Fully-coupled vehicle positioning method and system thereof

• US 6,424,914 B1
• Filed: 12/26/2000
• Issued: 07/23/2002
• Est. Priority Date: 12/26/2000
• Status: Expired due to Term

• Current Assignee: American GNC Corporation
• Original Assignee: American GNC Corporation
• Inventors: Lin, Ching-Fang
• Primary Examiner(s): ARTHUR JEANGLAUDE, GERTRUDE
• Application Number:
  US09/751,549
• Publication Number:
  US 20020120400A1
• Time in Patent Office: 574 Days
• Field of Search: 701/213, 701/214, 701/215, 701/220, 701/207, 342/357.01, 342/357.02, 342/357.05, 342/357.06, 342/357.12, 342/450, 342/451
• US Class Current: 701/214
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking
• CPC Class Codes: G01S 19/28 Satellite selection
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method
• CPC Class Codes: G01S 19/55 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

A fully-coupled vehicle positioning method and system with differential GPS substantially solves problems encountered in either the global positioning system-only or the inertial novigation system-only, such as loss of global positioning satellite signal, sensitivity to jamming and spoofing, and an inertial solution'"'"'s drift over time, in which 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.

Claims

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 IMI 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.

2. An improved fully-coupled vehicle positioning system, as recited in claim 1, wherein said GPS processor further comprises:

a RF (radio frequency) unit for converting the RF GPS signals from a plurality of GPS antennas to a plurality of digital base band GPS signals;

a correlation and tracking loops for receiving said digital base band GPS signals of said GPS antenna to perform the tracking processing of the GPS signals and to derive GPS carrier phase, psuedorange, and range rate measurements;

a satellite and antenna selection module for choosing a GPS antenna with a maximum number of GPS satellites in view and performing the carrier phase difference processing among said GPS antenna to derive the carrier phase difference measurements of said GPS antenna, wherein said GPS carrier phase, psuedorange, and range rate measurements of the chosen GPS antenna with maximum number of GPS satellites in view are sent to said central navigation processor to perform the fully-coupled GPS/IMU processing;

an attitude determination processor for receiving the carrier phase difference measurements of said GPS antenna to derive the GPS attitude measurement.

3. An improved fully-coupled vehicle positioning method comprises steps of:

(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.