Vehicle positioning method and system thereof

• US 6,292,750 B1
• Filed: 04/24/2000
• Issued: 09/18/2001
• Est. Priority Date: 11/04/1998
• Status: Expired due to Term

• Current Assignee: American GNC Corporation
• Original Assignee: Ching-Fang Lin
• Inventors: Lin, Ching-Fang
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Beaulieu, Yonel
• Application Number:
  US09/556,343
• Time in Patent Office: 512 Days
• Field of Search: 701/213, 701/214, 701/215, 701/220, 342/357.01, 342/357.02, 342/357.05, 342/357.06, 342/357.12, 342/357, 342/14, 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 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

An improved fully-coupled vehicle positioning process and system thereof can substantially solve the problems encountered in global positioning system-only and inertial navigation system-only, such as loss of global positioning satellite signal, sensibility to jamming and spoofing, and inertial solution'"'"'s drift over time, in which the velocity and acceleration from an inertial navigation processor 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. The improved fully-coupled GPS/IMU vehicle positioning system includes an IMU (inertial measurement unit) and a GPS processor which are connected to a central navigation processor to produce navigation solution that is output to an I/O (input/output) interface.

Claims

1. An improved vehicle positioning system, comprising:

a global positioning system (GPS) processor for providing GPS measurements including pseudorange, carrier phase, and Doppler shift;

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 and said IMU, comprising an inertial navigation system (INS) processor, a robust Kalman filter, and a carrier phase integer ambiguity resolution module; and

an input/output (I/O) interface connected to said central navigation processor;

wherein said GPS measurements are passed to said central navigation processor and said inertial measurements are injected into said inertial navigation system (INS) processor;

an output of said INS processor and said GPS measurements are blended in said robust Kalman filter;

an output of said robust Kalman filter is fed back to said INS processor to correct an INS navigation solution outputting from said central navigation processor to said I/O interface;

said INS processor provides velocity and acceleration data injecting into a micro-processor of said GPS processor to aid code and carrier phase tracking of GPS satellite signals;

an output of said micro-processor of said GPS processor, an output of said INS processor and an output of said robust Kalman filter are injected into said carrier phase integer ambiguity resolution module to fix global positioning system satellite signal carrier phase integer ambiguity number;

said carrier phase integer ambiguity resolution module outputs carrier phase integer number into said robust Kalman filter to further improve positioning accuracy; and

said INS processor outputs navigation data to said I/O interface.

2. An improved vehicle positioning system, as recited in claim 1, wherein said microprocessor of said GPS processor outputs pseudorange, Doppler shifts, global positioning system satellite ephemeris, and atmosphere parameters to said robust Kalman filter.

3. An improved vehicle positioning system, as recited in claim 2, wherein said INS processor processes said inertial measurements, which are body angular rates and specific forces, and said position error, velocity error, and attitude error coming from said robust Kalman filter to derive said corrected navigation solution.

4. An improved vehicle positioning system, as recited in claim 1, wherein said robust Kalman filter provides near-optimal performance over a large class of process and measurement models and for blending GPS measurements and said inertial sensor measurements.

5. An improved vehicle positioning system, as recited in claim 2, wherein said robust Kalman filter provides near-optimal performance over a large class of process and measurement models and for blending GPS measurements and said inertial sensor measurements.

6. An improved vehicle positioning system, as recited in claim 3, wherein said robust Kalman filter provides near-optimal performance over a large class of process and measurement models and for blending GPS measurements and said inertial sensor measurements.

7. An improved vehicle positioning method, comprising the steps of:

(a) receiving a plurality of global positioning system satellite signals to derive vehicle position and velocity information and a plurality of global positioning system (GPS) raw measurements, including pseudorange, carrier phase, and Doppler shift;

(b) sending said GPS raw measurements to a central navigation processor from a GPS processor;

(c) receiving a plurality of inertial measurements including body angular rates and specific forces from an inertial measurement unit (IMU);

(d) sending said inertial measurements from said IMU to an inertial navigation system (INS) processor of said central navigation processor for computing an inertial navigation solution which are position, velocity, acceleration, and attitude of a vehicle;

(e) blending an inertial navigation solution derived from said INS processor and said GPS raw measurements from said GPS processor in a robust Kalman filter to derive a plurality of INS corrections and GPS corrections;

(f) feeding back said INS corrections from said robust Kalman filter to said INS processor to correct said inertial navigation solution; and

(g) 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.

8. An improved vehicle positioning method, as recited in claim 7, after step (f), further comprising the steps of:

injecting said GPS raw measurements from said micro-processor of said GPS processor, said inertial navigation solution from said INS processor, and said inertial corrections and said GPS corrections from said robust Kalman filter into a carrier phase integer ambiguity resolution module to fix a plurality of global positioning system satellite signal carrier phase integer ambiguity numbers; and

sending said global positioning system satellite signal carrier phase integer numbers from said carrier phase integer ambiguity resolution module to said robust Kalman filter to derive a further improved vehicle navigation solution.

9. An improved vehicle positioning method, as recited in claim 8, before step (g) further comprising the steps of:

injecting said GPS raw measurements from said micro-processor of said GPS processor, said inertial navigation solution from said INS processor, and said inertial corrections and said GPS corrections from said robust Kalman filter into a carrier phase integer ambiguity resolution module to fix a plurality of global positioning system satellite signal carrier phase integer ambiguity numbers; and

sending said global positioning system satellite signal carrier phase integer numbers from said carrier phase integer ambiguity resolution module to said robust Kalman filter to derive a further improved vehicle navigation solution.