Civil Aircraft System Integration Research

The 2nd International Conference on Computer Application and System Modeling (2012)

Li Haomin Wu Jianhua shanghai aircraft design and research institute, comac shanghai aircraft design and research institute, comac shanghai,China shanghai,China

Abstract-This paper according as the experience of china new civil aircraft developed, introduce the concept and methods of II. SYSTEM INTEGRATION PROCESS civil aircraft systems integration. Top-down system developed process was described. The systems integration and The Systems Integration Process is a comprehensive, comprehensive approach, such as requirements analysis, iterative and recursive problem solving process, applied functional analysis & allocation, safety assessment, system sequentially top-down by integrated teams. It transforms design synthesis and verification, was detailed described. This needs and requirements into a set of system product and philosophy and methods have reference and inspiration effect process descriptions, generate information for decision for developing large complex systems. makers, and provides input for the next level of development. The process is applied sequentially, one level Keyword-sRequirements analysis, Functional at a time, adding additional detail and definition with each analysis/Allocate, System integration, Safety assessment, Design synthesis, Verification level of development. As shown by Figure 2, the process includes: inputs and outputs; requirements analysis; functional analysis and allocation; requirements loop; I. INTRODUCTION synthesis; design loop; verification; and system analysis and control[1]. Civil aircraft as a highly complex large integration systems, which characterized meet customer requirements based on ensuring safety. Based on this characteristic, the development process of civil aircraft generally use a top- down process, first determine the requirements, then the functional define, then the aircraft design, then the system design, component design and produce further, and then successive components to system integration verification, functional and requirements verification, and finally delivered to the user, shown as Figure 1.

Figure 2. The system integration process • System Integration Process Inputs: Input consist primarily of the customer’s needs, objectives, requirements and project constraints. • Requirements Analysis: Requirements analysis is Figure 1. Civil aircraft develop process used to develop functional and performance requirements; The advantages of doing so is very obvious, to ensure that is, customer requirements are translated into a set of that each requirements are met and the integrity of the requirements that define what the system must do and how design, to ensure compatibility between the systems, can be well it must perform. integrated, verification and airworthiness certification • Functional Analysis/Allocation: Functions are relatively easily, and better to understand the impact of a analyzed by decomposing higherlevel functions identified single function to the aircraft. International aircraft through requirements analysis into lower-level functions. manufacturer has developed this top-down process applied The performance requirements associated with the higher to a number of new aircraft development process, and have level are allocated to lower functions. solidified to the industry standard such as "ARP SAE 4754 • Safety Assessment: The safety assessment process is guidelines to civil aircraft and systems development". used by a company to show compliance with certification requirements and in meeting its own internal safety standards. [2].

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• Design Synthesis is the process of defining the product • Functional View: The Functional View focuses on or item in terms of the physical and software elements WHAT the system must do to produce the required which together make up and define the item. operational behavior. It includes required inputs, outputs, • Verification: For each application of the system states, and transformation rules. engineering process, the solution will be compared to the • Physical View: The Physical View focuses on HOW requirements. This part of the process is called the the system is constructed. It is key to establishing the verification loop, or more commonly, Verification. Each physical interfaces among operators and equipment, and requirement at each level of development must be verifiable. technology requirements.

III. REQUIREMENTA ANALYSIS IV. . FUNCTIONAL ANALYSIS AND ALLOCATION

A. Type Of Requirements A. Functional Analysis And Allocation Requirements are categorized in several ways. The The purpose of functional analysis and allocation is to following are common categorizations of requirements that transform the functional, performance, interface and other relate to technical management: requirements that were identified through requirements • Customer Requirements: Statements of fact and analysis into a coherent description of system functions that assumptions that define the expectations of the system in can be used to guide the Design Synthesis activity that terms of mission objectives, environment, constraints, and follows. The designer will need to know what the system measures of effectiveness and suitability. must do, how well, and what constraints will limit design • Functional Requirements: The necessary task, action flexibility. or activity that must be accomplished. Functional (what has This top-down process of translating system level to be done) requirements identified in requirements analysis requirements into detailed functional and performance will be used as the toplevel functions for functional analysis. design criteria includes: • Performance Requirements: The extent to which a • Defining the system in functional terms, then mission or function must be executed; generally measured decomposing the top-level functions into subfunctions, in terms of quantity, quality, coverage, timeliness or • Translating higher-level performance requirements into readiness. detailed functional and performance design criteria or • Derived Requirements: Requirements that are constraints, implied or transformed from higher-level requirement. For • Identifying and defining all internal and external example, a requirement for long range or high speed may functional interfaces, result in a design requirement for low weight. • Identifying functional groupings to minimize and • Allocated Requirements: A requirement that is control interfaces (functional partitioning), established by dividing or otherwise allocating a high-level • Determining the functional characteristics of existing requirement into multiple lower-level requirements. or directed components in the system and incorporating them in the analysis and allocation, B. Requirements Analysis • Performing trade studies to determine alternative Requirements analysis involves defining customer needs functional approaches to meet requirements. and objectives in the context of planned customer use, environments, and identified aircraft characteristics to B. Functional Architecture determine requirements for aircraft functions. Prior analyses The functional architecture is a top-down decomposition are reviewed and updated, refining mission and environment of aircraft functional and performance requirements. The definitions to support aircraft definition. architecture will show not only the functions that have to be The purpose of Requirements Analysis is to: performed, but also the logical sequencing of the functions • Refine customer objectives and requirements; and performance requirements associated with the functions. • Define initial performance objectives and refine them It also includes the functional description of existing. into requirements; This is an example of functional analysis and • Identify and define constraints that limit solutions; and architecture. Functions come mainly from requirements and • Define functional and performance requirements based aircraft operation philosophy. Modern civil aircraft on customer provided measures of effectiveness. operating philosophy is the safety of passengers and cargo movement from the beginning to the end, with minimal C. Requirements Analysis Output impact to the environment, and ensure the operational The requirements that result from requirements analysis efficiency and continuing airworthiness, the aircraft must be are typically expressed from one of three perspectives or maintained. In support of flight, must provide the human views. These have been described as the Operational, interface, hydraulic energy, gas supply and power supply Functional, and Physical views. and other public resources. So the aircraft basic function is • Operational View: The Operational View addresses payload, move, provide common resource, ensure safety, how the system will serve its users. support operation and compatibility with environment, shown as Figure 3.

