Method and apparatus for differential global positioning system (DGPS)-based real time attitude determination (RTAD)
First Claim
Patent Images
1. A differential global positioning system (DGPS) processor, comprising:
- an almost fixed integer ambiguity (AFIA) module configured to generate, in real-time, a multiple dimensional state vector of integer ambiguities and multiple dimensional corrections using double difference (DD) measurements for pseudo-range (PR) and carrier phase (CP) pairs generated from at least three global positioning system (GPS) receivers, wherein, to generate the multiple dimensional state vector, the AFIA module is operative to (i) determine a difference between a double difference (DD) measurement error and a DD measurement vector for a defined number of GPS satellites in view and at least three GPS receivers, and (ii) divide the difference by an observation matrix for the PR and CP pairs, wherein the AFIA module is stored in a digital memory device or is implemented in a hardware circuit;
an attitude module configured to generate an attitude from the multiple dimensional state vector of integer ambiguities and multiple dimensional corrections, wherein the attitude module is stored in a digital memory device or is implemented in a hardware circuit;
a single difference (SD) module configured to generate at least two single difference observables, wherein a single difference observable is the difference between two receiver observables, wherein a receiver observable includes observable GPS data or a LOS unit vector for each receiver, wherein the SD module is stored in a digital memory device or is implemented in a hardware circuit; and
a DD module configured to generate at least two double difference observables, wherein a double difference observable is the difference between SD observables of two GPS satellites, wherein the DD module is stored in a digital memory device or is implemented in a hardware circuit,wherein a number of single difference observables or a number of double difference observables is less than a number of GPS receivers used to generate observable GPS data.
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Abstract
A differential global positioning system (DGPS) processor can include an almost fixed integer ambiguity (AFIA) module for generating in real-time a multiple dimensional state vector of integer ambiguities and multiple dimensional corrections. The AFIA module can use double difference (DD) measurements for pseudo-range (PR) and carrier phase (CP) pairs generated from at least three global positioning system (GPS) receivers. A DGPS processor can be included in a high data rate real time attitude determination (RTAD) system to achieve high heading accuracy with high integrity.
78 Citations
17 Claims
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1. A differential global positioning system (DGPS) processor, comprising:
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an almost fixed integer ambiguity (AFIA) module configured to generate, in real-time, a multiple dimensional state vector of integer ambiguities and multiple dimensional corrections using double difference (DD) measurements for pseudo-range (PR) and carrier phase (CP) pairs generated from at least three global positioning system (GPS) receivers, wherein, to generate the multiple dimensional state vector, the AFIA module is operative to (i) determine a difference between a double difference (DD) measurement error and a DD measurement vector for a defined number of GPS satellites in view and at least three GPS receivers, and (ii) divide the difference by an observation matrix for the PR and CP pairs, wherein the AFIA module is stored in a digital memory device or is implemented in a hardware circuit; an attitude module configured to generate an attitude from the multiple dimensional state vector of integer ambiguities and multiple dimensional corrections, wherein the attitude module is stored in a digital memory device or is implemented in a hardware circuit; a single difference (SD) module configured to generate at least two single difference observables, wherein a single difference observable is the difference between two receiver observables, wherein a receiver observable includes observable GPS data or a LOS unit vector for each receiver, wherein the SD module is stored in a digital memory device or is implemented in a hardware circuit; and a DD module configured to generate at least two double difference observables, wherein a double difference observable is the difference between SD observables of two GPS satellites, wherein the DD module is stored in a digital memory device or is implemented in a hardware circuit, wherein a number of single difference observables or a number of double difference observables is less than a number of GPS receivers used to generate observable GPS data. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for determining attitude data in real time, comprising:
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under control of one or more computer systems configured with executable instructions; generating, using one or more processors of the computer systems, in real time a multiple dimensional state vector of integer ambiguities and multiple dimensional corrections using double difference (DD) measurements for pseudo-range (PR) and carrier phase (CP) pairs generated from at least three global positioning system (GPS) receivers, wherein the multiple dimensional state vector is generated by;
(i) determining a difference between a double difference (DD) measurement error and a DD measurement vector for a defined number of GPS satellites in view and at least three GPS receivers, and (ii) dividing the difference by an observation matrix for the PR and CP pairs;generating, using the one or more processors of the computer systems, an attitude from the multiple dimensional state vector of integer ambiguities and multiple dimensional corrections; generating at least two single difference (SD) observables, wherein a single difference observable is the difference between two receiver observables, wherein a receiver observable includes at least one of observable GPS data and a LOS unit vector for each receiver; and generating at least two double difference (DD) observables, wherein a double difference observable is the difference between SD observables of two GPS satellites, wherein a number of single difference observables or a number of double difference observables is less than a number of GPS receivers used to generate observable GPS data. - View Dependent Claims (8, 9, 10, 11)
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12. A system for facilitating real time attitude determination (RTAD), comprising:
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a processor; a memory device including a data store to store a plurality of data and instructions that, when executed by the processor, cause the processor to; generate in real time periodic attitude data from global positioning system (GPS) receiver data or GPS-aided navigation data using a multiple dimensional state vector of integer ambiguities and multiple dimensional corrections, wherein, to generate the multiple dimensional state vector, the processor is operative to;
(i) determine a difference between a double difference (DD) measurement error and a DD measurement vector for a defined number of GPS satellites in view and at least three GPS receivers, and (ii) divide the difference by an observation matrix for at least two pairs of double difference (DD) pseudo-range (PR) and carrier phase (CP) measurements;generate at least two single difference (SD) observables, wherein a single difference observable is the difference between two receiver observables, wherein a receiver observable includes at least one of observable GPS data and a LOS unit vector for each receiver; generate at least two double difference (DD) observables, wherein a double difference observable is the difference between SD observables of two GPS satellites, wherein a number of single difference observables or a number of double difference observables is less than a number of GPS receivers used to generate observable GPS data, wherein the GPS receiver data is generated from at least three GPS receivers and the GPS-aided navigation data combines GPS data of each GPS receiver with inertial measurement unit (IMU) data. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification