OXTS RT1003, Руководство пользователя

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Local co-ordinates
Figure 10. Local co-ordinate frame
Because the local co-ordinate frame is planar, it is not suitable for measurements over large distances.
As well as the reference frames already mentioned, the software supplied with your INS
makes it possible to define a new frame of reference called
local co-ordinates
. A local co-
ordinate frame is shown in Figure 10.
To define a new local co-ordinate reference frame, the INS needs to know several things.
First, it needs an origin. This is defined using latitude and longitude to at least six decimal
places. It then needs an altitude offset for the frame (positive or negative), which is applied to
the WGS 84 altitude at the assigned lat/lon co-ordinates. The offset is applied parallel to the
gravity vector at the defined origin.
Finally, the X-axis angle must be defined relative to north. A value of 0° causes the X-axis to
point north while the Y-axis points east. A value of 90° causes the X-axis to point west while
the Y-axis points north. The Z-axis always points down, perpendicular to the plane and is
only aligned to the gravity vector at the local co-ordinate origin. Because the local co-
ordinate frame is planar, it is not suitable for measurements over large distances.
Table 14. Local co-ordinate frame
Axis Description
X The X-axis is offset anti-clockwise from the north vector by the angle specified in the local
co-ordinate settings panel. It is perpendicular to the gravity vector at the origin