Unsupervised Anomaly Detection in Wearable Sensor Time Series Data

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Solution Overview

Problem

Current anomaly detection techniques in time series data rely on a priori information and struggle when applied to data from wearable sensors, failing to effectively identify abnormalities without pre-defined patterns or variations in human activities.

Innovation Solution

A system and method that receive multi-dimensional time series data, extract activity primitives, derive an activity structure through graph clustering, and classify abnormal instances based on temporal overlap and similarity, eliminating the need for prior knowledge and focusing on frequent activity patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If current anomaly detection techniques are applied to time series data from wearable sensors, then detection capability is improved, but reliability deteriorates due to failure to effectively identify abnormalities without pre-defined patterns

Engineering Contradiction:
Improveanomaly detection capabilityVSAvoididentification accuracy without pre-defined patterns
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system performs self-training by automatically learning normal activity patterns from the collected time series data without requiring pre-defined patterns or external training data. The unsupervised learning algorithm enables the system to autonomously establish baseline behavior models and identify deviations, making the detection reliable for wearable sensor applications where labeled training data is unavailable.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system collects and stores time series data from wearable sensors in advance, building a historical database of user activities before anomaly detection is needed. This preliminary data accumulation enables the unsupervised learning algorithm to establish normal patterns through analysis of accumulated evidence, improving detection reliability when actual anomalies occur.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If unsupervised learning is implemented for anomaly detection, then adaptability to wearable sensor data is improved, but device complexity increases

Engineering Contradiction:
Improveadaptability to wearable sensor dataVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system segments the complex unsupervised learning process into distinct functional modules: data collection from multiple sensors, feature extraction from time series data, pattern recognition through clustering algorithms, and anomaly classification. This modular segmentation manages complexity by organizing the unsupervised learning pipeline into manageable, independent components that can be developed and tuned separately.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system introduces intermediate processing layers between raw sensor data and final anomaly detection, including feature extraction modules that transform raw time series into meaningful characteristics, and clustering algorithms that organize data into normal vs. abnormal patterns. These intermediaries simplify the overall system complexity by breaking down the unsupervised learning task into sequential, less complex stages.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS9833196B2Apparatus, system, and method for detecting activities and anomalies in time series data
Publication Date: 2017.12.05 RGT UNIV OF CALIFORNIA
  • US9833196B2 patent drawing
  • US9833196B2 patent drawing
  • US9833196B2 patent drawing

AI summary

Activities and abnormalities in activities are detected by: (1) receiving data corresponding to measurements of an activity occurring during a time interval; (2) determining a plurality of primitives associated with the data, wherein each of the plurality of primitives represents a characteristic pattern in a portion of the time interval; (3) derive an activity structure relating a first subset of the plurality of primitives that are correlated in time; and (4) based on the activity structure, classify a second subset of the plurality of primitives as an abnormal instance of the bodily activity.