The University of Sheffield
Rolls-Royce University Technology Centre (UTC)

Wireless Interconnectivity and Control of Active Systems - WICAS

The aircraft industry is seeking to respond to environmental concerns by developing technologies that will allow sustained air travel growth whilst minimising overall carbon footprint. Active flow control, achieved through local modulation of aircraft skin surfaces, offers great potential for significantly reducing drag and the related fuel consumption and emissions. Implementing this requires thousands of sensor/controller/actuator systems to be embedded across the aircraft wings and fuselage to create an 'Active Aircraft'. However, the scale of such a smart skin friction reduction system poses a huge challenge in terms of interconnectivity, maintenance and fault-tolerance.
The WICAS concept addresses this by providing a wireless network solution that is capable of interconnecting and enabling such a large number of components whilst providing communication to other airframe systems. This research brings together new ideas in fault-tolerance and condition monitoring, wireless network control systems and wireless networks to create an advanced 'nervous system' for the active aircraft.

Principal Investigator

  • Professor Haydn Thompson

Other Investigators

This research is conducted by the University of Sheffield in collaboration with ECIT Queens University Belfast and supported by Grant Number EP/F004834/1 from the Engineering and Physical Research Council in the UK and through contributions from Airbus S.A.S.
EPSRC and Airbus logos

Project Overview

The aircraft industry is constantly seeking technologies that will enable strict emissions and efficiency targets to be met, allowing sustained air travel growth whilst having zero additional environmental impact. The aim is to achieve a 50% reduction in both fuel consumption and CO2 emissions to meet strict targets by 2020. Leading manufacturers such as Airbus are investing in the development of technologies that will support the concept of the Active Aircraft where active aerodynamic flow control will reduce drag significantly.
A significant increase in fuel efficiency can be expected with successful drag reduction via active control of smart skin friction systems. This will bring a step change benefit not only to aircraft, but any flying vehicle. However, a practical active skin system would require between hundreds to thousands of sensors embedded across aircraft surfaces. At this scale, wireless connectivity can offer significant advantages in increased reliability, reduced complexity and reduced weight. It will eliminate a significant amount of cabling normally required and will allow traversal of corrosive environments. However, to maximise these advantages and justify development cost, it is necessary to consider the possibility of integrating other existing aircraft systems such as health monitoring, aircraft surface actuation, structural health monitoring, anti-icing etc. in this wireless network strategy.
Airbus A350

Active Flow Control

Boundary layer separation results in significant energy losses due to flow unsteadiness and reduced effectiveness of aerodynamic flow devices. Active flow control achieved through local modulation of aircraft skin surfaces will offer great potential for significantly reducing profile drag, the largest component of overall drag. Traditional, passive flow control technologies such as vortex generators have, in the past, been used to control boundary layer separation to some limited extent. Whilst preferred for their simplicity and fail-safe nature, they are generally limited in their effect outside of their narrow operating range and often contribute to increased drag at non-ideal conditions such as high-speed cruise. Suppression or manipulation via active flow control devices is easily carried out but this usually entails energy-consumption where, in most cases, the energy loss exceeds any potential savings. Here, the challenge is to achieve the desired effect in a dependable manner whilst minimising energy expenditure.

Wireless Networked Control System

Implementing the Active Aircraft will require a reliable, highly fault tolerant network of active skin friction reduction components. This network will constitute of anywhere between hundreds to thousands of sensors, controllers and actuator systems (smart skin patches) that will be embedded across the aircraft wings and fuselage. However, the scale of such a system poses a huge challenge in terms of interconnectivity, maintenance and fault-tolerance. Wireless networking will remove the need for complex, heavy, fixed and replicated wiring looms normally required to implement duplex or triple redundancy. With wireless connectivity, it will no longer be necessary to have a totally redundant network to allow reconfiguration.
The work carried out in this programme seeks to address this by providing a wireless network solution that is capable of interconnecting and enabling such a large number of components whilst providing communication to other airframe systems. The development of this “nervous system” will seek to address the quality-of-service (QoS) requirements and the safety critical nature of the system performance in a manner that will enable air-worthiness certification of the resulting networking system.

Fault Tolerance and Health Monitoring

An active skin system, like any other complex aircraft system, will require adequate condition monitoring in order to ensure flight safety and to optimise maintenance schedules. In typical aircraft monitoring systems, pilot displays usually indicate engine and airframe status through vital information such as speeds, pressure ratios, gas temperatures, vibration, load, etc. In addition to these crucial parameters, the status of vital electrical and electronic systems is constantly monitored during pre-flight checks and during in-flight operation to detect any anomalies. Knowledgeable use of these parameters can become early indicators to prevent costly component damage and/or catastrophic failure, and thus help to avoid any undesirable incidents and to reduce the cost of maintaining the aircraft. Although a demanding task, aircraft Equipment Health Monitoring (EHM) systems have achieved much success over the last two decades and have become increasingly mandatory today in line with advances in aircraft design and computing technologies.

Aircraft Health Map

The external surfaces of the aircraft or aircraft skin can be represented by generating a digital real-time health map of the aircraft skin. This health map would provide the key status information of the active skin system and indicate the location and severity of any occurring fault condition. Using this information, it will then be possible to calculate the performance of the system in terms of the reduction in skin friction for a given aircraft. This can then be translated into a prediction of the fuel burn over the course of the planned flight. This key information will be invaluable for optimising fuel planning policies to achieve ultimate efficiency. From a wider aircraft health monitoring perspective, an aircraft health map may also be used to better understand and optimise on strategies as the aircraft ages.
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