Spatial Reference Manual
Page 47 of 158
Version 4.4
04/06/2019
9.7
Magnetics
Spatial contains magnetometers which it uses to measure the Earth's magnetic field in
order to determine its heading. The principle is the same as that of a compass. When
operating Spatial with magnetic heading enabled, sources of magnetic interference
can degrade Spatial's solution if not compensated for. There are two types of magnetic
interference, these are static and dynamic.
Static magnetic interference is caused by steel and other magnetic materials mounted
in the vehicle. Static disturbances are easily compensated for by running a magnetic
calibration, see section 10.5. A magnetic calibration should always be run after
installation into a vehicle.
Dynamic magnetic interference is generally a much bigger issue. Sources of dynamic
magnetic interference include high current wiring, electric motors, servos, solenoids
and large masses of steel that don't move with Spatial. Spatial should be mounted as
far as possible from these interference sources.
Spatial contains a special algorithm to remove the effects of dynamic magnetic
interference. This is able to compensate for most typical interference sources
encountered, however certain types of prolonged dynamic interference cannot be
compensated for. The best way to check for dynamic magnetic interference is to use
the raw sensors view in Spatial Manager and watch the magnetometer outputs whilst
the vehicle is operating but stationary, see section 11.7.4. The values should be
constant, if the values are fluctuating there is dynamic magnetic interference present.
If dynamic magnetic interference is causing performance problems and there is no
way to mount Spatial away from the interference source, the magnetometers should
be disabled, see section 10.5.4.
9.8
Vibration
Spatial is able to tolerate a high level of vibration compared to other inertial systems.
This is due to a unique gyroscope design and a special filtering algorithm. There is
however a limit to the amount of vibration that Spatial can tolerate and large levels of
vibration will cause Spatial's accuracy to degrade.
When mounting Spatial to a platform with vibration there are several options. It is
recommended to first try mounting Spatial and see whether it can tolerate the
vibrations. The raw sensor view in the Spatial Manager software can give you a good
idea of how bad the vibrations are, see section 11.7.4. If the vibrations are causing the
sensors to go over range you will need to increase the sensors range, see section
10.6.
If you are unsure about your vibration level, we recommend emailing a Spatial log file
of the vibration to
for feedback.
If Spatial is unable to tolerate the vibrations there are several options:
1. Try to find a mounting point with less vibration.
2. Spatial can be mounted with 3M foam rubber double sided tape or a small flat
piece of rubber.
