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Document MT0605P.2018.E
© Xsens Technologies B.V.
MTi User Manual
magnetic field alone, a homogenous or calibrated-for magnetic field is essential for good-performance
yaw. Other parameters are tuned the same as in the General filter profile.
The
Automotive
filter profile assumes that the yaw of the MTi-G-710 is also the GNSS course over
ground (holonomic constraints). This assumption holds for most automotive/ground vehicles, except for
those who experience side slip, such as racing cars, tracked vehicles, some articulated vehicles
(depending on where the MTi-G-710 is mounted) and vehicles driving on rough terrain. The Automotive
filter profile thus uses GNSS to determine the yaw. Note that it is essential to mount MTi-G exactly in
the direction of movement in order to prevent an offset. Please refer to 5.2.3 for proper mounting. When
GNSS is lost, yaw will be determined by the velocity estimation algorithm for 60 seconds, before yaw is
determined by gyroscopes integration only. Should GNSS outages recur regularly or if you have bad
GNSS-availability (e.g. in urban canyons), consider using HighPerformanceEDR.
The
HighPerformanceEDR
filter profile replaces the previously available AutomotiveUrbanCanyon filter
profile. This filter profile is specially designed for ground-based navigation applications where
deteriorated GNSS conditions and GNSS outages (0-60s) are a regular feature. Note that the accuracy
of position, velocity and orientation estimates may still deteriorate during GNSS outages. This filter
profile does not use the holonomic constraints and thereby removes the need for mounting
considerations. Target applications: slow moving ground vehicles and locomotive navigation. The filter
profile HighPerformanceEDR automatically estimates the gyro bias when the MTi is not moving. The
sensor fusion algorithm detects when the MTi is motionless. Vibrations and very slow movements may
influence the accuracy of the gyro bias estimation.
Every application is different and although example applications are listed above, results may vary from
setup to setup. It is recommended to reprocess recorded data with different filter profiles in MT Manager
to determine the best results in your specific application.
4.3.5 GNSS Platform
u-blox receivers support different dynamic platform models in order to adjust the navigation engine to
the expected application environment. The MTi-G-710 can be configured to communicate a desired
platform model upon start-up. This enables the user to adjust the u-blox receiver platform to match the
dynamics of an application. The setting influences the estimates of Position and Velocity and therefore
it affects the behaviour of the Xsens filter output. Currently, only the Portable (default) and Airborne
(<4g) platforms are supported.
The platform model can be configured using MT Manager [MTM] or low-level communication [LLCP].
For more details on GNSS platform settings, refer to the u-blox Receiver Description Manual.
4.4 Active Heading Stabilization (AHS)
One powerful feature when it comes to heading estimation is Active Heading stabilization (AHS). The
AHS is a software component within the sensor fusion engine designed to give low-drift unreferenced
heading solution This way, drift in heading can be as low as 1° after 60 minutes for the MTi 100-series
and 3° after 60 minutes for the MTi 10-series. When the magnetic field is disturbed, AHS will still function.
There is one known situation where AHS will have a detrimental effect on the performance. When the
magnetic field is changing very slowly (e.g. when an object is rotating slowly, less than e.g. 0.5 °/s), AHS
might estimate the gyro bias incorrectly.
In the past, only the "vru_general" filter profile used AHS. However now AHS has been introduced as
an option to all filter profiles for all sensors. AHS is available but is considered to be in beta for our