Method and system for determining protection limits with integrated extrapolation over a given time horizon
First Claim
1. Method for determining protection limits at a future moment associated with navigation states of a carrier comprising:
- measuring data on navigation states of the carrier through sensors of the carrier;
based on said measured data,estimating, with an estimating filter, navigation states of the carrier at the present moment,producing a statistical model of estimation errors of navigation states of the carrier at the present moment in the form of a covariance matrix,extrapolating the statistical model of estimation errors to a future moment, wherein said extrapolating comprising a multiplication of;
a transition matrix, with constant and positive coefficients, witha standard deviation vector constructed from the square roots of the elements of the diagonal of the covariance matrix of the estimating filter, in order to propagate standard deviations of the navigation states produced at the present moment, to a future moment, the propagation of standard deviations of navigation states being independent from previous dynamics of the carrier, andcalculating a protection limit at the future moment using the extrapolated statistical model.
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Abstract
A method for determining protection limits at a future moment associated with navigation states of a bearer by estimating the navigation states of the bearer at the present moment, developing a statistic model of the estimation errors of navigation states of the bearer at the present moment in the form of a covariance matrix, extrapolating, for a future moment, the statistical model of the estimation errors, calculating protection limits at the future moment from the extrapolated statistical model, the extrapolation of the statistical model of the estimation errors implements the application of a constant and positive transition matrix to a standard deviation vector constructed from the square root of the elements of the diagonal of the covariance matrix, to propagate, up to the future moment, the standard deviations developed at the present moment. The invention also relates to a navigation system configured to implement the method.
28 Citations
11 Claims
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1. Method for determining protection limits at a future moment associated with navigation states of a carrier comprising:
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measuring data on navigation states of the carrier through sensors of the carrier; based on said measured data, estimating, with an estimating filter, navigation states of the carrier at the present moment, producing a statistical model of estimation errors of navigation states of the carrier at the present moment in the form of a covariance matrix, extrapolating the statistical model of estimation errors to a future moment, wherein said extrapolating comprising a multiplication of; a transition matrix, with constant and positive coefficients, with a standard deviation vector constructed from the square roots of the elements of the diagonal of the covariance matrix of the estimating filter, in order to propagate standard deviations of the navigation states produced at the present moment, to a future moment, the propagation of standard deviations of navigation states being independent from previous dynamics of the carrier, and calculating a protection limit at the future moment using the extrapolated statistical model. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Carrier navigation system comprising:
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an estimation module providing navigation state estimates of the carrier at the present moment and a statistical model for estimation errors of the carrier navigation states at the present moment in the form of a covariance matrix, a protection limits calculation module to calculate protection limits providing protection limits starting from estimates of navigation states and the statistical estimation errors model, and an extrapolation module to extrapolate the statistical model of estimation errors configured to multiply a transition matrix with constant and positive coefficients to a vector of standard deviations constructed from the square roots of the elements of the diagonal of the covariance matrix, in order to propagate standard deviations of navigation states produced at the present moment to a future moment, the propagation of standard deviations of navigation states being independent from previous dynamics of the carrier, such that the protection limits calculation module calculates the protection limits at the future moment starting from the extrapolated statistical model.
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Specification