Control method and device that resolves closed loops in automatic fault tree analysis of a multi-component system

A computer-implemented method performed by a processor, comprising:

• analyzing a multi-component safety-critical system comprising closed-loop circuitry of a closed-loop controller using a fault tree to identify a system failure, a cause of the system failure, and an impact to safety as a result of the system failure, wherein, prior to the analyzing, arbitrary circular logics of the fault free are removed from the fault tree by:
• modeling the multi-component system using a fault tree, the fault tree comprising elements associated with components of the multi-component system and interconnections between the elements associated with functional dependencies between the components;
• back-tracing failure propagation paths from an output element of the fault tree via the interconnections towards one or more input elements of the fault tree;
• checking, for all failure propagation paths, if the respective failure propagation path contains a closed loop associated with the closed-loop circuitry of the closed-loop controller to control a component of the multi-component safety critical system by identifying a downstream element of the respective failure propagation path having a dependency of its output value on an output value of an upstream element of the failure propagation path;
• setting the input value corresponding to a loop interconnection of each such downstream element to Boolean TRUE;
• replacing any Boolean AND-gate having, independently of the specific values of the input elements, Boolean TRUE as output value with a Boolean OR-gate between the respective downstream element and the respective upstream element;
• cutting off any Boolean TRUE input to any Boolean AND-gate remaining between the respective downstream element and the respective upstream element;
• and
• setting the input value of each respective downstream element corresponding to the loop interconnection to Boolean FALSE;
• automatically optimizing the multi-component safety-critical system with regards to at least one of reliability, availability, maintainability, and safety, as a function of the analyzing;
• and
• in response to the automatically optimizing, controlling a component of the multi-component safety critical system with the closed-loop controller by outputting a control signal to the component.