Crowdsourced Magnetic Map Creation for Indoor Positioning
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Solution Overview
Problem
Current positioning technologies face challenges in indoor and outdoor environments with degraded GNSS signals, particularly in urban areas and buildings, due to signal attenuation and multipath issues, leading to performance degradation over longer durations and increased costs with the use of additional sensors like cameras and lidars.
Innovation Solution
A method and system for creating a magnetic map using crowdsourced data from platforms equipped with magnetometers and motion sensors, which determines poses and updates magnetic field values to enhance positioning accuracy, leveraging the long-term stability of magnetic fields and infrastructure-free infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GNSS signals are used for positioning in indoor and urban environments, then absolute navigational information can be obtained, but signal attenuation and multipath interference cause performance degradation
Solution Approach 1:
The patent introduces magnetic field measurements as an intermediary to bridge the gap between GNSS and INS. Magnetometers detect ambient magnetic fields which serve as a mediator to correct INS drift, providing reliable positioning in environments where GNSS signals are attenuated or interfered with by buildings and urban structures.
Solution Approach 2:
The patent substitutes the reliance on electromagnetic GNSS signals with a magnetic field-based positioning approach using magnetometers. This replacement allows the system to function independently of satellite signals, using magnetic field characteristics instead of radio wave trilateration to determine position.
2Reliability
If Inertial Navigation System is used for positioning without external references, then positioning can function in GNSS-denied environments, but sensor drift and bias accumulate over time causing performance degradation
Solution Approach 1:
The patent implements feedback by using magnetic field measurements to continuously correct INS drift. The magnetometer readings provide feedback information about the ambient magnetic field at the current position, which is used to update and correct the accumulated INS errors, preventing long-term drift accumulation.
Solution Approach 2:
The system uses the ambient magnetic field environment itself as a reference, eliminating the need for external infrastructure. The magnetic field naturally present in the environment serves the dual purpose of being both the measurement medium and the reference frame for correction.
3Measurement precision
If additional sensors like cameras and lidars are used to improve positioning accuracy, then navigation precision can be enhanced, but system cost and complexity increase
Solution Approach 1:
The patent employs magnetometers, which are relatively inexpensive sensors compared to cameras and lidars. By using multiple low-cost magnetometer units distributed across the environment or on moving platforms, the system achieves accurate positioning without the high costs associated with sophisticated optical and laser sensing systems.
Solution Approach 2:
The patent makes magnetometers serve multiple functions: they provide both the positioning reference through magnetic field measurements and the correction mechanism for INS drift. This multi-functionality eliminates the need for separate correction sensors, reducing overall system complexity compared to using specialized cameras or lidars for each function.
4Adaptability or versatility
If magnetometer measurements are used for positioning, then infrastructure-free positioning is achieved, but magnetic field ambiguity makes pose determination challenging
Solution Approach 1:
The patent performs preliminary mapping of magnetic field characteristics in the environment before actual positioning occurs. By pre-characterizing the magnetic field signature at various locations and creating a magnetic map, the system prepares reference data that simplifies real-time pose determination, reducing the ambiguity problem during operational use.
Solution Approach 2:
The patent resolves magnetic field ambiguity by incorporating temporal and spatial dimensions into the measurement process. Instead of relying solely on static magnetic field magnitude, the system uses time-series magnetic field vectors from moving platforms, adding temporal evolution and spatial trajectory information as additional dimensions for disambiguation.
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 robust and cost-effective indoor and outdoor positioning by mitigating ambiguity in magnetic fields and accommodating varying magnetometer positions, improving navigation accuracy and reducing reliance on expensive sensor equipment.
Implementation Method 1
obtaining magnetic field measurements from at least one magnetometer associated with each of a plurality of platforms traversing at least a portion of the area
Implementation Method 2
motion sensor data from a sensor assembly associated with each platform
Implementation Method 3
gyroscopes to measure the object's rate of rotation/angle and accelerometers to measure the object's specific force
Data Source
AI summary
Systems and methods are disclosed for creating a magnetic map by obtaining magnetic field measurements from a plurality of platforms. A first set of poses for each platform is determined and information from the magnetic map is obtained for any existing magnetic field values for the first set. Magnetic constraints on poses of the platform are determined and used for determining a second set of poses for each platform. The magnetic field values of the magnetic map are then updated based at least in part on the second set of poses for each platform.