Determining a dynamic gaps between a proximity probe and a conductive target material
First Claim
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1. - A device for digitally measuring electrical impedance, comprising in combination:
- a network including a first electrical component and a second electrical component serially connected;
a signal generating means operatively coupled to said network for driving a current through said serially connected components;
means for sampling a first voltage impressed across said network and a second voltage impressed across said second component into digitized voltages;
means for convolving each said digitized voltage with a digital waveform for forming a first complex number and a second complex number correlative to said first voltage impressed across said network and said second voltage impressed across said second component respectively;
means for determining a ratio of said second complex number to a difference between said first and said second complex number, and means for calculating an electrical impedance of said second component by multiplying said ratio by a value of said first component wherein said electrical impedance of said second component is digitally measured.
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Abstract
A digital eddy current proximity system including a digital impedance measuring device for digitally measuring the proximity probes impedance correlative to displacement motion and position of a metallic target object being monitored. The system further including a cable-length calibration method, an automatic material identification and calibration method, a material insensitive method, an inductive ratio method and advanced sensing characteristics.
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Citations
126 Claims
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1. - A device for digitally measuring electrical impedance, comprising in combination:
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a network including a first electrical component and a second electrical component serially connected;
a signal generating means operatively coupled to said network for driving a current through said serially connected components;
means for sampling a first voltage impressed across said network and a second voltage impressed across said second component into digitized voltages;
means for convolving each said digitized voltage with a digital waveform for forming a first complex number and a second complex number correlative to said first voltage impressed across said network and said second voltage impressed across said second component respectively;
means for determining a ratio of said second complex number to a difference between said first and said second complex number, and means for calculating an electrical impedance of said second component by multiplying said ratio by a value of said first component wherein said electrical impedance of said second component is digitally measured. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. - A method for digitally measuring electrical impedance, the steps including:
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forming a network including providing a first electrical component and a second electrical component serially connected;
driving the network with a dynamic signal for impressing a voltage across the network and each component;
digitizing the voltage across the network and the voltage across the second electrical component;
convolving each of the digitized voltages with a digital waveform for forming a first complex number and a second complex number correlative to the voltages across the network and across the second electrical component respectively;
determining a ratio of the second complex number to a difference between the first complex number and the second complex number;
calculating an electrical impedance of the second electrical component by multiplying the ratio by a know digitized value of the first electrical component wherein said electrical impedance of the second component is digitally measured. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. - An apparatus for determining a gap between a proximity probe and a conductive target material, said apparatus comprising in combination:
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a network including a first electrical component and a proximity probe serially connected;
a signal generating means operatively coupled to said network for driving a current through said serial connection wherein a first analog voltage is impressed across said network and a second analog voltage is impressed across said proximity probe;
means for sampling and digitizing said first analog voltage impressed across said network and said second analog voltage impressed across said proximity probe into digitized voltages;
means for convolving each said digitized voltage with a digital waveform for forming a first complex number and a second complex number correlative to said first analog voltage impressed across said network and said second analog voltage impressed across said proximity probe respectively;
means for determining a voltage ratio of said second complex number to a difference between said first complex number and said second complex number;
means for processing said voltage ratio into a gap value correlative to a gap between said proximity probe and a conductive target material. - View Dependent Claims (23, 24, 25, 26)
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27. - An apparatus for determining a gap between a proximity probe and a conductive target material, said apparatus comprising in combination:
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a network including an extension cable interposed between and serially connected to a first electrical component and a proximity probe;
a signal generating means operatively coupled to said network for driving a current through said serial connection wherein a first analog voltage is impressed across said network and a second analog voltage is impressed across said serial connection of said extension cable and said proximity probe;
means for sampling and digitizing said first analog voltage impressed across said network and said second analog voltage impressed across said serial connection of said extension cable and said proximity probe into digitized voltages;
means for convolving each said digitized voltage with a digital waveform for forming a first complex number and a second complex number correlative to said first analog voltage impressed across said network and said second analog voltage impressed across said serial connection of said extension cable and said proximity probe respectively;
means for determining a voltage ratio of said second complex number to a difference between said first complex number and said second complex number;
