Fault detection and exclusion for global position systems
AssigneeHoneywell International Inc.
InventorsKevin D. Vanderwerf, Mats Brenner
Life of this patent
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Abstract
A global positioning system for use with a plurality of transmitting satellites is disclosed wherein a full position solution is obtained from a number N of satellite transmissions and a plurality of sub-solutions each based on a different number (N−1) of satellite transmissions are obtained to determine if a satellite is faulty. A plurality of sub-sub-solutions is then obtained based on a different combination of N−2 satellites with each combination containing the satellites of different sub-solutions and excluding one other satellite in addition. An examination of the sub-sub-solutions provides an indication of which one of the satellites is the failed satellite.
Claims23
In a system for determining the position of a vehicle from the transmissions of a plurality of transmitters, one of which could be faulty, wherein a full position solution for the vehicle is determined from a combination of N transmissions and a plurality of position sub-solutions is determined from combinations of the N transmissions, each position sub-solution being based on different combination of the N transmissions but each excluding a different one of the transmissions to determine if there is a faulty transmission, the improvement comprising:
- sub-sub-solution means for producing a plurality of position sub-sub-solutions from the sub-solutions, each position sub-sub-solution based on a different combination of the transmissions used in a sub-solution with a different additional one of the transmissions being also excluded;
- and
- failure detection means for analyzing the position sub-sub-solutions to determine which, if any, of the transmissions is faulty.
In a position determining system for a vehicle having receiving means for receiving signals from a plurality of transmitters, one of which may be faulty, and having a processor for determining a full position solution for the vehicle based on the plurality of signals and determining a plurality of position sub-solutions for the vehicle with each position sub-solution based on a respective subset of the plurality of signals, the improvement comprising:
- means producing a plurality of position sub-sub-solutions for the vehicle with each position sub-sub-solution based on a respective subset of the position sub-solutions;
- and
- failure detector means for determining which, if any, of the transmitters is faulty from the plurality of position sub-sub-solutions.
The method of operating a position determining system, which includes a processor which receives transmission signals from a plurality of transmitters, one of which may be faulty, comprising the steps of:
- A. determining a full position solution from a plurality of transmissions signals;
- B. determining a plurality of position sub-solutions, each based on a subset of the plurality of transmission signals;
- C. determining a plurality of position sub-sub-solutions, each based on a subset of one of the position sub-solutions;
- and
- D. determining from the plurality of sub-sub-solution, which of the transmitters, if any, is faulty.
The method of calculating separation parameters, Dnm, comprising the steps of:
- A. computing the separation covariance matrix describing the statistical separation between the nth sub-solution and its mth sub-sub-solution according to the equation:
- dPnm(k)=Pn(k)−Pnmcross(k)−[Pnmcross(k)]T+Pnm(k)
- where
- Pn is the error covariance matrix for the sub-solution ΔXn(k), Pnm(k) is the error covariance matrix for the mth sub-sub-solution of the nth sub-solution ΔXnm(k), and Pnmcross(k) is the matrix describing the cross-covariance between the nth sub-solution ΔXn(k) and its mth sub-sub-solution ΔXnm(k);
- B. determining the eigenvalues of the error covariance matrix;
- and,
- C. determining the separation parameters Dnm according to
- Dnm={square root}{square root over ((λdPnm)max)}Q−1[PFD/2(N−1)]
- where Q−1 denotes the inverse of
- 7 Q ( x ) = 1 2 π - ∫ x ∞ ⅇ - r 2 2 ⅆ r
Dependencies are inferred from the claim text.