METHOD AND APPARATUS FOR LOOSENING OF FASTENERS ON STRUCTURES
First Claim
1. A method of detecting a loosening of a fastener on a structure, comprising:
- retrieving a first set of data corresponding to a first signal transmitted through a structure having a fastener;
determining a second set of data corresponding to a second signal transmitted through the structure;
calculating a value of an index according to the first set of data and the second set of data;
comparing the calculated index value to a predetermined threshold value; and
determining the loosening of the fastener according to the comparing.
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Accused Products
Abstract
Methods and apparatuses for detecting fastener loosening. Sensors query a structure at a baseline value of an environment variable, such as temperature, and this baseline signal is stored for later use. Subsequently, users can query the structure remotely and at any time, and the signals from these queries are compared to the stored baseline signal. In some embodiments, an index is calculated, and the system determines that one or more fasteners have come loose if the calculated index exceeds a predetermined threshold value. It is desirable to select a time window within which the query signal is most sensitive to fastener loosening but least sensitive to variations in the environment variable. Accordingly, embodiments of the invention include methods and apparatuses for determining an optimal time window for use in calculating the above described index.
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Citations
51 Claims
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1. A method of detecting a loosening of a fastener on a structure, comprising:
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retrieving a first set of data corresponding to a first signal transmitted through a structure having a fastener; determining a second set of data corresponding to a second signal transmitted through the structure; calculating a value of an index according to the first set of data and the second set of data; comparing the calculated index value to a predetermined threshold value; and determining the loosening of the fastener according to the comparing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of detecting a loosening of a fastener on a structure, comprising:
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querying a structure by transmitting first signals through the structure; receiving first data corresponding to the transmitted first signals; retrieving second data corresponding to second signals transmitted through the structure; calculating a value of an index at least partially according to the first data and the second data; comparing the calculated index value to a threshold value; and determining a loosening of the fastener on the structure when the calculated index value exceeds the threshold value. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A method of determining an optimal time window for facilitating detection of a loosening of a fastener on a structure, comprising:
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determining a first set of data corresponding to first signals transmitted through the structure, differing ones of the first signals transmitted through the structure at differing values of an environment variable; determining values of an objective function for various time windows, wherein the respective values are determined at least partially according to a portion of the first set of data corresponding to the respective time window; and determining the optimal time window according to a one of the various time windows corresponding to a maximum one of the values. - View Dependent Claims (33, 34, 35, 36)
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37. A computer-readable medium storing instructions for carrying out a method of detecting a loosening of a fastener on a structure, the method comprising:
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retrieving a first set of data corresponding to a first signal transmitted through a structure having a fastener; determining a second set of data corresponding to a second signal transmitted through the structure; calculating a value of an index according to the first set of data and the second set of data; comparing the calculated index value to a predetermined threshold value; and determining the loosening of the fastener according to the comparing. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51)
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Specification