Assured-integrity monitored-extrapolation navigation apparatus
First Claim
1. A navigation apparatus comprising a digital processor and a memory that utilizes a first subset and a second subset of a set of measured quantities which do not vary by amounts that are improbable or impossible, the set of measured quantities being provided at periodic time intervals delta-time by an external source for determining the state of a platform on which the apparatus is mounted, the set of measured quantities being presumptively useful in determining platform state, the number of members of the first subset being equal to or greater than zero but less than the total number of members of the set of measured quantities, the members of the set of measured quantities not included in the first subset being subject to selection for the second subset by the apparatus in accordance with a predetermined set of selection rules.
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Accused Products
Abstract
The assured-integrity monitored-extrapolation (AIME) navigation apparatus selectively utilizes measurements provided by ancillary sources at periodic intervals in determining the state of the platform on which the apparatus is mounted. The measurements have attributes which are measures of quality, quality being a measure of the usefulness of the measurement in accurately estimating the state of a platform. The AIME apparatus makes its selection of measurements for state determination on the basis of estimates of the values of these quality attributes. The determination of the quality of a time sequence of measured values of a particular quantity requires an evaluation time for its accomplishment. The AIME apparatus therefore determines the platform'"'"'s state in two phases. It obtains highly-accurate determinations of the states of the platform at times prior to present time minus the evaluation time by using the quality measures available at these times and using only those measurements that are determined to be of high quality in the determination of state at these times. The platform state at present time is then obtained by extrapolation of the highly-accurate state at time minus the evaluation time using measurements whose quality is more uncertain.
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Citations
89 Claims
- 1. A navigation apparatus comprising a digital processor and a memory that utilizes a first subset and a second subset of a set of measured quantities which do not vary by amounts that are improbable or impossible, the set of measured quantities being provided at periodic time intervals delta-time by an external source for determining the state of a platform on which the apparatus is mounted, the set of measured quantities being presumptively useful in determining platform state, the number of members of the first subset being equal to or greater than zero but less than the total number of members of the set of measured quantities, the members of the set of measured quantities not included in the first subset being subject to selection for the second subset by the apparatus in accordance with a predetermined set of selection rules.
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58. A method that utilizes a first subset and a second subset of a set of measured quantities which do not vary by amounts that are improbable or impossible, the set of measured quantities being provided at periodic time intervals delta-time by an external source for determining the state of a platform, the measured quantities being presumptively useful in determining platform state, the number of members of the first subset being equal to or greater than zero but less than the total number of members of the set of measured quantities, the members of the set of measured quantities not included in the first subset being subject to selection for the second subset in accordance with a predetermined set of selection rules, the method comprising the steps:
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selecting the measured quantities in the second subset; determining the state of the platform. - View Dependent Claims (59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89)
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Specification