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Estimating the gravity vector in a world coordinate system using an accelerometer in a mobile device

A mobile device, accelerometer technology, applied in the direction of velocity/acceleration/shock measurement, navigation through velocity/acceleration measurement, testing/calibration of velocity/acceleration/shock measurement equipment, etc., can solve problems such as low accuracy

Inactive Publication Date: 2015-07-01
QUALCOMM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Existing accelerometer-assisted techniques for measuring the gravity vector in the target coordinate system often have low accuracy due to the accumulation of errors in multiple transformation steps, each of which can introduce errors

Method used

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  • Estimating the gravity vector in a world coordinate system using an accelerometer in a mobile device
  • Estimating the gravity vector in a world coordinate system using an accelerometer in a mobile device
  • Estimating the gravity vector in a world coordinate system using an accelerometer in a mobile device

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Embodiment Construction

[0014] The word "exemplary" or "example" is used herein to mean "serving as an example, instance, or illustration." Any aspect or embodiment described herein as "exemplary" or as "example" is not necessarily to be construed as preferred or advantageous over other aspects or embodiments.

[0015] Embodiments of the present invention provide a method for estimating a gravity vector relative to a target plane using an accelerometer in a mobile device, such as a mobile phone. For AR applications, the target plane is the feature plane on which the AR target will be displayed. The target plane may have any orientation; for example, the target plane may be aligned with the horizontal axis, aligned with the vertical axis, or inclined relative to the horizontal or vertical axis. This target plane defines the world coordinate system for the AR application. The mobile device can be used as a convenient tool for estimating or measuring the gravity vector in the world coordinate system. ...

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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.

Description

Background technique [0001] The subject matter disclosed herein relates generally to the use of accelerometers for measuring gravity vectors. [0002] Accelerometers (also known as motion sensors) measure intrinsic acceleration, which is the acceleration experienced by the accelerometer relative to free fall (or inertia). The intrinsic acceleration is related to the gravitational phenomenon experienced by a proof mass residing in the reference frame of the accelerometer. Accelerometers measure weight per unit mass—a quantity also known as specific force or gravitational force. Conceptually, an accelerometer behaves as a damped mass spring. When the accelerometer experiences acceleration, the position of the proof mass shifts relative to the coordinate system. Measure displacement to determine acceleration. [0003] A gyroscope (also known as a rotation sensor) measures the angular velocity of the system in an inertial frame of reference. The current orientation of the sys...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F1/16G06F3/0346G01P21/00G01P15/18
CPCG01C25/005G01C21/12G06F3/0346G01P13/02G01C19/00G06F1/1694G01C9/00H04M2250/12G01C21/10
Inventor A·拉马南达恩M·拉马钱德兰C·布鲁纳M·R·查里
Owner QUALCOMM INC
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