inertial reference unit on:
[Wikipedia]
[Google]
[Amazon]
An inertial reference unit (IRU) is a type of inertial sensor which uses gyroscopes (electromechanical, ring laser gyro or MEMS) and accelerometers (electromechanical or MEMS) to determine a moving 
Another name often used interchangeably with IRU is
Optical Inertial Reference Units (IRUs)
Navigational equipment Aircraft instruments Avionics {{technology-stub
aircraft
An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...
’s or spacecraft’s change in rotational attitude (angular orientation relative to some reference frame) and translational position (typically latitude
In geography, latitude is a geographic coordinate system, geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at t ...
, longitude and altitude
Altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum (geodesy), datum and a point or object. The exact definition and reference datum varies according to the context (e.g., aviation, geometr ...
) over a period of time. In other words, an IRU allows a device, whether airborne or submarine, to travel from one point to another without reference to external information.
Another name often used interchangeably with IRU is Inertial Measurement Unit
An inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the Orientation (geometry), orientation of the body, using a combination of accelerometers, gyroscopes, an ...
. The two basic classes of IRUs/IMUs are "gimballed" and "strapdown". The older, larger gimballed systems have become less prevalent over the years as the performance of newer, smaller strapdown systems has improved greatly via the use of solid-state sensors and advanced real-time computer algorithms. Gimballed systems are still used in some high-precision applications where strapdown performance may not be as good.
See also
* Air data inertial reference unit *Inertial measurement unit
An inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the Orientation (geometry), orientation of the body, using a combination of accelerometers, gyroscopes, an ...
External links
Optical Inertial Reference Units (IRUs)
Navigational equipment Aircraft instruments Avionics {{technology-stub