Magnetofluidic accelerometer with active suspension
First Claim
1. A method of measuring acceleration comprising:
- suspending a non-magnetic inertial body using a magnetic fluid;
generating a magnetic field within the magnetic fluid;
modulating the magnetic field to counteract and minimize a displacement of the inertial body due to acceleration; and
calculating the acceleration based on the modulation,wherein the change in the position of the inertial body is calculated based on changes of magnetic flux line distribution within the magnetic fluid.
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Accused Products
Abstract
A method of measuring acceleration includes suspending an inertial body using a magnetic fluid; generating a magnetic field within the magnetic fluid; modulating the magnetic field to counteract a change in position of the inertial body relative to sources of the magnetic field due to acceleration; and calculating the acceleration based on the modulation. The calculating step derives the acceleration based on an amount of current through drive coils required for the modulation. The acceleration includes linear acceleration and/or angular acceleration. The drive coils include permanent magnets, electromagnets, or a combination of a permanent magnet and an electromagnet. Sensing coils can be used for detecting the displacement of the inertial body. Each sensing coil can be positioned substantially within a corresponding drive coil. The inertial body can be non-magnetic, weakly magnetic, or have a ferromagnetic coating.
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Citations
31 Claims
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1. A method of measuring acceleration comprising:
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suspending a non-magnetic inertial body using a magnetic fluid; generating a magnetic field within the magnetic fluid; modulating the magnetic field to counteract and minimize a displacement of the inertial body due to acceleration; and calculating the acceleration based on the modulation, wherein the change in the position of the inertial body is calculated based on changes of magnetic flux line distribution within the magnetic fluid. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for measuring acceleration comprising:
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suspending a non-magnetic inertial body in a magnetic fluid; measuring behavior of the inertial body in response to acceleration; applying a force to the inertial body to counteract the acceleration and minimize a displacement of the inertial body; and calculating the acceleration as a function of the applied force, wherein the displacement of the inertial body is calculated based on changes of magnetic flux line distribution within the magnetic fluid.
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9. A method of measuring acceleration comprising:
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suspending a non-magnetic object using a fluid; generating a magnetic field within the fluid; detecting a change in position of the object due to acceleration; controlling the magnetic field to counteract and minimize the change in position of the object; and calculating the acceleration as a function of the control of the magnetic field, wherein the change in the position of the inertial body is calculated based on changes of magnetic flux line distribution within the magnetic fluid.
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10. An A sensing element of an accelerometer comprising:
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a non-magnetic inertial body; a plurality of separate drops of magnetic fluid holding the inertial body in suspension; a plurality of magnetic poles maintaining the drops in contact with the inertial body; a controller that modulates magnetic fields generated by the magnetic poles to counteract and minimize a displacement of the inertial body due to acceleration; a sensor that detects changes in the magnetic flux distribution due to the change in position of the inertial body, wherein the change of the magnetic flux line distribution is indicative of the acceleration. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A sensing element of an accelerometer compnsing:
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a non-magnetic inertial body; a plurality of magnets located in proximity to the inertial body and on opposing sides of the inertial body; a magnetic fluid between the magnets and the inertial body; and a circuit that modulates magnetic fields generated by the magnets to counteract and minimize a displacement of the inertial body due to acceleration; and a sensor that detects changes in the magnetic flux distribution due to the displacement of the inertial body, wherein the change of the magnetic flux line distribution is indicative of the acceleration. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A sensing element of an accelerometer comprising:
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a non-magnetic inertial body; a plurality of magnets generating a repulsive force acting on the inertial body; a circuit that modulates magnetic fields generated by the magnets so as to counteract and minimize a displacement of the inertial body due to acceleration; and a sensor that detects changes in the magnetic flux distribution due to the displacement of the inertial body, wherein the change of the magnetic flux line distribution is indicative of the acceleration.
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30. A sensor comprising:
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a non-magnetic inertial body; a magnetic fluid exerting a force on the inertial body; a plurality of magnets generating magnetic fields within the magnetic fluid, wherein a position of the inertial body relative to the magnets is maintained by modulation of the magnetic fields by minimizing a displacement of the inertial body; a circuit that derives acceleration based on the modulation; and a sensor that detects changes in the magnetic flux distribution due to the displacement of the inertial body, wherein the change of the magnetic flux line distribution is indicative of the acceleration.
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31. A sensor comprising:
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a non-magnetic inertial body; a fluid exerting a force on the inertial body; a plurality of magnets generating magnetic fields within the fluid, a position sensor detecting a change in position of the inertial body due to acceleration; a controller that drives the magnets in response to the change so as to minimize the change in position of the inertial body; and a sensor that detects changes in the magnetic flux distribution due to displacement of the inertial body, wherein the change of the magnetic flux line distribution is indicative of acceleration of the sensor, and wherein the acceleration is derived from current required by the magnets.
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Specification