Problema general

From the start of this project it was acknowledged that a visualisation of UCAV behaviour must be realised. As described in the problem statement, the MVP should ideally be developed through low cost and even open source software. This initiated a preliminary research in suitable software for the realisation of the MVP. The software packs are existing applications in the aerospace sector or programs that offer room for 3D simulation and development. The software packs that are evaluated are summed up below:

Stage

One of the two in house environments of the NLR is Stage. Stage is used in the NLR to work with CGFs for the simulation of combat scenarios. The F4S mentioned in the previous chapter operates with the Stage software. The Stage environment is not portable and working in Stage comes with relatively large technical barriers (for interns) making rapid prototyping challenging. Furthermore, the ease of implementation of different, externally developed modules, models or software is relatively due to the fact that Stage is off-liimhe software however accurately represents air combat scenario dynamics and the aerodynamics models are furthermore accurate. The F4S is aimed to be recognisable for aircraft pilots, which makes the ease of use for the pilot or operator high.

LWACS

LWACS, short for Light Weight Air Combat Simulator, is a simulation program originally developed by an employee of the NLR, to simulate a large amount of air combat scenarios. This program was developed for a machine learning technique that can train an artificial intelligence agent into selecting the right combat manoeuvre in each combat situation. There are no software licenses bounded to this software and it is fully programmed in Java and thus to a large extent adaptable by the user. Since its focus lies on housing the machine learning technique there are no accurate flight dynamics models included in this software. A primitive visualisation of the battlefield and the aircraft is however included. X-Plane

X-Plane is a flight simulator that includes a broad range of aircraft models, from commercial aircraft to military aircraft. It furthermore possesses scenery models which are modelled after real life data of the earth’s surface. X-plane comes in a desktop version on mac OS, Windows and Linux. The mobile version is available for Android, iOS and webOS. X-Plane uses a unique aerodynamic model which named the “blade element theory” [76]. In comparison; a number of different flight simulators utilise empirical flight data about various aircraft to calculate or determine the aerodynamic forces on the model in the simulation. Depending on the amount of data that is available for a certain aircraft, well performing models can be realised in software. X-Plane, on the contrary, breaks an aircraft model into separate parts and calculates the aerodynamic forces for each individual part (which consequently can be broken into smaller sub-parts). In a later stage, all the forces on the different sections are combined resulting in accurate representation of forces on the aircraft model which in turn leads to realistic flight behaviour. Users of X-Plane are encouraged to design their own aircraft, and design software is included with the program. This has created an active community of users who use the simulator for a variety of purposes. X-Plane has possibilities for the customisation and creation of aircraft models by its users and the software comes with a plugin interface to create new features. Because of the sophisticated flight dynamics model, X-Plane has an option for FAA certification to allow for training of pilots with aid of the software [77].

Microsoft Flight Simulator

Microsoft Flight Simulator consists of a series of flight simulators especially designed to work with Windows operating systems. The long history and popularity of this flight simulator have led to several add-on packages that allow for the tweaking and development of the flight simulator by third party agents. The most editable parts of the simulator are the scenery and the aircraft models. A user can cus- tomise cockpit layout, external models, sounds and scenery through simple programs such as notepad. The flight dynamics model is stored in the form of a large amount of parameters in one single file. All these individual parameters define the aircraft’s flight behaviour and can easily be modified.

Unity 3D

Unity is a cross-platform game engine for developing video games for PC, consoles, mobile devices and websites. Unity focuses on portability and currently has over 20 target platforms on which it can operate. The program is free for personal use, but comes with a license for commercial use. The program is suitable for rapid prototyping and developing simulations of all sort. The program is user friendly and game dynamics can be programmed with the aid of the C# scripts. The integrated graphics engine allow for realistic graphics. In the case of aeronautical applications it may offer room for realistic flight dynamics models, but these have to be programmed by the user, which can be exceptionally complex. In contrast, the user can tweak and modify all parameters within the program, making it suitable for building systems or simulations from scratch.

FlightGear Flight Simulator is a free, open source (under the GNU General Public License) multi- platform flight simulator developed originally by David Murr. There are versions available for multiple operating systems including Windows, MacOSX and Linux. Since it is an open source flight simulator, the source code is made available through a repository and programmers with knowledge of C and C++ programming language can develop and alter core functionalities of the flight simulator itself. The flight dynamics are, in a similar fashion to X-Plane, scripted in .xml files with a large amount of parameters denoting the flight behaviour. FlightGear can be fully transformed towards individual needs and this has led to the fact that FlightGear is widely used for academic and professional research [78] [79] [80]. FlightGear can for example be interfaced and controlled with the aid of MatLab and Simulink [81]. Consequently, the fact that FlightGear is freeware makes it suitable for researchers with a small budget. FlightGear lives from a large community that develops and maintain the software. There is a dedicated wiki available on the organisation and functions of FlightGear along with tutorials for programmers.