Mobile Device Orientation Compensation via Visual Reference Markers
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Solution Overview
Problem
Existing mobile devices face challenges in accurately determining orientation in indoor environments due to magnetic anomalies and sensor drift, requiring a technique that does not modify the device hardware or environment.
Innovation Solution
Utilizing a mobile device camera and image recognition processing to compensate orientation by referencing orthogonal, regularly oriented markers such as ceiling-mounted light fixtures, which provide known orientation data to correct sensor estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetometer data is used to determine orientation, then orientation information can be obtained, but magnetic anomalies in the environment render the data inaccurate or useless
Solution Approach 1:
The patent introduces visual markers (intermediaries) placed in the environment that serve as a mediator between the mobile device and the orientation determination system. Instead of directly relying on magnetometer data affected by magnetic anomalies, the device captures images of these markers and uses their known positions and orientations to calculate accurate orientation, effectively bypassing the harmful magnetic interference.
2Measurement precision
If inertial navigation with internal reference techniques is used to track orientation, then orientation tracking can be performed, but errors accumulate and the system is subject to drift
Solution Approach 1:
The patent implements a feedback mechanism where the mobile device continuously captures images of environmental markers and compares the observed marker positions with their known reference positions. This feedback loop allows the system to detect and correct any drift in orientation estimation, maintaining accurate orientation determination over extended operational durations without the accumulation of errors characteristic of inertial navigation systems.
3Measurement precision
If sensor compensation techniques are used to correct magnetometer data, then some accuracy can be maintained, but the internal sensors are low cost and subject to drift
Solution Approach 1:
The patent replaces reliance on unstable internal sensors with external visual markers as intermediaries. These markers provide a stable, external reference frame that is not subject to sensor drift. By using the markers' known positions and orientations in the environment, the system achieves reliable and stable orientation determination without depending on the long-term stability of internal sensors.
4Object-affected harmful factors
If orientation sensors are used to compensate each other, then some magnetic anomaly effects can be corrected, but the sensors provide relatively low orientation accuracy
Solution Approach 1:
The patent substitutes the mechanical sensor-based compensation system with an optical/image-based system. Instead of using magnetometers and accelerometers that are subject to drift and limited accuracy, the system uses the device's camera to capture images of visual markers and processes these images computationally to determine orientation. This substitution of mechanical sensing with optical sensing and image processing achieves significantly higher orientation accuracy while still providing compensation for environmental interference.
Data Source
AI summary
A method and system for orientation compensation of a mobile device within an environment includes providing a plurality of reference markers having straight edges and having a defined, regular orientation with respect to the environment. Information about the orientation of the reference markers is supplied to a mobile device operating within the environment. An orientation sensor disposed within the mobile device estimates an orientation of the mobile device. An image of one reference marker is captured, and at least one edge of that reference marker is located. The estimated orientation is compensated by correcting for the reference marker orientation and aligning the corrected estimated orientation to the at least one edge of the reference marker that is closest to being parallel to the corrected estimated orientation.