means for processing said voltage ratio into a gap value correlative to a gap between said proximity probe and a conductive target material. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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44. - An apparatus for determining a dynamic gaps between a proximity probe and a conductive target material, said apparatus comprising in combination:
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means for establishing dynamic voltage signals correlative to dynamic gaps between a proximity probe and a conductive target material;
sampling means for digitizing said established dynamic voltage signals into digital voltage signals;
a digital multiplier for multiplying each said digital voltage signal by a digital sine signal and a digital cosine signal;
means for accumulating values of each multiply in a memory, and means for processing each multiply for obtaining complex voltage representations correlative to dynamic gaps between said proximity probe and a conductive target material. - View Dependent Claims (45, 46, 47, 48)
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49. - A method for measuring a gap between a proximity probe and a conductive target material, said method including the steps of:
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providing a network of components including a first electrical component and a proximity probe component serially connected;
driving a dynamic current through the serially connected electrical components for impressing a first analog voltage across the network and a second analog voltage cross the proximity probe component;
sampling and digitizing the first analog voltage impressed across said serially connected resistance and probe components to obtain a first digitized voltage value;
sampling and digitizing a second analog voltage impressed across the probe component to obtain a second digitized voltage value;
digitally convolving said first digitized voltage and said second digitized voltage into a first complex number and a second complex number respectively;
calculating a voltage ratio of said second complex number to a difference between said first complex number and said second complex number;
processing said voltage ratio into a gap value correlative to a gap between said proximity probe and a conductive target material. - View Dependent Claims (50, 51, 52, 53, 54)
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55. - A method for measuring a gap between a proximity probe and a conductive target material, said method including the steps of:
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providing a network of components including a first electrical component and a proximity probe component serially connected;
driving a dynamic current through the serially connected electrical components including the resistance component and the proximity probe component for impressing a first analog voltage across the network and a second analog voltage cross the proximity probe component;
sampling and digitizing the first analog voltage impressed across said serially connected resistance and probe components to obtain a first digitized voltage value;
sampling and digitizing a second voltage impressed across the probe component to obtain a second digitized voltage value;
digitally convolving said first digitized voltage and said second digitized voltage into a first complex number and a second complex number respectively;
calculating a voltage ratio of said second complex number to a difference between said first complex number and said second complex number;
multiplying the voltage ratio by a value of the first electrical component for determining an impedance of the proximity probe;
correlating the determined impedance of the proximity probe to a gap between the proximity probe and a conductive target material. - View Dependent Claims (56, 57)
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58. - A method for measuring a gap between a proximity probe and a conductive target material, said method including the steps of:
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providing a network of components including a first electrical component, an extension cable component and a proximity probe component respectively serially connected, and locating the proximity probe adjacent a conductive target material;
driving a dynamic current through the serially connected electrical components for impressing a first analog voltage across the network and a second analog voltage across the serial connection of the extension cable component and the proximity probe component;
sampling and digitizing the first analog voltage impressed across said network to obtain a first digitized voltage value;
sampling and digitizing a second analog voltage impressed across the serial connection of the extension cable component and the proximity probe component to obtain a second digitized voltage value;
digitally convolving the first digitized voltage value and the second digitized voltage value into a first complex number and a second complex number respectively;
calculating a voltage ratio of the second complex number to a difference between the first complex number and the second complex number;
processing the voltage ratio into a gap value correlative to a gap between the proximity probe and the conductive target material. - View Dependent Claims (59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 75, 76)
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72. - A method for measuring a position of a conductive target material, the steps including:
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sampling and digitizing a first voltage impressed across a serial connection of a resistance means and a proximity probe located adjacent a conductive target material to obtain a first digitized voltage;
sampling and digitizing a second voltage impressed only across the probe to obtain a second digitized voltage, transforming the two digitized voltages into complex voltage numbers;
calculating an electrical impedance of the proximity probe by using both complex voltage numbers;
correlating the calculated electrical impedance to a gap between the proximity probe and the conductive target material. - View Dependent Claims (73, 74)
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77. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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sampling and digitizing a first voltage impressed across a serial connection of a first electrical component and a proximity probe located adjacent a conductive target material to obtain a first digitized voltage;
sampling and digitizing a second voltage impressed across the probe to obtain a second digitized voltage, transforming the two digitized voltages into complex voltage numbers;
determining an electrical impedance of the proximity probe by using both complex voltage numbers;
normalizing the electrical impedance of the proximity probe;
