Hi, I have a new drone, and did the first flight test today. Everything was running nicely. I was switching several times between loiter and stabilize. Then, during a switch to loiter, it seemed that all motors turned off, and the copter crashed (luckily above very soft ground and at very low altitude). This happens in the log at 15:00:40 .
I know that there are occasional peaks in the vibration and even clipping. And also it seems that motor power is too low. These are issues I need to fix. But is there an obvious reason why the motors seemed to turn off?
of thrust loss on one Motor in this case #2. Motor 1 (opposite arm) drops to compensate attitude, lack of thrust, which as you say it was lacking anyway, and down it goes. ESC, Motor, Prop…
thanks… Duringa quick test after the crash, all 4 motors were spinning. So I need to find out why there was a temporal thrust loss… After the first few minutes, I checked the motor temperature, and it felt like 21 °C on all motors.
What a pity, this is the first copter that I did not build myself from scratch, and immediately, I get problems with vibrations and crashes
but… why… how can I find in flight vibration levels before the first flight…? 21 °C isn’t really hot when the outside temperature is 21 °C I would say…
You could have been much better prepared if this was the 1st flight. Some of those PID’s look random and you missed some Initial Tune parameters which are pre 1st flight.
These almost certainly won’t work:
ATC_ANG_PIT_P,3
ATC_ANG_RLL_P,3
Need this:
INS_ACCEL_FILTER,10
These not set:
MOT_BAT_VOLT_MAX,0
MOT_BAT_VOLT_MIN,0
Probably not right:
MOT_SPIN_MIN,0.15
The pids are copied from a very similar Copter with an identical distribution of mass and the same motor type. They are not random but tuned from acro mode to stabilize to loiter. The mass distribution required some very special parameters to fly in high winds:
@dkemxr : I am always open for suggestions. But I don’t see why it is so important to set INS_ACCEL_FILTER to 10 (Arducopter default was 20 for a looooong time and didn’t cause crashes afaik). I also don’t see why MOT_BAT_VOLT_MAX / MIN is so important. This is an “advanced parameter” that I would set at a much later stage (if at all). As I said, this is the first flight using parameters copied from an almost identical drone (that flies perfectly for years). I know that I will have to account for slight differences. But this is something I usually do after the first flight, and not before.
Here, I was asking for help detecting the root of a crash after the first 5 minutes in the air. You helped me by pointing out that motor 2 has a thrust loss. I will now try to find out which part of the gear failed (T-motor gear ESCs / motors, I wouldn’t usually expect a hardware fail in the first 5 minutes of flight).
MOT_SPIN_MIN seems ok for me at .15. These are not copters that are highly overpowered.
I don’t know, and I fear there will be no way to find out. Desyncing with MF1806 on 5006 motors at 6S and T-Motor F55 BLHeli32 does not seem too likely to me unless there is an electronic defect. Or do you have other experience with this?
I think one of the first flight tests in @amilcarlucas methodic configurator is a quick hover to initially check for extreme vibrations and hot motors/ESCs.
I wouldn’t copy parameters from another drone out of principle. Even if they’re (in theory) identical. Still too many unknown variables that can scale up to result in very different behavior.
I agree that you shouldn’t copy paste parameters. But the problem is that this drone doesn’t fly with default settings due to the enormous moments of inertia…
Something I don’t think was adequately covered here:
High vibration levels can lead to overheats because they can result in rapid throttle oscillation, which creates heat in the ESC switching circuitry along with heat in the motors themselves as torque changes rapidly (and sometimes imperceptibly to our eyes/ears). A moderate OAT may help but will not prevent such an overheat potential.
There are a multitude of other negative consequences to high vibrations but the takeaway here seems to be heat contribution.
I will check it out because my drone was misbehaving .
Yes absolutely agree that this is important and has caused many crashes.
I even did a number of tests in the past to minimize vibrations; e.g. by using 18" 3-blade propellers instead of 2-blade, which has quite an effect when not only hovering at zero wind:
But I am not sure about this case here: The ESC has 55A continuous per channel, the copter draws 27A (total current, validated) before the crash, and 70A max. total during very short peaks.
I think that additional heat produced in the ESCs due to additional losses via rapid throttle oscillation should be somewhat visible in the current trace. The motors did not heat up at all during the flight (the average 7A per motor are way inside their max (20A)).
I cannot afford another crash where I am less lucky. So I think I’ll replace all components involved in the crash: ESCs + motors (need higher kV anyway…). First, I’ll do some additional bench tests, but I think it will be hard to find the root cause.
need to use the configurator. Just have fun and enjoy flying your copter.
.