Question about GPS_POS#_X, GPS_POS#_Y and GPS_POS#_Z

ArduCopter Copter 3.6
1

Hi.

I have a pair of doubts about GPS_POS#_ variables:

  • They are offsets relative to body frame. Could i think that they are realitive to the frame 3D center point ?

  • Which value should i use to set an offset of 2,5 centimeters ? Maybe 0,025 ?

Thanks in advance.

Miguel.

1 Like
2

They are relative to the center if the fligh controller’s IMU.
And the unit is Meter, so 2.5cm is 0.025 indeed.

3

Hi again.

Should i consider the center of the Cube Black (just Cube, not carrier board) as an aproximate origin ? Correct ?

Thanks.

Miguel.

4

If you want absolute precision, it is the center of the cube.

5

Thanks a lot.

Miguel.

6

No it’s not. You can offset the IMU’s as well, look into INS_POS* parameters. If you don’t provide any IMU offsets then the IMU’s happen to be at the body frame origin, but it’s not always a valid assumption.

1 Like
7

Got me, you are right.
Although it is recommended to put the FC in frame center, or as close as possible.
But yes, it is related to the body frame origin (which is not same as the CG, but should be as close as possible).

8

Hi.

If i’ve understood in the correct way, both of them (GPS_POS#_ and INS_POS*) should be set relative, the closest as posible, to the frame’s 3D central point (assuming an almost simetrical weight distribution). Shouldn’t it ?

Thanks.

Miguel.