IEEE 1559-2009 pdf download IEEE Standard for Inertial Systems Terminology
1.3 Related standard
Only inertial system related terms are given in this standard. lnertial sensor terms are covered inEEE Std 528.1EEE Standard for Inertial Sensor Terminology.
2. Definitions
2.1 acceleration: The time rate of change of an object’s velocity. Acceleration is the sum of gravitationalacceleration and nongravitational accelcration.
NOTE-In order to denote angular acceleration, the qualifying word “angular” must be used.
2.2 AHRS: An acronym for attitude and heading reference system.
2.3 aiding: The use of noninertial information to control the unbounded growth of inertial navigationerrors.
NOTE-Aiding types include altimeters, depth meters, odometers, air speed indicators, radars, sonars, speed logsterrain recognition, map matching, magnctomcters, magnetic compasscs, space- or terrestrial-baseid radio navigatiorsystems.stellar aiding.
2.4 air speed: The speed, cspecially of an aircraft, relative to the air.
2.5 air speed indicator: A device that measures the air speed of a vehicle.
NOTE-An air spced indicator can be used for inertial system uiding
2.6 alignment: The process of determining or controlling the orientation of the lSA relative to a referenceframe. See: gyrocompass alignment; in-flight alignment; stored hcading alignment; transferalignment.
2.7 almanac: Information transmitted by each GNSS satellite, which describes the orbits and state (healthof every satellite in the GNSS constellation. Almanac data facilitates the rapid acquisition of satellites aftetthe GNSS receiver is turned on.
NOTE-Almanac orbital data is less accurate than ephemeris data, but remains valid for a longer period of time.
28 altimeter: An instrument that measures the altitude. There are two common types, as follows?
aBarometric altimeters, which typically measure relative to sea levelblRanging altimeters, which measure relative to the local terrainNOTE-An altimeter can be used for inertial systerm aiding
2.9 altitude: The height of an object with respect to a reference level or pointNOTE-Common reference levels include the geoid and the ellipsoid,
210 analytic platform frame: A rectangular coordinate system into which the ISA frame outputs aretransformed.
NOTE-The analytic platform frame is the mathematical equivalent of the stabilized platform frame in a gimbaledIMU.
2.11 angular acceleration: The time rate of change of an objects angular velocity
2.12 anti-spoofing (A-S): Use of encryption to prevent false GNSS transmissions from corrupting the trueGNSS transmissions.
2.13 A-S: An abbreviation for anti-spoofing
2.14 atomic clock: A clock that is slaved to the frequency provided by an atomic transition.
NOTE 1–The cesium atomic clock provides the fundamental definition of the SI second, with a present accuracy of apart in 1014
NOTE 2–Atomic clocks are used to generate reference time systems, such as UTC and navigation satellite time.
2.15 attitude: The orientation of a vehicle with respect to a reference frame.
NOTE–In local level mechanizations attitude is usually expressed by roll, pitch, and yaw angles.
2.16 attitude and heading reference system (AHRS): An inertial system that estimates the attitude andheading of a vehicle. The attitude is with respect to the local level coordinate system.
2.17 attitude integration: The process of integrating gyroscope data in three dimensions to provideorientation of an ISA relative to a reference coordinate frame. Attitude integration must account for non-commutativity of rotations and commonly uses quaternions or direction cosine matrices. See: directioncosine matrix integration algorithm; quaternion integration algorithm.