Magnetometer-Based Position Determination for Mobile Terminals in Tunnels
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Solution Overview
Problem
Existing navigation systems, such as GNSS, face inaccuracies due to signal obstruction and require extensive database creation for GSM and WiFi-based methods, while inertial navigation systems suffer from sensor drift, making efficient and accurate position determination in tunnels and public transportation challenging.
Innovation Solution
A device comprising a magnetometer sensor unit, classification unit, and position-determining unit that uses magnetometer sensor data to classify electric motor states and determine positions without additional location information, potentially aided by GSM and WiFi signals for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS satellite signals are used for position determination, then position can be determined directly, but signal obstruction by obstacles causes reduced accuracy or complete loss of position determination
Solution Approach 1:
The patent introduces magnetometer sensor data as an intermediary measurement source. Instead of directly relying on obstructed satellite signals, the system uses magnetometer readings to detect and classify electric motor states (acceleration, braking, stationary) as a mediating indicator of vehicle position and movement, bypassing the signal obstruction problem entirely
Solution Approach 2:
The patent replaces the electromagnetic signal-based GNSS system with a magnetometer-based detection system. The magnetometer senses magnetic field changes caused by electric motors in the vehicle, converting electromagnetic field measurements into mechanical state information (acceleration, braking) that indicates position, thus substituting one physical measurement domain for another that is not subject to satellite signal obstruction
2Reliability
If GSM tower or WiFi station signals are used for position determination, then position can be determined without satellite signals, but extensive database creation with tower and station positions is required
Solution Approach 1:
The system uses magnetometer sensors already present in the mobile terminal for self-positioning. The mobile terminal's own magnetometer detects magnetic field signatures from vehicle motors, and the onboard classification unit processes this data locally to determine vehicle states and position, eliminating the need for external infrastructure databases
Solution Approach 2:
The patent changes the measurement parameter from electromagnetic signal strength (GSM/WiFi) to magnetic field intensity (magnetometer). This parameter change enables position determination through detection of motor-generated magnetic fields rather than through database matching of tower/WiFi positions, fundamentally altering how position information is obtained
3Object-affected harmful factors
If inertial navigation system with accelerometers and gyroscopes is used, then position can be determined without external signals, but sensor drift causes quick loss of accuracy over time
Solution Approach 1:
The system uses magnetometer measurements as feedback to detect and classify vehicle motor states. By continuously monitoring magnetic field changes and classifying acceleration, braking, and stationary states, the system provides feedback-based position estimation that does not suffer from drift, as each measurement is an absolute indication of current vehicle state rather than a cumulative calculation
Solution Approach 2:
The patent uses the mobile terminal's existing magnetometer sensor (already present for compass functionality) as a disposable, drift-free measurement source. Each magnetometer reading provides a fresh, independent measurement of vehicle state without accumulating error, replacing the need for long-term integration of accelerometer data that suffers from drift
4Adaptability or versatility
If classification of electric motor states using magnetometer data is implemented, then position can be determined without additional location information, but new infrastructure setup is avoided
Solution Approach 1:
The magnetometer sensor performs multiple functions: it serves as both a digital compass for orientation and a detector for electric motor states. By classifying motor states from magnetometer data, the system uses an existing sensor for a secondary purpose, eliminating the need for dedicated position determination infrastructure while leveraging already-deployed sensor hardware
Solution Approach 2:
The mobile terminal uses its own magnetometer sensor and onboard processing units to determine position independently. The classification unit within the terminal processes magnetometer data to identify vehicle states, and the position-determining unit calculates position from these states, making the system self-sufficient without requiring external infrastructure setup
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 efficient and accurate position determination in challenging environments like tunnels and public transportation, with the ability to remind users of their destination stop, while providing quality estimates of the position determination.
Implementation Method 1
An electric motor is based on the principle that electric energy is converted into mechanical energy. To this end, the force exerted by a magnetic field on the current-carrying conductors of a coil is converted into mechanical energy. The resulting effects can be measured even outside of an electric motor using an appropriate sensor. For example, the amount of the magnetic flux density changes with the desired torque and/or the speed of the electric motor.
Implementation Method 2
A mobile terminal can be used to measure the effects. Preferably, the components of the mobile terminal are highly integrated and the user can carry the mobile terminal, similar to a modern smart phone, for example. Such a modern smart phone usually has a magnetometer sensor to implement a digital compass.
Data Source
AI summary
A device for determining at least one position of a mobile terminal includes at least one memory apparatus, a magnetometer sensor unit, a classification unit, and a position-determining unit to determine the position of the mobile terminal. The classification unit is configured to determine states, in particular operating states, of at least one electric motor and/or a vehicle driven by means of at least one electric motor using the magnetometer sensor data. The classification unit is also configured to store the determined states in the at least one memory apparatus. The position-determining unit reads out the states from the at least one memory apparatus and determines the at least one position of the mobile terminal with the help of the states.