Vehicle ToF Antenna Array Localization Under Signal Absorption
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Solution Overview
Problem
Conventional mobile device localization methods using Time-of-Flight (ToF) technologies face challenges due to signal interference and absorption, particularly human body signal absorption, which can skew Received Signal Strength Indicator (RSSI) measurements, affecting accuracy and reliability in determining device position and distance.
Innovation Solution
Implementing a ToF localization system with multiple ToF modules disposed around a vehicle, utilizing a 360° coverage algorithm that checks various distance and communication conditions with multiple tags to accurately determine the mobile device's position and distance from the vehicle, even in scenarios where some modules fail to communicate, thereby overcoming signal interference issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ToF localization methods are used, then device localization can be performed, but signal absorption and interference significantly impact measurement accuracy and reliability
Solution Approach 1:
The system divides the localization task into multiple independent measurements by using multiple ToF modules distributed around the vehicle. Each module performs separate distance measurements to the mobile device, and the system selects or combines results from multiple valid measurements to determine final position, thereby overcoming signal blockage from human bodies or other obstructions.
Solution Approach 2:
Different ToF modules are positioned at specific locations around the vehicle (front, rear, left, right sides) to create localized measurement zones. Each module is optimized for detecting devices in its specific spatial region, and the system determines which module's measurement is most reliable based on the device's apparent position and signal characteristics.
2Reliability
If multiple ToF modules are deployed around the vehicle, then coverage and reliability improve, but system complexity increases
Solution Approach 1:
Multiple ToF modules are integrated into a unified localization system with a central controller that coordinates measurements across all modules. The system merges data from multiple sources using standardized protocols and algorithms, achieving improved reliability while managing complexity through systematic integration rather than independent operations.
Solution Approach 2:
The ToF modules serve multiple functions: they perform distance measurement, determine device angular position, identify which region the device is in, and provide redundancy when signal blockage occurs. This multi-functionality justifies the added hardware complexity by extracting maximum utility from each module.
3Ease of operation
If RSSI measurements are used for localization, then device position can be determined, but human body signal absorption skews measurements and reduces accuracy
Solution Approach 1:
The system replaces RSSI-based localization (which relies on signal strength affected by human body absorption) with ToF-based localization (which measures the time for radio waves to travel to and from the device). This substitution eliminates the sensitivity to signal attenuation caused by human bodies, as ToF measurements depend on the speed of light and travel time rather than signal intensity.
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
The system achieves robust and accurate localization of mobile devices around a vehicle, ensuring reliable vehicle access operations by providing precise distance calculations and region determination, even in complex environments with signal interference.
Implementation Method 1
Incorporating ToF enables the use of Time-of-Flight (ToF) between two ToF devices, which communicates between the devices at a high frequency. ToF measures the time taken for the high frequency signal to go back and forth between the two devices.
Data Source
AI summary
A method for localizing a user device using a Time-of-Flight (ToF) antenna array disposed on a vehicle, the method includes determining via a ToF localization controller, that a user device is positioned at a front region of a vehicle, calculating a distance to the user device from a combination of two ToF antennae of the ToF antenna array, and performing a 2-dimensional (2D) trilateration calculation. The method further includes evaluating a confidence metric value, determining a position of the user device based on the confidence metric value, and generating an unlock signal that unlocks a vehicle door.