Threshold-Based Maintenance for Series-Parallel Systems

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Solution Overview

Problem

Industrial and mission-critical assets with series-parallel systems face challenges in optimal maintenance scheduling due to computationally intensive resource allocation, especially when resources are sparse and shared across multiple subsystems, leading to excessive downtime and costly breakdowns.

Innovation Solution

A threshold-based heuristic maintenance policy is implemented, which determines optimal resource allocation by balancing immediate and long-term rewards, prioritizing repairs based on maximum marginal reward and asset reliability, using a scalable linear backward recursion to derive near-optimal maintenance schedules in real-time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optimal maintenance scheduling is implemented using traditional resource allocation methods, then asset reliability is improved, but computational complexity and time required for resource allocation increases significantly

Engineering Contradiction:
Improveasset reliabilityVSAvoidcomputational complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the maintenance scheduling problem into discrete decision epochs and divides resources into allocable units. The series-parallel system is decomposed into independent subsystems with parallel components, allowing separate analysis and allocation decisions for each component group, thereby reducing overall computational complexity while maintaining reliability optimization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transforms the continuous resource allocation problem into a discrete parameter optimization problem by defining threshold-based maintenance triggers and integer resource allocation units. This parameter discretization enables the use of dynamic programming and heuristic algorithms that are computationally tractable while still achieving near-optimal asset reliability.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If traditional resource allocation methods are used for maintenance scheduling, then maintenance effectiveness is improved, but downtime increases due to excessive computational requirements

Engineering Contradiction:
Improvemaintenance effectivenessVSAvoiddowntime
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent pre-calculates threshold values and maintenance policies during idle periods or using historical data, storing these decisions for rapid deployment during operational periods. This preliminary action separates the computationally intensive optimization phase from the time-critical execution phase, reducing downtime during actual maintenance decisions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses real-time monitoring data and automated threshold comparisons to trigger maintenance actions without requiring complex real-time computational optimization. The pre-established policies enable the system to self-determine maintenance timing and resource allocation based on monitored component conditions, eliminating computational delays during critical periods.

Inventive Principle:
Principle #25Self-service

3Reliability

If more maintenance resources are allocated to subsystems, then asset reliability is improved, but the cost of maintenance increases

Engineering Contradiction:
Improveasset reliabilityVSAvoidmaintenance resources
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies differentiated resource allocation strategies to different subsystems and components based on their individual reliability characteristics, criticality to asset operation, and failure consequences. High-criticality components receive prioritized resource allocation while less critical components receive minimal or preventive-only maintenance, optimizing the ratio of reliability improvement to resource consumption.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements threshold-based maintenance triggers that activate maintenance actions only when component degradation reaches predetermined levels, rather than applying continuous or excessive maintenance. This partial action approach maintains reliability by intervening only when necessary, avoiding unnecessary resource consumption on components that have not yet reached critical degradation states.

Inventive Principle:
Principle #16Partial or excessive action

4Productivity

If real-time maintenance scheduling is implemented, then operational efficiency is improved, but computational resources and processing power are consumed

Engineering Contradiction:
Improveoperational efficiencyVSAvoidcomputational resources
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The system employs automated threshold monitoring and rule-based decision triggers that require minimal computational processing. Real-time monitoring data is automatically compared against pre-established thresholds, and maintenance actions are triggered based on simple conditional logic rather than complex real-time optimization algorithms, reducing computational resource consumption while maintaining operational efficiency.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent uses lightweight, computationally inexpensive threshold-based policies instead of heavy real-time optimization algorithms. These simple decision rules can be executed with minimal computational resources, enabling real-time scheduling decisions without consuming excessive processing power or energy, effectively using 'cheap' computational approaches for time-critical decisions.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS11755971B2Threshold based selective maintenance of series-parallel systems
Publication Date: 2023.09.12 NOVITY INC
  • US11755971B2 patent drawing
  • US11755971B2 patent drawing
  • US11755971B2 patent drawing

AI summary

A condition of an asset including one or more subsystems connected in series is monitored. Each subsystem includes one or more components connected in parallel. The asset has one or more jobs. A probability of the asset surviving a predetermined amount of time is determined based on the monitoring and one or more shared resources. The one or more shared resources are configured to be shared between the subsystems. A model is established using a threshold based heuristic maintenance policy. The model is configured to maximize a number of successful jobs that the asset is able to complete based on the determined probability. The one or more shared resources are allocated to the one or more subsystems based on the model.