Online Fault Detection and Avoidance Framework for Distributed Factory Control Systems
AssigneeSiemens Corporate Research, Inc.
InventorsPeng Zhao, Yan Lu
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Abstract
An on-line fault detection and avoidance method is provided for industrial control systems that include multiple interacting process controllers. The method addresses the problem that not all faults can be determined and removed at the time of system design and testing. When a fault translates into a time-out condition in one or more controllers, symptoms are identified, persistence is measured, other involved controllers are identified, the fault condition is identified and control laws are reconfigured to avoid the fault condition in the future.
Claims20
A method for detecting and avoiding faults in a distributed factory control system having a plurality of industrial controllers, each said controller controlling at least one underlying process, the method comprising the steps of:
- in a first controller, identifying a symptom of a fault condition by identifying a deviation of a state of an underlying process controlled by the first controller from a corresponding state kept by the controller;
- in the first controller, measuring a persistence of the symptom, and ignoring the symptom if the measured persistence is below a threshold value;
- finding other controllers involved in the fault condition by generating in at least the first controller a search tree having leaf nodes that are monitored conditions;
- identifying the fault condition including identifying states of the other controllers involved in the fault condition;
- and
- reconfiguring control rules controlling states of the involved controllers to avoid the fault condition in the future.
The method of claim 6, wherein the step of identifying the fault condition further comprises:
- analyzing a search tree of a last controller in the chain of controllers where maximum token holding time has been exceeded.
A computer program product comprising a computer readable recording medium having recorded thereon a computer program comprising code means for, when executed on an industrial controller, instructing said controller to control steps in a method for detecting and avoiding faults in a distributed factory control system having a plurality of industrial controllers, each said controller controlling at least one underlying process, the method comprising the steps of:
- in a first controller, identifying a symptom of a fault condition by identifying a deviation of a state of an underlying process controlled by the first controller from a corresponding state kept by the controller;
- in the first controller, measuring a persistence of the symptom, and ignoring the symptom if the measured persistence is below a threshold value;
- finding other controllers involved in the fault condition by generating in at least the first controller a search tree having leaf nodes that are monitored conditions;
- identifying the fault condition including identifying states of the other controllers involved in the fault condition, and
- reconfiguring control rules controlling states of the involved controllers to avoid the fault condition in the future.
The computer program product of claim 16, wherein the step of identifying the fault condition further comprises:
- analyzing a search tree of a last controller in the chain of controllers where maximum token holding time has been exceeded.
Dependencies are inferred from the claim text.