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A2 Flight Controller Yaw TBE Problem
4705 16 2014-9-27
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lennyschway
lvl.4
Flight distance : 1708412 ft
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I have a Sky Hero Spyder 1000. It is an X8 (Octorotor) I am using the A2 Flight Controller. I am flying with a few different 6S Batteries and the problem exists regardless of which battery I am flying with. My Takeoff weight is around 12.5 lbs.

The problem I am having is as follows.

I am flying this in GPS Mode.
When I am in a hover and attempt to Yaw in either direction, The craft will start to drift heavily during the Yaw. Similiar to TBE.
The faster i apply Yaw, the worse the TBE get's.

Any Ideas?

2014-9-27
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DJI-Andy
lvl.1

China
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hi, lennyschway,

it maybe many factors for TBE, such as:
firstly,  maybe the compass need calibration.
second, maybe the imu sensor bias is a little bigger than normal, please recalibrate the imu by assistant software.
thirdly, please check the install information, it need a  level position, and right offset configration.

please check them
2014-9-27
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lennyschway
lvl.4
Flight distance : 1708412 ft
United States
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Thank you for your reply Andy..

I have already performed the Advanced imu calibrations. All my readings are well within the desired ranges. My calibrations are done on a level table.
I calibrate the compass prior to each flight.
My imu is mounted directly on the manufactures COG location and is facing forward. My GPS Antenna is mounted behind and higher than the imu. The Antenna logo is facing up and the arrow points straight forward. I have input the GPS Antennas Negative Offsets in cm in the software.

My procedure for compass calibration is that i power on the craft and wait for GPS and home Lock. Then i go into compass calibration mode and do the calibration. After that I will sometimes power cycle the craft or just set it back on the ground and wait a minute before i takeoff.

Any ideas?
2014-9-27
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Blade_Strike
First Officer
Flight distance : 872694 ft
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can you please let me know where the craft hovers in manual mode? Can you also post a picture of IMU location on craft, a picture without the shell looking straight down at the craft would be great.
2014-9-29
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lennyschway
lvl.4
Flight distance : 1708412 ft
United States
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The craft hovers fine in Manual Mode. I will try a Yaw while in Manual Mode.
I am unable to remove the top frame at this time. It is a huge ordeal.
Here is a photo from when i was doing the build.


A2 imu Location

A2 imu Location
2014-9-29
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Blade_Strike
First Officer
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It doesn't look like you have the IMU you the correct location(could be wrong since the depth of the picture could be fooling me). I have attached a picture of the correct placement of imu @ CoG. What are your yxz values for imu and GPS?
_jpg.jpg
2014-9-29
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lennyschway
lvl.4
Flight distance : 1708412 ft
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That is exactly where I have the imu. The COG on the Spyder is over a center circle on the Frame plates near the rear of the craft. My imu is mounted on the bottom frame plate directly over the cog position. my X,Y,Z Axis for the imu offset is 0,0,0
This is a photo of where the cog is located on a Spyder Frame. It's directly over the center of that hole near the rear of the craft. (Photo is a generic photo)

My GPS Antenna is mounted on the top frame plate at the rear. The Gps Antenna mast is 5cm towards the rear of the center of the imu. So I have my GPS X Axis offset at -5cm.
The height from the bottom of the GPS Antenna down to the base of the imu is 12cm so I have my Z Axis offset at -12cm

I removed the canopy and moved the Mark II OSD out of the way to take some photos.
Block.jpg
A2 mounted location 1-2.jpg
Gps and Top Plate-2.jpg
2014-9-29
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Blade_Strike
First Officer
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Well your Z value should not be zero.  What are the values for your GPS?
2014-9-30
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lennyschway
lvl.4
Flight distance : 1708412 ft
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Blade_Strike Posted at 2014-9-30 22:25
Well your Z value should not be zero.  What are the values for your GPS?

I had listed the GPS Offset Values above.
They are, GPS (X) value is -5cm
GPS (Z) Value is -12 CM

You say the Z value should not be 0? Why?
2014-9-30
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Blade_Strike
First Officer
Flight distance : 872694 ft
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Because the craft will have negative z value with battery under it.
2014-9-30
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lennyschway
lvl.4
Flight distance : 1708412 ft
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I checked the CG with the battery installed and the craft balances perfectly at the CG Point.
I position the battery so I get the craft to balance where the CG/imu is.
2014-10-1
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Blade_Strike
First Officer
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Yes but you are not taking in account for you Z axis balance point. Z axis is a vertical balance point.. It should be a little below your main plate.
2014-10-2
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lennyschway
lvl.4
Flight distance : 1708412 ft
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Blade_Strike Posted at 2014-10-3 02:12
Yes but you are not taking in account for you Z axis balance point. Z axis is a vertical balance poi ...

How do i figure out that number?
Thank you Blade_Strike for all your assistance
2014-10-2
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Blade_Strike
First Officer
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You turn the craft on its side and find its balance point. Doesn't have to be perfect but try to get it as close as possible.
2014-10-3
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lennyschway
lvl.4
Flight distance : 1708412 ft
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Blade_Strike Posted at 2014-10-3 21:24
You turn the craft on its side and find its balance point. Doesn't have to be perfect but try to get ...

I will try this.. Thanks
2014-10-3
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lennyschway
lvl.4
Flight distance : 1708412 ft
United States
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Blade_Strike Posted at 2014-10-3 21:24
You turn the craft on its side and find its balance point. Doesn't have to be perfect but try to get ...

Ok,
I've got my Z Axis located on the craft.
I think I got all the correct figures now in the A2 Offset configuration.
Did I get this right?


CG Offset Photos.jpg
2014-10-29
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lennyschway
lvl.4
Flight distance : 1708412 ft
United States
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Can anybody confirm my settings?
2014-10-30
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