Analysis Techniques For Man-Machine Systems Design

NATO UNCLASSIFIEDAC/243(Pane1-8)TR/ 7 - 22 -Volume 12.3 OVERVIEW OF HUMAN ENGINEERING ANALYSIS TECHNIQUES37. Thirty-one human engineering analysis techniques, including most of the techniquesreported by survey respondents, are reviewed to a standard format in Volume 2 of this report.The following is an overview of the six classes of technique reviewed.2.3.1 Mission and Scenario Analysis38. These analyses define the overall requirements of the system under development, interms which provide information for subsequent human engineering analyses. They are used todefine what the system must do (the operational requirements) and the circumstances andenvironment in which it must be done. Two techniques were reviewed:* Narrative mission descriptions* Graphic mission profiles2.3.2 Functional Analysis39. Functional analysis is an essential step in the systems engineering process.Analyzing the system in terms of the functions which must be performed. rather than interms ofa set of specific sub-systems, has become increasingly important as the software component ofsystems has grown. Complex modem systems are high on functionality but low on in-placeobjects (Tooze, 1989). For example, a menu-driven human-computer interface can makehundreds of control functions available to the user though two controls: a rollball (or joystick ormouse) and a selection key. Functional analvsis has demonstrated value for coordinating theactivities of system engineering and engineering specialists. Seven techniques were reviewed:* Function flow diagrams* Sequence and timing (SAT) diagrams* Structured analysis and design technique (SADT)* Information flow and processing analysis* State transition diagrams* Petri nets* Behaviour graphs2.3.3 Function Allocation Analysis40. Typically, decisions about the functions performed by system operators andmaintainers are made implicitly in the design process, or through the selection of equipment andsoftware. Such decisions are made without systematic consideration of their impact on the roles,functions, and tasks of the human components of the system. A rational allocation of functionsto people (liveware), hardware, or software is necessary for optimal system design. Functionallocation analyses provide the basis for subsequent efforts relating to crew or operator taskanalysis and description, operator workload analysis, display and control selection or design(including communication systems design), and crew station design, development, andevaluation. In particular, decisions on the allocation of functions have a significant effect on crewor operator workload, system performance, manning, selection, and training requirements. Fivetechniques were reviewed:* Ad-hoc function analysis* Fitts' list* Review of potential operator capabilities* Function allocation evaluation matrix* Requirements Allocation Sheets (RAS)NATO UNCLASSIFIED- 22 -