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V. SAFETY ASSESSMENT VII. VERIFICATION Safety assessment is a important and complex aircraft The objectives of the Verification process include using system integration work. The output of safety assessmemt established criteria to conduct verification of the physical confirm many requirements of system and item design, and architecture (including software and interfaces) from the the safety assessment process can validate the system Figure lowest level up to the total system to ensure that cost, 4 shows the fundamental relationships between these four schedule, and performance requirements are satisfied with specific assessments and the system development processes. acceptable levels of risk. Safety assessment includes: System design solutions are verified by the following • Functional Hazard Assessment (FHA): Examines types of activities: aircraft and system functions to identify potential functional • Analysis – the use of mathematical modelingand failures and classifies the hazards associated with specific analytical techniques to predict the compliance of a design failure conditions. to its requirements based on calculated data or data derived • Preliminary Aircraft Safety Assessment/Preliminary from lower level component or subsystem testing. It is System Safety Assessment (PASA/PSSA): Establish the generally used when a physical prototype or product is not aircraft or specific system or item safety requirements and available or not cost effective. provide a preliminary indication that the anticipated aircraft • Inspection – the visual examination of the system, or system architectures can meet those safety requirements. component, or subsystem. It is generally used to verify • Aircraft Safety Assessment/System Safety Assessment physical design features or specific manufacturer (ASA/SSA): Collects, analyzes, and documents verification identification, that the aircraft and systems, as implemented, meet the • Demonstration – the use of system, subsystem, or safety requirements established by the PASA and the PSSA. component operation to show that a requirement can be • Common Cause Analysis (CCA): Establishes and achieved by the system. It is generally used for a basic verifies physical and functional separation, isolation and confirmation of performance capability and is differentiated independence requirements between systems and items and from testing by the lack of detailed data gathering, or verifies that these requirements have been met. • Test – the use of system, subsystem, or component operation to obtain detailed data to verify performance or to provide sufficient information to verify performance VI. DESIGN SYNTHESIS through further analysis. Testing is the detailed quantifying Design synthesis is a creative activity that develops a method of verification, and as described later in this chapter, physical architecture (a set of product, system, and/or it is ultimately required in order to verify the system design.. software elements) capable of performing the required functions within the limits of the performance parameters VIII. . SUMMARIES prescribed. The objective of design synthesis is to combine and restructure hardware and software components in such a Large and complex system require added design way as to achieve a design solution capable of satisfying the discipline and development structure to ensure that safety stated requirements. Design synthesis begins with the and operational requirements can be fully realized and output of Functional Analysis and Allocation (the functional substantiated. A top-down sequence for developing a architecture). The functional architecture is transformed into specific system implementation from knowledge of an a physical architecture by defining physical components intended aircraft function provides a convenient conceptual needed to perform the functions identified in Functional model for the system development process. A typical system Analysis and Allocation. development progresses in an iterative and concurrent Depending on the nature of the system and the fashion using both top-down and bottom-up strategies. development process used, initial item electronic hardware and software synthesis may occur on breadboards, REFERENCES prototypes, computer emulation, lab or flight-worthy articles. The output is equipment under configuration control [1] Systems Engineering Fundamentals. SYSTEMS MANAGEMENT together with development assurance data and hardware COLLEGE. DEPARTMENT OF DEFENSE. January 2001 [2] SAE ARP4754A Guidelines for Development of Civil Aircraft and and/or software life cycle data. Detailed procedures Systems. 12.2010 developed during the design-build process should be used to verify that all electronic hardware and software synthesis requirements are met.

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Aircraft Function

Com patibility Basic Provide Support Payload Move Safety with Function Common Operation Resouce Environment

Main Main Main Provide Provide Main Main Function Function 1 Function X Power Expendable Function Y Function N

Provide Provide Provide Function Function 1 Function N Hydraulic Electric Pneum atic Power Power

Sub Provide Sub Subfunction Air supply Distribution Function 1 Indication Function N Information

Figure 3. An example of arcraft fnctional achitecture

Figure 4. Safety assessment process mode[2]