Suspended weight under Quad

ArduCopter
1

Hi

The quad is a 400mm 1.6kg with 10" props. Tuned and flying nicely and has done many flights.

I added a 150g weight suspended on chord under the quad from the 4 arms. I also had it on a long tether just in case. For 30 secs it flew ok holding position you could see the learned hover setting was a little low with the extra weight. Then it had motor oscillations and lost height and lost position control.

I believe this is because of sway of the weight under neath and the chords tugging on the drone causing motors to respond and make the oscillations worse. The parameters are currently amped for responsive path following with PSC_Jerk at 20 and could be a cause.

When lifting a weight I don’t need such critical path following, so I’m thinking of reducing the PSC Jerk right down. Should I decrease the PIDs too? by what %? I’m not going to attempt an auto tune with a hanging weight.

Thanks for you guidance.
Will be upgrading to 4.0 in the next month or so.
Log file: WeTransfer - Send Large Files & Share Photos Online - Up to 2GB Free

2

You should update to ArduCopter 4.4.0 not to ArduCopter 4.0.0

3

OK, you’re already on 4.3.6, that’s good. Definitely update to latest stable though.

Suspend a payload from a single central point, or points as close as possible to the centre.
I think you are correct that the cords attached to arms exaggerated the oscillations.

Your Roll P is much higher than pitch, and in fact Roll was suffering from the oscillations much more than Pitch. So I would set:
ATC_ANG_RLL_P,25.5583 down to 18.5
and see how the attitude control is after that.

You should have

BATT_CRT_VOLT,14.0
INS_HNTCH_FM_RAT,0.7