I am using 850mm x 850mm carbon fiber frame with 240kv 6s motors, 200amps mauch power module and Hobbywing 40amps Escs, 24 inch foldable prop with 33.6ah batteries connected in parallel. Was planned a mission after completion of 3 lines, in the mid-air it toppled and crashed. Can some one help me to find the root cause.
The most common cause and the easiest one to spot. Thrust loss on Motor 2, Motor 1 drops to stabilize and down it goes.
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Set your logging to 180222 for helpful information needed in the future.
How much tuning had you completed before this flight? Harmonic notch, etc?
Thank you dave, But as i inspected the system physically there is no dis-solder found. As analysed the log found motor 2 got saturated and it toppled and yawingly it crashed. after crash i bench test the motors every motors are running fine but still couldn’t able to fine exact cause. whether it is motor or ESCs fault.
Sure, After tuning it has flown for 5 hours. and have applied 2 harmonic notch filters.
Note: I have used customised motors so without applying 2nd notch it was not tuning proprly.
The signal fluctuates up and down intermittently, which makes me think it’s likely a contact issue—possibly with a solder joint, connector, servo line, or banana plug. I’ve encountered several cases like that before. If the motor or ESC were burnt out, the PWM signal would typically stay maxed out rather than fluctuate like that.
The log doesn’t always provide a cause for thrust loss. If there is extended ESC telemetry it can sometimes provide insight.
@PMTAug comment is good. A cold solder joint can be intermittent with heat for example that you won’t see on the bench.
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This seems like a potential clue as well. Customized how?
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This is the one which we used 6s configuration with 24inch hobbywing propeller.
The reason you have an unnecessarily complex harmonic notch filter settings is because motor 2 was working quite a bit harder than the other 3 motors. This gave a broad spread of noise with two peaks where there should have been one.
If you can better balance the copter you will get a more defined primary noise peak to target with just the throttle-based filter. You should not need a fixed notch filter.
Apart from the notch filter settings, that weight imbalance would have affected the tuning.
The same weight bias may have even contributed to the ESC or a connection over heating.
The old Hobbywing 40A ESCs might not be up to the job.
Definitely DO NOT have any bullet connectors in the system - only have properly soldered connections to ESCs and motors.
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The reason i applied fixed notch filter was for better tuning, without applying it the autotune provided the sluggish values and observed oscillations. And the Cg was well balanced though. Yes your right as we didn’t use bullet connectors but soldered connection using joints plate.
As I inspected the drone physically, there were no soldering issues, no ESCs and motors were burnt. After the crash I see the motor stator has been displaced. But it might happen after the crash. May I know any other possibilities for the crash.