Magnet Ring with Jittered Poles
First Claim
1. An apparatus for determining a rotational position by correlating a characteristic shift pattern to a measured magnetic field pattern, the apparatus comprising:
- a first platform having a first side;
a second platform having a second side that at least partially overlaps with the first side of the first platform, wherein the second platform is configured to rotate relative to the first platform about an axis;
a magnet ring mounted to the first side of the first platform and centered around the axis, wherein the magnet ring comprises four or more magnetized poles, wherein the four or more magnetized poles are positioned such that each respective boundary between neighboring poles of the four or more poles is shifted relative to a corresponding nominal boundary defined by a uniform spacing of boundaries of the four or more poles around the magnet ring, and wherein the shifted boundaries of the four or more poles define the characteristic shift pattern of the magnet ring; and
a magnetic field sensor connected to the second side of the second platform and configured to generate the measured magnetic field pattern by measuring characteristics of a magnetic field generated by the four or more poles.
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Accused Products
Abstract
An apparatus includes a first platform and a second platform configured to rotate relative to the first platform about an axis. A magnet ring is mounted to the first platform and centered around the axis. The magnet ring includes four or more magnetized poles positioned such that each respective boundary between neighboring poles is shifted relative to a corresponding nominal boundary defined by a uniform spacing of boundaries of the poles around the magnet ring. The shifted boundaries of the poles define a characteristic shift pattern for the magnet ring. A magnetic field sensor is connected to the second platform. Circuitry is configured to (i) determine a magnetic field pattern generated by the poles based on data generated by the sensor and (ii) determine a rotational position of the first platform relative to the second platform by correlating the magnetic field pattern to the characteristic shift pattern.
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Citations
20 Claims
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1. An apparatus for determining a rotational position by correlating a characteristic shift pattern to a measured magnetic field pattern, the apparatus comprising:
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a first platform having a first side; a second platform having a second side that at least partially overlaps with the first side of the first platform, wherein the second platform is configured to rotate relative to the first platform about an axis; a magnet ring mounted to the first side of the first platform and centered around the axis, wherein the magnet ring comprises four or more magnetized poles, wherein the four or more magnetized poles are positioned such that each respective boundary between neighboring poles of the four or more poles is shifted relative to a corresponding nominal boundary defined by a uniform spacing of boundaries of the four or more poles around the magnet ring, and wherein the shifted boundaries of the four or more poles define the characteristic shift pattern of the magnet ring; and a magnetic field sensor connected to the second side of the second platform and configured to generate the measured magnetic field pattern by measuring characteristics of a magnetic field generated by the four or more poles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method comprising:
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generating a first magnetic field that interacts with a second magnetic field generated by four or more poles of a magnet ring mounted to a first platform such that the first platform rotates about an axis of rotation relative to a second platform; receiving, from a magnetic field sensor connected to the second platform, data indicative of characteristics of the second magnetic field, wherein each respective boundary between neighboring poles of the four or more poles is shifted relative to a corresponding nominal boundary defined by a uniform spacing of boundaries of the four or more poles around the magnet ring; determining a magnetic field pattern based on the data received from the magnetic field sensor; and determining a rotational position of the first platform relative to the second platform by correlating the magnetic field pattern to a characteristic shift pattern of the magnet ring, wherein the characteristic shift pattern is defined by the shifted boundaries of the four or more poles of the magnet ring. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A non-transitory computer-readable storage medium having stored thereon instructions that, when executed by a computing device, cause the computing device to perform operations comprising:
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providing instructions to generate a first magnetic field by causing an electrical current to flow through an electrically conductive path, wherein the first magnetic field interacts with a second magnetic field generated by four or more poles of a magnet ring mounted to a first platform such that the first platform rotates about an axis of rotation relative to a second platform, wherein the electrically conductive path is included in the second platform; receiving, from a magnetic field sensor connected to the second platform, data indicative of characteristics of the second magnetic field, wherein each respective boundary between neighboring poles of the four or more poles is shifted relative to a corresponding nominal boundary defined by a uniform spacing of boundaries of the four or more poles around the magnet ring; determining a magnetic field pattern based on the data received from the magnetic field sensor; and determining a rotational position of the first platform relative to the second platform by correlating the magnetic field pattern to a characteristic shift pattern of the magnet ring, wherein the characteristic shift pattern is defined by the shifted boundaries of the four or more poles of the magnet ring. - View Dependent Claims (19, 20)
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Specification