公开(公告)号：EP0760463A3

公开(公告)日：1998-05-13

申请号：EP96305478

申请日：1996-07-25

Applicant: LITTON SYSTEMS INC

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

IPC: G01C19/72

CPC classification number: 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：DE60133291D1

公开(公告)日：2008-04-30

申请号：DE60133291

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.

公开(公告)号：CA2218014C

公开(公告)日：2006-01-10

申请号：CA2218014

申请日：1997-10-10

Applicant: LITTON SYSTEMS INC

Inventor： TAZARTES DANIEL A ,  MARK JOHN G

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

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.V B(n) derived at times n.DELTA.t from the outputs of one or more accelerometers. Separately compensated quantities .DELTA.V Bc(m,p) calculated at times (pJ+1/2).DELTA.t for M values of m are obtained by summing A(m,k).DELTA.V B(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.V Nc(m,p) quantities where d .DELTA.V Nc(m,p) is the representation of .DELTA.V Bc(m,p) in the navigation frame of reference. The final compensated quantity .DELTA.V Bc(p) is obtained by summing B(m).DELTA.V Bc(mp) over m where the constants B(m) are chosen to minimize sculling error in .DELTA.V Nc(p) where .DELTA.V Nc(p) is the representation of .DELTA.V Bc(p) in the navigation frame of reference.

公开(公告)号：DE69903203D1

公开(公告)日：2002-11-07

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：TR9701295A2

公开(公告)日：1998-05-21

申请号：TR9701295

申请日：1997-11-03

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  TAZARTES DANIEL A

IPC: G01C21/16 ,  G01C

CPC classification number: G01C21/16

公开(公告)号：TR199701295A2

公开(公告)日：1998-05-21

申请号：TR9701295

申请日：1997-11-03

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  TAZARTES DANIEL A

IPC: G01C21/16 ,  G01C

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.

公开(公告)号：FR2680241A1

公开(公告)日：1993-02-12

申请号：FR9209701

申请日：1992-08-05

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  TAZARTES DANIEL A

IPC: G01C19/66 ,  H01S3/139

公开(公告)号：DE69624057D1

公开(公告)日：2002-11-07

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：CA2329262A1

公开(公告)日：2001-09-30

申请号：CA2329262

申请日：2000-12-20

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  LOTTMAN DEAN E ,  LOTTMAN BRIAN T ,  TAZARTES DANIEL A

IPC: G01C5/00 ,  G01C21/16 ,  G01C5/06 ,  B64D47/00 ,  G01C25/00

Abstract: A system and method for improving the accuracy of altitude determinatio ns in an inertial navigation system. Pressure measurements available to the inertial navigation system are used to initially calculate an estimated pressure altitude using the standard day model for the atmosphere. Temperature measurements ar e further utilized in the physical relationship between temperature, pressure, and altitude to compute a second estimated altitude, such as a Blanchard altitud e estimation. A change between subsequent second altitude estimations is computed and compared with a respective change in the computed pressure altitude in order to generate a correction signal. The error correction signal is then used to modify the computed pressure altitude to generate a more accurate determination of the absolute altitude of the inertial navigation system. The error correction signal is calculated to account for changes in atmospheric conditions which may be encountered by an aircraft and to further reduce the effects of erroneous temperature and pressure measurements in subsequent altitude determinations. Thus, the system and method of the present invention provides an absolute altitude determination having improved stability and improved accuracy over prior systems.

公开(公告)号：DE4126905C2

公开(公告)日：2000-04-13

申请号：DE4126905

申请日：1991-08-14

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  TAZARTES DANIEL A

IPC: G01C19/66 ,  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.