INTEGRATED INERTIAL/GPS NAVIGATION SYSTEM
First Claim
1. A method for adjusting the phase and frequency of a received GPS signal in an inertial-GPS navigation system comprising an inertial measurement unit (IMU) and a GPS receiver, the GPS receiver having an input port for inputting a delta-phase at delta-time intervals into a received satellite signal, the GPS receiver having an output port for outputting a carrier phase error, the carrier phase error being the difference between the actual phase of the received GPS signal and a reference value, the GPS receiver having an output port for outputting a pseudorange associated with the received GPS signal, the IMU having an output port for outputting acceleration and angular velocity of the IMU, the delta-phase being the sum of at least two delta-phase components, the method comprising the step:
- (a) determining a Kalman delta-phase component, a plurality of candidate Kalman delta-phase components being obtained by performing a first set of more than one Kalman filter processes, the inputs to each first-set Kalman filter process including the carrier phase error and a position vector associated with the IMU, a candidate Kalman delta-phase component being produced as an output of each first-set Kalman filter process, the Kalman delta-phase component being determined from a candidate Kalman delta-phase components selected from the plurality of candidate Kalman delta-phase components by applying a predetermined Kalman delta-phase component selection rule;
(b) determining an IMU delta-phase component from the EMU outputs and a direction-cosine matrix that translates the body coordinates of the IMU into the navigation coordinates of the inertial-GPS navigation system.
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Accused Products
Abstract
The invention is a method and apparatus for adjusting the phase and frequency of a received GPS signal in an inertial-GPS navigation system by inputting a delta-phase at delta-time intervals into the received satellite signal. The method comprises the steps of determining two delta-phase components: (a) a Kalman delta-phase component derived from a plurality of candidate Kalman delta-phase components obtained by performing a first set of more than one Kalman filter processes and (b) an IMU delta-phase component derived from the IMU outputs and a direction-cosine matrix that translates the body coordinates of the IMU into the navigation coordinates of the inertial-GPS navigation system.
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Citations
23 Claims
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1. A method for adjusting the phase and frequency of a received GPS signal in an inertial-GPS navigation system comprising an inertial measurement unit (IMU) and a GPS receiver, the GPS receiver having an input port for inputting a delta-phase at delta-time intervals into a received satellite signal, the GPS receiver having an output port for outputting a carrier phase error, the carrier phase error being the difference between the actual phase of the received GPS signal and a reference value, the GPS receiver having an output port for outputting a pseudorange associated with the received GPS signal, the IMU having an output port for outputting acceleration and angular velocity of the IMU, the delta-phase being the sum of at least two delta-phase components, the method comprising the step:
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(a) determining a Kalman delta-phase component, a plurality of candidate Kalman delta-phase components being obtained by performing a first set of more than one Kalman filter processes, the inputs to each first-set Kalman filter process including the carrier phase error and a position vector associated with the IMU, a candidate Kalman delta-phase component being produced as an output of each first-set Kalman filter process, the Kalman delta-phase component being determined from a candidate Kalman delta-phase components selected from the plurality of candidate Kalman delta-phase components by applying a predetermined Kalman delta-phase component selection rule;
(b) determining an IMU delta-phase component from the EMU outputs and a direction-cosine matrix that translates the body coordinates of the IMU into the navigation coordinates of the inertial-GPS navigation system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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13. Apparatus for adjusting the phase and frequency of a received GPS signal in an inertial-GPS navigation system comprising an inertial measurement unit (IMU) and a GPS receiver, the GPS receiver having an input port for inputting a delta-phase at delta-time intervals into a received satellite signal, the GPS receiver having an output port for outputting a carrier phase error, the carrier phase error being the difference between the actual phase of the received GPS signal and a reference value, the GPS receiver having an output port for outputting a pseudorange associated with the received GPS signal, the IMW having an output port for outputting acceleration and angular velocity of the IMU, the delta-phase being the sum of at least two delta-phase components, the apparatus comprising:
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(a) a processor for determining a Kalman delta-phase component, a plurality of candidate Kalman delta-phase components being obtained by performing a first set of more than one Kalman filter processes, the inputs to each first-set Kalman filter process including the carrier phase error and a position vector associated with the IMU, a candidate Kalman delta-phase component being produced as an output of each first-set Kalman filter process, the Kalman delta-phase component being determined from a candidate Kalman delta-phase components selected from the plurality of candidate Kalman delta-phase components by applying a predetermined Kalman delta-phase component selection rule;
(b) a processor for determining an IMU delta-phase component from the IMU outputs and a direction-cosine matrix that translates the body coordinates of the IMU into the navigation coordinates of the inertial-GPS navigation system.
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Specification