Hi guys,
I recently acquired a QU4D quadcopter from Steadidrone with a PixHawk controller. During the first flight in AltHold mode the copter was flying fine for the first five minutes but then started loosing altitude and did not respond to throttle increase resulting in an ugly crash. The same problem occurred in all subsequent flights each time around the 5 min mark both in AltHold and Stabilize mode.
I first thought of a battery issue but there appear to be plenty of juice left in the battery after each crash. The problem still occurs when using a different battery.
Here are the results from auto analysis:
Size (kb) 578.7431640625
No of lines 9096
Duration 0:07:19
Vehicletype ArduCopter
Firmware Version V3.1.5
Firmware Hash ee63c88b
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:-62.49, Y:-127.97, Z:-238.78)
No MAG data, unable to test mag_field interference
Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = GOOD -
Test: GPS = GOOD -
Test: Parameters = GOOD -
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = FAIL - Avg climb rate 35.17 cm/s for throttle avg 756
Test: VCC = GOOD -
Despite running the compass live calibration procedure, the unit keeps failing the compass test. It seem that there is also a recurrent problem with Thrust.
Could someone help me figuring this out? (log file attached)
Thanks for the reply.
I re-calibrated the ESCs but the problem still persists.
Any idea what else could be causing the copter to hover at 80% throttle?
You might be able to get a tiny bit of margin out of increasing that a few percent. You could also get more throttle margin out of improving your center of gravity.
I still haven’t been able to fix the issue. It’s actually getting worse. On takeoff, the quad starts drifting backward pretty fast. Even 100% forward trim on the Tx is not enough to offset the drift.
After Jschall’s comment about the unit being under-powered, I started to think that I may have a bad motor (or two). When looking at the motors spinning at low RPM, I can see a slight wobble on the shaft of the rear left engine.
Here is the graph showing ThrIn vs ThrOut during a crash.
And the associated video: http://youtu.be/UZu4n8I1O8Q
Note how ThrOut goes to 100% just before the crash without input from the Tx.
Do you guys think that this is consistent with an engine failure? I am thinking it could also be an ESC issue. I have already changed the Pixhawk so I know for sure it’s not a flight controller issue.
I am having exactly the same problem, but worth noting that my quad was flying perfectly for a month or 2 until this started to occur, AUW is 2.2kg and I have a 3.2kg capable lift.
I also changed the Flight controller (APM) and recalibrated the ESC and radio and all appears fine as per previous working setup
Like you, when I take off initially all is good, indicating everything is doing what it should and functional. However after a couple of minutes the thrust will reduce until the quad is landing on full throttle (again not a battery issue). I am running a 4in1 ESC from AGM, which I thought was the problem as there is a temperature failsafe built in, which mean the throttle will reduce when it gets hot, however on a bench test It doesn’t appear to be overly hot so not sure.
Appreciate any thoughts from anyone, as this is taking over my life, trying to resolve…
Hi Craig,
I haven’t solved the problem yet and it’s taking over my life too!
Do you get the same kind of graph than the one I posted above (i.e., ThrOut at 100% and Alt still decreasing)?
Here are the three hypothesis I am working on right now:
1- Faulty ESC. I am using a Hobbywing Skywalker 25A Quattro ESC (4in1). I have read a number of threads from people having trouble with these ESCs suggesting that there might be a bad batch that has been produced.
2- Faulty motor. One of my rear motor shaft seems to have a bit of wobble which could indicate that it has been damaged. This would be consistent with the backward drift I am experiencing.
3- Slipping propeller. I realized last night that the Tmotors MT3506 that I am using come with a small washer that is supposed to go on top of the propeller… I have been using it underneath the propeller (Doh!). I am thinking this could have caused my props to slip during flight. I checked the props last night and there is no scratches or scuff marks that would support this idea. I’ll have to do some flight tests once the weather improves here.
I’ll test #3 first. If that doesn’t fix it, I think I’ll end up changing the ESC and 4 motors all at once… unless someone else on the forum is able to help pinpoint the exact source of the problem.
[quote=“Benflyfish”]Hi Craig,
I haven’t solved the problem yet and it’s taking over my life too!
Do you get the same kind of graph than the one I posted above (i.e., ThrOut at 100% and Alt still decreasing)?
Here are the three hypothesis I am working on right now:
1- Faulty ESC. I am using a Hobbywing Skywalker 25A Quattro ESC (4in1). I have read a number of threads from people having trouble with these ESCs suggesting that there might be a bad batch that has been produced.
2- Faulty motor. One of my rear motor shaft seems to have a bit of wobble which could indicate that it has been damaged. This would be consistent with the backward drift I am experiencing.
3- Slipping propeller. I realized last night that the Tmotors MT3506 that I am using come with a small washer that is supposed to go on top of the propeller… I have been using it underneath the propeller (Doh!). I am thinking this could have caused my props to slip during flight. I checked the props last night and there is no scratches or scuff marks that would support this idea. I’ll have to do some flight tests once the weather improves here.
