Indoor Positioning via Magnetic Field Anomaly Mapping
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Solution Overview
Problem
Indoor location-finding technologies face challenges due to the fluctuating nature of Wi-Fi signals and large coverage areas of cellular base stations, resulting in low accuracy, as they rely on infrastructure-dependent methods rather than infrastructure-independent positioning tools.
Innovation Solution
Utilizing anomalies in the Earth's magnetic field, which are location-specific and temporally stable, to create a map or database that can be used by mobile devices to determine their position, combining magnetic field strength measurements with inertial measurement units and particle filtering techniques for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Wi-Fi signals are used for indoor location-finding, then the method is infrastructure-dependent and can provide location information, but the signals are highly fluctuating and severely affected by physical layout, resulting in low precision
Solution Approach 1:
The patent replaces Wi-Fi based radio signal measurement with magnetic field measurement. The magnetic field sensor (magnetometer) measures the Earth's magnetic field anomalies which are caused by the building's structure. These magnetic anomalies are location-specific and temporally stable, providing reliable and precise location information without the fluctuations and physical layout dependencies that affect Wi-Fi signals.
2Measurement precision
If cellular phone signals are used for indoor location-finding, then the method can provide location information, but the large coverage area of cellular base stations results in large margin of error, reducing location accuracy
Solution Approach 1:
The patent exploits local magnetic field anomalies caused by the building's structure (walls, columns, metal objects) to create location-specific magnetic fingerprints. These local anomalies provide fine-grained location discrimination within the building, enabling precise location determination without relying on the large coverage areas of cellular base stations. The magnetic field measurements are taken at multiple locations and stored in a database for later queries.
3Measurement precision
If magnetic field measurements are taken at multiple locations to create a map, then location precision is improved, but the survey process requires time and resources
Solution Approach 1:
The patent performs magnetic field measurements and map construction as a preliminary action during building construction or renovation. The magnetic field anomalies are measured at multiple locations and stored in a database before the building is put into service. This preliminary survey eliminates the need for time-consuming field surveys during actual location determination operations, as the magnetic map is already available for queries.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a precise and accurate method for indoor location-finding, leveraging the geomagnetic field as a pervasive positioning tool, improving location determination by integrating magnetic field data with other technologies like Wi-Fi for synergistic results.
Implementation Method 1
anomalies in the Earth's magnetic field may be caused by the building's structure. The indoor geomagnetic field, including anomalies, tends to be location specific and temporally stable
Data Source
AI summary
Techniques for indoor location-finding are described herein. Inside buildings, anomalies in the Earth's magnetic field may be caused by the buildings' structures. These anomalies tend to be location specific and temporally stable. Accordingly, a database or map may be constructed of field strength measurements, and made available to clients, either online (e.g., through cloud services) or offline. As a user carrying a portable device walks within a building, magnetic field measurements may be made. The measurements may be configured in as vectors and compared to the database. A specific location may be indicated by anomaly information seen in both the vector(s) and database. Optionally, techniques may be combined with a particle filter that may be operated step-by-step as the user moves within the building. In another option, fusion with Wi-Fi signals may be performed, such as with a two-pass bidirectional particle filtering.