1、BRITISH STANDARD AEROSPACE SERIES BS EN 14514:2004 Space engineering standards Functional analysis The European Standard EN 14514:2004 has the status of a British Standard ICS 49.140 BS EN 14514:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committ
2、ee on 19 April 2005 BSI 19 April 2005 ISBN 0 580 45756 7 National foreword This British Standard is the official English language version of EN 14514:2004. The UK participation in its preparation was entrusted to Technical Committee ACE/68, Space systems and operations, which has the responsibility
3、to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “Internationa
4、l Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British S
5、tandard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and Eur
6、opean developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 22, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. A
7、mendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN14514 August2004 ICS49.140 Englishversion SpaceengineeringstandardsFunctionalanalysis NormesdingnieriespatialeAnalysefonctionnelle RaumfahrttechnikNormenFunktionenanalyse ThisEuropeanStandardwas
8、approvedbyCENon21February2003. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicatio
9、ntotheCentralSecretariatortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheCentralSecretariathasthesamestatusast heofficial versions. CENmembersare
10、thenationalstandardsbodiesofAustria,Belgium,Cyprus,CzechRepublic,Denmark,Estonia,Finland,France, Germany,Greece,Hungary,Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands,Norway,Poland,Portugal, Slovakia, Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDAR
11、DIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2004CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN14514:2004:EEN 14514:2004 (E) 2 Contents page Foreword4 1 Scope.5 2 Normative referen
12、ces.5 3 Terms, definitions and abbreviated terms .5 3.1 Terms and definitions .5 3.2 Abbreviated terms .6 4 Principles and methods of functional analysis .6 4.1 Principles6 4.2 Methods6 4.3 Objectives.7 4.4 Logic and implementation overview .7 4.4.1 Performance7 4.4.2 Implementation .7 4.4.3 Functio
13、nal status10 5 Functional analysis process10 5.1 Definition and identification .10 5.1.1 System definition10 5.1.2 Definition of the level of detail 10 5.1.3 Identification of functions10 5.2 Representation of the system 11 5.2.1 General 11 5.2.2 Function tree.11 5.2.3 Functional matrix13 5.2.4 Func
14、tional block diagram 14 5.3 Functional analysis and engineering disciplines.16 5.3.1 General 16 5.3.2 Functional analysis and requirements .16 5.3.3 Functional specification 17 5.3.4 Offtheshelf item assessment.17 5.3.5 Software.17 5.3.6 Operations.18 5.3.7 Traceability18 5.3.8 Verification 18 5.4 F
15、unctional analysis and other disciplines 19 5.4.1 Dependability and safety .19 5.4.2 Functional analysis and management19 6 Functional analysis and project phases 20 6.1 Objectives.20 6.2 Project phases .20 6.2.1 Phase 0 20 6.2.2 Phase A20 6.2.3 Phase B21 6.2.4 Phase C21 Bibliography 22 EN-14514:200
16、4 (E) 3 List of figures Figure 1 Functional analysis implementation overview9 Figure 2 Function tree 12 Figure 3 Function tree 13 Figure 4 Functional matrix 14 Figure 5 Functional block diagram . 16 EN 14514:2004 (E) 4 Foreword This document (EN 14514:2004) has been prepared by CMC. This European St
17、andard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by February 2005, and conflicting national standards shall be withdrawn at the latest by February 2005. It is based on a previous version 1)prepared by the ECSS Engine
18、ering Standard Working Group, reviewed by the ECSS Technical Panel and approved by the ECSS Steering Board. The European Cooperation for Space Standardization (ECSS) is a cooperative effort of the European Space Agency, National Space Agencies and European industry associations for the purpose of de
19、veloping and maintaining common standards. This document is one of the series of ECSS Standards intended to be applied together for the management, engineering and product assurance in space projects and applications. Requirements in this document are defined in terms of what shall be accomplished,
20、rather than in terms of how to organize and perform the necessary work. This allows existing organizational structures and methods to be applied where they are effective, and for the structures and methods to evolve as necessary without rewriting the standards. The formulation of this document takes
21、 into account the existing ISO 9000 family of documents. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germa
22、ny, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. 1)ECSS-E-10-05A EN-14514:2004 (E) 5 1 Scope This document defines the requirements to perform functional analy
23、sis and the information output of that analysis. It applies to all types and combinations of space systems, projects and products. It also applies to project phases 0, A, B and C and at all levels. When viewed from the perspective of a specific project context, the requirements defined in this docum
24、ent should be tailored to match the genuine requirements of a particular profile and circumstances of a project. NOTE Tailoring is a process by which individual requirements of specifications, standards and related documents are evaluated and made applicable to a specific project by selection, and i
25、n some exceptional cases, modification of existing or addition of new requirements. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of th
26、e referenced document (including any amendments) applies. EN 13701:2001, Space systems Glossary of terms EN 13290-4, Space project management General requirements Part 4: Project phasing and planning 3 Terms, definitions and abbreviated terms 3.1 Terms and definitions For the purposes of this docume
27、nt, the terms and definitions given in EN 13701:2001 and following apply. 3.1.1 constraint characteristic, result or design feature which is made compulsory or has been prohibited for any reason NOTE 1 Constraints are generally restrictions on the choice of solutions in a system. NOTE 2 Two kinds of
28、 constraints are considered, those which concern solutions, and those which concern the use of the system. NOTE 3 For example constraints can come from environmental and operational conditions, law, standards, market demand, investments and means availability, organizations policy. NOTE 4 Adapted fr
