Showing papers on "Inertial reference unit published in 1989"

Inertial measurement unit with aiding from roll isolated gyro

Abstract: In the present invention the inertial measurement unit system comprises a basic strapdown inertial measurement unit and an isolated fourth gyro strapped to a rotatable platform which is commanded to rotate at a rate equal to the spin rate of the vehicle body but in an opposition direction. The rotatable platform is controlled substantially by a control signal to cause the rotatable platform to turn at a rate substantially equal to the roll of the vehicle body but in an opposite direction. A signal processing means operates on (i) the output of an inertial navigational system computer representative of the rate of rotation of the inertial measurement unit along the roll axis, (ii), the output of the isolation gyro, and (iii) an output of a counter which counts the complete revolutions of the rotatable platform. In turn, an error signal is provided which is related to the rotation measurement error of the first rotation signal. In turn the error signal is fed into the navigational system computer for correction of the navigational system data for correcting that data affected by scale factor stability of the roll gyro of the inertial measurement unit.

Position aided evader maneuvering re-entry vehicle navigator

Abstract: A navigation system 12 for an evasive maneuvering reentry vehicle (EMRV) 10 includes a three-axes strapdown inertial navigator 14 which includes RLGs or other types of gyroscopes and also accelerometers. An altimeter, such as a radar altimeter 16, which is normally provided on the EMRV 10, provides an output (h) to the navigation system 12, the output being expressive of the altitude of the EMRV 10 from the earth's surface. The altitude measurement output (h) is processed by a statistical filter, such as a Kalman filter 18, in conjunction with the inertial solution (X) from the navigator 14. The output of the filter 18 is an estimated inertial correction which is combined with the inertial position and velocity output of the navigator 14 at a block 20 to yield a corrected position and velocity output. It is shown that a single altitude measurement is sufficient to derive three position and three velocity compensations for the EMRV 10.

Separation of Gravitational and Inertial Accelerations with a Combined Inertial Navigation and Gravity-Gradiometer System

Abstract: With the advent of high-precision gravity-gradiometers it seems to be necessary to reconsider whether it is advantageous to combine inertial navigation with gradiometer systems. For such a combined accelerometer-gradiometer system the equations of motion are presented. Especially the online integration of the gravitational-gradients has been investigated. For the Odenwald test-profile a numerical simulation study was carried out.