BLE Node Passive Entry FOB Location Detection
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Solution Overview
Problem
Current passive entry and passive start (PEPS) systems using low frequency signals face limitations in power consumption and antenna size, and struggle to accurately determine whether a Bluetooth Low Energy (BLE) device is inside or outside the vehicle due to signal reflection at high frequencies like 2.4 GHz.
Innovation Solution
Employing BLE nodes within the vehicle to interrogate a FOB using Bluetooth signals, employing propagation models like knife edge diffraction and two ray propagation to differentiate between signal loss patterns when the FOB is inside or outside, allowing accurate determination of its location without the need for multiple antennas or high power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If low frequency pulsed signals are used for FOB polling in PEPS system, then the ability to detect FOB directionally and determine user approach is improved, but the power consumption increases significantly (700 mA per pulse) reducing vehicle battery life
Solution Approach 1:
The patent combines multiple low frequency antennas into a single BLE antenna operating at 2.4 GHz. By merging the functionality of five separate low frequency antennas into one Bluetooth Low Energy antenna, the system achieves comparable FOB detection capabilities while dramatically reducing power consumption and antenna package complexity.
Solution Approach 2:
The patent changes the operating frequency parameter from low frequency (30-300 kHz) to Bluetooth Low Energy frequency (2.4 GHz). This parameter change enables the system to maintain FOB detection precision while consuming significantly less power, as BLE technology is designed for low power consumption in wireless communication.
2Measurement precision
If multiple low frequency antennas are used for directional FOB polling, then the ability to determine user approach direction is improved, but the antenna size and packaging difficulty increase
Solution Approach 1:
The patent merges five separate low frequency antennas into a single BLE antenna. This consolidation reduces the antenna quantity from five to one, simplifying the antenna package and making it easier to integrate into the vehicle structure while maintaining the capability to detect FOB signals from different directions.
Solution Approach 2:
The single BLE antenna performs multiple functions that previously required five separate low frequency antennas. The antenna provides omnidirectional FOB detection capability and enables the system to determine user approach direction through signal strength analysis, replacing the need for multiple specialized antennas.
3Use of energy by moving object
If 2.4 GHz Bluetooth signals are used for FOB detection, then power consumption is reduced, but the ability to determine whether FOB is inside or outside vehicle is compromised due to signal reflection
Solution Approach 1:
The patent introduces a machine learning model as an intermediary between the raw Bluetooth signal measurements and the FOB location determination. The model processes the received signal strength indicators (RSSI) and other signal characteristics, learning to distinguish between signals originating from inside versus outside the vehicle despite the presence of reflections and multipath effects.
Solution Approach 2:
The patent replaces traditional signal processing methods with a data-driven machine learning approach. Instead of using conventional algorithms to analyze Bluetooth signal characteristics for location determination, the system employs trained neural networks that have learned the complex patterns of signal behavior inside versus outside the vehicle, achieving higher 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
Enables extended vehicle operation with reduced power consumption and accurate FOB location detection, allowing for secure and efficient vehicle access and start functions without the need for a physical key.
Implementation Method 1
a Bluetooth Low Energy (BLE) node integrated on the vehicle to determine whether a vehicle fob is within the vehicle or outside of the vehicle
Implementation Method 2
employing propagation models like knife edge diffraction and two ray propagation to differentiate between signal loss patterns when the FOB is inside or outside
Implementation Method 3
struggle to accurately determine whether a Bluetooth Low Energy (BLE) device is inside or outside the vehicle due to signal reflection at high frequencies like 2.4 GHz
Data Source
AI summary
A system and method for employing BLE nodes in a PEPS system to determine whether a FOB is within or outside of a vehicle. The method includes interrogating the FOB using a signal transmitted by a BLE device on the vehicle to determine whether the FOB is in a predetermined vicinity of the vehicle and receiving a Bluetooth signal at the BLE device that is transmitted by the FOB if the FOB is in the vicinity of the vehicle. The method also included determining a transmit power of the Bluetooth signal transmitted by the FOB and determining a receive power of the Bluetooth signal transmitted by the FOB and received by the BLE device. The method uses the transmit power and the receive power in a comparison process to determine whether the FOB is inside or outside of the vehicle.