Digital eddy current proximity system: apparatus and method
First Claim
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1. An apparatus for determining a gap between a proximity probe and a conductive target material, said apparatus comprising in combination:
- 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.
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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.
104 Citations
25 Claims
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1. 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 (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. 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 (19, 20, 21, 22, 23, 24, 25)
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Specification