Flight Simulation Laboratory

The static flight simulator JFS²

JFS² was designed as a simulator for research purposes. Its remit ranges from stability tests for new aircraft which are still in the planning stage and simulations of the latest fly-by-wire control systems for small aircraft through to the development of autonomous control systems for unmanned aerial vehicles (UAVs). State-of-the-art software technologies and modern, three-channel external visual systems have been combined into a high-tech simulator of a most challenging design.

Flight dynamics equations and control algorithms are computed using the numerical solution of differential equations to generate precision, state-of-the-art models of aircraft physics. The flight dynamics is computed using MATLAB/Simulink, differentiating this simulator from those used in computer games. These simulation programs are not based on real flight dynamics computations; a commercial flight simulation program (X-Plane 10) is only used to generate the graphic display of the exterior view.

Command inputs given by the pilot and co-pilot using the primary controls – side-stick, pedals and throttle – are sent to the simulation program via the CAN data bus. The simulation program then computes the new flight status based on the ambient conditions and command inputs. The position and attitude data are then transferred to the vision calculator, where the graphic display of the exterior view is computed. A portion of the flight status data, such as altitude and speed, is returned to the cockpit for presentation on the instruments and displays. A console also provides the option of adding external input into the simulation, for example to simulate engine and instrument failure, or to alter the weather conditions.

Application in teaching and research

The simulator is primarily designed for use as a research simulator for aviation teaching and applied research. Students can immediately apply their theoretical knowledge of flight dynamics and control technologies and test the feasibility of their newly developed algorithms (basic controller, autopilot, path controller, etc.).

The simulator can also be used in industrial research, for example to examine the performance of new aircraft even before a prototype is built. The simulation allows adverse flight characteristics to be identified and the relevant parameters optimised until the desired performance is achieved.

The full-motion simulator JFSM

In contrast to the JFS², the smaller JFSM is designed as a full-motion research simulator. The motion platform is based on the mechanical principle of a Gough-Stewart platform and can execute movement in six degrees of freedom: simultaneous linear movements in three directions and rotations around three spatial axes are possible. The movements of the cockpit are computed using motion cueing algorithms which provide the pilot with the most realistic flight sensations possible. These sensations are also enhanced through optical and acoustic isolation from the outside world.

On this simulator the input values for computing the movements can either be taken from commercial flight simulation programs, or from simulation models programmed by the Institute. The computed movements of the platform are converted into length changes for each linear actuator. All six cylinders are synchronised in order to effect the desired movement of the platform as a whole – this synchronisation is achieved using real-time capable software and communication via a real-time capable data bus (EtherCat).

Broad range of potential applications

With its modular construction consisting of the moving platform and mounted cockpit, the JFSM can be used for a broad range of applications over and above its role as a flight simulator: for example, structures for JXP-V landing gear can be subjected to stress tests, or acceleration cycles simulated to determine fluid distribution in fuel tanks. With its high degree of positional precision in the sub-millimetre range, the platform can be used to test positioning sensors or validate control algorithms using hardware-in-the-loop simulations.

Using the flight simulator with the mounted cockpit allows a variety of flight scenarios to be simulated for various models of aircraft. The cockpit design incorporates generic controls such as thrust lever, side-stick and pedals, and flight-specific displays can be shown on the touch panel installed on the dashboard.

The JFSM is explicitly used as a research simulator. With completely modular programming of the entire control software, individual modules can be exchanged at will for the purposes of teaching and research. This allows the parameters to be adapted, with students flying and experiencing the impact of these changes in practice.