Simulating transient-state system effectiveness for human-machine systems

System effectiveness is a combined measure of readiness and reliability at each task-arrival time, when transient (human) operator behavior is considered in conjunction with the machine operating state. The authors derive effectiveness evaluation models for human-machine systems that have several machines. Each machine has an operator and contains several components (hardware and/or software). The system is modeled as a series system where all components and operators must be ready and reliable for every task in a mission. The probabilistic model for system effectiveness is quite complex in computation and provides solutions only for the steady state of the system. Simulation is used to estimate the effectiveness of the human-machine system and to obtain the transient performance. The modeling and simulation techniques can also be used for large human-machine systems that consist of computers, processors, and software. This study extends Abbas and Kuo (1990) that assumed one machine with multiple components in the human-machine system. Even one more machine and one more operator can make the probabilistic model much more complex. The authors have learned that computer simulation is necessary to analyze such multiple human-machine systems