Accelerometer-Based Alarm Activation for Firefighter Safety Devices

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Solution Overview

Problem

Existing personal alert safety system (PASS) devices for firefighters face issues with manual emergency alarm activation, particularly sensitivity to electromagnetic fields and wear-out of buttons, making them difficult to operate in hazardous situations.

Innovation Solution

A PASS device utilizing a digital accelerometer to detect tapping motions, enabling easy activation of an emergency alarm through double taps on the device housing, independent of button operation and insensitive to electromagnetic fields or anti-static materials, with reduced mechanical parts for lower manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an electromechanical push button system is used for manual alarm activation, then the alarm can be manually generated to alert others of hazardous situations, but the buttons can wear out and become difficult to operate

Engineering Contradiction:

Improvealarm activation reliabilityVSAvoidbutton operation difficulty

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces the electromechanical push button system with a capacitive touch sensor system. The touch sensor detects changes in capacitance when a firefighter touches the housing, triggering the alarm without requiring mechanical button movement. This eliminates wear and tear associated with mechanical buttons while maintaining reliable alarm activation capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Extent of automation

If sensors are used for alarm activation, then the alarm can be triggered automatically, but the sensors may be sensitive to electromagnetic fields or antistatic plastic

Engineering Contradiction:

Improveautomatic alarm activationVSAvoidelectromagnetic field sensitivity

Core Design Contradiction:

Extent of automationVSObject-affected harmful factors

Solution Approach 1:

The patent replaces electromagnetic sensors with a capacitive touch sensing system that detects physical contact through capacitance changes. This approach is inherently immune to electromagnetic field interference and antistatic plastic issues that affect traditional electromagnetic sensors, while still enabling automatic alarm activation when contact is detected.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If a reed switch and magnet coupling system is used, then the alarm can be activated by magnet movement, but the system requires precise positioning and may be affected by electromagnetic interference

Engineering Contradiction:

Improvealarm activation easeVSAvoidelectromagnetic interference sensitivity

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the reed switch and magnet coupling system with a capacitive touch sensor that detects finger contact directly on the housing. This eliminates the need for precise magnet positioning and removes sensitivity to electromagnetic interference, as capacitive sensing operates on electrical field principles that are not affected by external electromagnetic fields.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Ease of operation

If mechanical buttons are used for alarm activation, then the system can be operated manually, but the buttons wear out over time reducing device lifespan

Engineering Contradiction:

Improvemanual operation capabilityVSAvoiddevice lifespan

Core Design Contradiction:

Ease of operationVSDuration of action of stationary object

Solution Approach 1:

The patent replaces mechanical buttons with a capacitive touch interface that has no moving parts. The touch sensor detects contact through changes in electrical capacitance when a conductor (such as a gloved finger) touches the housing. This solid-state solution eliminates mechanical wear, significantly extending device lifespan while maintaining full manual operation capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution allows for reliable and easy manual initiation of emergency alarms, even with gloves, reducing the risk of misoperation and extending device lifespan while maintaining functionality in challenging environments.

Implementation Method 1

The accelerometer 36 measures dynamic acceleration resulting from pre-defined motion. Particularly, tap sensing functionality is able to detect single and double taps in any direction.

Methodology Applied

Scientific EffectAccelerometer: Accelerometer

Implementation Method 2

The magnet is push by a plastic part (the button) to approach the reed switch. The magnetic field of the magnet has enough power of attraction to close the reed switch.

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP2645349B1Method to activate emergency alarm on a personal alarm safety system device

Publication Date: 2020.05.06 HONEYWELL INTERNATIONAL INC

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AI summary

A personal alert safety system comprises a housing adapted to be worn by a user. An accelerometer is in the housing. An alarm device is operatively associated with the housing. A control in the housing is operatively connected to the accelerometer and the alarm device. The control is configured to operate the alarm device responsive to select acceleration movement of the housing sensed by the accelerometer.