公开(公告)号：DE69826373T2

公开(公告)日：2005-09-29

申请号：DE69826373

申请日：1998-06-24

Applicant: LITTON SYSTEMS INC

Inventor： WYSE STANLEY F ,  TAZARTES DANIEL A ,  FLAMM JUERGEN K P ,  LEE CHARLES A

IPC: G01C19/5705 ,  G01C19/5776 ,  G01C19/56 ,  G01P9/04

Abstract: A dithered Coriolis acceleration sensor system has a proof mass that is free of feedback in the accelerometer servo loop at the dither frequency by totally notching out all feedback torque at this frequency. The proof mass relative motion is then a direct measure of the rate because there is no feedback torque to alter the proof mass response to the acceleration. The feedback modulation system according to the invention captures the Coriolis-sensor output such that the phase and gain of the signal generated from the sensor are of no concern in maintaining good scale factor.

公开(公告)号：DE69903203T2

公开(公告)日：2003-08-28

申请号：DE69903203

申请日：1999-02-04

Applicant: LITTON SYSTEMS INC

Inventor： TAZARTES DANIEL A ,  MARK JOHN G ,  WELKER JAMES G

IPC: G01C19/72

Abstract: The invention is a method for improving the performance of a fiber-optic gyro comprising counter-propagating light beams from a broadband source in an optical fiber configured as a coil. The fiber-optic gyro is of the type where the phases of the light beams are step-modulated at one or both ends of the optical fiber at time intervals equal to the light propagation time tau through the optical fiber, the step being in the range from 0 to 2 pi - delta radians where delta is an infinitesimal. The step is the sum of an estimate of the Sagnac phase residual phi SE with reversed sign and the quantity (2 pi k + j phi M) where the index k can take on the values -1, 0, and 1, and the index j can take on the values -1 and 1. The phase angle phi M is a positive constant less than pi radians. The method comprises the steps of determining the interferometer output light intensity, determining the Sagnac fringe number n , calculating the error Pnkj in the interferometer output light intensity attributable to the use of a broadband light-beam source for particular values of an index pair (k,j), determining estimates Akj of the probabilities of the index pairs (k,j) by counting the occurrences of each index pair (k,j) over a period of time, and determining the bias epsilon in the output of a fiber-optic gyro. The bias epsilon can be made independent of the Sagnac fringe number by proper design of the statistical properties of the phase modulating function.

公开(公告)号：DE69624057T2

公开(公告)日：2003-06-12

申请号：DE69624057

申请日：1996-07-25

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  TAZARTES DAVID I ,  TAZARTES DANIEL A

IPC: G01C19/72

Abstract: A loop controller for a fiber optic gyroscope employs distributed data processing to compress numerous additional useful functions into each loop transit time. The architecture of the loop controller (10) includes a field programmable gate array (36) for generating variables of varying sign. In addition, the array (36) acts to buffer the transmission of parameters between a gyro processor (32) and an auxiliary processor (34). The auxiliary processor (34) updates such parameters (which do not require updating every loop transit time) and a number of such parameters are multiplied by values generated by the array in operations performed by the gyro processor (32) that replace what would otherwise require throughput intensive test and branch operations. The combination of the offloading of selected variable and parameter generation and updating with programming of the gyro processor for parallel processing permits the loop controller (10) to perform numerous useful operations not previously possible during a realistic loop transit time.

公开(公告)号：CA2246974A1

公开(公告)日：1999-10-23

申请号：CA2246974

申请日：1998-09-14

Applicant: LITTON SYSTEMS INC

Inventor： TAZARTES DANIEL A ,  LITMANOVICH YURY A ,  MARK JOHN G

IPC: G01C21/16

Abstract: The invention is a method and apparatus for updating the attitude of a body by utilizing a plurality of gyros to measure as a function of time the angular rate vector or the integrated angular rate vector for the body. The method comprises the steps of (1) obtaining measured values of the angular rate vector at a plurality of readout intervals, (2) obtaining a smoothed value of each of one or more smoothed representations of the angular rate vector at the end of each of a plurality of smoothing intervals, and (3) obtaining the updated attitude of the body at the end of an update interval by utilizing the attitude at the beginning of the update interval and the smoothed values of the smoothed representations of the angular rate vector obtained during the update interval. A smoothed representation is a weighted sum of the measured values obtained during a smoothing interval. The attitude is updated at the end of an update interval by applying a rotation vector to the attitude at the end of the prior update interval, the rotation vector being a weighted sum of (1) a plurality of the smoothed values and (2) the values of a plurality of cross-products of the smoothed values, the smoothed values having been obtained during the update interval.

