On e-constraint based methods for the generation of Pareto frontiers

Over the years, a number of methods have been proposed for the generation of uniform and globally optimal Pareto frontiers in multi-objective optimization problems. This has been the case irrespective of the problem definition. The most commonly applied methods are the normal constraint method and the normal boundary intersection method. The former suffers from the deficiency of an uneven Pareto set distribution in the case of vertical (or horizontal) sections in the Pareto frontier, whereas the latter suffers from a sparsely populated Pareto frontier when the optimization problem is numerically demanding (ill-conditioned). The method proposed in this paper, coupled with a simple Pareto filter, addresses these two deficiencies to generate a uniform, globally optimal, well-populated Pareto frontier for any feasible bi-objective optimization problem. A number of examples are provided to demonstrate the performance of the algorithm.peer-reviewe

Towards optimized profile descents at Malta International Airport through revised approach procedures

The work presented in this paper was conducted as part of the CLEAN-FLIGHT project which is financed by the Malta Council for Science and Technology through the National Research and Innovation Programme 2011 (Grant Agreement R&I-2011-021).Traditionally, aircraft descend from cruise level towards the aerodrome in a stepped manner as directed by Air Traffic Control to ensure safe separation between aircraft, particularly in the terminal area. A descent methodology that is now being preferred is that of optimised profile descents (OPD). In OPDs, the aircraft descends from the top-of-descent (TOD) point towards the aerodrome following a smooth, continuous descent profile that is optimal from an operational perspective of choice, until it intersects the final approach glide path such as that of the Instrument Landing System (ILS). OPDs are advantageous because they consume less fuel and generate fewer emissions than their stepped counterparts. This paper presents a proposal of new approach procedures for use in the approaches to Malta International Airport (MIA) that will facilitate the introduction of OPDs. With around 28,000 aircraft movements per annum at MIA, this can be achieved by giving Air Traffic Control Officers (ATCOs) a selection of approach procedures on which to direct in-trail inbound and outbound aircraft without imposing altitude constraints. The discussion includes a study of current procedures, a statistical analysis of historical radar plots, the presentation of the proposed approaches, and a forecast of the potential gains in terms of fuel burn and emissions expected through fast-time simulation.peer-reviewe

A new computational technique for the generation of optimised aircraft trajectories

A new computational technique based on Pseudospectral Discretisation (PSD) and adaptive bisection ε-constraint methods is proposed to solve multi-objective aircraft trajectory optimisation problems formulated as nonlinear optimal control problems. This technique is applicable to a variety of next-generation avionics and Air Traffic Management (ATM) Decision Support Systems (DSS) for strategic and tactical replanning operations. These include the future Flight Management Systems (FMS) and the 4-Dimensional Trajectory (4DT) planning and intent negotiation/validation tools envisaged by SESAR and NextGen for a global implementation. In particular, after describing the PSD method, the adaptive bisection ε-constraint method is presented to allow an efficient solution of problems in which two or multiple performance indices are to be minimized simultaneously. Initial simulation case studies were performed adopting suitable aircraft dynamics models and addressing a classical vertical trajectory optimisation problem with two objectives simultaneously. Subsequently, a more advanced 4DT simulation case study is presented with a focus on representative ATM optimisation objectives in the Terminal Manoeuvring Area (TMA). The simulation results are analysed in-depth and corroborated by flight performance analysis, supporting the validity of the proposed computational techniques.peer-reviewe

A generic framework for multi-parameter optimization of flight trajectories

The project is co-funded by the European Community’s Seventh Framework Programme (FP7/2007-2013) for the Clean Sky Joint Technology Initiative.This paper presents the requirements and design concept of a multi-parameter optimization tool to be used on flight trajectories. The tool, referred to as GATAC, is being developed as part of the EU-funded Clean Sky Joint Technology Initiative (JTI) programme, and a preliminary version is discussed in this paper. The tool has been evaluated and the results obtained confirm the validity of the tool, opening the way for further development. The paper also addresses the architectural design and a number of key features of the tool.peer-reviewe

