Avionics Architecture

Avionics System Growth

• Avionic systems represent a growing part of aircraft costs: 35 to 40% in civil aircraft, and more than 50% in military aircraft. • Need avionic architectures, composed of digital processing modules

and communication buses,• important requirements: safety, robustness to equipment failures,

determinism, and real-time.

Federated Architecture

• One function = One Computer

Problems with FA

• The amount of digital information exchanged by LRUs has grown beyond the capability of ARINC 429 to carry it. • the weight and volume of the dedicated subsystems hit the envelope

restrictions of the aircraft.• the huge number of different resources significantly increased the

maintenance costs for airlines in terms of worldwide computer spares provisioning and handling.

Integrated Modular Avionics

• two complementary principles.’• The first principle is to integrate multiple software functions with

possibly different criticality levels on single avionic computing resources in order to keep the weight, volume and cost of the avionic architecture within reasonable limits. • strict and robust partitioning, i.e. a set of principles implemented by

hardware and software means (such as middleware) which prevent interference between functions, exactly as if each function runs on its own virtual resources with guaranteed performances whatever the behaviour of other functions.

ARINC 653

• ARINC 653 specifies the management of avionic applications on common processing modules. According to ARINC 653 principles, functions from different applications resident in a processing module are partitioned with respect to space (resources partitioning) and time (temporal partitioning).

ARINC 664

• ARINC 664 describes the management of communication resources (i.e., the communication network). It has been implemented in the Avionics Full Duplex Ethernet (AFDX) architecture.

Avionics Full-Duplex Switched Ethernet (AFDX)• AFDX is a aircraft data network (ADN) based upon IEEE 802.3 Ethernet • AFDX takes existing Ethernet physical layer technology and, using

switched Ethernet in full-duplex mode as a basis, adds deterministic packet delivery, and high-integrity and high-availability mechanisms.• A given LRU may now communicate with many other LRUs over one

set of AFDX wires as opposed to one ARINC 429 bus pair for each set of one-way data words and each set of recipient LRUs

CPIOMs

• LRU functions are done by avionics "applications". These independent applications are hosted in shared IMA modules, called Core Processing Input/Output Modules(CPIOMs)• seven CPIOMs • additional IMA modules called Input/Output Modules (IOMs). • CPIOMs and IOMs are Line Replaceable Modules (LRMs).

CPIOMs

• CPIOM-A: Pneumatic and optional air conditioning applications,• CPIOM-B: Air conditioning applications,• CPIOM-C: Cockpit and flight controls applications,• CPIOM-D: Data link applications,• CPIOM-E: Energy applications,• CPIOM-F: Fuel applications,• CPIOM-G: Landing gear applications