Decision-making in supervisory control of a flexible manufacturing system

Human intervention is a component of many flexible manufacturing system (FMS) control structure designs. As FMS control systems become more ‘intelligent’, the role of the human in the control structure will also evolve. An FMS may become more of a tool for the human who controls it, with the human responsible for achieving system goals. Thus, defining an appropriate role for the human as a function of the FMS objectives may be critical in the design of the FMS control structure. Knowledge of the decision processes used by humans in an FMS environment can help to define this role. This paper evaluates the decision processes of humans in an FMS environment. GT-FMS, a real-time simulator of an FMS, was implemented with data from an actual FMS installation. An experiment was conducted in which humans interacted with the control system of GT-FMS from an aggregate level. The humans described each of their control actions, and their decision processes were evaluated by mapping these descriptions onto a Rasmussen’s model of human decision-making. The experimental results support making humans an integral part of the FMS control process, since an intricate knowledge of the system state and system sensitivity were crucial to human decision-making in GT-FMS. Human subjects in this experiment used detailed status information, rather than system performance history, as the basis of their control decisions and were inconsistent in defining their goals.