Passive and wireless displacement measuring device
First Claim
1. A system for performing a remote measurement of the displacement between two adjacent objects, comprisinga sensor for attachment between the objects, the sensor having a magnetic rod, the rod having a first end and a second end, and a sensor coil, the sensor coil having the shape of a hollow cylinder having a first end and a second end and having a longitudinal axis between the first end and the second end;
- wherein the first end of the rod is insertable into the first end of the sensor coil and moveable along the longitudinal axis of the sensor coil;
wherein the rod has an end mount at the second end of the rod, the end mount operable to be attached to one of the objects, and wherein the sensor coil has an end mount at the second end of the sensor coil, the end mount operable to be attached to the other of the objects, and an interrogator having a transmit coil and at least one receive coil, transmit circuitry for delivering to the sensor coil an excitation signal through a range of frequencies, and receive circuitry for receiving a response signal from the sensor coil;
wherein the transmit coil and the at least one receive coil are configured in a nulling geometry.
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Accused Products
Abstract
A system that remotely measures displacement between two objects. A passive sensor is affixed between the objects. The internal sensor uses magnetic coupling between two sensor elements to measure their relative displacement. The sensors are either a) a permeable rod and a complimentary coil in parallel with a tuning capacitor; or b) two permeable rods, each having its own surrounding coil and a tuning capacitor. One of the sensor elements is affixed to each object which is to be monitored. When an interrogating device is placed near the sensors, a resonance can be measured whose frequency characteristics change in a reproducible manner with the relative displacement of the sensors. The resulting resonance characteristics can be calibrated in such a way as to enable the displacement of the objects to be determined.
112 Citations
24 Claims
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1. A system for performing a remote measurement of the displacement between two adjacent objects, comprising
a sensor for attachment between the objects, the sensor having a magnetic rod, the rod having a first end and a second end, and a sensor coil, the sensor coil having the shape of a hollow cylinder having a first end and a second end and having a longitudinal axis between the first end and the second end; -
wherein the first end of the rod is insertable into the first end of the sensor coil and moveable along the longitudinal axis of the sensor coil;
wherein the rod has an end mount at the second end of the rod, the end mount operable to be attached to one of the objects, and wherein the sensor coil has an end mount at the second end of the sensor coil, the end mount operable to be attached to the other of the objects, and an interrogator having a transmit coil and at least one receive coil, transmit circuitry for delivering to the sensor coil an excitation signal through a range of frequencies, and receive circuitry for receiving a response signal from the sensor coil;
wherein the transmit coil and the at least one receive coil are configured in a nulling geometry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for determining displacement between two objects, comprising the steps of:
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attaching a first end of a magnetic rod to a first object;
attaching a first end of a sensor coil to a second object;
wherein the attaching steps are performed such that the rod is partially inserted into the coil and the rod and coil extend between the objects, thereby forming a sensor;
interrogating the sensor with an interrogation signal; and
receiving a response signal from the sensor, said response signal having a frequency that indicates motion of the rod within the sensor coil;
wherein the receiving step is performed with at least one receive coil and at least one transmit coil configured in a nulling geometry. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method for determining displacement between two objects within a living body, comprising the steps of:
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attaching a first end of a magnetic rod to a first skeletal object;
attaching a first end of a sensor coil to a second skeletal object;
wherein the attaching steps are performed such that the rod is partially inserted into the coil and the rod and coil extend between the objects, thereby forming a sensor;
interrogating the sensor with an interrogation signal;
receiving a response signal from the sensor, said response signal having a frequency that indicates motion of the rod within the sensor coil;
wherein the receiving step is performed with at least one receive coil and at least one transmit coil configured in a nulling geometry. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification