HYBRIDIZATION DEVICE WITH SEGREGATED KALMAN FILTERS

• US 20110243194A1
• Filed: 12/16/2009
• Published: 10/06/2011
• Est. Priority Date: 12/17/2008
• Status: Active Grant

• Current Assignee: Safran Electronics & Defense
• Original Assignee: Sagem Defense Securite (Safran SA)
• Inventors: Mauger, Victor, Vourc'h, Sébastien
• Granted Patent: US 8,625,696 B2
• Time in Patent Office: Days
• US Class Current: 375/140
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial

Abstract

The invention relates according to a first aspect to a hybridization device (1) comprising a virtual platform (2) calculating inertial measurements (PPVI), a bank (3) of Kalman filters each formulating a hybrid navigation solution on the basis of the inertial measurements of the virtual platform (2) and of measurements of signals emitted by a constellation of satellites, which measurements are delivered by a satellite positioning system (GNSS), characterized in that it comprises, for each filter of the bank, a module for correcting the satellite measurements (4) delivering to the filter the measurements of the satellite positioning system (GNSS) which are used by the filter after correction with the aid of the hybrid navigation solution formulated by the filter.

Claims

1. Hybridization device (1) comprising a virtual platform (2) calculating inertial measurements (PPVI), a bank (3) of Kalman filters each formulating a hybrid navigation solution on the basis of inertial measurements of the virtual platform (2) and of measurements of signals emitted by a constellation, of satellites delivered by a satellite positioning system (GNSS), characterised in that it comprises, for each filter of the bank, a module for correcting the satellite measurements (4) delivering to the filter the measurements of the satellite positioning system (GNSS) which are used by the filter after correction with the aid of the hybrid navigation solution formulated by the filter.

2. Device according to claim 1, wherein the module for correcting the satellite measurements (4) receives at the input the hybrid navigation solutions formulated by the filters and the measurements corresponding to the set of the constellation delivered by the satellite positioning system (GNSS).

3. Device according to one of claims 1 to 2, wherein the measurements of the satellite positioning system (GNSS) which are used by a filter are pseudo-measurements.

4. Device according to one of claims 1 to 3, formulating a hybrid output (SH) corresponding to the inertial measurements (PPVI) calculated by the virtual platform (2) and corrected by a stabilisation vector (dC).

5. Device according to claim 4, wherein the stabilisation vector corresponds to a state vector estimated by a filter of the bank not affected by a satellite fault.

6. Device according to claim 4, wherein each component of the stabilisation vector (dC[state]) is formulated as a function of the corresponding components of the set of state vectors estimated by the filters of the bank.

7. Device according to claim 6, comprising a module for formulating the stabilisation vector configured, for each component of the stabilisation vector (dC[state]), so as:

to analyse the sign of the set of corresponding components (dX0[state]-dXn[state]) of the state vectors;

when the set of said corresponding components are not of same sign, to formulate a component of zero value (dC[state]=0) for the stabilisation vector;

when the set of said corresponding components are of same sign, to formulate a component of non zero value for the stabilisation vector, determined as a function of the value of each of said components of state vectors.

8. Device according to claim 7, wherein the non zero value of the component of the stabilisation vector corresponds to the minimum of the set of corresponding components of the state vectors when the set of said corresponding components are positive, and corresponds to the maximum of the set of corresponding components of the state vectors when the set of said corresponding components are negative.

9. Device according to claim 7, wherein the non zero value of the component of the stabilisation vector corresponds to the average of smallest P corresponding components of state vectors, taken in absolute value.

10. Device according to one of claims 1 to 9, wherein the stabilisation vector is applied at the input of the set of filters of the bank of filters.

11. Device according to one of claims 1 to 10, wherein the hybrid output is re-looped at the input of the virtual platform.

12. Device according to one of claims 1 to 11, wherein the bank of Kalman filters (3) comprises a main Kalman filter (8) receiving the measurements of signals emitted by n satellites corrected by the main hybrid navigation solution that it formulates, and n secondary Kalman filters (9i, 9n) each receiving the signal measurements emitted by the n satellites with the exception of one satellite corrected with the aid of the secondary hybrid navigation solution that it formulates.

13. INS/GNSS hybridization method implementing a bank of Kalman filters each formulating a hybrid navigation solution on the basis of inertial measurements calculated by a virtual platform (2) and of measurements of signals emitted by a constellation of satellites delivered by a satellite positioning system (GNSS), characterised in that the satellite measurements used by each filter of the bank are corrected beforehand with the aid of the hybrid navigation solution formulated by the filter.