Analysis Techniques For Man-Machine Systems Design

NATO UNCLASSIFIEDAC/243(Panel 8 TR/7 - 58 -Volume 2ResourcesrequiredThe analysis can be conducted using manual methods. It requires a collaborative effort between sub-system designersand human engineers or human factors specialists to obtain the extensive knowledge of hardware, software, andhuman capabilities required to make the comparisons.AdvantagesDoD-HDBK-763 notes that, although the technique doesnot ensure the optimum allocation of functions, it goesa long way beyond the informal, or "gut feel," methodsso often used in design.DisadvantagesThe function allocation procedure is of averagecomplexity. It may be used at either a gross or detailedlevel of analysis, but it is used more often for grossfunction allocation. The technique does not deal well withfunction allocation between multiple operators. As withother function allocation techniques which are.initiated bya system function decomposition. it does not includehuman functions such as collaborative decision making,supervision, etc.Users report difficulty in accessing data on humancapabilities and limitations for use in the analysis. Someusers report the technique is inaccurate. Technically, themathematical treatment of subjective ratings (weightingand addition) is inappropriate.Relative contributionDoD-HDBK-763 rates function allocation techniques as having medium cost-cffectiveness. One user (out of twelvesurveyed) sees it as a necessary step to support sub-systems development.ApplicationsAlthough the technique is quite widely published, there are few reports on its use. It was used for the development ofa military training system and for an aircraft.Quality assurance considerationsTo be effective the technique must start from a comprehensive and complete list of system functions. The verb-nounphrase used to describe functions is obviously important in the identification of candidate function allocations.Relationship to system performancerequirementsThe technique is related to system performance requirements through the list of system functions. The allocationdecisions are usually made on the basis of qualitative statements, rather than performance parameters. Thus the outputof the analysis cannot be related directly to system performance. Additional analyses such as workload prediction arerequiredNATO UNCLASSIFIED- 58 -