FULLY-COUPLED VEHICLE POSITIONING METHOD AND SYSTEM THEREOF
First Claim
1. An improved fully-coupled vehicle positioning system, comprising:
- a global positioning system (GPS) processor for providing GPS measurements including pseudorange, carrier phase, and Doppler shift, for a slave system;
a data link for receiving GPS-like signal from a master system, where said GPS-like signal is a frequency shift GPS signal and generated by said master system;
an inertial measurement unit (IMU) for providing inertial measurements including body angular rates and specific forces;
a central navigation processor, which are connected with said GPS processor, said IMU and said data link, comprising an inertial navigation system (INS) processor, a Kalman filter, a new satellites/cycle slips detection module, and an on-the-fly ambiguity resolution module; and
an input/output (I/O) interface connected to said central navigation processor;
a GPS antenna of said master system for receiving GPS signal;
a frequency mixer of said master system for shifting carrier frequency of said GPS signal received from said GPS antenna to generate said GPS-like signal;
a data link of said master system for transmitting said GPS-like signal;
wherein said GPS measurements from said GPS processor and GPS-like signal from said data link are passed to said central navigation processor and said inertial measurements are injected into said inertial navigation system (INS) processor;
wherein said GPS-like signal is processed by said central navigation processor to derive GPS measurements;
wherein an output of said INS processor and said GPS measurements are blended in said Kalman filter;
an output of said Kalman filter is fed back to said INS processor to correct an INS navigation solution, which is then output from said central navigation processor to said I/O interface;
wherein said INS processor provides velocity and acceleration data injected into said GPS processor to aid code and carrier phase tracking of GPS satellite signals;
wherein an output of said GPS processor, an output of said data link, and an output of said INS processor are injected into a new satellites/cycle slips detection module to test the occurrence of new satellites and cycle slips, wherein as said new satellites/cycle slips detection module is on, said on-the-fly ambiguity resolution module is activated to resolve global positioning system satellite signal carrier phase integer ambiguities;
wherein said on-the-fly ambiguity resolution module outputs the integer ambiguities into said Kalman filter to further improve positioning accuracy, and said INS processor outputs navigation data to said I/O interface.
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Abstract
An improved fully-coupled vehicle positioning method and system with differential GPS can substantially solve the problems encountered in either the global positioning system-only or the inertial navigation system-only, such as loss of global positioning satellite signal, sensitivity to jamming and spoofing, and an inertial solution'"'"'s drift over time. In the present invention, the velocity and acceleration from an inertial navigation processor of the integrated GPS/INS system are used to aid the code and carrier phase tracking of the global positioning system satellite signals, so as to enhance the performance of the global positioning and inertial integration system, even in heavy jamming and high dynamic environments. To improve the accuracy of the integrated GPS/INS navigation system, phase measurements are used and the idea of the differential GPS is employed. A master-slave relative positioning scheme is invented and is effective for high accuracy formation driving and flight.
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Citations
3 Claims
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1. An improved fully-coupled vehicle positioning system, comprising:
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a global positioning system (GPS) processor for providing GPS measurements including pseudorange, carrier phase, and Doppler shift, for a slave system;
a data link for receiving GPS-like signal from a master system, where said GPS-like signal is a frequency shift GPS signal and generated by said master system;
an inertial measurement unit (IMU) for providing inertial measurements including body angular rates and specific forces;
a central navigation processor, which are connected with said GPS processor, said IMU and said data link, comprising an inertial navigation system (INS) processor, a Kalman filter, a new satellites/cycle slips detection module, and an on-the-fly ambiguity resolution module; and
an input/output (I/O) interface connected to said central navigation processor;
a GPS antenna of said master system for receiving GPS signal;
a frequency mixer of said master system for shifting carrier frequency of said GPS signal received from said GPS antenna to generate said GPS-like signal;
a data link of said master system for transmitting said GPS-like signal;
wherein said GPS measurements from said GPS processor and GPS-like signal from said data link are passed to said central navigation processor and said inertial measurements are injected into said inertial navigation system (INS) processor;
wherein said GPS-like signal is processed by said central navigation processor to derive GPS measurements;
wherein an output of said INS processor and said GPS measurements are blended in said Kalman filter;
an output of said Kalman filter is fed back to said INS processor to correct an INS navigation solution, which is then output from said central navigation processor to said I/O interface;
wherein said INS processor provides velocity and acceleration data injected into said GPS processor to aid code and carrier phase tracking of GPS satellite signals;
wherein an output of said GPS processor, an output of said data link, and an output of said INS processor are injected into a new satellites/cycle slips detection module to test the occurrence of new satellites and cycle slips, wherein as said new satellites/cycle slips detection module is on, said on-the-fly ambiguity resolution module is activated to resolve global positioning system satellite signal carrier phase integer ambiguities;
wherein said on-the-fly ambiguity resolution module outputs the integer ambiguities into said Kalman filter to further improve positioning accuracy, and said INS processor outputs navigation data to said I/O interface. - View Dependent Claims (2)
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3. An improved fully-coupled vehicle positioning method comprises steps of:
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(a) receiving global positioning system raw measurements, including pseudorange, carrier phase, and Doppler shift;
(b) receiving a GPS-like signal from a data link;
(c) sending said GPS raw measurements to a central navigation processor from a GPS processor and said data link;
(d) receiving a plurality of inertial measurements including body angular rates and specific forces from an inertial measurement unit (IMU);
(e) computing an inertial navigation solution which are position, velocity, acceleration, and attitude of a vehicle by sending said inertial measurements from said IMU to an inertial navigation system (INS) processor of said central navigation processor for (f) fixing integer ambiguities based on testing the occurrence of new satellites or cycle slips using said GPS rover raw measurements from said GPS processor, GPS reference raw measurements, position, and velocity from said data link, and said inertial navigation solution from said INS processor and send the integer ambiguities to a Kalman filter;
(g) blending an inertial navigation solution derived from said INS processor and said GPS raw measurements from said GPS processor and said data link in said Kalman filter to derive INS corrections and GPS corrections;
(h) feeding back said INS corrections from said Kalman filter to said INS processor to correct said inertial navigation solution; and
(i) sending said inertial navigation solution from said INS processor to an I/O interface, so as to provide navigation data for an on-board avionics system.
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Specification