Dependent failures in multifunctional ACS

The article discusses theinterference ofelements of the automatedcontrol system.We study thesafety and survivability. Gradationfailure is given. The consequences of failurecells and modulesof the system, causingfailures of other cells and modules, the possibility of preventing thesefailures are highlighted.A range of possibledependent failures is provided. It is shown thata possible source ofdanger can be asmodule failure, and failureof backupelements in these modules. It is postulated that the increase in the number of redundantelements at least does not reduce to zerothe potential danger. The variouslogicalstructures of the compoundelements in ACS are discussed. A typical structureof reliabilityof automated control systemthat performsseveral functions, the tree structure is shown. It is deducedthat one systemAPCS performs several functions. Onespacecraftoften performsseveral functions.Also there are functions of the ACS which do notaffect theoperation. Andto determine the reliabilityof the system wemust determine which elementsinvolved in performing anyfunctions. It is necessary to determine thesequence of elements to perform a functional task. It is illustrated by the development of failures in multi-functionalsystems, the mutual influence of elements in them in case of simple linear andbranchedredundantstructures. We consider the negative effects of redundancy.An example ofcalculating thereliability of the systemwith a parallelconnection of elementsinto accountand dependent failures caused by the elements is given. The conclusion of necessity of non-redundant methodsto improve reliabilityand hazard prevention was made.