Modelling the dynamics of an unmanned aircraft using a graphical simulation tool

Abstract: Complex systems can be modelled using graphical tools such as Simulink. Here, the equations of motion in combination with the necessary data were modelled using Simulink to describe and analyze the unmanned Predator C Avenger. The aerodynamic data was obtained from the potential 　ow solver dwfs (dry water 　ow solver). The Simulink model is initially in steady state, disturbances are then added to investigate the 　ying qualities of the aircraft both in the longitudinal and lateral direction. The modes calculated from the model are compared to the modes produced from the linearized matrices containing the aerodynamic derivatives. The other task for the Simulink model is for some of its subsystems to be integrated with the simulation program ARES, which is used at Saab. The Simulink subsystems are converted into C code and are built into ARES. The rst expected result is that the modes from the linearized model should indicate the values of the modes from the Simulink model. The largest dierence - which regards the spiral mode - was about 24% and assumed acceptable as the approximative solution for this mode is considered poor [4]. The other dierences were at most about 15%. The second expected result is that the outputs from simulating the complete model using Simulink should match the outputs obtained from simulating through ARES connected to the Simulink subsystems. It was the discovered that the obtained results - which are the values of the longitudinal trim parameters and the modes - from Simulink match almost exactly the results from ARES with some few deviations. The trim results had a maximum difference of about 6% and the values of the modes had a maximum dierence of about 10% and also assumed acceptable.