Heading Determination Using Magnetic Maps for Indoor Navigation
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Solution Overview
Problem
Current navigation technologies face challenges indoors due to the unavailability of GNSS signals and distortion of the geomagnetic field by ferrous materials in building construction, making it difficult to determine heading and orientation accurately.
Innovation Solution
A heading determination device and method that utilize magnetic field sensor data, position estimates, and pre-recorded magnetic maps to derive local azimuth distortion values, allowing for accurate heading estimation in a reference coordinate system, combined with a rendering device that determines relative positions of targets and renders target information based on orientation and position data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GNSS signals are used for outdoor navigation, then navigation accuracy is improved, but GNSS signals are not available indoors
Solution Approach 1:
The patent introduces magnetic field sensors and pre-recorded magnetic maps as intermediary elements to enable navigation indoors. The magnetic field sensor measures the local magnetic field vector, which is then compared against pre-recorded magnetic field characteristics stored in a magnetic map to determine position and heading, serving as a mediator between the unavailable GNSS signals and the need for indoor navigation
Solution Approach 2:
The patent replaces the electronic/GNSS-based navigation system with a magnetic field-based system for indoor environments. Instead of relying on satellite signals, the system uses magnetic field measurements and compares them with stored magnetic field characteristics to determine position and orientation
2Adaptability or versatility
If magnetic field sensors are used for indoor navigation, then indoor positioning capability is improved, but ferrous materials in building construction heavily distort the geomagnetic field
Solution Approach 1:
The patent applies preliminary action by pre-recording the magnetic field characteristics (including distortions from ferrous materials) during an offline mapping phase. These pre-recorded magnetic field characteristics are stored in a magnetic map, allowing the system to account for and compensate for magnetic distortions caused by building construction materials during actual navigation
Solution Approach 2:
The patent converts the harmful effect of ferrous material distortion into a beneficial feature by using the distorted magnetic field pattern itself as a unique fingerprint for location identification. The pre-recorded magnetic map captures the specific distortion pattern at each location, and the system uses this characteristic distortion to accurately determine position and heading despite the presence of ferrous materials
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
Enables accurate indoor navigation and rendering of target information, such as virtual sound sources, with low power consumption, suitable for mobile and wearable devices, independent of user or device orientation, and requires no dedicated infrastructure.
Implementation Method 1
magnetic field sensor data sensed by a magnetic field sensor
Data Source
AI summary
A heading determination device comprises data input circuitry configured to obtain magnetic field sensor data sensed by a magnetic field sensor in sensor coordinates, position input circuitry configured to obtain a position estimate of the magnetic field sensor, and estimation circuitry configured to derive, from a magnetic map, a local azimuth distortion value in a reference coordinate system at the current position of the magnetic field sensor indicated by the obtained position estimate and to estimate the heading of the magnetic field sensor in the reference coordinate system based on the obtained magnetic field sensor data and the derived local azimuth distortion value.