Today I did a maiden flight of a Droidworx SkyJib that I built with an APM. It's an octocopter in coax configuration using Tiger 4014 motors and 14 inch props. With batteries it weighs 5.8Kg.
Upon take off it swung back and forth in what I think people refer to as 'toilet bowling'. I managed to land it without any damage and then turned down the P rates in the Stabilization before attempting another flight. The next flight seemed better but it was very short as I landed straight away because it was obvious it wasn't flying right.
I've attached the logs and would appreciate any help to figure out if the APM is suitable for this large of a copter.
Replies
Hi Darrel,
Are you using 6S batteries? How did you managed to control battery voltage and current consumption (since the stock power module is not enough)? I'll be using 40A ESCs.
Thank for your help,
Jonathan
Hi Darrell
Just downloaded my skyjib param file. need to lower the alt hold P value a bit from where it is here...as it is a fraction bouncy on decents and climbs but holds height very well. It is usually flown auto from takeoff to touchdown, but I tune in manual with video to get it as good as I can.
I am about to go to v3.0rc1 and do some more tuning, then hopefully get the X4 octo going this afternoon....
I use them mainly for photogrametry / survey work, however my testing and setup is with video so I can see the results from the aircraft, if the video is smooth the photos should be good!
The skyjib is now so smooth in and out of waypoints and so straight on tracks that I would not go back to naza !!
i hope I can help you get there too.
Cheers
Steve
The skyjib has done a few jobs already, But the X4 octo is still unlfown. designed a few weeks ago and nearly finished the build, putting all the electronics in at the moment. I am hoping it is as stable or better than the skyjib, cause it is much easier to fit into a car and can pull the arms of in a minute or two for shipping...
One thing I have found is the wiring from the battery's to the speedies is CRITICAL on placement. I have the positive wire from one speedy twisted with the negative wire from the next speedy going to the central distribution point. If they are not twisted then the MAG interference is huge~!
also the lower you can get this the better, ie mine is below the frame and I have just lifted the apm nearly 60mm above the top deck to lower the magnetic interference on the compass.
The other thing that is now critical is the vibration dampening for the apm. I have done a lot of testing in this area and have got mine down pretty low using sorbathane. Moongel works a little better for vibration dampening but I can't guarantee that it doesn't change, seems to "set" a little when it is under a little pressure and then the properties chance a little or it might lean a fraction. Love it on my smaller toys but for the work machines, not acceptable.. I can take some pics and email if you like...
skyjib.param
Also setting scratch built X4 octo, same motors, props, 5 cell packs, should be testflying this afternoon, will post param file for it also once setup.
Hang in there with the apm, have flown the naza but happier with apm performance.
Maybe give me a call sometime today and i can fill you in on where i'm at
0407750815
Also most of my settings are lots lower than default...
I should also add i am running v3.0 on apm2.5
Cheers
Steve
I have a coaxial octo with APM, with Axi 2814/22, xoar 12x6 and E-prop 11x5 running it on 5 cells lipo. The total weight is 5kg. I fly only in manual mode and so far without any problem. I like how it behaves and I can directly compare it with my other copters Mikrokopter flat octo, DJI naza and Wookong coax hexacopters.
Hi Darrell, Got a feeling from somewhere that you are in oz.... I'm in port macquarie and have a skyjib flying quite nicely on v3.0.0. I am currently setting up a coax octo of my own design at the moment using very similar motors.
I am happy to help tune if you are not to far away.... ahh, just played one of your log files, canberra is just a little further than a arvo drive!!
We could arrange to meet up in sydney if you need a hand still. I get down there occasionally....
just for a quick hint. My throttle settings are WAY lower than default. roll KP is 0.1 (again lower than default)
throttle accel values also lower than default. My beast weighs in around 6.5kg and is hovering around 40% throttle. ~20 min endurance...
Cheers
Steve
Darrell,
Some feedback from looking at the logs:
Looks like you haven't done the radio calibration.
Your vibration levels look a bit high especially on the x-y axis. Do you have the APM attached directly to the frame or have you used some vibration absorbing material like duBro foam?
Your copter is not overpowered (this is good!) because it hovers at about 50% throttle.
Your roll and pitch PID values are too high and this is causing a serious wobble in stabilize mode. I think you should reduce your Roll and Pitch Rate P to 0.10 (default is 0.15)
Compass offsets look good!
Hope this helps!