ZED-F9R - Integration manual
misalignment angles output in the UBX-ESF-ALG are not stable in time. Note however that
each individual set of IMU-mount misalignment angles output in such a case still describes the
correct rotation. Moreover, the internal rotation applied for aligning the IMU readings does not
suffer from this singularity issue and optimal fusion can still be achieved.
3.2.6.4 Navigation output
3.2.6.4.1 Local-level north-east-down (NED) frame
The local-level frame is a geodetic frame with the following features:
• The origin (O) is a point on the Earth's surface;
• The x-axis points to north;
• The y-axis points to east;
• The z-axis completes the right-handed reference system by pointing down.
The frame is referred to as North-East-Down (NED) since its axes are aligned with the North, East
and down directions.
3.2.6.4.2 Vehicle frame
The vehicle frame is a right-handed 3D Cartesian frame rigidly connected with the vehicle and is
used to determine the attitude of the vehicle with respect to the local-level frame. It has the following
features:
• The origin (O) is the VRP;
• The x-axis points towards the front of the vehicle;
• The y-axis points towards the right of the vehicle;
• The z-axis completes the right-handed reference system by pointing down.
3.2.6.4.3 Vehicle position and velocity output
The position and velocity information is output in several messages, for example, UBX-NAV-PVT.
Position and velocity computed by the HPS navigation filter are referenced to the IRP.
3.2.6.4.4 Vehicle attitude output
The transformation between the vehicle-frame and the local-level frame is described by three
attitude angles about the local-level axes denoted as
vehicle roll
,
vehicle pitch
and
vehicle heading
.
All three angles are referred to as
vehicle attitude
and are illustrated in the figure below:
UBX-20039643 - R01
3 Receiver functionality
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Advance information
