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    Automatic gain control of a closed loop fiber optic gyroscope using non-linear control laws
    31.
    发明专利
    Automatic gain control of a closed loop fiber optic gyroscope using non-linear control laws 未知

    公开(公告)号：AU7901301A

    公开(公告)日：2002-02-13

    申请号：AU7901301

    申请日：2001-07-25

    Applicant: LITTON SYSTEMS INC

    Inventor： TAZARTES DANIEL A ,  WELKER JAMES G

    IPC: H03G3/30

    Abstract: A closed loop gain circuit controls the gain of a variable gain amplifier and provides a stable AGC response irrespective of the actual gain level. The amplifier may be arranged to amplify electrical signals output from a fiber optic gyroscope. A perturbation injection circuit provides a perturbation signal ±d to a phase modulator connected to the fiber optic gyro. A perturbation compensation circuit applies perturbation compensation signals to signals output from the variable gain amplifier and produces a compensated signal by reducing the magnitude of the perturbation in the amplified signal output from the variable gain amplifier. A gain error circuit connected to the perturbation compensation circuit produces a gain error signal that indicates the magnitude of the perturbation signal remaining in the amplified signal after perturbation compensation. A feedback system provides a gain control signal to the variable gain amplifier to reduce the magnitude of the gain error signal.

    METHOD FOR IMPROVING THE PERFORMANCE OF FIBER-OPTIC GYROS
    33.
    发明专利
    METHOD FOR IMPROVING THE PERFORMANCE OF FIBER-OPTIC GYROS 未知

    公开(公告)号：CA2254493A1

    公开(公告)日：1999-08-06

    申请号：CA2254493

    申请日：1998-11-25

    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 ~ 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 ~SE with reversed sign and the quantity (2.pi.k + j~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 ~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 P nkj in the interferometer output light intensity attributable to the use of a broadband light-beam source for particular values of an index pair (kj), determining estimates (A kj) of the probabilities of the index pairs (kj) by counting the occurrences of each index pair (kj) 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.

    COMPUTER GENERATED CAVITY LENGTH CONTROL WITH AUTOMATIC GAIN CONTROL FOR LASER GYROS
    35.
    发明专利
    COMPUTER GENERATED CAVITY LENGTH CONTROL WITH AUTOMATIC GAIN CONTROL FOR LASER GYROS 未知

    公开(公告)号：CA2048357C

    公开(公告)日：1995-12-19

    申请号：CA2048357

    申请日：1991-08-02

    Applicant: LITTON SYSTEMS INC

    Inventor： MARK JOHN G ,  TAZARTES DANIEL A

    IPC: G01C19/66

    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 loops demodulates the beam signal at a second harmonic of the demodulation of the first loop to produce a voltage signal which controlsthe 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 digitalto-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.

    38.
    发明专利
    未知

    公开(公告)号：DE69733301D1

    公开(公告)日：2005-06-23

    申请号：DE69733301

    申请日：1997-10-28

    Applicant: LITTON SYSTEMS INC

    Inventor： MARK JOHN G ,  TAZARTES DANIEL A

    IPC: G01C21/16

    Abstract: The invention is a method and apparatus for compensating for sculling in a strapdown inertial navigation system. The method operates on a sequence of inputs DELTA VB(n) derived at times n DELTA t from the outputs of one or more accelerometers. Separately compensated quantities DELTA VBc(m,p) calculated at times (pJ+1/2 ) DELTA t for M values of m are obtained by summing A(m,k) DELTA VB(pJ-j-k) over k from 0 to K-1 and over j from 0 to J-1 where the constants A(m,k) are chosen to minimize sculling error in the individual DELTA VNc(m,p) quantities where DELTA VNc(m,p) is the representation of DELTA VBc(m,p) in the navigation frame of reference. The final compensated quantity DELTA VBc(p) is obtained by summing B(m) DELTA VBc(m,p) over m where the constants B(m) are chosen to minimize sculling error in DELTA VNc(p) where DELTA VNc(p) is the representation of DELTA VBc(p) in the navigation frame of reference.

    SCULLING COMPENSATION IN STRAPDOWN INERTIAL NAVIGATION SYSTEMS
    40.
    发明专利
    SCULLING COMPENSATION IN STRAPDOWN INERTIAL NAVIGATION SYSTEMS 未知

    公开(公告)号：CA2218014A1

    公开(公告)日：1998-05-01

    申请号：CA2218014

    申请日：1997-10-10

    Applicant: LITTON SYSTEMS INC

    Inventor： MARK JOHN G ,  TAZARTES DANIEL A

    IPC: G01C21/16 ,  G01C25/00 ,  G01C23/00 ,  G06F17/10

    Abstract: The invention is a method and apparatus for compensating for sculling in a strap down inertial navigation system. The method operates on a sequence of inputs .DELTA.V B(n) derived at times n.DELTA.t from the outputs of one or more accelerometers. Separately compe nsated quantities .DELTA.VBc(m,p) calculated at times (pJ+1/2).DELTA.t for M values of m are obtai ned by summing A(m,k).DELTA.VB(pJ-j-k) over k from 0 to K-1 and over j from 0 to J-1 where the constants A(m,k) are chosen to minimize sculling error in the individual .DELTA.VNc(m,p) quantiti es where .DELTA.VNc(m,p) is the representation of .DELTA.VBc(m,p) in the navigation frame of reference. T he final compensated quantity .DELTA.VBC(P) is obtained by summing B(m).DELTA.VBc(m,p) over m where t he constants B(m) are chosen to minimize sculling error in a .DELTA.VNC(P) where .DELTA.VNC(P) is the representation of .DELTA.VBC(P) in the navigation frame of reference.

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