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Technical Paper

Wireless Sensing - Future's Password to Digital Avionics System

Performance of Avionics systems is dictated by the timely availability and usage of critical health parameters. Various sensors are extensively used to acquire and communicate the desired parameters. In today's scenario, sensors are hardwired. The number of sensors is growing due to automation which increases the accuracy of intended Aircraft functions. Sensors are distributed all over the Aircraft and they are connected through wired network for signal processing and communication. LRUs (Line Replaceable Unit) which are integrating various sensors also use a wired approach for communication. The use of a wired network approach poses challenges in terms of cable routing, stray capacitances, noise, mechanical structure and added weight to the structure. The weight of cables contributes significantly to the overall weight of the aircraft. As the weight of Aircraft increases, the required fuel quantity also increases. The Key driver for Airline operational cost is fuel.
Technical Paper

Wavelet-based Fouling Diagnosis of the Heat Exchanger in the Aircraft Environmental Control System

The Environmental Control System (ECS) of an aircraft provides thermal and pressure control of the engine bleed air for comfort of the crew members and passengers onboard. For safe and reliable operation of the ECS under complex operating environments, it is critical to detect and diagnose performance degradations in the system during early phases of fault evolution. One of the critical components of the ECS is the heat exchanger, which ensures proper cooling of the engine bleed air. This paper presents a wavelet-based fouling diagnosis approach for the heat exchanger.
Technical Paper

Power Dissipation Optimization for Solid State Power Control Modules in the Aircraft Secondary Power Distribution System

In the last two decades, an aerospace industry trend in the secondary power distribution concept has been dominated by power electronics technology which includes power converters and Power Control Modules based on Solid State Power Control (SSPC) switching elements. These Power Control Modules, grouped around microprocessor based controllers and combined in a single electronic chassis, have become a backbone of electrical power distribution systems on all major commercial and military transport aircraft. Due to the resistive properties of the semiconductor-based SSPC devices, whose behaviors can be described as nonlinear functions of ambient operating temperature, power distribution system integration with SSPCs is challenged and heavily affected by operating temperatures and power dissipation limits. Although aircraft compartments where Power Control Modules are located are considered temperature and pressure controlled, high ambient operating temperatures are possible and expected.
Technical Paper

Power Density of Multi-Purpose Motor Controllers - Challenge Beyond Switches

There are many identical large solid-state switching Multi-Purpose Motor Controllers on board of one of the More Electric Aircrafts (MEA). The controllers drive over twice as many different machines with wide torque and speed ranges. The common motor controllers are installed in a central location. The machines are located at diverse and distant positions. Power is delivered and routed from the controllers to machines via a large network comprising of unshielded feeders and multiplexing units. The controllers are required to produce sine wave voltage output to machines, and draw clean power from the source to meet Power Quality (PQ) and Electromagnetic Interference (EMI) requirements. There are significant aircraft level weight savings with that concept. However, designing such a clean motor controller was a major power density challenge beyond switches, accounting for high torque main propulsion engine start and high speed Cabin Air Compressors.
Technical Paper

Heat Exchanger Fouling Diagnosis for an Aircraft Air-Conditioning System

This paper addresses the issue of fault diagnosis in the heat exchanger of an aircraft Air Conditioning System (ACS). The heat exchanger cools the air by transferring the heat to the ram-air. Due to a variety of biological, mechanical and chemical reasons, the heat exchanger may experience fouling conditions that reduces the efficiency and could considerably affect the functionality of the ACS. Since, the access to the heat exchanger is limited and time consuming, it is preferable to implement an early fault diagnosis technique that would facilitate Condition Based Maintenance (CBM). The main contribution of the paper is pre-flight fault assessment of the heat exchanger using a combined model-based and data-driven approach of fault diagnosis. A Simulink model of the ACS, that has been designed and validated by an industry partner, has been used for generation of sensor data for various fouling conditions.
Technical Paper

Embedded COTS - A Gateway for New Processors/High Performing Machines to Digital Avionics System Industry

Today's digital avionics systems leverage the use of the Embedded COTS (Commercial Off The Shelf) hardware to fit the need of small form factor, low power, reduced time to market and reduced development time with efficient use of DO-254 for compliance of product. COTS modules are entering in digital avionics systems such as COM (Computer On Module)/SOM (System On Module)/SIP (System In Package) with huge advancement in semiconductor and packaging industry. In today's scenario COTS are very useful for DAL (Development Assurance Level) C and below as the efforts on compliance for DAL A and B are huge. This paper proposes to use these for DAL A and B as well, where one can get enormous benefit on efforts of compliance and time to market. This paper makes an attempt to explain the current scenario of the Embedded COTS usage in Avionics Systems.
Technical Paper

Electromagnetic Compatibility and Interference - Design Methodology, Challenges and Guidelines for Avionics Product and Systems

Avionics industry is moving towards more electric & lightweight aircrafts. Electromagnetic effects becomes significantly challenging as materials starts moving towards composite type. Traditional methods for controlling EMC will not be sufficient. This shift increases the complexity of in-flight hardware elements for EMI/EMC control. This paper discusses the need for EMI/EMC Control and brings out the analysis & applicability of various EMI/EMC standards in aerospace, commercial and industrial electronic products, provides comparative study with respect to levels. The study include various sections of DO-160 and applicable guidelines for controlling EMI/EMC with respect to LRU (Line Replaceable Unit) & wire/cable harnesses. Also presents guidelines with respect to shielding of components, selection of components, grounding schemes, filter topologies and layout considerations.
Technical Paper

DO-254/ED-80 - An Application Guidelines to Redesign/Re-Engineering Airborne Electronic Hardware

Avionics industry is moving towards fly-by wire aircrafts with less reliance on mechanical systems leading to increase in the complexity of in-flight hardware elements. RTCA/DO-254 and EUROCAE ED-80 plays a vital role in the design assurance of airborne electronic hardware. RTCA/ DO-254 and EUROCAE ED-80 are the industry standards for Design Assurance Guidance for Airborne Electronic Hardware. The two different agencies FAA and EU regulate and apply this design assurance guidance to the regulatory law in CFR and EASA CS respectively. This paper discusses the need for DO-254 /ED-80 certification in Aerospace industry, the advantages and benefits to the avionics manufacturers. The paper presents the study made on similarities and differences between DO-254/ED-80.
Technical Paper

A Lightweight Spatio-Temporally Partitioned Multicore Architecture for Concurrent Execution of Safety Critical Workloads

Modern aircraft systems employ numerous processors to achieve system functionality. In particular, engine controls and power distribution subsystems rely heavily on software to provide safety-critical functionality, and are expected to move toward multicore architectures. The computing hardware-layer of avionic systems must be able to execute many concurrent workloads under tight deterministic execution guarantees to meet the safety standards. Single-chip multicores are attractive for safety-critical embedded systems due to their lightweight form factor. However, multicores aggressively share hardware resources, leading to interference that in turn creates non-deterministic execution for multiple concurrent workloads. We propose an approach to remove on-chip interference via a set of methods to spatio-temporally partition shared multicore resources.