APM Copter V3.2 - "DJI S900" with "3DR Pixhawk" board and "UBlox Neo M8" gps

APM Copter V3.2 revolutionizes the world of multirotors, incredible functionality and stability make this release a milestone, offering at an acceptable cost...

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Developer
Comment by Michael on December 23, 2014 at 12:40am

Would you be willing to share the tuning file used with this? It looks like I will be getting my hands on a s900 soon and I'd like to minimize initial risk with getting it in the air the first couple of times.

Thanks for your time.

Comment by Vesselin Goranov on January 5, 2015 at 3:57am

It will be very helpful to give us details of the Pixhawk mount to S900, and some initial PIDs, to get it fly stable before autotune process.

Thanks for all you efforts, Marco!

Comment by Vesselin Goranov on January 5, 2015 at 1:49pm

I have instability issue with the S900.

Use Taranis, X8R, 3DR telemetry, Ublox Neo7 GPS (awaiting the M8N in days).

Made velcro bed for Pixhawk to the S900 lower base. Seems not much vibrations.

Compass (Neo7) is on 10 cm pylon (wondering to make it higher) It gives MAG data: Z: -166.00, no idea why...

It flies like drunken, and cannot go high enough for autotune.The data is here.

Will be glad to have some help!!!

Comment by Glenn M on January 5, 2015 at 7:35pm

I have an s900 with a pixhawk too, and I'm not really getting satisfactory performance either. I've got the neo-m8n, but seem to get a glitch from time to time where it will try and take off sideways at speed.

The main problem is that it's not flying perfectly smooth, the legs shake when they're down, and while the copter shakes less when they're up, the gimbal still seems to be shaken. I'm running rate pitch and roll P 0.17 and rate D 0.004, which works better than defaults, but isn't perfect. Also I get an initial drop in altitude when flying forward.

I have the pixhawk mounted on an omnimac 3d printed vibration mount on the top plate (logs show low levels of vibration), but I haven't tried hard mounting the pixhawk to the top plate yet. I ran autotune on mine with the gimbal attached, but it didn't give a good result.

Marco can you please please ask your friend who you built this s900 for, to send you his parameters file for the s900 so that the rest of us can get some better performance? Also can you please confirm how the FC is mounted to the frame? Is it mounted solidly to the top plate, or is it on the black foam that 3dr provideos, or something else?

Thanks

Comment by Vesselin Goranov on January 6, 2015 at 6:05am

Thanks for the support Glenn!

What MAG offset you have on the Z axis? I got -166.00. My GPS/compass Neo7 is mounted on 10 cm rod, on the top plate.  Pixhawk is just below it, on the lower plate. Should be no other magnetic source around...

Comment by Vesselin Goranov on January 6, 2015 at 12:39pm

Marco, could you please advice, if you replaced the original motor dampers with the New Vibration Absorbing Kit for DJI 4114 Motors Spare parts No35, described here?

Thanks in advance!


Developer
Comment by Marco Robustini on January 9, 2015 at 1:27am

Hi, everything is original, I have not replaced any components.
Pixhawk is mounted on a diy support, simply two carbon plates with four damper in the corner, like that:

https://www.facebook.com/marcocopter/photos/pb.1811252655682304.-22...


The difficulty is to make a good tuning and verify that there's no abnormal vibrations to the board.
In all my Pixhawk i replace the sponge for the barometer inside the box.
I'm sorry but this S900 is not here anymore, and I had not saved the parameters.
To have this reactivity have enabled and configured ATC section.
Comment by Vesselin Goranov on January 9, 2015 at 3:00pm

Thanks Marco!

What kind of sponge you use? Dense polyurethane rubber?


Developer
Comment by Marco Robustini on January 11, 2015 at 1:55am

Yes!

Comment by Vesselin Goranov on January 24, 2015 at 12:37pm

Thanks Marco!

Do you configured the EKF - Extended Kalman Filter? What else important?

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