Analysis Techniques For Man-Machine Systems Design

NATO UNCLASSIFIEDAC/24 3 (6PanelVolume 28TR/3.5 REQUIREMENTS ALLOCATION SHEETS (RAS)What the technique doesRequirements allocation sheets are used to translate functions into performance and design requirements. Thefunctional analysis (usually a Function Flow Diagram) is used as a basis for the data entered on the sheets. RAS arenormally prepared for each function block. In some cases, closely related functions may be analysed using the sameRAS. Design requirements are identified in terms of the purpose of the function, parameters of the design, designconstraints, and requirements for reliability, human performance, accuracy, safety, operability, maintainability, andtransportability (USAF, 1971; US Defense Systems Management Collcge, 1990). Thus the RAS bridges the systemsengineering activities of function analysis and synthesis. The format of an RAS is not fixed: typical entry headingsare shown below. Each RAS documents the performance requirements and the design requirements for a specificsystem function, as follows.Table 3.4:Requirements allocation sheetREOUIREMENTS FUNCTIONAL DIAGRAM TITLE EQUIPMENT PERSONNEL AND TRAINING EQUIPMENT REOUlREMENTS PROCEDURAL)ATAALLOCATION SHEET & No.REGUIREMENTSIDENTIFICATIONFunctional performance and design Facility Nomenc Spec.or Tasks rime Performan Trng. &requirements requmt ature index equird. re reumt trng. equip.requmtmastercontrolFunctional Diagram Title & No. - the title and number of the drawing containing the function diagram or analysis.Function number - the reference for the function from the functional analysis diagram.Functional performance and design requirements - including: input & output values; requirements which constrain thedesign solution; engineering speciality requirements such as safety, accessibility criteria etc.Facility requirements - for the environment, utilities, architecture etc. imposed by the performance requirements.Equipment identification - the type, name, and specification number of the equipment which performs the function.Personnel and training related requirements - those which affect the performance of the function, described at a levelwhich permits identification of human engineering requirements; with an alphanumeric reference number derivedfrom the function number.Time required - the elapsed time required to perform the task.Performance requirements - for crew coordination, knowledge, skill, decision making, safety procedures, performanceunder stress, life support etc.Training and training equipment requirement - the level of training required and whether training equipment isProcedural data requirements - the need for data which govern procedures (test directives, test procedures. equipmentoperating procedures etc.) for hazardous or complicated functions involving personnel.NATO UNCLASSIFIED-60 -