Reliability Models of Multi-state UAV-based Monitoring Systems: Mission Efficiency Degradation Issues.

General classification of multi-state UAV-based monitoring systems (MsUMSs) in view of types of used main and redundant unmanned aerial vehicles (UAVs), automatic battery maintenance stations (ABMSs), and mission efficiency degradation parameters is presented. General classification of reliability models for the MsUMS in view of the numbers of the main routes, route sections, UAVs, ABMSs, and degradation levels, is given and discussed. Reliability models for the MsUMS with various parameters are developed. The mission efficiency of the MsUMS and the probability of successful UAV mission plan fulfilment within the specified time frame on each of the degradation levels are utilized as basic indicators. Zero, one, and two-level-degradation reliability models for the MsUMS are explored and discussed in detail. A comparative analysis of the developed models is carried out.