Mobile Device Orientation Sensor Alignment with Earth Coordinates
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Solution Overview
Problem
Existing techniques for determining accurate absolute orientation of mobile devices in augmented reality applications are limited by hardware capabilities and software configurations, often requiring constant displacement, road information, and are not applicable to devices lacking certain sensors or providing only relative orientation.
Innovation Solution
A software process aligns the orientation sensor of a mobile device with the Earth's coordinate system by prompting the user to move in a straight line, capturing position information, and using linear regression to determine the orientation difference, enabling the calculation of absolute orientation without constant displacement or road information, and accommodating various sensor types and API limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional orientation determination methods are used, then relative orientation can be obtained, but absolute orientation cannot be determined due to hardware and software limitations
Solution Approach 1:
The patent uses GPS position data as an intermediary to bridge the gap between relative sensor orientation and absolute Earth-coordinate orientation. By tracking changes in position over time and calculating movement vectors, the system can determine absolute orientation even when sensors only provide relative data, thus resolving the contradiction between measurement precision and sensor compatibility
Solution Approach 2:
The patent replaces direct mechanical sensing of absolute orientation (which requires specialized sensors like magnetometers) with a computational approach using position data and movement analysis. This substitution allows absolute orientation to be derived through mathematical calculations from GPS positions rather than direct physical measurement, enabling compatibility with devices lacking advanced sensors
2Measurement precision
If figure-8 calibration method is used, then compass orientation can be determined, but it requires specific movement patterns and is not applicable to all devices
Solution Approach 1:
The patent extracts the essential information needed for orientation determination (movement direction and distance) from the complex figure-8 calibration process. Instead of requiring the full figure-8 motion pattern, the system only needs to track position changes along the movement path, simplifying the operational requirements while maintaining orientation accuracy
Solution Approach 2:
The patent performs preliminary calculation of movement vectors and orientation differences during the calibration phase. By pre-computing the relationship between sensor orientation and Earth coordinates based on GPS position data, the system eliminates the need for complex real-time calibration operations during actual use
3Measurement precision
If manual feature correspondence method is used, then absolute orientation can be determined, but it is time-consuming and burdensome
Solution Approach 1:
The patent enables the system to automatically determine absolute orientation using GPS position data and movement vector calculations without requiring manual user input for feature correspondence. The device self-calibrates by tracking its own movement through space and computing orientation from position changes, eliminating time-consuming manual operations while maintaining accuracy
Data Source
AI summary
In one embodiment, a technique for providing absolute orientation of a mobile device involves aligning the orientation sensor of the mobile device with the Earth's coordinate system. An initial orientation from the orientation sensor of the mobile device is accessed, a user is prompted to move the mobile device in a direction of the initial orientation, and using a position sensor, a set of position information that describes positions of the mobile device is captured while the mobile device is being moved in the direction. Based on the set of position information, a vector of movement is determined. Using the vector of movement, an orientation difference is calculated between the Earth's coordinate system and a coordinate system of the mobile device. Upon demand, an absolute orientation of the mobile device may be produced by accessing a live orientation from the orientation sensor and adding the orientation difference.