Autonomous Control Using Martingale Risk-Constrained MDPs

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Solution Overview

Problem

Controlling dynamical systems in uncertain environments with a bounded probability of failure is challenging, as existing methods struggle to efficiently manage risks and ensure safe operation in dynamic conditions such as autonomous vehicles or financial systems.

Innovation Solution

A computer-based method that diffuses a risk constraint into a martingale to represent risk tolerance, augmenting the state and control spaces of the dynamical system, and iteratively constructing Markov Decision Processes (MDPs) to refine the system model and compute control signals, ensuring a bounded probability of failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If risk constraints are strictly enforced to maintain bounded probability of failure, then system safety is improved, but control flexibility and performance deteriorate

Engineering Contradiction:
Improvebounded probability of failureVSAvoidcontrol flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces a martingale process as an additional dimension to the traditional state space, transforming the risk-constrained control problem into an unconstrained optimization problem in the augmented space. This dimensional extension allows the controller to navigate between safety and performance by adjusting the martingale component, effectively resolving the contradiction between maintaining bounded failure probability and preserving control flexibility.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent transforms the fixed risk constraint parameter into a dynamic martingale process that evolves over time. By changing the parameter representation from a static bound to a stochastic process, the system can adaptively balance safety requirements with performance objectives, allowing control flexibility to vary according to the evolving risk landscape rather than being constrained by a fixed parameter.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If complex risk management models are used to ensure safety, then reliability is improved, but computational complexity increases

Engineering Contradiction:
Improvesafety guaranteeVSAvoidcomputational complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical risk management mechanisms with a mathematical transformation approach. Instead of using intricate safety verification systems or complex control algorithms, the method substitutes the risk constraint with an equivalent martingale formulation, which can be handled by standard optimization techniques. This substitution dramatically reduces computational complexity while maintaining safety guarantees.

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

Solution Approach 2:

By transforming the risk constraint into a martingale process parameter, the patent changes the problem formulation from one requiring complex risk management computations to one solvable with conventional optimization methods. This parameter transformation simplifies the computational burden while preserving the safety properties through the mathematical equivalence of the martingale formulation.

Inventive Principle:
Principle #35Parameter changes

3Speed

If real-time control is implemented to respond to dynamic conditions, then responsiveness is improved, but computational time requirements increase

Engineering Contradiction:
Improvereal-time responsivenessVSAvoidcomputational time
Core Design Contradiction:
SpeedVSLoss of time

Solution Approach 1:

The patent performs preliminary transformation of the risk constraint into a martingale formulation before the actual control optimization is executed. This pre-processing step converts a complex constrained problem into a simpler unconstrained form, so that when real-time control decisions are needed, the computationally intensive constraint handling has already been completed. This allows faster real-time responses without sacrificing safety guarantees.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS11073802B2Autonomous control of dynamical systems
Publication Date: 2021.07.27 MASSACHUSETTS INST OF TECH
  • US11073802B2 patent drawing
  • US11073802B2 patent drawing
  • US11073802B2 patent drawing

AI summary

A computer-based method controls a dynamical system in an uncertain environment within a bounded probability of failure. The dynamical system has a state space and a control space. The method includes diffusing a risk constraint corresponding to the bounded probability of failure into a martingale that represents a level of risk tolerance associated with the dynamical system over time. The state space and the control space of the dynamical system are augmented with the martingale to create an augmented model with an augmented state space and an augmented control space. The method may include iteratively constructing one or more Markov Decision Processes (MDPs), with each iterative MDP represents an incrementally refined model of the dynamical system. The method further includes computing a first solution based on the augmented model or, if additional time was available, based on one of the MDP iterations.