Method and apparatus for electromagnetic non-contact position measurement with respect to one or more axes
First Claim
1. An apparatus for determining the position of a reference point with respect to at least one axis, said reference point and said at least one axis being movable relative to each other, said apparatus comprising:
- a. a reference electrode located at the reference point;
b. at least one elongated antenna movable along said at least one axis, said elongated antenna;
i. having a signal transmission property as measured between a first end of said elongated antenna and a variable measurement point along said axis, which signal transmission property varies with the location of the measurement point; and
ii. capable of being electromagnetically coupled to said reference electrode;
c. means for applying an input electric signal to said reference electrode to generate an electromagnetic field to be picked up by said elongated antenna;
d. means for measuring an output electric signal at said first end of said at least one elongated antenna due to the detection of said field; and
e. means for evaluating the relation between said output electric signal and said input electric signal to determine;
i. the distance from said reference point relative to said axis along a line perpendicular to said axis; and
ii. the distance from said first end of said elongated antenna to the intersection of said perpendicular line and said axis.
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Abstract
A preferred embodiment of the invention is an apparatus for measuring the position of a point with respect to at least one axis. The apparatus includes a reference electrode located at the reference point and at least one axial electrode fixed along the at least one axis. The axial electrode has a signal transmission property, such as resistivity, as measured between a first end and a point along the axis, which signal transmission property varies with the location of the point of measurement. The axial electrode is coupled to the reference electrode, typically capacitively. The apparatus also includes means for applying an electric signal to the reference electrode; means for measuring an output electric signal at the first end of the at least one axial electrode; and means for evaluating the relation between the output electric signal and the input electric signal to determine the position of the reference point relative to the axis. The invention also includes method of using the apparatus to determine the location of the reference point to the axis. The invention includes embodiments of one and more axes.
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Citations
16 Claims
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1. An apparatus for determining the position of a reference point with respect to at least one axis, said reference point and said at least one axis being movable relative to each other, said apparatus comprising:
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a. a reference electrode located at the reference point; b. at least one elongated antenna movable along said at least one axis, said elongated antenna; i. having a signal transmission property as measured between a first end of said elongated antenna and a variable measurement point along said axis, which signal transmission property varies with the location of the measurement point; and ii. capable of being electromagnetically coupled to said reference electrode; c. means for applying an input electric signal to said reference electrode to generate an electromagnetic field to be picked up by said elongated antenna; d. means for measuring an output electric signal at said first end of said at least one elongated antenna due to the detection of said field; and e. means for evaluating the relation between said output electric signal and said input electric signal to determine; i. the distance from said reference point relative to said axis along a line perpendicular to said axis; and ii. the distance from said first end of said elongated antenna to the intersection of said perpendicular line and said axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for determining the position of a reference point with respect to at least one axis, said reference point and said at least one axis being movable relative to each other, said method comprising the steps of:
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a. providing; i. a reference electrode located at the reference point; ii. at least one elongated antenna movable along said at least one axis, said elongated antenna; (a). having a signal transmission property as measured between a first end of said elongated antenna and a variable measurement point along said axis, which signal transmission property varies with the location of the measurement point; and (b). capable of being electromagnetically coupled to said reference electrode; b. applying an input electric signal to said reference electrode to generate an electromagnetic field to be picked up by said elongated antenna; c. measuring an output electric signal at said first end of said at least one elongated antenna due to the detection of said field and d. evaluating the relation between said output electric signal and said input electric signal to determine; i. the distance from said reference point relative to said axis along a line perpendicular to said axis; and ii. the distance from said first end of said elongated antenna to the intersection of said perpendicular line and said axis. - View Dependent Claims (13, 14, 15, 16)
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Specification