Foreign object detection for ferromagnetic wire-like objects
First Claim
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1. An apparatus for detecting an object, comprising:
- a sense coil; and
a detection circuit configured to;
determine an amount of change in a reactance of the sense coil from a reference reactance value for the sense coil;
determine an amount of change in a resistance of the sense coil from a reference resistance value for the sense coil; and
selectively increase a sensitivity of the detection circuit as a ratio of the amount of change in the resistance and the amount of change in the reactance of the sense coil approaches a value of one, the sensitivity increased by reducing a detection threshold by an amount that is a function of the ratio.
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Abstract
Systems and methods are described for improving foreign object detection for ferromagnetic wire-like objects. In particular, aspects include increasing FOD sensitivity using at least one inductive sense loop in response to detecting a change in resistance that is substantially equal to the change in reactance of a sense coil. By increasing the FOD sensitivity, objects such as ferromagnetic wire-like objects can be detected that are potentially hazardous objects. Detecting these potentially hazardous objects that were previously undetectable can reduce the chances of damage to surrounding materials or harm to humans.
14 Citations
29 Claims
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1. An apparatus for detecting an object, comprising:
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a sense coil; and a detection circuit configured to; determine an amount of change in a reactance of the sense coil from a reference reactance value for the sense coil; determine an amount of change in a resistance of the sense coil from a reference resistance value for the sense coil; and selectively increase a sensitivity of the detection circuit as a ratio of the amount of change in the resistance and the amount of change in the reactance of the sense coil approaches a value of one, the sensitivity increased by reducing a detection threshold by an amount that is a function of the ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for detecting an object, the method comprising:
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detecting, by a detection circuit, an amount of change in a reactance of a sense coil from a reference reactance value for the sense coil; detecting, by the detection circuit, an amount of change in a resistance of the sense coil from a reference resistance value for the sense coil; selectively increasing a sensitivity of a detection circuit as a ratio of the amount of change in the resistance and the amount of change in the reactance of the sense coil approaches a value of one, the sensitivity increased by reducing a detection threshold by an amount that is a function of the ratio; and detecting a presence of the object based on a relationship between the amount of change in the reactance of the sense coil and the amount of change in the resistance of the sense coil. - View Dependent Claims (13, 14, 15, 16, 17)
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18. Non-transitory computer-readable media comprising code that, when executed, causes an apparatus for detecting an object to:
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determine that an amount of change in reactance of a sense coil from a reference reactance value for the sense coil is substantially equal to an amount of change in resistance of the sense coil from a reference resistance value for the sense coil; adjust a sensitivity of a detection circuit based on the determination, the adjustment including a selective increase in the sensitivity of the detection circuit as a ratio of the amount of change in the resistance of the sense coil and the amount of change in reactance of the sense coil approaches a value of one, the sensitivity increased based on a reduction to a detection threshold by an amount that is a function of the ratio; and detect a presence of the object based on a relationship between the amount of change in the reactance of the sense coil and the amount of change in the resistance of the sense coil. - View Dependent Claims (19, 20, 21, 22, 23)
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24. An apparatus for detecting an object, the apparatus comprising:
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means for determining that an amount of change in a resistance of a sense coil from a reference resistance value of the sense coil is substantially equal to an amount of change in a reactance of the sense coil from a reference reactance value of the sense coil; means for selectively increasing a sensitivity of a detection circuit based on a determination that the amount of change in the resistance of the sense coil is substantially equal to the amount of change in the reactance of the sense coil, the sensitivity of the detection circuit increased as a ratio of the amount of change in the resistance of the sense coil and the amount of change in the reactance of the sense coil approaches a value of one, the sensitivity increased by reducing a detection threshold by an amount that is a function of the ratio; and means for detecting a presence of the object based on a relationship between the amount of change in the reactance of the sense coil and the amount of change in the resistance of the sense coil. - View Dependent Claims (25, 26, 27, 28, 29)
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Specification