Vehicle Key Fob Localization Using Obstacle Reflections
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Solution Overview
Problem
Existing solutions for locating a communication device near a vehicle to trigger specific functions are limited, as they require at least three transceivers for triangulation, which is not possible when fewer transceivers are visible.
Innovation Solution
A method using a vehicle equipped with at least two transceivers operating in both active and passive modes. In active mode, the distance to the communication device is determined, and in passive mode, obstacles are detected and identified, allowing precise location of the communication device at the intersection of a circle and an ellipse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If triangulation is used to locate the communication device, then location precision is improved, but at least three transceivers are required which increases device complexity
Solution Approach 1:
The patent uses reflected signals from obstacles as an intermediary to enable location with fewer transceivers. By detecting signals reflected off obstacles, the system creates virtual transceiver positions, effectively achieving triangulation-like precision without requiring three physical transceivers to be visible to the device.
Solution Approach 2:
The patent transitions from purely active transceiver communication to incorporating passive reflection detection, adding a new dimension to the signal interaction model. This allows the system to calculate device position by analyzing reflected signal characteristics from obstacles, enabling location precision without increasing the number of active transceivers.
2Reliability
If passive mode triangulation is used, then location capability is improved, but it fails when fewer than three transceivers are visible to the communication device
Solution Approach 1:
The patent performs preliminary detection of obstacles in the environment before attempting location. By pre-identifying reflective obstacles and their positions, the system can use these as virtual transceivers when fewer than three actual transceivers are visible, ensuring location capability is maintained across different visibility conditions.
Solution Approach 2:
The patent converts the previously harmful effect of signal reflection (which caused multipath interference) into a beneficial feature for location. By deliberately detecting and utilizing reflected signals from obstacles, the system transforms an adverse phenomenon into a useful mechanism for achieving location when direct transceiver visibility is limited.
3Reliability
If active mode communication is used, then communication reliability is improved, but location precision deteriorates when fewer than three transceivers are visible
Solution Approach 1:
The patent merges active mode communication with passive reflection detection into a hybrid location approach. By combining the reliable communication channel of active mode with the geometric precision potential of reflection-based passive detection, the system achieves both communication reliability and location precision even with limited transceiver visibility.
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 precise location of the communication device to within a few centimeters, allowing for accurate triggering of vehicle functions such as unlocking doors, adjusting seats, and activating welcome lighting, even when fewer transceivers are visible.
Implementation Method 1
determination of the distance between said communicating transceiver and the communication device on the basis of the communication signals exchanged during the communication
Implementation Method 2
signals received by one of the transceivers are signals transmitted by one of the transceivers that have been reflected by an obstacle
Data Source
AI summary
A method for locating a communication device borne by a user in proximity to a vehicle in order to trigger at least one function of said vehicle, the method especially including, in a locating phase, steps of detection of a set of obstacles, called “current” obstacles, of identification of the communication device in the set of current obstacles and of location of the identified communication device among the obstacles of the set of obstacles.