Spatial Reference Manual
Page 49 of 158
Version 4.4
04/06/2019
10 Operation
10.1 Initialisation
There are four different levels of initialisation on Spatial. These are orientation,
navigation, heading and time. Upon a cold start (more than 48 hours without power)
all four levels will typically initialise within 30 seconds and for a hot start (less than 48
hours without power) all four levels will typically initialise within 2 seconds. The
initialisation can be monitored by inspecting the status view in Spatial Manager, see
section 11.7.2.
After all four levels of initialisation, Spatial's filter takes several minutes to achieve full
accuracy. It is recommended to wait two minutes after initialisation for applications
requiring high accuracy.
10.1.1
Orientation Initialisation
Orientation initialisation occurs automatically upon power on and typically completes
within several seconds. Once orientation initialisation is complete, the roll, pitch and
angular velocity values will be valid.
When Spatial starts up, it assumes that it can be in any orientation. To determine its
orientation it uses the accelerometers to detect the gravity vector. Whilst this is
occurring, if there are random accelerations present, these can cause an incorrect
orientation to be detected. To prevent this, Spatial 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. In this scenario Spatial will progressively correct
the orientation error over a period of several seconds.
10.1.2
Navigation Initialisation
Navigation initialisation completes once the system has determined a starting
position. The most common method of navigation initialisation is for the system to get
a 3D GNSS fix. If the system is hot starting it will remember its position from when it
was switched off and use this as the starting position. The other possibility for
Illustration 20: The
four initialisation
levels
