Barrier Function Learning for Unsafe State Avoidance in Control Systems

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Solution Overview

Problem

Current methods for generating safety conditions in control systems are limited, as they often rely on manual identification of barrier functions and do not provide absolute guarantees of safety, especially for complex dynamical systems, and existing machine learning approaches are restricted to specific scenarios or initial conditions.

Innovation Solution

A machine learning system that learns barrier functions using neural networks to minimize specific loss functions, ensuring the functions are supported in the globally safe region of the state space, allowing for automated generation of safety conditions and proactive safety measures in cyber-physical systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual identification of barrier functions is used, then safety guarantees can be obtained for simple systems, but the method does not scale to complex dynamical systems and lacks versatility

Engineering Contradiction:
Improvesafety guaranteeVSAvoidapplicability to complex systems
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces manual analytical methods with a machine learning system that automatically learns barrier functions from trajectory data. The neural network hθ learns to approximate barrier functions by minimizing loss functions based on safety specifications and system trajectories, eliminating the need for manual identification while maintaining safety guarantees for complex dynamical systems.

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

Solution Approach 2:

The system enables the control system to automatically generate its own safety certificates through the learned barrier function. The neural network self-trains on system trajectories and safety specifications, producing a barrier function that certifies safety for the specific system without requiring external manual analysis for each new system.

Inventive Principle:
Principle #25Self-service

2Extent of automation

If existing machine learning approaches are used to approximate safe regions, then automation is achieved, but absolute safety guarantees are not provided

Engineering Contradiction:
Improveautomated safety condition generationVSAvoidabsolute safety guarantee
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The patent incorporates feedback through loss functions that enforce barrier function properties during training. The loss function includes terms that penalize violations of safety specifications and ensure the learned function satisfies barrier function conditions, providing automated generation with absolute safety guarantees through continuous validation feedback.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary training of the neural network on system trajectories and safety specifications before deployment. This preliminary action ensures the barrier function is pre-validated to satisfy safety guarantees, allowing automated operation while maintaining absolute safety through pre-established mathematical certificates.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If barrier functions are learned from data without specific guidance, then automation is improved, but the quality and accuracy of safety guarantees decrease

Engineering Contradiction:
Improveautomation speedVSAvoidaccuracy of safety guarantee
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent changes the parameters of the learning process by using specifically designed loss functions that incorporate safety specifications as constraints. The loss function parameters are tuned to balance automation efficiency with accuracy, ensuring the learned barrier function maintains high precision in safety guarantees while achieving automated generation.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS11663370B2Automated system for generating approximate safety conditions for monitoring and verification
Publication Date: 2023.05.30 HRL LAB
  • US11663370B2 patent drawing
  • US11663370B2 patent drawing
  • US11663370B2 patent drawing

AI summary

Described is a system and method for generating safety conditions for a cyber-physical system with state space S, action space A and trajectory data labelled as either safe or unsafe. In operation, the system receives inputs and ten minimizes loss functions to cause a neural network to become a barrier function. Based on the barrier function, the system can then determine if the cyber-physical system is entering an usafe state, such that if the cyber-physical system is entering the usafe state, then the cyber-physical system is caused to initiate a maneuver to position the cyber-physical system into a safe state.