Formal approach to include a human material handler in a computer-integrated manufacturing (CIM) system

Abstract

Formal modelling techniques that employ principles of finite state automata have been increasingly used for shop-floor control. These approaches have focused primarily on unmanned systems where the self-contained logic for control of the systems is embedded within the model(s). To date, human operators are seldom configured within the modelling detail required for these systems. The result has been that the interface of humans within automatic systems has been limited. In general, humans performing physical activities in an automatic system must mimic the detailed responses normally transmitted via control computers and equipment, making the human interaction painful and prone to error. This paper discusses (1) the formal modelling specifics required for the control of such an automated shop floor system; and (2) the role and interactions of the human primarily in automatic systems. The human in the automatic manufacturing system addressed here serves primarily as a material handler and material transporter, providing almost unlimited possibilities regarding the accessibility of product flow from any system resource to any other system resource—a major constraint in many operational systems. The impact on the complexity of the accessibility graph, issues related to automatically controlling such a system and the human interactions within such a system are also developed. The paper introduces many complex issues and interactions, and concludes with an example of how a human handler can be effectively included in a finite state automaton.

Keywords:

• Shop-floor control
• Supervisory control
• Human computer interaction