Commands
Appendix B
SPAN-SE User Manual Rev 1
139
B.4.31 SETINITATTITUDE
Set initial attitude of SPAN in degrees
This command allows you to input a known attitude to start SPAN operation, rather than the usual
coarse alignment process. The caveats and special conditions of this command are listed below:
•
This alignment is instantaneous based on the user input. This allows for faster system startup;
however, the input values must be accurate or SPAN will not perform well.
•
If you are uncertain about the standard deviation of the angles you are entering, err on the side of
a larger standard deviation.
•
Sending SETINITATTITUDE resets the SPAN filter. The alignment is instantaneous, but some
time and vehicle dynamics are required for the SPAN filter to converge. Bridging performance is
poor before filter convergence.
•
The roll (about the y-axis), pitch (about the x-axis), and azimuth (about the z-axis) are with
respect to the SPAN frame. If the IMU enclosure is mounted with the z axis pointing upwards, the
SPAN frame is the same as the markings on the enclosure. If the IMU is mounted in another way,
SPAN transforms the SPAN frame axes such that z points up for SPAN computations. You must
enter the angles in SETINITATTITUDE with respect to the transformed axis. See
SETIMUORIENTATION for a description of the axes mapping that occurs when the IMU is
mounted differently from z up.
•
This command is not save configurable (see the SAVECONFIG command on
) and, if
needed, must be entered at startup.
1. Azimuth is positive in a clockwise direction when looking towards the z-axis origin.
2. You do not have to use the SETIMUORIENTATION command, see
unless
you
have your IMU mounted with the z axis not pointing up. Then use the tables in the
SETIMURIENTATION command, on
, to determine the azimuth axis that
SPAN is using.
Abbreviated ASCII Syntax:
Message ID: 862
SETINITATTITUDE pitch roll azimuth pitchSTD rollSTD azSTD
