System and method of magnetically sensing position of a moving component
First Claim
1. A position-sensing system, comprising:
- a first component;
a second component movably coupled to the first component for movement with respect thereto;
a magnetically hard layer formed on the second component to provide a recording medium, a plurality of regions of the magnetically hard layer being magnetized to provide an encoding scheme for determining a position of the second component relative to the first component; and
a plurality of magnetic-field sensors coupled to the first component in proximity of the magnetically hard layer to sense the magnetized regions while the second component is moving with respect to the first component, at least two of the magnetic-field sensors being axially positioned to sense the same set of magnetized regions in succession and to generate signals in response to the sensed magnetized regions that can be used to determine a position of the second component.
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Accused Products
Abstract
A position-sensing system magnetically senses the position of a piston rod moving with respect to a cylinder. A magnetically hard layer on the piston rod provides a recording medium. Information is magnetically recorded in regions of the magnetically hard layer. These regions provide a relative encoding scheme for determining the position of the piston rod. Magnetic-field sensors are positioned over redundant tracks of magnetically recorded regions. Each magnetic-field sensor positioned over a given track senses the same magnetized regions while the piston rod moves with respect to the cylinder. Other magnetic-field sensors can sense ambient fields for use in performing common-mode rejection. A write head can dynamically repair damaged or erased regions detected by the magnetic-field sensors. Energized by a battery- backup power source, the magnetic-field sensors and associated circuitry can continue to track movement of the piston rod when the machinery is off.
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Citations
27 Claims
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1. A position-sensing system, comprising:
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a first component;
a second component movably coupled to the first component for movement with respect thereto;
a magnetically hard layer formed on the second component to provide a recording medium, a plurality of regions of the magnetically hard layer being magnetized to provide an encoding scheme for determining a position of the second component relative to the first component; and
a plurality of magnetic-field sensors coupled to the first component in proximity of the magnetically hard layer to sense the magnetized regions while the second component is moving with respect to the first component, at least two of the magnetic-field sensors being axially positioned to sense the same set of magnetized regions in succession and to generate signals in response to the sensed magnetized regions that can be used to determine a position of the second component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for sensing a position of a first component moving relative to a second component, the method comprising:
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forming a magnetically hard layer on the first component to provide a recording medium for storing information;
magnetically recording information at a plurality of regions of the magnetically hard layer along a direction of motion of the first component;
reading, by a plurality of magnetic field sensors, the same magnetically recorded regions of the magnetically hard layer while the first component is moving relative to the second component; and
generating output signals by the plurality of magnetic field sensors from which a position of the first component with respect to the second component can be determined. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. An apparatus, comprising:
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a cylinder;
a piston rod movably coupled to the cylinder for movement with respect thereto;
a magnetically hard layer formed on a surface of the piston rod to provide a recording medium, information being magnetically recorded in a plurality of regions of the magnetically hard layer to provide an encoding scheme for determining a position of the piston rod relative to the cylinder;
a first plurality of magnetic field sensors positioned over one or more tracks of magnetically recorded regions to sense the magnetically recorded regions while the piston rod moves with respect to the cylinder; and
a second plurality of magnetic field sensors for sensing ambient fields near the first plurality of magnetic field sensors for use in performing common-mode rejection. - View Dependent Claims (22, 23, 24, 25, 26)
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27. An apparatus, comprising:
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a cylinder;
a piston rod movably coupled to the cylinder for movement with respect thereto;
a magnetically hard layer formed on a surface of the piston rod to provide a recording medium, information being magnetically recorded in a plurality of regions of the magnetically hard layer to provide an encoding scheme for determining a position of the piston rod relative to the cylinder;
a first plurality of magnetic field sensors positioned over redundant tracks of magnetically recorded regions, at least two magnetic field sensors being positioned over each track to sense the magnetically recorded regions while the piston rod moves with respect to the cylinder;
a second plurality of magnetic field sensors for sensing ambient fields near the first plurality of magnetic field sensors for use in performing common-mode rejection;
a write head for dynamically repairing damaged or erased magnetically recorded regions detected by one or more magnetic field sensors of the first plurality of magnetic field sensors; and
a power source supplying electrical power to the magnetic field sensors and associated read-head electronics when the apparatus is off so that the magnetic field sensors can continue to sense movement of the piston rod with respect to the cylinder while the apparatus is off.
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Specification