GATAC - A generic framework for multi-parameter optimization of flight trajectories

Simulations in different scenarios requires the use of various models, the interfacing of which typically requires extensive effort and programming resources that may not be readily available in most industrial and academic environments. This paper discusses the development of GATAC - a generic framework that was developed for simulation and multiparameter optimization purposes allowing users to easily set up a simulation by making use of models developed using different technologies with different interfaces.peer-reviewe

A flexible framework for configurable real-time flight simulators

This paper presents the design and development of a Simulation and Integration Framework for use in research and teaching simulators. The design of the framework facilitates the integration of different simulation models of various formats without the need of software programming skills in a simulation environment. This is achieved through a Graphical User Interface (GUI) allowing the user to easily set up a flight simulator utilizing models programmed in different languages and having different interfaces. The framework allows for dynamic parallel processing over a distributed system providing the capability of concurrent model processing.peer-reviewe

A quasi-real-time ground-based trajectory optimization tool for greener operations

This paper describes the methodology adopted in designing a quasi-real-time ground-based trajectory optimization tool for use by air traffic control officers. The tool is primarily intended for the optimization of aircraft trajectories during the climb and descent phases in which the user can define the trajectory in four dimensions. The optimized trajectories would then contribute to a reduction in fuel burn and emissions. The designed tool takes into account different aircraft types and sub-types through BADA performance and engine coefficients. A simple case study for an approach in Malta International Airport has also been presented to illustrate the use of the tool.peer-reviewe

Multi-objective optimisation of a constrained 2000 km trajectory using genetic algorithms

This paper presents a study whereby a typical 2000 km trajectory flown by an aircraft of the Airbus A320 and Boeing 737 family, is imposed operational constraints such as altitude restrictions and operational speeds, and optimised for the reduction of fuel, nitrous oxides (NOx) and time. The trajectory is divided into two phases, the first encompasses the initial climb following take-off up to 3,000 ft, and it is optimised for NOx and fuel, while the second encompasses the en-route climb starting from 6,000 ft, the cruise phase, and descent to 8,000 ft and it is optimised for fuel and time. The resulting pareto frontiers and the corresponding extremal trajectories are analysed and discussed from an aircraft performance point of view, from which salient conclusions are drawn on the optimal trajectories generated.peer-reviewe

Bi-objective pseudospectral optimal control techniques for aircraft trajectory optimisation

This paper presents the adoption of a number of optimisation techniques to solve aircraft trajectory optimisation problems formulated as optimal control problems. The adaptive bisection εconstraint method is adapted to enable the solution of problems in which two performance indices are to be minimized simultaneously leading to the generation of Pareto frontiers. The techniques are applied to an aircraft trajectory optimisation problem in which a generic model of an Airbus A320 model aircraft is used. The problem involves the generation of a Pareto set of solutions which find a compromise between flight time and fuel consumption for a climb from 35 ft to a cruising level of 35,000 ft in a range of 900 km. The results are then analysed in-depth and corroborated with flight performance theory.peer-reviewe

Design and validation of a detailed aircraft performance model for trajectory optimisation

A key component in flight optimization studies is the aircraft performance model. This must be capable of representing to a high degree of fidelity the performance of the aircraft over its typical flight envelope if meaningful conclusions are to be made from the optimization studies. Flexibility is also required in order to facilitate robust trajectory definition and interoperability with secondary multidisciplinary tools. This paper describes the structure and main features of an Aircraft Performance Model (APM) specifically designed for use within a multi-disciplinary optimization environment. A validation exercise has been carried out against data generated with another aircraft performance model designed using the Base of Aircraft Data coefficients. Climb, cruise and descent phases have been investigated for the comparison. The performance of the aircraft predicted by the two models has been compared and found to compare well, with most cases resulting in less than a 0.5% mean variation between the two models.peer-reviewe