SETINSTRANSLATION

Specifies translational offsets between the IMU frame and other reference frames

Platform:

OEM719, OEM729, OEM7500, OEM7600, OEM7700, OEM7720, PwrPak7, CPT7, CPT7700, SMART7-S

Use the SETINSTRANSLATION command to specify translational offsets between the IMU frame and other reference frames, including GNSS antennas or the desired output frame. Offsets must be entered as the vector from the IMU, to the frame or position of interest. Offsets can be entered either in the IMU body frame, or the vehicle frame; offsets in the vehicle frame will be automatically rotated into the IMU body frame using the best available IMU Body to Vehicle Rotation (RBV).

For details on entering the RBV rotation or other angular offsets, see the SETINSROTATION command.

Message ID: 1920

Abbreviated ASCII syntax:

SETINSTRANSLATION INSTranslation XTranslation YTranslation ZTranslation [XTranslationSD] [YTranslationSD] [ZTranslationSD] [InputFrame]

Abbreviated ASCII example:

SETINSTRANSLATION USER 1.0 2.0 3.0 0.05 0.05 0.05 VEHICLE

Field	Field type	ASCII value	Binary value	Description	Format	Binary bytes	Binary offset
1	Command header	-	-	SETINSTRANSLATION header This field contains the command name for abbreviated ASCII or the message header for ASCII or Binary.	-	H	0
2	InsTranslation	See Table: Translation offset types		Translation offset to be set	Enum	4	H
3	XTranslation	±100		X translation offset from IMU origin (m)	Float Array [3]	12	H+4
	YTranslation	±100		Y translation offset from IMU origin (m)
	ZTranslation	±100		Z translation offset from IMU origin (m)
4	XTranslationSD	0 to 10		Optional X translation offset standard deviation (m)	Float Array [3]	12	H+16
	YTranslationSD	0 to 10		Optional Y translation offset standard deviation (m)
	ZTranslationSD	0 to 10		Optional Z translation offset standard deviation (m)
5	InputFrame	Table: Translation input frame		Optional input frame for translation offset values	Enum	4	H+28

For the ANT1, ANT2, EXTERNAL and GIMBAL translations, the standard deviation defaults are set to 10% of the translation value (up to a max of 10 metres).

The offset standard deviation values are not optional when entering a value for the Input Frame.

For USER translations, standard deviation values are assumed to be zero unless specified by the user. When a USER offset is configured in the system, the INS solution standard deviations calculated at the IMU centre of navigation will be propagated taking into account the INS attitude errors, USER offset values, and the USER offset standard deviations. This will result in larger scale INS position and velocity standard deviations compared to those calculated without a USER offset configured, but will be more representative of the estimated variance at the location of interest.

It is important to keep in mind that as the USER offset is moved further from the IMU centre of navigation, the PVA solution will become noisier due to the projection of angular changes over a longer distance.

For MARK1, MARK2, MARK3 and MARK4 translations, standard deviations values are not used in the solution.

Large translation standard deviations can lead to an inaccurate INS position and velocity solution. Therefore, it is highly recommended to measure translation offsets as accurately as possible and to manually enter translation offset standard deviations that reflect that accuracy.

Translation offset types
ASCII	Binary	Description
ANT1	1	Offset from the IMU centre of navigation to the phase centre of the primary GNSS antenna. The standard deviation defaults are set to 10% of the translation value (up to a max of 10 meters). Do not use the ANT1 option (SETINSTRANSLATION ANT1) on a SMART7-S. The correct lever arm value has been set at the factory.
ANT2	2	Offset from the IMU centre of navigation to the phase centre of the secondary GNSS antenna. The standard deviation defaults are set to 10% of the translation value (up to a max of 10 meters). Do not enter an ANT2 translation offset that is identical to the ANT1 offset. If the translation offsets are identical, SPAN will not be able to compute a valid SETINSROTATION ALIGN rotation.
EXTERNAL	3	Offset from the IMU centre of navigation to the external position source location. This offset type is for use with the EXTERNALPVAS command. The standard deviation defaults are set to 10% of the translation value (up to a max of 10 meters).
USER	4	Translation from the IMU centre of navigation to the new common position and velocity output location. This offset shifts the position and velocity information in the standard INS positioning logs. USERVEL and/or USERPOS offsets will be applied on top of this offset. It is recommended to just use USERPOS/USERVEL. The standard deviation defaults are set to 0.
MARK1	5	Translation from the IMU centre of navigation to the MARK1 output location. This offset shifts the position and velocity information in the MARK1PVA log. The standard deviation values are not used in the solution. The default values are set to 0.
MARK2	6	Translation from the IMU centre of navigation to the MARK2 output location. This offset shifts the position and velocity information in the MARK2PVA log. The standard deviation values are not used in the solution. The default values are set to 0.
GIMBAL	7	Translation from the IMU centre of navigation to the gimbal mount centre of rotation. The standard deviation defaults are set to 10% of the translation value (up to a max of 10 meters).
MARK3	9	Translation from the IMU centre of navigation to the MARK3 output location. This offset shifts the position and velocity information in the MARK3PVA log. The standard deviation values are not used in the solution. The default values are set to 0.
MARK4	10	Translation from the IMU centre of navigation to the MARK4 output location. This offset shifts the position and velocity information in the MARK4PVA log. The standard deviation values are not used in the solution. The default values are set to 0.
USERVEL	19	Translation of INS velocity from common INS output location (IMU centre of navigation, or USER offset if it exists) to the defined location. The covariances calculated from the entered standard deviations are added with those entered in USER offset should it exist. This offset shifts the velocity information in the standard INS positioning logs. See Output location for logs. The standard deviation defaults are set to 0.
USERPOS	20	Translation of INS position from common INS output location (IMU centre of navigation, or USER offset if it exists) to defined location. The covariances calculated from the entered standard deviations are added with those entered in USER offset should it exist. This offset shifts the position information in the standard INS positioning logs. See Output location for logs. The standard deviation defaults are set to 0.

Translation input frame
ASCII	Binary	Description
IMUBODY	0	Offset is provided in the IMU enclosure frame. Default: IMUBODY
VEHICLE	1	Offset is provided in the vehicle frame. Offsets entered in the vehicle frame will be automatically rotated into the IMU frame using the best available RBV (rotation from IMU Body to Vehicle) information when required. Vehicle frame offsets should only be used if the RBV is known accurately, either though user measurement or calibration. The order of entry for vehicle frame offsets and the RBV rotation does not matter.