Inertial reference unit

An Inertial Reference Unit (IRU) is a type of Inertial guidance system which uses only gyroscopes to determine a moving aircraft’s or spacecraft’s change in angular direction (referred to as "delta-theta" or Δθ) over a period of time. Unlike the Inertial Measurement Unit, IRUs are generally not equipped with accelerometers, which measure acceleration forces.

IRUs are used for attitude control and navigation of vehicle’s with relatively constant acceleration rates, such as geosynchronous satellites and deep space probes.

See also

• Optical Inertial Reference Units (IRUs)