Deep Belief Network Feature Importance Visualization

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Solution Overview

Problem

Traditional collision prediction methods for road safety, such as safety performance functions, suffer from low accuracy due to the random nature of collision occurrences and the 'black box' nature of deep learning models, making it difficult to extract and analyze traffic features effectively.

Innovation Solution

A visual feature importance method using a deep belief network that performs unsupervised and supervised learning processes to visualize and analyze the contributions of input features, allowing for better understanding and evaluation of feature importance in traffic safety prediction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If deep learning models are used for collision prediction, then prediction accuracy is improved, but the model becomes a black box making feature extraction and importance analysis difficult

Engineering Contradiction:
Improveprediction accuracyVSAvoidfeature importance information
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent introduces an intermediary layer of visualization tools and methods that mediate between the deep learning model's internal computations and external interpretability requirements. This intermediary layer translates hidden neural network computations into visual representations and feature importance metrics, allowing users to understand model decisions without exposing the complex internal architecture.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct inspection of the black box model's internal mechanics with alternative mechanisms for understanding model behavior. Instead of trying to decipher the hidden computational layers directly, the system uses substitution methods such as feature importance algorithms, visualization techniques, and surrogate models that provide interpretability without requiring access to the model's internal mechanical processes.

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

2Ease of operation

If traditional safety performance functions are used, then ease of application is maintained, but prediction accuracy deteriorates due to random nature of collisions and strong distribution assumptions

Engineering Contradiction:
Improveease of applicationVSAvoidprediction accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent segments the prediction system into two distinct parts: a traditional safety performance function component that maintains ease of application and distribution assumptions, and a deep learning component that handles complex pattern recognition and improves accuracy. This segmentation allows each component to operate in its optimal regime while contributing to the overall system performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent merges the advantages of both traditional SPF methods and deep learning models into a hybrid system. The traditional SPF provides interpretability and ease of application, while the deep learning component adds accuracy by capturing non-linear relationships and random collision patterns. The combination leverages the strengths of both approaches while mitigating their individual weaknesses.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentUS11556800B2Decipherable deep belief network method of feature importance analysis for road safety status prediction
Publication Date: 2023.01.17 THE CHINESE UNIVERSITY OF HONG KONG
  • US11556800B2 patent drawing
  • US11556800B2 patent drawing
  • US11556800B2 patent drawing

AI summary

A method for visualizing and analyzing contributions of various input features for traffic safety status prediction is provided. The method includes initializing a deep belief network (DBN) with input features; performing unsupervised learning/training by observing changes of weights of the input features during the unsupervised learning/training; when the unsupervised learning/training process is complete, performing supervised learning/training process by generating a reconstructed input layer based on results of each hidden layer; and continually running the supervised learning/training and generating a weight diagram based on both visualization and numerical analysis that calculates contributions of the input features. The input features may include one or more of annual average daily commercial traffic (AADCT), median width, left shoulder width, right shoulder width, curve deflection, and exposure for traffic safety status prediction.