公开(公告)号：CA2238904A1

公开(公告)日：1999-01-15

申请号：CA2238904

申请日：1998-05-28

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  TAZARTES DANIEL A

IPC: G01C19/72

Abstract: A closed-loop system for regulating a fiber optic gyroscope is configured so that the residual error of a so-called deadbeat system assumes a higher order function of frequency. The closed-loop gyro includes a rate controller within the feedback path. The rate controller receives the gyro output from the last loop transit corrected for d.c. offset and for nominal dither and outputs a gyro rate estimate. The rate controller includes a plurality of feedback integrators in cascaded relationship. In this way, the residual gyro error associated with inherent loop delay is elevated to a higher-order relationship to sensed gyro rate. As a result, a substantial reduction in residual error as a function of sensed gyro rate occurs throughout the range of operational gyro frequencies.

公开(公告)号：CA2202433A1

公开(公告)日：1998-10-11

申请号：CA2202433

申请日：1997-04-11

Applicant: LITTON SYSTEMS INC

Inventor： TAZARTES DANIEL A ,  MARK JOHN G ,  CORDOVA AMADO

IPC: G01C19/72

Abstract: A phase modulator applies sequences of artificial phase shifts in the region of overmodulation between light beams counterpropagating within the sensor coil of a Sagnac interferometer to obtain improved random walk performance. The sequences are composed of phase shifts of ~a.pi./2b and ~(4b-a).pi./2b where a is an odd integer and b is an integer greater than 1. The waveform for driving the phase modulator is derived from a 2.pi. radian mapping plotted so that adjacent driving signal values differ by a.pi./2b or -(4b-a).pi./2b in a first angular direction and by -a.pi./2b or by (4b-a).pi./2b in the opposite angular direction. Angular transitions about the mapping may be predetermined to generate a deterministic, random, or pseudo-random modulation sequence. In the event that a deterministic sequence is chosen, it is examined for orthogonality properties to assume zero average output bias from crosstalk.

公开(公告)号：DE69406239T2

公开(公告)日：1998-02-19

申请号：DE69406239

申请日：1994-07-20

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  MCLANE DANIEL P ,  TAZARTES DANIEL A ,  WYSE STANLEY F

IPC: G01P15/00 ,  G01P15/13

Abstract: A closed-loop accelerometer (10) has a rebalance loop (14) controlled by a first clock and the output of which loop is supplied to a utilization circuit (24) controlled by a second clock (22). The loop and the utilization circuit are coupled by a converter which converts the output of the loop into a stream of pulses distributed over one accelerometer rebalance-cycle period, these pulses being sampled over the period of the second clock and counted to produce a count which is delivered to the utilization circuit (24). There are means (29) responsive to the output of the second clock (22) for gating the pulse count to the utilization circuit (24).

公开(公告)号：DE4212998A1

公开(公告)日：1996-07-04

申请号：DE4212998

申请日：1992-04-21

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  TAZARTES DANIEL A ,  EBNER ROBERT E ,  DAHLEN NEAL J ,  DATTA NIBIR K

IPC: G01C19/66 ,  H01S3/083 ,  H03H15/00 ,  H03H17/00 ,  G01P15/14

公开(公告)号：GB2254184B

公开(公告)日：1994-11-23

申请号：GB9200476

申请日：1992-01-10

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  TAZARTES DANIEL A

IPC: G01C19/66 ,  H01S3/139 ,  H01S3/083

Abstract: A ring laser gyro having a ring laser that preferably has four legs and four corner mirrors. At least one of the corner mirror is partly transmissive, and the transmitted beam is sensed and converted into a digital signal. The digital signal is fed back in two computer loops to at least one digital-to-analog converter, and thence to a transducer which drives at least one corner mirror inward and outward. One of the computer loops includes a stepped demodulator having four steps per cycle. The steps have voltages at the operating voltage of the transducer, that voltage plus an increment, the operating voltage, and that voltage less a decrement. The first loop sends an operating voltage to the digital-to-analog converters. The second loop demodulates the beam signal at a second harmonic of the demodulation of the first loop to produce a voltage signal which controls the amplitude of dithering of the movable mirrors. A stepped modulator, in synchronism with the demodulator of the first loop, delivers a modulation signal to the digital-to-analog converters to step the movable mirrors. The operating voltage moves the mirrors into a position wherein the laser cavity operates at its intensity mode peaks.

公开(公告)号：ITRM920287A1

公开(公告)日：1993-10-17

申请号：ITRM920287

申请日：1992-04-17

Applicant: LITTON SYSTEMS INC

Inventor： DAHLEN NEAL J ,  EBNER E ROBERT ,  MARK JOHN G ,  TAZARTES DANIEL A

IPC: G01C19/66 ,  G01S20060101 ,  H01S3/083 ,  H03H15/00 ,  H03H17/00