IEEE 1559:2009 pdf free download – IEEE Standard for Inertial Systems Terminology
2.37 coning: Motion of an axis that results from a combination of oscillatory motions about perpendicularaxes and generally describes a cone.An apparent angular drift rate is generated about the coning axis equalto the solid angle swept per unit time and is a function of the amplitudes and frequencies of oscillationspresent and the phasc anglcs between them.
NOTE—In a strapdown inertial system high rate (typically on the order of hundreds or thousands of hertz) samplingand/or compensation algorithms are required for proper compensation of the apparent drift rate.
2.38 coning algorithm: An algorithm that compensates for coning motion in a strapdown inertial system.Itcombines samples from the three gyroscopes to form a coning correction that compensates for the apparentdrift rate and for finite sampling of the gyroscope outputs.Mathematically，the purpose of the coningalgorithm is to provide a high fidelity approximation of the rotation vector representing the compositerotational motion across one attitude integration or update period.High performance coning algorithmsutilize several samples of gyro data per attitude integration period.
2.39 control moment gyro: Gimbaled spinning wheel gyroscope for controlling vehicle attitude throughthe reaction caused by torquing the gimbals.
2.40 control segment (space-based radio navigation system): The ground sites of a space-based radionavigation system that obtain telemetry and tracking data,and control the satellites. They determine theorbits and monitor the health of the satellites. They send the satellite ephemeris and status data, and stationkeeping, clock correction, and other commands to the satellites.
2.41 coordinated universal time(UTC): The Greenwich atomic clock time broadcast by the national timeservices. A leap second is introduced in the time service broadcasts if required on either January 1 or July 1to keep UTC within 0.9 s of Greenwich mean solar time (UT1).
NOTE—The UTC second is the international system (SI) second.
2.42 craft rate: The angular velocity resulting from level flight over the curvature of the earth.Craft rate isVA(R.-+h), where Vis the velocity in the horizontal plane, R。 is the local radius of curvature of the earth inthe direction of V, and h is the altitude.
2.43 data fusion: The process of combining diverse types of data. Inertial systems often use data fusion tocombine inertial sensor outputs with the outputs of various aiding devices producing an output that iscommonly referred to as a blended solution. These systems are often referred to as aided or integratedincrtial systems.
NOTE—Data fusion techniques include Kalman filter and maximum likelihood estimation.
2.115 inertial navigation computations: Either the gyro outputs are used to compute the orientation of theISA with respect to the navigation frame, or are used to mechanically stabilize the ISA using gimbals orother means. The IMU accelerometer outputs are compensated for size and lever arm effects andtransformed to the navigation frame. In a mechanically stabilized system the ISA may be maintained in anavigation frame and as such the transformation is not needed. The navigation frame accelerometer outputsare compensated for the inertial rotation of the navigation frame. The modeled gravitational acceleration isadded to the compensated navigation frame accelerometer outputs. The result is numerically integrated toobtain the vehicle motion.
NOTE—In a strapdown INS,the computation rate must be high enough (typically on the order of hundreds orthousands of hertz) to reduce the effects of coning and sculling.