One of the challenges in the design of a sophisticated safety critical control system is to accommodate the ever increasing complex avionic modules while limiting the weight, size and cost of the components as well as improving the safety and reliability of the system. The vision of the FT-SSY avionics group is the design and development of simple, safe, reliable and cost efficient data transmission systems for the safety critical flight control system. As an alternative to the present wire-based system, we are focusing on the successful integration of fiber optic and wireless data transmission technologies. The inherent advantages of these technologies promise flexibility and novelty for the future avionics system.
Main Research Topics
Wireless Data Communication
The replacement of cable-based data-communication systems by means of wireless technologies aims to reduce the cost of manufacturing and maintenance, cable weight resulting in less fuel-consumption and increase the flexibility for adding new functions. However, several challenges arise in terms of safety and reliability due to the unprotected wireless transmission medium. Interferences such as environmental disturbances and intentional interference in the transmission channel can degrade the transmission performance, which might cause failures which severe consequences, especially for safety-critical systems.
The main scope of the group is to develop and assess advanced techniques to overcome these drawbacks. Several methods are investigated to enhance the performance of wireless data-communication for the flight-control system concept, which is depicted in an exemplary and schematic picture in Figure 1. For these implementations, flexible hardware technologies are used, which provide reconfigurable resources, such as Software-Defined Radio (SDR), shown in Figure 2. Moreover, cognitive wireless systems are also one of the research fields of the group as well as burgeoning interest of wireless communication market. The dynamic aspects of cognitive radios are analyzed to improve the safety and reliability of avionic systems. Current projects of the group also focus on system definition and safety assessment by using model-based tools. The safety and reliability aspects of cable-based networks are compared with wireless substitutes to evaluate their performance.
Polymer Optical Fiber Communication
Fly-by-light systems in aircraft gained immense interest during the last few years since the fiber optic based data transmission in telecommunication and automotive industry are matured steadily. Various applications in the aerospace industry benefited from the high data transmission capacity together with improved security, immunity to electromagnetic interferences and higher reliability of fiber optic media. However, the stringent requirements of avionic data networks do not allow the direct mapping of the fiber optic technology as it is. In order to exploit the full advantage of optical media, the avionics group together with the Institut für Hochfrequenztechnik, TU-Braunschweig initiated their research on the prospects of integrating polymer optical fiber (POF) in aircraft data networks. POF with its large core diameter and numerical aperture has acceptable flexibility, relaxed connector tolerance, easy and efficient coupling to high numerical aperture light sources, as well as quick and easy termination procedures. Figure 1 shows the POF link under consideration for the aircraft data network (AFDX, ARINC 825).
The minimum requirements for POF based data transmission for aircraft applications are defined depending of the data transmission rates, and the criticality of the function. Furthermore, the validation of these derived performance requirements projects the deviation which has to be applied to the existing fiber optic military standards. In order to make the assessment of photonic components more stable and reliable for aircraft applications, different test procedures and test setups are derived. These test procedures include performance characterization and harsh environmental measurements methods for fiber, connectors and other link components. Test results are expected to give a clear idea on the practical impacts on the signal carried by the link due to wider and unique operating conditions of the aircraft system.
KASI – CoNtESSA