ESTIMATING THE GRAVITY VECTOR IN A WORLD COORDINATE SYSTEM USING AN ACCELEROMETER IN A MOBILE DEVICE
First Claim
1. A method for estimating a gravity vector on a target plane using an accelerometer located within a mobile device, comprising:
- receiving a plurality of measurements by a processor of the mobile device from the accelerometer, each of the measurements being taken when the mobile device is held stationary on the target plane and a surface of the mobile device faces and is in contact with a planar portion of the target plane;
calculating an average of the measurements;
retrieving a rotational transformation between a coordinate system of the accelerometer and a coordinate system of the mobile device from a memory in the mobile device, wherein the coordinate system of the mobile device is aligned with the surface of the mobile device; and
applying the rotational transformation to the average to obtain an estimated gravity vector in a world coordinate system defined by the target plane.
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Accused Products
Abstract
An accelerometer located within a mobile device is used to estimate a gravity vector on a target plane in a world coordinate system. The accelerometer makes multiple measurements, each measurement being taken when the mobile device is held stationary on the target plane and a surface of the mobile device faces and is in contact with a planar portion of the target plane. An average of the measurements is calculated. A rotational transformation between an accelerometer coordinate system and a mobile device'"'"'s coordinate system is retrieved from a memory in the mobile device, where the mobile device'"'"'s coordinate system is aligned with the surface of the mobile device. The rotational transformation is applied to the averaged measurements to obtain an estimated gravity vector in a world coordinate system defined by the target plane.
18 Citations
38 Claims
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1. A method for estimating a gravity vector on a target plane using an accelerometer located within a mobile device, comprising:
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receiving a plurality of measurements by a processor of the mobile device from the accelerometer, each of the measurements being taken when the mobile device is held stationary on the target plane and a surface of the mobile device faces and is in contact with a planar portion of the target plane; calculating an average of the measurements; retrieving a rotational transformation between a coordinate system of the accelerometer and a coordinate system of the mobile device from a memory in the mobile device, wherein the coordinate system of the mobile device is aligned with the surface of the mobile device; and applying the rotational transformation to the average to obtain an estimated gravity vector in a world coordinate system defined by the target plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A mobile device comprising:
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an accelerometer; a memory to store a rotational transformation between a coordinate system of the accelerometer and a coordinate system of the mobile device; and a processor coupled to the memory and the accelerometer, the processor configured to; receive a plurality of measurements from the accelerometer, each of the measurements being taken when the mobile device is held stationary on a target plane and a surface of the mobile device faces and is in contact with a planar portion of the target plane; calculate an average of the measurements; retrieve the rotational transformation from the memory, wherein the coordinate system of the mobile device is aligned with the surface of the mobile device; and apply the rotational transformation to the average to obtain an estimated gravity vector in a world coordinate system defined by the target plane. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A computer program product comprising:
a computer-readable medium comprising code for; receiving a plurality of measurements from an accelerometer in a mobile device, each of the measurements being taken when the mobile device is held stationary on a target plane and a surface of the mobile device faces and is in contact with a planar portion of the target plane; calculating an average of the measurements; retrieving a rotational transformation between a coordinate system of the accelerometer and a coordinate system of the mobile device from a memory in the mobile device, wherein the coordinate system of the mobile device is aligned with the surface of the mobile device; and applying the rotational transformation to the average to obtain an estimated gravity vector in a world coordinate system defined by the target plane. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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28. A mobile device comprising:
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means for receiving a plurality of measurements from an accelerometer, each of the measurements being taken when the mobile device is held stationary on a target plane and a surface of the mobile device faces and is in contact with a planar portion of the target plane; means for calculating an average of the measurements; means for retrieving a rotational transformation between a coordinate system of the accelerometer and a coordinate system of the mobile device from a memory in the mobile device, wherein the coordinate system of the mobile device is aligned with the surface of the mobile device; and means for applying the rotational transformation to the average to obtain an estimated gravity vector in a world coordinate system defined by the target plane. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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Specification