Chapter 4 SPAN Operation
CPT7 and CPT7700 Installation and Operation User Manual v12
103
Frame
Description
Notation
IMU Body frame
The physical IMU axes
(b)
Vehicle frame
Default reference frame for attitude output in SPAN logs
(v)
Mount body frame
The physical axes of the gimballed mount
(m)
Gimbal body frame
The physical axes of the gimbal plane. This frame matches the mount
body frame when gimbal angles are zero and rotates relative to the
mount body frame when the gimbal is active.
(g)
User Output Frame
An arbitrary frame, used to define the desired reference for attitude
output, typically matching a gimbal mounted sensor
(ou)
Mark Output Frame
An arbitrary frame, used to define the desired reference for attitude
output for the MARKxPVA logs, typically matching a gimbal mounted
sensor
(om)
Figure 31: Sample Configuration
on the next page and
on the next page illustrate
a basic scenario for the information in the table above.
Figure 31: Sample Configuration
shows a possible configuration for the mount body frame, IMU body frame and a user output frame, with the
gimbal in a locked position. The extra rotation commands required to configure Variable Lever Arm for this
setup are:
SETINSROTATION RBM 180 0 0
SETINSROTATION USER 0 0 90
SETINSROTATION RBV 0 0 -90
on the next page shows the gimbal in operation; the gimbal platform has moved
relative to the mount body frame. The gimbal frame and IMU Body frame move together, as does the user
output (or mark output) frame.
