Chapter 4 SMART7 with SPAN Operation
SMART7 Installation and Operation User Manual v6
62
Figure 19: ALIGN Translation Offset
If the distances measured in this example were X Offset = 1.5 m, Y Offset = 1 m and Z Offset = 0 m, the fol-
lowing values would be entered, based on the IMU Body Frame:
l
x = 1.5
l
y = 1.0
l
z = 0
The translational offsets are entered using the
SETINSTRANSLATION
command. For this example, the com-
mand to enter these offsets is:
SETINSTRANSLATION ANT2 1.5 1.0 0
The measurements for the translational offsets should be done as accurately as possible, preferably to
within millimeters especially for RTK operation. Any error in the offsets will translate into an error in the
INS position.
By default, the translational offsets are entered in the IMU Body frame. However, in some systems the IMU
Body frame may not be known precisely. For these cases, the
SETINSTRANSLATION
command has an
option that allows the offsets to be entered relative to the Vehicle frame. In these cases, the rotation from the
IMU Body frame to the Vehicle frame (RBV) is used to rotate offsets into the default IMU Body frame as
required. To achieve the best results, this means that the RBV rotation must be known very precisely. Typically
this is achieved through the SPAN RBV Calibration procedure. See
Body to Vehicle Frame Rotation Calibration
on page 76 or
Multi-Line Body to Vehicle Frame Rotation Calibration Routine
on page 77 for information
about this calibration procedure.
4.3.2 Rotational Offsets
The differences in orientation between the SMART7 and other SPAN components are called rotational offsets.
Rotational offsets are given as the rotation from the IMU Body frame to the frame of interest.
