Vehicle Access System Using Bluetooth and LF Authentication
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Solution Overview
Problem
Existing vehicle access systems, such as passive entry and passive starting (PEPS) systems, require significant energy to generate Low Frequency (LF) electromagnetic fields, leading to battery drain and potential delays in unlocking the vehicle, as they rely on user-initiated triggers for key fob authentication.
Innovation Solution
The system employs two communication channels, using Bluetooth® for energy-efficient communication with smart devices as the first channel and RF or LF for key fob authentication, allowing seamless vehicle access with minimal battery impact and reduced delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Low Frequency (LF) electromagnetic field is generated to wake up the key fob, then the key fob can be authenticated, but significant energy is consumed leading to battery drain
Solution Approach 1:
The system performs preliminary detection using Bluetooth® Low Energy (BLE) to identify the presence and approximate location of the smartphone before initiating the energy-intensive LF electromagnetic field generation. This preliminary action filters out cases where key fob authentication is not needed, saving battery energy.
Solution Approach 2:
The patent introduces an intermediary communication layer using BLE between the vehicle and smartphone. This intermediary serves as a low-energy proxy that precedes the high-energy LF authentication, reducing unnecessary energy consumption while maintaining reliable key fob authentication when needed.
2Use of energy by moving object
If a trigger is used to initiate the authentication sequence, then energy consumption is reduced, but delays occur in vehicle unlocking
Solution Approach 1:
The system continuously scans for BLE signals in the background and preliminarily identifies approaching users before they reach the trigger zone. This preliminary detection enables the system to prepare for authentication in advance, reducing perceived delay while maintaining low energy consumption during idle periods.
Solution Approach 2:
The system dynamically adjusts its scanning and response behavior based on detected signal strength and user proximity. When a smartphone is detected within threshold distance, the system transitions from idle scanning to active authentication preparation, optimizing the balance between energy consumption and response time.
3Speed
If continuous scanning for key fob is performed, then rapid access is achieved, but energy consumption increases significantly
Solution Approach 1:
The authentication process is segmented into two distinct phases: a low-energy BLE scanning phase for initial detection, and a high-energy LF authentication phase only when needed. This segmentation allows the system to maintain rapid access capability while minimizing overall energy consumption by keeping the high-power components dormant most of the time.
Solution Approach 2:
Instead of continuous scanning, the system employs periodic BLE scanning at optimized intervals. The scanning frequency is dynamically adjusted based on environmental factors and detected signal patterns, achieving rapid access when users are present while conserving energy during periods of low activity.
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
This approach reduces energy consumption and minimizes delays by using Bluetooth® for initial detection and RF/LF for key fob validation, enabling efficient and rapid vehicle access while maintaining battery life.
Implementation Method 1
a Bluetooth transceiver (150) arranged to receive Bluetooth signals from a smart device
Implementation Method 2
the base station emits a powerful Low Frequency (LF) electromagnetic field, the energy from which wakes up the key fob
Implementation Method 3
The key fob can then respond to a challenge over a Radio Frequency (RF) communications channel
Data Source
AI summary
A method of operating an access system for a vehicle, the method comprising: 5 scanning for a first communication signal from a first communications device using a first communication channel; and initiating a vehicle access process in dependence on detecting the first communication signal from the first communications device; wherein the vehicle access process comprises: comparing a received signal strength indication, RSSI, of the received first communication signal to a predetermined 10 threshold signal strength value; sending a challenge signal for a second communications device using a second communication channel in the event that the RSSI of the received first communication signal exceeds the threshold signal strength value; and controlling the vehicle access system in dependence on a response signal received from the second communications device, the response signal having been 15 sent in response to the challenge signal.