correlating the normalized electrical impedance of the proximity probe to a gap between the proximity probe and the conductive target material. - View Dependent Claims (78, 79)
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80. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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sampling and digitizing a first voltage impressed across a serial connection of a first electrical component, an extension cable and a proximity probe located adjacent a conductive target material to obtain a first digitized voltage;
sampling and digitizing a second voltage impressed across the probe to obtain a second digitized voltage, transforming the two digitized voltages into complex voltage numbers;
determining an electrical impedance of the proximity probe by using both complex voltage numbers and compensating for the extension cable;
normalizing the electrical impedance of the proximity probe;
correlating the normalized electrical impedance of the proximity probe to a gap between the proximity probe and the conductive target material. - View Dependent Claims (81, 82)
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83. - A method for measuring a gap between a proximity probe and a conductive target material, said method including the steps of:
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digitally measuring an electrical impedance of a proximity probe located adjacent a conductive target material;
combining a predetermined digitized impedance with the digitally measured impedance of the proximity probe;
correlating the combined impedance to a gap interposed between the proximity probe and the conductive target material being monitored. - View Dependent Claims (84, 85, 86, 87, 88)
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89. - A method for measuring a gap between a proximity probe and a conductive target material, said method including the steps of:
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digitally measuring an electrical impedance of an a proximity probe and an extension cable connected thereto, the proximity probe is located adjacent a conductive target material;
combining a predetermined digitized impedance with the digitally measured impedance;
correlating the combined impedance to a gap interposed between the proximity probe and the conductive target material being monitored. - View Dependent Claims (90, 91, 92, 93, 94, 96, 97, 98)
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99. - A method for measuring a gap between a proximity probe and a conductive target material, said method including the steps of:
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measuring an impedance of a proximity probe located proximate a conductive target material and an extension cable operatively coupled to the proximity probe;
compensating the measured impedance by using compensation coefficients stored in a memory means;
combining a predetermined impedance with the compensated measured impedance for forming a combination impedance;
determining a gap between the proximity probe and the conductive target material as a function of the combination impedance;
iteratively repeating the measuring, compensating, combining and determining steps to substantially continuously monitor the gap between the probe and the target as a function of the combination impedance. - View Dependent Claims (100)
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101. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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providing a database of normalized impedance curve representations for different conductive target materials;
measuring an impedance of a proximity probe located proximate a conductive target material being identified;
normalizing the measured probe impedance;
utilizing the normalized probe impedance and the database of normalized impedance curve representations for identifying the conductive target material;
determining a gap value between the proximity probe and the conductive target material from the normalized probe impedance and the identified target material. - View Dependent Claims (102, 103)
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104. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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providing a representation of a defined series of gap locus each representative of the same gap for different target materials;
measuring an impedance of a proximity probe located proximate a conductive target material;
normalizing the measured probe impedance;
determining a gap value between the proximity probe and the conductive target material from the normalized probe impedance and the representation of the defined series of gap locus wherein the gap value is substantially correct for any conductive target material adjacent the proximity probe thereby providing a material insensitive method for measuring gap values between the proximity probe and different conductive target materials. - View Dependent Claims (105, 106, 107)
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108. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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providing a representation of a defined series of gap locus each representative of the same gap for different target materials;
measuring an impedance of a proximity probe located proximate a conductive target material, the proximity probe, including a probe cable;
compensating an impedance contribution of the probe cable from the measured probe impedance to define a measured coil impedance;
normalizing the measured coil impedance;
determining a gap value between the proximity probe and the conductive target material from the normalized coil impedance and the representation of the defined series of gap locus wherein the gap value is substantially correct for any conductive target material adjacent the proximity probe thereby providing a material insensitive method for measuring gap values between the proximity probe and different conductive target materials. - View Dependent Claims (109)
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110. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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measuring a proximity probe impedance at a first frequency and a second different frequency, the proximity probe including an integral sensing coil;
determining an impedance of the sensing coil from the measured proximity probe impedance at the first frequency and the second different frequency;
dividing a reactance of the impedance of the sensing coil at the first frequency by the reactance of the impedance of the sensing coil at the second different frequency for defining an inductive ratio;
correlating the inductive ratio to a value representative to a gap between the proximity probe and the conductive target material.
