Period: February 2007 - February 2010

Project chair: Anders Hansson (Linköping University)

Participants: ONERA, Linköping University (Sweden), DLR (Germany), FOI (Sweden), Universita degli studi di Siena (Italy), AIRBUS France

Project overview: Before an aircraft can be tested in flight, it has to be proven to the authorities that the flight control system is safe and reliable, i.e. it has to go through a certification and qualification process. Currently significant time and money is spent by the aeronautical industry on this task. An important part of the certification and qualification process is the clearance of flight control laws (CFCL). The overall objective of this project is to develop and apply optimisation techniques to CFCL in order to improve efficiency and reliability of the certification and qualification process. The application of an optimisation-based approach relies on clearance criteria derived from the certification and qualification requirements. To evaluate these criteria different types of models of the aircraft are employed, which usually both serve for clearance as well as for control law design purposes. The development of different models and of suitable clearance criteria are therefore also objectives of the project. Because of wider applicability optimisation-based CFCL will open up the possibility to design innovative aircraft that today are out of the application field of classical clearance tools. Optimisation-based CFCL will not only increase safety but it will also simplify the whole certification and qualification process, thus reduce costs. The speedup achieved by using the new optimisation-based approach will also support rapid modelling and prototyping and reduce "time to market".

Web site: http://er-projects.gf.liu.se/~COFCLUO

Publication: Andras Varga, Anders Hansson and Guilhem Puyou (Eds). Optimization based clearance of flight control laws. Lecture Notes in Control and Information Sciences, vol. xxx, Springer-Verlag, 2011.

Period: September 2004 - October 2007

Project chair: Martin Hagström (Swedish Defence Research Agency)

Participants: ONERA, FOI (Sweden), DLR (Germany), NLR (Netherlands), University of Bristol (UK), University of Leicester (UK), DeMontfort University (UK), University of Liverpool (UK), AIRBUS France, EADS Military Aircraft (Germany), Saab (Sweden)

Title: Nonlinear Analysis and Synthesis Techniques for Aircraft Control (NASTAC)

Project overview: Despite many significant advances in the theory of nonlinear control in recent years, the majority of control laws implemented in the European aerospace industry are still designed and analysed using predominantly linear techniques applied to linearised models of the aircrafts' dynamics. Given the continuous increase in the complexity of aircraft control laws, and the corresponding increase in the demands on their performance and reliability, industrial control law designers are highly motivated to explore the applicability of new and more powerful methods for design and analysis. The successful application of nonlinear control techniques to aircraft control problems indeed offers the prospect of improvements in several different areas. Firstly, there is the possibility of improving design and analysis criteria to more fully reflect the nonlinear nature of the dynamics of the aircraft. Secondly, the time and effort required on the part of designers to meet demanding specifications on aircraft performance and handling could be reduced. Thirdly, nonlinear analysis techniques could potentially reduce the time and resources required to clear flight control laws, and help to bridge the gap between design, analysis and final flight clearance. The above considerations motivated the three-year research effort organised by the Group for Aeronautical Research and Technology in EURope. The overall objective of the Action Group was to explore new nonlinear design and analysis methods that have the potential to reduce the time and cost involved with control law development for new aerospace vehicles, while simultaneously increasing the performance, reliability and safety of the resulting controller. This objective was to be achieved by investigating the full potential of nonlinear design and analysis methods on demanding benchmarks.

Publication: Declan Bates and Martin Hagström (Eds). Nonlinear analysis and synthesis techniques for aircraft control. Lecture Notes in Control and Information Sciences, vol. 365, Springer-Verlag, 2007.