Rear Occupant Alert Using LF Antenna Fob Positioning

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Solution Overview

Problem

Conventional Rear Occupant Alert (ROA) systems generate unnecessary alerts and fail to accurately detect occupants who are still in the rear seat, especially if they are asleep or not moving, and suffer from continuous dark current issues due to ultrasonic sensor operation after the driver leaves the vehicle.

Innovation Solution

A method using low-frequency (LF) antennas to sense the positions of a master fob and a slave fob, determining their positions before and after a vehicle door event, and performing alerts based on these determinations to prevent occupant neglect or exit, with the slave fob being a wearable device for rear occupants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If ultrasonic sensors are used to detect rear seat occupants, then movement-based detection is achieved, but occupants who are asleep or not moving cannot be detected

Engineering Contradiction:

Improveoccupant detection accuracyVSAvoiddetection coverage for different occupant states

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces the ultrasonic sensor-based mechanical vibration detection system with an LF antenna-based electromagnetic detection system. The LF antenna detects the presence of the slave fob (worn by the rear occupant) through electromagnetic field interaction, enabling detection regardless of the occupant's movement state. This substitution resolves the limitation of ultrasonic sensors that cannot detect stationary or sleeping occupants.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If ultrasonic sensors operate continuously after driver leaves, then occupant presence is monitored, but dark current is continuously generated

Engineering Contradiction:

Improveoccupant monitoring reliabilityVSAvoiddark current consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements periodic action by triggering the LF antenna-based detection only at specific events (door opening/closing) rather than continuous operation. The system senses fob positions before and after door events, determining occupant status based on these periodic measurements. This eliminates continuous dark current generation while maintaining reliable detection through event-driven monitoring.

Inventive Principle:

Principle #19Periodic action

3Device complexity

If conventional ROA systems generate alerts based on door events, then simple implementation is achieved, but unnecessary alerts are generated when no occupant is present

Engineering Contradiction:

Improvealert system complexityVSAvoidalert accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements feedback by using LF antennas to detect the actual presence and position of the slave fob before generating alerts. The system compares the detected fob position with the expected position (inside vs. outside vehicle) and only generates alerts when the feedback confirms an abnormal condition (master fob outside, slave fob inside). This feedback mechanism eliminates unnecessary alerts while maintaining simple system architecture.

Inventive Principle:

Principle #23Feedback

4Adaptability or versatility

If slave fob is equipped with full communication module, then comprehensive functionality is achieved, but manufacturing cost increases

Engineering Contradiction:

Improvefob functionalityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies this principle by equipping the slave fob (intended for rear occupants including infants) with only essential low-cost communication modules (LF and RF) rather than full-featured modules. The slave fob's limited functionality is sufficient for its purpose of enabling detection and alert generation, significantly reducing manufacturing costs while maintaining the core safety function.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 solution effectively reduces unnecessary alerts, accurately detects rear seat occupants even if they are not moving, and eliminates dark current issues, providing a cost-effective and accurate passenger-seat occupant alert function while preventing safety accidents.

Implementation Method 1

sensing a master fob and a slave fob through low frequency (LF) antennas in the vehicle to obtain first position information of the master fob and the slave fob

Methodology Applied

Scientific EffectLow frequency electromagnetic radiation: Electromagnetic Induction

Data Source

PatentUS10814781B2Rear occupant alert method and vehicle fob device using the same

Publication Date: 2020.10.27 HYUNDAI MOTOR CO LTD

AI summary

A rear occupant alert method for a vehicle may include: before a door opening or closing event of the vehicle, sensing a master fob and a slave fob through low frequency (LF) antennas in the vehicle to obtain first position information of the master fob and the slave fob; after the door opening or closing event of the vehicle, sensing the master fob and the slave fob through the LF antennas to obtain second position information of the master fob and the slave fob; determining positions of the master fob and the slave fob, respectively, by comparing the first position information of the master fob and the slave fob with the second position information of the master fob and the slave fob; and performing a rear occupant alert function in accordance with the determined positions of the master fob and the slave fob.