I am pretty new to quads but have some understanding. I’m hoping somebody can point me in the right direction. I have a new build that is reasonably tuned that I’ve been experimenting with. I’ve found that with every flight, after a few minutes the quad will become uncontrollable and crash. Even though it flies great the first few minutes. There is still battery capacity/voltage remaining so I’m not sure what happening. I have read other posts that suggest overweight/underpowered, but I doubt that is the case. My hover throttle is maybe 40%. Will attach the most recent log.
The tuning could be better, you’ll need to set a few more params, gather data for Harmonic Notch filter and set that up, then run Autotunes again - later…
Weight is a bit of an issue too. Those smaller motors struggle at their top end, despite the low KV rating.
MOT_THST_HOVER=0.6875 which is quite high.
When the quad starts to lose stability 3 motors (except Motor 2 for some reason) get commanded to maximum alternately. So they are losing effectiveness.
I would check if the ESCs have some sort of low voltage cutout and disable it or set as low as possible.
If they are BLHELI32 ESCs then also disable Low RPM Power Protect.
Connect to MissionPlanner and press Alt A to finish setting up some initial parameters, particularly the motor/battery scaling:
MOT_BAT_VOLT_MAX and MOT_BAT_VOLT_MIN
and I would set this too BATT_FS_CRT_ACT,1
Set this to gather data for the Harmonic Notch filter, and just do a gentle hover flight in Alt Hold mode for a couple of minutes, maybe a few stick movements but not much.
INS_LOG_BAT_MASK,1
then get back to use with the next .bin log
Whoever told you that is right. You don’t look at Hover throttle you look at RC out at Hover. You are at ~1650µs and it should be ~1500µs. Lose ~ 230g and it would be about right with 3S power. You should have built for 4S Power then you would have plenty of reserve thrust to work with.
Thank you all for the input. I will try your suggestions and get back to you after testing. A couple questions I have:
Regarding the ESCs, they are BLHELI32, how do I change settings in them? Can that be done via Mission Planner?
Regarding the battery, if my motors and ESCs can handle 4S voltage, is it possible to simply swap out for a 4S battery? Would this require any tuning changes or param changes?
You would use BLHelisuite for that. Configure a Dshot protocol and set SERVO_BLH_AUTO to 1 before attempting to connect.
Ah, you have a Pixhawk. Dshot and passthru will not work on the main outputs you have configured for motors. You need to connect them to the Aux outputs and assign them. Aux 1-4 is Outputs 9-12.
Do some reading: Passthru Dshot
Yes, for sure. But your craft needs tuning anyway.
After making the suggested updates I did a test flight. I did a simple position hold and just observed. I noted that as the voltage dropped, the throttle RC out continued to rise to compensate. I assume that means that the scaling is working after setting MOT_BAT_VOLT_MIN/MAX.
The bad news was that when the battery voltage hit ~11.0, the throttle RC out maxed, at which point the copter began to wobble and fall. I’m assuming this validates that my copter is underpowered, and my best course of action would be to use 4S power?