Applanix POS MV V5 Installation And Operation Manual page 216

POS MV V5 Installation and Operation Guide
Theory
of Operation
Inertial Frame
The inertial frame of reference is a Newtonian reference frame that experiences zero specific force
and angular rate of its own. It is an absolute frame of reference and has a fixed, convenient
orientation in space.
Earth Frame
The Earth co-ordinate frame is fixed to the Earth with its axis arranged as follows:
• The x-axis coincides with the axis of Earth rotation.
• The z-axis is in the equatorial plane at zero longitude (on the Greenwich meridian).
• The y-axis completes the right-handed orthogonal frame.
Note: This definition of the Earth frame differs from the WGS-84 definition in which the z-axis
coincides with the Earth rotation axis and the x-axis coincides with the intersection of the Greenwich
meridian and the equator.
The Earth frame rotates relative to the inertial frame at a nominal 15°/hr (or, more accurately,
15.04107°/hr).
Geographic Navigation Frame
The geographic navigation frame is a locally level frame of reference. The north and east axis are
tangential to the Earth surface at the current latitude and longitude, and are defined by the north and
east directions respectively.
The third axis of the geographic navigation frame is the down axis and is a local vertical that passes
through the centre of the Earth.
Body Frame
The body frame is a co-ordinate frame fixed to the vessel with its axis arranged as follows:
• The x-axis coincides with the surveyed fore-aft line of the vessel.
• The y-axis is perpendicular to the x-axis and coincides with the port-starboard line of the
vessel.
• The z-axis is perpendicular to both the x- and the y-axis and coincides with the surveyed
vertical of the vessel.
IMU Body Frame
The IMU body frame uses the right-handed orthogonal co-ordinate system with its origin at the
sensing centre of the IMU. These axis are fixed relative to the IMU and are marked by a label on the
IMU housing.
B-6
Copyright © Applanix Corporation, 2017