Analysis Techniques For Man-Machine Systems Design

NATO UNCLASSIFIEDIAC243(Panei-8)=Volume-- 10-ispriualsub-systems which may be required. This change of viewpoint (see Fig. 1.8) is particularlyimportant if novel system designs are to be developed, for example, a tank with reducedmanning, or a system with improved maintenance. If a function-oriented view is not taken. thendevelopment from one generation of system to the next will be evolutionary, rather thanrevolutionary. Even if revolutionary changes are not required. the quality of design is improvedby taking a functional viewpointrequirement& constraintviewtfuture missionrequirements andrequirementstem conorientedviewsystem functionsimproed/narefuctonlcocetsystemorientedviewFigure 1.8:identity existingsubsystems &comoonentseveiop concepts ofuture subsystemsSystem and function viewpoints on development(after Haberfellner, 1978)18. The design/development process should be iterative (Dbring, 1983; Meister, 1985).IThis means that mission and function analysis, allocation of functions. and determination oftasks and interface requirements are repeated several times in the course of synthesis, analysis ordesign of the system (see Fig. 1.9). By analyzing the mission. system functions are determined.The analysis of system functions leads to functional requirements which are the basis forallocating the functions to humans and machines. The detailed function analysis identifies thetask performance required of the operator and the required machine processes. Finally theanalvsis of the operator tasks and the machine processes gives the data for work station design.work environment design, workload evaluation, and personnel selection and training.19. Despite the similarity in aims and procedure, human engineering analyses are notalwavs conducted concurrently with other systems engineering activities. In current practice. thesystem concept is often developed well beyond the point of function allocation before humanfactors issues are considered-This makes the human engineering function allocation analyses oflittle value. Yet the increasing levels of automation in current systems make it more important thatthe roles and functions of the human operators been analyzed in detail. One of the aims of thisreport is to highlight those human engineering activities and analytical techniques which have astrong link to current developments in systems engineering, particularly the increasing use ofstructured analysis and design techniques for software development.NATO UNCLASSIFD