Procedural Task Management of. Operations. Se Woo Cheon and M. Modarres. A. JAMES CLARK SCHOOL OF ENGINEERING. UNIVERSITY OF MARYLAND ...
CTRS-DS-26 Vol. DS No. 26 1998
Design of Function-Based HumanMachine Interfaces For Procedural Task Management of Operations Se Woo Cheon and M. Modarres
A.
JAMES CLARK SCHOOL OF ENGINEERING
UNIVERSITY OF MARYLAND AT COLLEGE PARK
DESIGN OF FUNCTION-BASED HUMAN-MACHINE INTERFACES FOR PROCEDURAL TASK MANAGEMENT OF OPERATORS
Se Woo Cheon and Mohammad Modarres Department of Materials and Nuclear Engineering University of Maryland, College Park, MD 20742, USA E-mails: {swcheon, modarres)@eng. umd. edu
Keywords: functional modeling, goal tree success tree (GTST), human-machine interfaces (HMis), visual display units (VDUs), function-based display, procedural tasks EXTENDED SUMMARY
In complex plants such as chemical process plants and nuclear power plants, efficient designs of human-machine interfaces (HMis) for process monitoring and controls might be a crucial factor for enhancing both plant availability and safety. For HMis designs, there have been many trials to devise compact control panels that consist of several visual display units (VDUs) rather than hardware-based panels in traditional control panels. Because of the limited number of installable VDUs on a control panel, all of the process information cannot be provided to operators at one time. Thus, the VDU-based displays should provide operators with appropriate arrangement and navigation hierarchy of process information. The traditional VDU designs in navigation scheme have been based on the structural decomposition of a plant: i.e., the classification of display pages based on the whole-part decomposition of a physical plant. Based on this scheme, operators may have some cognitive workload during the management of procedural tasks to find out adequate process information and control slots from the numerous VDU display pages. Figure 1 shows the advantage of function-based HMis rather than system structure based HMis. In the function-based HMI approach, display pages in VDUs are associated with the operators' tasks, functions, and goals to be performed. In this way, operators can take shortest navigation route in following procedural tasks. This paper describes an approach to design the navigation scheme of VDU-based human machine interfaces (HMis) using the functional modeling technique of Goal Tree Success Tree (GTST) (Modarres, 1993). The GTST modeling is a functional decomposition framework to
model complex physical systems: i.e, a GTST is a functional hierarchy of a system organized in levels starting with a "Functional Objective" at the top. In the function-based HMis, a VDUbased display page encompasses a specific system part that performs a related task or function. Using the GTST technique, the structural hierarchy in a complex system can be defined in relation with the functional hierarchy (i.e., function-centered representation) (Modarres, 1996).
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