Hands-Free Vehicle Access Using Magnetic Field Position Profiles
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Solution Overview
Problem
Existing vehicle function activation systems using ultra-wideband communication for hands-free access are prone to location precision issues due to sensitivity to reflections and interference, necessitating multiple transceivers, which increases cost.
Innovation Solution
A method and device utilizing a magnetometer and optionally an accelerometer in the access device to measure and compare magnetic field amplitudes and orientations, correcting these measurements with accelerometer data via scalar product, and activating vehicle functions based on predetermined profiles, using at least two radiofrequency transceivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ultra-wideband communication is used for hands-free access, then communication capability is improved, but location precision deteriorates due to sensitivity to reflections and interference
Solution Approach 1:
The patent introduces magnetic field measurements as an intermediary parameter to improve location precision. Instead of relying solely on ultra-wideband signal strength which is affected by reflections, the system uses the magnetometer to detect magnetic field variations caused by the vehicle's metallic structure, providing a more reliable location indicator that is less susceptible to environmental interference.
Solution Approach 2:
The patent replaces the purely electromagnetic ultra-wideband positioning mechanism with a hybrid approach that incorporates magnetic field sensing. The magnetometer detects the vehicle's magnetic signature, substituting the unreliable RF signal strength measurements with magnetic field-based location determination that is immune to reflections and interference.
2Measurement precision
If multiple transceivers are deployed to improve location precision, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the access device multi-functional by equipping it with both ultra-wideband communication capability and magnetometer sensing. This allows a single device to perform both communication and high-precision location determination, eliminating the need for multiple specialized transceivers while maintaining location accuracy.
Solution Approach 2:
The patent changes the measurement parameter from radio signal strength (RSSI) to magnetic field strength. This parameter change enables location determination using the vehicle's inherent magnetic signature detected by the magnetometer, providing accurate positioning without requiring an array of transceivers.
3Measurement precision
If magnetometer and accelerometer are used in access device, then location precision is improved, but use of energy increases
Solution Approach 1:
The patent implements periodic measurement and comparison of magnetic field and accelerometer data rather than continuous operation. The access device periodically samples the magnetic field, compares it with stored vehicle profiles, and determines location only when needed for authentication, significantly reducing energy consumption while maintaining measurement precision.
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
Improves location precision and reduces costs by eliminating the need for multiple transceivers, providing reliable and efficient hands-free vehicle access without additional hardware.
Implementation Method 1
the access device continuously measuring an amplitude of the magnetic field and an orientation of said magnetic field
Implementation Method 2
the access device is provided with an accelerometer, the measurements of the magnetic field are corrected by scalar product with measurements originating from the accelerometer
Implementation Method 3
the activation device comprising at least one external radiofrequency transceiver able to transmit outside the vehicle
Data Source
AI summary
A method for activating a vehicle function, by an activation device, from a “hands-free” access device carried by a user and provided with a magnetometer. The activation of the function being triggered by detecting the presence of the device in a predetermined zone around the vehicle or in a passenger compartment of the vehicle, and according to an authentication result of the device, the device including at least one external transceiver able to transmit outside the vehicle and one internal transceiver able to transmit in the passenger compartment of the vehicle. The method including: detecting the presence of the device in a predetermined zone; the access device continuously measuring an amplitude of the magnetic field and an orientation of the magnetic field; comparing the measurements with predetermined amplitude and orientation profiles; activating a vehicle function according to the result of the comparisons.