Modelling human performance in semi-automated systems

The analysis of the human component of complex systems is an important element of the design process at all stages. This paper outlines the application of task network modelling to the identification of critical subtasks in the interaction between man and machine. By applying the Integrated Performance Modelling Environment (IPME) tool it is possible to consider the effects of both environmental stressors and workload in conjunction with subsystem performance. Under different operational conditions aspects of crew performance will be affected differentially. As a consequence, the aspects of system operation which lie on the critical path may change. The application of IPME to the analysis of a simple case study is described. By considering the variation of task performance with operational conditions, critical paths are identified and overall system performance quantified. The automation of specific system elements is investigated and it is shown that overall performance can be optimised whilst minimising the cost of modification.