Hi. I’ve been attempting to autotune a large octo but not having any luck.
Even after setting the autotune axis bitmask to only tune one axis, it seems the autotune doesn’t finish after a 10 minute flight, and no PIDs are saved.
Mission Planner informs me that I have entered Autotune, but never gives me a ‘Success’ message. I am landing when the battery failsafe triggers and disarming with the ch 7 autotune switch ON.
The copter itself is very stiff, with carbon fibre arms. I have installed an anti-vibration mount under the Pixhawk, and have acceptable vibration levels on the FPU. Everything is screwed down tight!
I have made several attempts to try to ‘help’ the autotune converge on a solution by investigating the dataflash logs after each flight, and setting the PIDs to the last values the autotune reached on the previous attempt (as found under ATUN: RP/ RD/ SP). After a flight in which the gains seemed to settle but not save, I input the values settled on, change batteries and start again, but on the next flight the values seem to diverge again during autotune, and again nothing is saved.
My question is: Is this a valid approach? If I repeat this sequence enough will the Autotune converge on a solution?
Or is there something I am missing to get the autotune to complete?
Is it possible that the low battery warning and failsafe land behaviour is messing with the autotune save?
Any help would be greatly appreciated.
850 mm wingspan carbon fibre frame from quadframe: http://quadframe.com/collections/octocopter-frames/products/fol-octo-pro
8 x T-motor MN3110 with 12" x 4.5 props (700 kv)
Pixhawk runnning APM Copter 3.3.3
4s 10000 mAh batt
AirT 20A ESCs with SimonK
AUW: 2670 g