Smartwatch Vibration Authentication via Dynamic Time Warping

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Solution Overview

Problem

Traditional smartwatch authentication methods are unsuitable for wearable devices due to their bulkiness, vulnerability to cyber threats, and high costs associated with specialized hardware, making them impractical for secure user identification.

Innovation Solution

A vibration signal-based authentication method using a smartwatch's vibration motor and inertial sensors to generate and analyze six-axis vibration signals, employing dynamic time warping and nearest neighbor models for two-factor discrimination, which is cost-effective and compatible with existing smartwatch hardware.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional authentication methods (password keyboards, biometric identifiers) are used in smartwatches, then authentication functionality is provided, but the device size increases, cost increases, and security vulnerabilities remain

Engineering Contradiction:
Improveauthentication securityVSAvoidhardware requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical/electronic authentication systems (keyboards, fingerprint sensors, face recognition cameras) with a vibration-based authentication system. The vibration motor generates characteristic vibration signals that are captured by the watch's existing sensors, creating a biometric-like authentication mechanism without requiring additional specialized hardware. This substitutes complex mechanical authentication interfaces with a simpler vibration signal processing system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The smartwatch uses its own existing vibration motor and sensor components for authentication purposes. The vibration motor, originally designed for haptic feedback, serves dual purposes: providing user feedback and generating authentication signals. The existing accelerometer and gyroscope, intended for motion tracking, are repurposed to capture authentication-relevant vibration characteristics. This self-service approach eliminates the need for separate authentication hardware.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If biometric identifiers (fingerprint, face recognition) are implemented, then authentication accuracy is improved, but hardware cost increases and device size increases

Engineering Contradiction:
Improveauthentication accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent makes the existing vibration motor and sensor system serve multiple functions: haptic feedback for user interaction and biometric authentication. The same hardware components that provide basic smartwatch functionality are leveraged for authentication, eliminating the need for dedicated biometric hardware. This multi-functionality approach maintains authentication accuracy while reducing manufacturing costs and device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the operational parameters of existing components to enable authentication. By controlling the vibration motor to generate specific vibration patterns and frequencies, and by analyzing the resulting signals through frequency domain analysis, the system transforms ordinary haptic components into precision authentication sensors. This parameter-based approach achieves biometric-level accuracy without biometric hardware.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If password keyboards with touch screens are used, then user authentication is enabled, but the device becomes vulnerable to cyber threats and requires user memory

Engineering Contradiction:
Improveuser interface capabilityVSAvoidsecurity vulnerability
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent replaces vulnerable software-based password authentication with a physics-based vibration authentication system. Instead of relying on user-remembered passwords that can be phished or hacked, the system uses the physical characteristics of vibrations generated by the motor and filtered through the user's body and wrist. This mechanical/physical authentication mechanism is inherently more resistant to cyber threats as it relies on physical rather than digital credentials.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces the user's body and wrist as an intermediary medium in the authentication process. The vibration signals pass through the user's skin and tissues, creating a unique physical signature that acts as a biological mediator between the authentication system and the user. This intermediary layer adds security by making authentication dependent on physical presence and physiological characteristics rather than vulnerable digital credentials.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Provides a secure, reliable, and cost-effective authentication solution that is applicable to a wide range of users, ensuring the safety and integrity of smartwatch devices without the need for additional hardware, while being practical for various smartwatch applications.

Implementation Method 1

generating incremental vibration by using the vibration motor in a smartwatch

Methodology Applied
Scientific EffectVibration: Vibration

Implementation Method 2

collecting six-axis vibration signals which are separately generated by the three-axis acceleration and the three-axis angular velocity

Methodology Applied
Scientific EffectInertial sensing: Accelerometer

Data Source

PatentUS11790073B2Vibration signal-based smartwatch authentication method
Publication Date: 2023.10.17 SHENZHEN UNIV
  • US11790073B2 patent drawing

AI summary

A vibration signal-based smartwatch authentication method includes generating incremental vibration signals using a vibration motor in a smartwatch; performing frequency band-based hierarchical endpoint segmentation to obtain vibration signals at a plurality of frequency bands; extracting frequency-domain features for the vibration signals at the plurality of frequency bands; training a dynamic time warping model by taking the vibration signals at the plurality of frequency bands as a training data set, training a nearest neighbor model by taking the extracted frequency-domain features as training data; collecting to-be-authenticated vibration signals which are processed to serve as test data signals; discriminating similarities between the test data signals and corresponding training data signals through the dynamic time warping model, giving a classification result through the nearest neighbor model, performing weighted calculation on a discrimination result of the dynamic time warping model and a discrimination result of the nearest neighbor model to obtain an authentication result.