I’ll test #3 first. If that doesn’t fix it, I think I’ll end up changing the ESC and 4 motors all at once… unless someone else on the forum is able to help pinpoint the exact source of the problem.[/quote]
Just quickly looked at your 17 log and your motor outputs are way off for a stable hover…WAY off. Motor 4 output is maxed out much of the time while one is at half and the others a bit above. If any channel is maxed out due to a problem the others are limited by the code in order to maintain level. I am amazed it even flies at all prior to crashing .
Have you tried each motor output on the bench with the relevant esc attached directly to the receiver throttle? Could be a bat esc, motor or slip…you need to do some fault finding.
Something is severely crippling your quad. My bet is once sorted it will have pretty decent performance with throttle pretty close to 50% for hover.
I just tested whether my props were slipping during flight and it doesn’t seem to be the case. So I am back to either a ESC or motor fault.
Thanks for your reply RabbitStu. Could you tell me which parameter you looked at to see the output of each motor independently?
no worries, I looked at RCout. these are the demands to the esc. So a higher value means the brain wants more. If for some reason that drive train is weak, it will be higher to compensate. For a quad look at 1-4
[quote=“Benflyfish”]Hi Craig,
I haven’t solved the problem yet and it’s taking over my life too!
Do you get the same kind of graph than the one I posted above (i.e., ThrOut at 100% and Alt still decreasing)?
Here are the three hypothesis I am working on right now:
1- Faulty ESC. I am using a Hobbywing Skywalker 25A Quattro ESC (4in1). I have read a number of threads from people having trouble with these ESCs suggesting that there might be a bad batch that has been produced.
2- Faulty motor. One of my rear motor shaft seems to have a bit of wobble which could indicate that it has been damaged. This would be consistent with the backward drift I am experiencing.
3- Slipping propeller. I realized last night that the Tmotors MT3506 that I am using come with a small washer that is supposed to go on top of the propeller… I have been using it underneath the propeller (Doh!). I am thinking this could have caused my props to slip during flight. I checked the props last night and there is no scratches or scuff marks that would support this idea. I’ll have to do some flight tests once the weather improves here.
I’ll test #3 first. If that doesn’t fix it, I think I’ll end up changing the ESC and 4 motors all at once… unless someone else on the forum is able to help pinpoint the exact source of the problem.[/quote]
regarding the graphs, I’m just learning how to interpret them. But yes, based on my graph at 100% throut I am descending to the point of landing. Given you have a 4in1 ESC also, I will be swapping mine out at the weekend for individual 30a Simonk’s to see if the problem persists… I am unable to identify internally any issues with the 4in1, but it should at least rule it out.
Slipping prop. How funny I also placed the washer under the prop (looked nicer and initially made more sense profile wise) but actually didn’t experience any slippage in the month or so I have been using it, it’s retained by a nylon locking nut which appears to hold well and delivery standard behaviour. (current issue aside) I have also swapped this around recently after seeing a picture of my motor on another machine.
Based on the previous post from RabbitStu, I’m now curious to see in the logs how I can identify specific motor activity as I can’t see this separated out by motor in the Mission planner log selections?
Will let you know how I go with swapping out the ESC… I’m sure we will get there, I don’t think it is rocket science - it just feels like it sometimes…
no worries, I looked at RCout. these are the demands to the esc. So a higher value means the brain wants more. If for some reason that drive train is weak, it will be higher to compensate. For a quad look at 1-4[/quote]
Just quickly looked at your 17 log and your motor outputs are way off for a stable hover…WAY off. Motor 4 output is maxed out much of the time while one is at half and the others a bit above. If any channel is maxed out due to a problem the others are limited by the code in order to maintain level. I am amazed it even flies at all prior to crashing .
Have you tried each motor output on the bench with the relevant esc attached directly to the receiver throttle? Could be a bat esc, motor or slip…you need to do some fault finding.
Something is severely crippling your quad. My bet is once sorted it will have pretty decent performance with throttle pretty close to 50% for hover.[/quote]
[quote=“Benflyfish”]I just tested whether my props were slipping during flight and it doesn’t seem to be the case. So I am back to either a ESC or motor fault.
Thanks for your reply RabbitStu. Could you tell me which parameter you looked at to see the output of each motor independently?[/quote]
So, i headed down the motor route for testing, however couldn’t see the problem was related to the motor itself…
However, surprise surprise, i swap out the 4in1 ESC for individual simonKs 30a and its now flying like a dream…
So much time wasted but worth it in the end to see it back in the air
.
regarding the graphs, I’m just learning how to interpret them. But yes, based on my graph at 100% throut I am descending to the point of landing. Given you have a 4in1 ESC also, I will be swapping mine out at the weekend for individual 30a Simonk’s to see if the problem persists… I am unable to identify internally any issues with the 4in1, but it should at least rule it out.