Figure 23: Initialisation Levels
After all four levels of initialisation, the Boreas INS filter takes several minutes to achieve its full accuracy. It is
recommended to wait two minutes after initialisation for applications requiring high accuracy.
8.1.1 Orientation Initialisation
Orientation initialisation occurs automatically upon power on and typically completes within seconds. To
determine its orientation it uses the accelerometers to measure the gravity vector. Random accelerations from
environmental sources can disturb this process, which can introduce minor orientation errors that will be
corrected within several seconds. To prevent this, Boreas monitors the accelerometers and gyroscopes and
restarts the orientation detection if there are sudden movements. It is however still possible under some
circumstances for it to miss minor movements and start with a small orientation error. Boreas will progressively
correct the orientation error over a period of several seconds.
Once orientation initialisation is complete, the roll, pitch and angular velocity values will be valid.
8.1.2 Navigation Initialisation
Navigation initialisation completes once the system has determined a starting absolute position. The most
common method of navigation initialisation is for the system to get a 3D GNSS fix or better. If the system is hot-
starting it will remember its position at the time it was switched off and use this as the starting position. The other
possibility for navigation initialisation is an external position source to be used, see 11.4.25 External Position
Packet for more information. In a situation where a GNSS fix is not available to initialise navigation, it can be
initialised manually by entering a position into the 9.1.3.9 Manual Initialisation page in the web UI or in Boreas
Manager.
Once navigation initialisation is complete, the position, velocity and acceleration values will be valid.
8.1.3 Heading Initialisation
Heading initialisation completes once the system has determined a heading using one of its several methods.
The conditions required to determine a heading depend upon the heading source being used, see 8.4 Heading
Sources The default heading source is dual antenna, which will initialise the heading to a high accuracy within
several minutes of power on assuming that both antennas are connected with an unobstructed view of the sky.
The system can be stationary or moving during this initialisation. If velocity heading is enabled and the vehicle is
moving, this will be very fast. If the system is hot-starting then it will use the heading from the heading from
when it was last switched off as the starting heading until another source becomes available.
Until the heading has been initialised, the system will not be able to navigate without a GNSS fix, and the roll
and pitch values will not reach full accuracy.
v1.2 Page 39 11 Oct 2022
Boreas Reference Manual • Using Boreas
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