Time Series Grammar Discovery for Scalable Vehicle Motion Prediction

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Solution Overview

Problem

Current time series analysis methods using context-free grammar are inefficient due to their cubic-time complexity, limiting the analysis to short-length data, and lack automatic grammar extraction, making them unsuitable for scalable applications.

Innovation Solution

A system that automatically extracts a subset of probabilistic context-free grammar (PCFG) from time series data using automatic segmentation, converting raw data into symbolic form and applying head-grammar rules to improve efficiency and scalability, specifically for analyzing moving vehicle data to predict vehicle movement and control autonomous vehicles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If unconstrained context-free grammar is used for time series analysis, then grammar extraction capability is improved, but computational complexity increases to cubic time

Engineering Contradiction:
Improvegrammar extraction capabilityVSAvoidcomputational complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts and applies only the necessary subset of grammar rules from the full context-free grammar, rather than using the complete grammar framework. This selective extraction reduces computational complexity while maintaining the essential grammar extraction capability for time series analysis.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the time series data into discrete symbols through automatic segmentation before applying grammar rules. This segmentation transforms continuous time series data into a discrete sequence that can be processed more efficiently by grammar-based algorithms, reducing the overall computational burden.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If unconstrained context-free grammar is used for time series analysis, then grammar extraction capability is improved, but analysis is limited to short-length data

Engineering Contradiction:
Improvegrammar extraction capabilityVSAvoiddata length
Core Design Contradiction:
Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent applies automatic segmentation to divide long time series data into discrete symbolic sequences. This transformation enables the grammar-based algorithm to process much longer data sequences by working with compressed symbolic representations rather than raw continuous data, thereby extending the analysis capability to long-length data.

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If hand-crafted grammar is used for time series analysis, then analysis accuracy is improved, but automation is reduced

Engineering Contradiction:
Improveanalysis accuracyVSAvoidautomation level
Core Design Contradiction:
Measurement precisionVSExtent of automation

Solution Approach 1:

The patent implements automatic grammar extraction from time series data without requiring manual hand-crafting of grammar rules. The system autonomously learns and extracts relevant grammar rules directly from the data, achieving both high automation and maintained analysis accuracy through data-driven grammar discovery.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS11801847B1Method for time series structure discovery
Publication Date: 2023.10.31 HRL LAB
  • US11801847B1 patent drawing
  • US11801847B1 patent drawing
  • US11801847B1 patent drawing

AI summary

Described is a system for analyzing time series data. A sequence of symbols is generated from a set of time series input data related to a moving vehicle using automatic segmentation. A grammar is extracted from the sequence of symbols, and the grammar is a subset of a probabilistic context-free grammar (PCFG). Using the grammar, time series input data can be analyzed, and a prediction of the vehicle's movement can be made. Vehicle operations for an autonomous vehicle are determined using the prediction.