29、om EN 1325-1. 3.1.2 function intended effect of a system, subsystem, product or part NOTE 1 Adapted from EN 1325-1. NOTE 2 Functions should have a single definite purpose. Function names should have a declarative structure (e.g. “Validate Telecommands”), and say “what” is to be done rather than “how
30、”. Good naming allows design components with strong cohesion to be easily derived. 3.1.3 functional analysis technique of identifying and describing all functions of a system NOTE Adapted from EN 1325-1. EN 14514:2004 (E) 6 3.1.4 operational mode manner or way of operating NOTE The mode is realized
31、by a group of related functions or tasks required to accomplish a specific operation. 3.1.5 operational scenario summary of sequences of events and the environment for a specific operation 3.1.6 functional specification document by which the customer establishes the intended purpose of a product, it
32、s associated constraints and environment, the operational and performances features, and the permissible flexibility NOTE 1 This document contains a complete set of provisional technical requirements for a product. NOTE 2 This term is equivalent to functional performance specification as defined in
33、EN 1325-1. 3.1.7 technical specification specification expressing technical requirements for designing and developing the solution to be implemented NOTE The technical specification evolves from the functional specification and defines the technical requirements for the selected solution as part of
34、a business agreement 3.2 Abbreviated terms The following abbreviated terms are defined and used within this document. Abbreviation Meaning FMECA failure modes effects and criticality analysis ROD review of design RAMS reliability, availability, maintainability and safety 4 Principles and methods of
35、functional analysis 4.1 Principles In order to design, develop and prove any space engineering system, the mission and consequent functions, that the system shall perform, is clearly established. This functionality is distributed throughout the different design levels (e.g. systems, subsystems and u
36、nits). This allocation of the system functions in a systematic way is an important step in establishing a design which meets all the design objectives. 4.2 Methods Functional analysis is the technique of identifying and describing all the functions of a system. The purpose of the analysis is to iden
37、tify and partition all the functions of any system required to perform the intended mission. The analysis is performed to establish the system functions and to control the distribution and maintenance of these functions in a systematic and useful manner. Three techniques: function tree, functional m
38、atrix and functional block diagram are described, although it is recognized that other representations can also prove suitable. EN-14514:2004 (E) 7 At the top system level, the required functions are derived from the mission statement and are the basis of the system functional specifications. All th
39、ese functions can be considered ”external” functions. The solution to meet these functions can lead to new lower level functions to be identified which are a result of the chosen solution. These new functions are either serviced at the system level where they were derived, in which case the function
40、 is satisfied, or passed to a lower level. A function, which is passed to a lower level, is a higher level function for the recipient level. As the detail of the design progresses, each tier of the design add additional functions necessary to support the higher level functions. Both types of functio
41、ns can be either solved internally within the system or refined into requirements and functions to be met at some lower level engineering unit. Thus, some functions have different levels of importance associated with them depending on how and where they originated. Some functions are readily achieva
42、ble, while others are complex and expensive to meet. Often at the lower levels, solutions are available which readily meet most of the functions or during development it is established that a particular function is only met under specific conditions. The knowledge of the origins of any function allo
43、ws to establish the consequences and impact of not meeting a requirement or to allow a function to be renegotiated. Changes to requirements can arise at top system level, in which case the ”sub”-derived functions, which are affected at the lower tier level, are readily identifiable. A realistic exam
44、ple of top system level changes occurs when the launch vehicle is changed and as a consequence, the vibration spectrum or human factors can alter. Functional analysis includes different activities. The complexity of the analyses adapts considering the design maturity, the evolution of the design and
45、 the complexity of the mission. The ultimate aim is to achieve the simplest final design which meets all the system requirements and offers the best value by achieving that all the functions are met and also partitioned in a logical manner. Functional analysis is performed in a systematic manner. Fu
46、nction are not passed from one system to another system of the same level, but are received from a higher level system and either serviced or further distributed (and divided if necessary) to lower level systems. Functional analysis excludes the assessment of the criticality of the functions in term
47、s of reliability and safety, but can serve as the basis of the functional failure analysis. Functional analysis also excludes any consideration of the engineering solution required to service an identified function, until ”internal” functions are identified as part of the required solution. By consi
48、dering a system in terms of functions (being the problem to solve) and not in terms of technology (a possible solution), alternative technologies are not excluded, duplication can be avoided and components standardization can be improved. 4.3 Objectives The objectives of functional analysis are to: a) identify or update the functional requirements; b) ensure the functions are partitioned in an appropriate manner; c) allow the traceability of the functions; d) identify the interfaces between functions. This allows a complex engineering system to be understood and realized. 4.4 Logi
