motor Balance = FAIL - 

b) Test: Parameters = FAIL - 'THR_MIN' not found

*any help is greatly appreciated. I have been trying to build this huge 1300mm octocopter with a 30AH battery and haven't been able to have a successful flight yet bcos of a lot of issues encountered 

Thanks in Advance

Cheers

Attachments:

Hi,

Judging from your flight log, you have a really high voltage drop. I'm not sure if that's the issue, but going from 24 V to 17 V on launch seems unusual. Maybe the C parameter of your battery is too low, or they are not in good shape. The peak of 90 A seems to cause this voltage drop, but the voltage drop is too high to be acceptable.

Regarding the motor balance, it could be that your motors are indeed not well balanced (test them with a level tool, just in case).

Best,

Javier

moriarty said:

HI all

today I performed my flight after much suggested changes in the power module and other power issues.

FIRST FLIGHT:

Test: Autotune = UNKNOWN - No ATUN log data
Test: Brownout = GOOD -
Test: Compass = FAIL - Large change in mag_field (59.65%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.46, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = FAIL - Motor channel averages = [1768, 1679, 1535, 1441, 1543, 1457, 1736, 1726]
Average motor output = 1610
Difference between min and max motor averages = 327
Test: NaNs = GOOD -
Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = UNKNOWN - 'BarAlt'
Test: Thrust = GOOD -
Test: VCC = WARN - VCC min/max diff 0.338379v, should be <0.3v

SECOND FLIGHT:

No of lines 5584
Duration 0:00:13
Vehicletype ArduCopter
Firmware Version V3.5.4
Firmware Hash 284349c3
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 (1.09%)

Test: Dupe Log Data = GOOD -
Test: Empty = FAIL - Empty log? Throttle never above 20%
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.14, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = WARN - Motor channel averages = [1231, 1229, 1167, 1176, 1220, 1216, 1253, 1201]
Average motor output = 1211
Difference between min and max motor averages = 86
Test: NaNs = GOOD -
Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = GOOD -

THIRD FLIGHT:

No of lines 51355
Duration 0:05:26
Vehicletype ArduCopter
Firmware Version V3.5.4
Firmware Hash 284349c3
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 (9.63%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.19, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = WARN - Motor channel averages = [1196, 1268, 1246, 1289, 1178, 1237, 1179, 1277]
Average motor output = 1233
Difference between min and max motor averages = 111
Test: NaNs = GOOD -
Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = WARN - VCC min/max diff 0.362548v, should be <0.3v

Now firstly all these three flights were on the same machine without changing anything on the machine, except the first flight was where the drone took off and crashed and the following two were flights with the drone tied down(bench tested). I fail to understand the following:

1) The volatility in the vcc when its all the same battery(TATTU 30AH 6S) same current sensor(ATTOPILOT 180AMP).

2) The volatility in the magnetic field.(my last bench tests, to which I uploaded the logs just a while ago, showed the magnetic fields in check when throttled all the way up and down and thru the other channels of roll/pitch/yaw.however today all of them had different values on the exact same setup)

3) the second and the third flights were actually bench tests with the drone tied down. I fail to understand why it has a crash error. further, I had the same issue bench testing the drone the other day, when it was absolutely static and tied down . still  had the same error message. following is a read from that log

No of lines 10375
Duration 0:00:28
Vehicletype ArduCopter
Firmware Version V3.5.4
Firmware Hash 284349c3
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 (1.91%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.18, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = FAIL - Motor channel averages = [1570, 1422, 1558, 1453, 1386, 1209, 1369, 1605]
Average motor output = 1446
Difference between min and max motor averages = 396
Test: NaNs = GOOD -
Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - 'THR_MIN' not found
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = FAIL - VCC below minimum of 4.6v (4.485938v)

4) I don't understand why all these flights have the following error messages:

a) Test: Motor Balance = FAIL - 

b) Test: Parameters = FAIL - 'THR_MIN' not found

*any help is greatly appreciated. I have been trying to build this huge 1300mm octocopter with a 30AH battery and haven't been able to have a successful flight yet bcos of a lot of issues encountered 

Thanks in Advance

Cheers

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