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111. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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sampling and digitizing a first voltage impressed across a serial connection of a resistance means and a proximity probe located adjacent a conductive target material to obtain a first digital voltage correlative to the first voltage at a first frequency;
sampling and digitizing a second voltage impressed only across the probe to obtain a second digital voltage correlative to the second voltage at the first frequency, digitally convolving the first digital voltage and the second digital voltage into a first complex voltage number and a second complex voltage number;
calculating an electrical impedance of the proximity probe at the first frequency by using the first complex voltage number and the second complex voltage number;
sampling and digitizing a third voltage impressed across the serial connection of the resistance means and the proximity probe located adjacent the conductive target material to obtain a third digital voltage correlative to the third voltage at a second frequency;
sampling and digitizing a fourth voltage impressed only across the probe to obtain a fourth digital voltage correlative to the fourth voltage at the second frequency, digitally convolving the third digital voltage and the fourth digital voltage into a third complex voltage number and a fourth complex voltage number;
calculating a complex electrical impedance of the proximity probe at the second frequency by using the third complex voltage number and the fourth complex voltage number;
dividing a reactance of the calculated complex electrical impedance of the sensing coil at the first frequency by the reactance of the calculated complex electrical impedance of the sensing coil at the second different frequency for defining an inductive ratio;
correlating the inductive ratio to a value representative to a gap between the proximity probe and the conductive target material.
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112. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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providing a proximity probe having a first end located adjacent a conductive target material and having a second end coupled to a first end of an extension cable;
measuring an impedance at a second end of the extension cable;
compensating the measured impedance by mathematically eliminating extension cable residuals from the measured impedance for defining a proximity probe impedance of the proximity probe;
correlating the proximity probe impedance with a value representative of a gap between the proximity probe and the conductive target material. - View Dependent Claims (113, 114, 115, 116)
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117. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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providing an extension cable having two ends;
determining a first impedance of the extension cable with one of the two ends opened for defining an open impedance;
determining a second impedance of the extension cable with one of the two ends shorted for defining a short impedance;
providing a proximity probe having an end located adjacent a conductive target material and having an opposite end coupled to one of the two ends of the extension cable;
measuring an impedance at the other end of the extension cable;
determining an impedance of the proximity probe as a function of the short impedance, the open impedance and the measured impedance for defining a proximity probe impedance;
correlating the proximity probe impedance with a value representative of a gap between the proximity probe and the conductive target material. - View Dependent Claims (118)
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119. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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providing an extension cable having two ends;
determining a first impedance of the extension cable with one of the two ends opened for defining a open impedance;
determining a second impedance of the extension cable with one of the two ends shorted for defining a short impedance;
determining a third impedance of the extension cable with one of the two ends coupled to a load having a known value for defining a load impedance;
providing a proximity probe having an end located adjacent a conductive target material and having an opposite end coupled to one of the two ends of the extension cable;
measuring an impedance at the other end of the extension cable;
determining an impedance of the proximity probe as a function of the short impedance, the open impedance, the load impedance and the measured impedance for defining the proximity probe impedance;
correlating the proximity probe impedance with a value representative of a gap between the proximity probe and the conductive target material. - View Dependent Claims (120)
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121. - A method for measuring a gap between a proximity probe and a conductive target material, the steps including:
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providing an extension cable having two ends;
determining a first load impedance of the extension cable with one of the two ends coupled to a first load;
determining a second load impedance of the extension cable with one of the two ends coupled to a second load;
the second load having an impedance that is less than the impedance of the first load;
providing a proximity probe having an end located adjacent a conductive target material and having an opposite end coupled to one of the two ends of the extension cable;
measuring an impedance at the other end of the extension cable;
calculating a proximity probe impedance of the proximity probe as a function of the measured impedance, the first load impedance and the second load impedance for compensating for extension cable residuals;
correlating the proximity probe impedance with a value representative of a gap between the proximity probe and the conductive target material. - View Dependent Claims (122, 123)
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124. - A method for measuring a characteristic of a conductive target material disposed adjacent a proximity probe, the steps including:
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providing a length of cable having a first end and a second end;
determining a first impedance of the cable with the first end opened for defining a open impedance;
determining a second impedance of the cable with the first end shorted for defining a short impedance;
coupling the first end of the cable to a proximity probe and having the second end of the cable coupled to a digital eddy current proximity system;
measuring, at the second end of the cable, an impedance of the coupled cable and proximity probe;
calculating the proximity probe impedance as a function of the measured impedance, the open impedance, and the short impedance for compensating for cable length residuals;
correlating the proximity probe impedance with a characteristic of a conductive target material disposed adjacent the proximity probe. - View Dependent Claims (125, 126)
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Specification