Litton Systems, Inc.

Northrop Grumman Systems Corporation

Peter Kyriacou

Daniel A Tazartes

John G Mark

Robert John Buchler

Shaw-Wen Fann

James G Marsden

A method for attitude alignment of a slave inertial measurement system connected to a rotationally mobile platform supported by a vehicle that is stationary relative to a reference navigation frame comprises the steps of mounting a master reference inertial measurement system on the rotationally mobile platform and determining a master reference system attitude using measurements of acceleration and angular rates of the master reference inertial measurement system relative to the reference navigation frame. A slave system attitude is determined using measurements of acceleration and angular rates of the slave inertial measurement system relative to a slave system navigation reference frame and comparing the slave system attitude to the master reference system attitude to determine an attitude difference. The attitude difference is processed to obtain a correction to the slave system attitude.

Attitude alignment of a slave inertial measurement system

A system and method for performing high performance quantizer processing of sensor data in a multiple-channel quantizer system. A reset prioritization scheme is provided for current sources connected to an integrator in the multiple-channel quantizer for preventing saturation of the various quantizer channels. The reset prioritization scheme determines the channels most in need of a reset to prevent saturation based upon predicted quantizer signals to appear on the channels during the next processing cycle of the quantizer system. This method of controlling the reset processing permits significantly higher acceleration capacity by preventing quantizer channel saturation in system utilizing accelerometers. The quantizer processing method further includes an improved calibration scheme for self-calibrating the various channels in a multiple-channel quantizer to account for multiple sources of error, including quantizer bias, asymmetry between applied positive and negative resets, and voltage scale factor of the quantizer channel in calibration.

System and method for providing high performance quantizer processing

The invention is a method for compensating for fringe visibility errors in a fiber-optic gyro. The light beam phase is modulated utilizing a phase-modulation generating function comprising a stepped waveform with steps of height 2.pi.k-.phi..sub.SE +j.phi..sub.M -.gamma..sub.ZS at time intervals .tau. where a phase step .phi. specified by the phase-modulation generating function is transformed into a change in light-beam phase of (.phi..sub.X /X).phi..sub.X where .phi..sub.X is the change in light phase produced by a phase step X. The integer k takes on the value -1, 0, or 1, j takes on the value -1 or 1, .phi..sub.SE is a phase determined by the fiber-optic gyro, .phi..sub.M is a predetermined phase value, and .gamma..sub.ZS is a phase designed to compensate for the fringe visibility errors. The phase .gamma..sub.ZS represents a small perturbation to the modulation and is a function of zone Z and state S where the zone identifier Z and state identifier S denote one of a plurality of operating conditions of the fiber-optic gyro. The zone identifier Z depends on the relative magnitudes and signs of .phi..sub.SE and .phi..sub.M, and the state identifier S is a function of k and j. Estimates of the Sagnac residual phase compensated for fringe visibility errors are then obtained by adding calculated fringe visibility compensation terms to .phi..sub.SE.

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Sun Valley, CA, United States of America

Peter Kyriacou