Modeling and simulation of a VTOL UAV for landing gear performance evaluation

A multibody dynamics model of a Vertical Take-off and Landing (VTOL) Unmanned Aerial Vehicle (UAV) is presented in this study. The scope of the project was to investigate a lightweight landing gear which has a stable and robust landing performance. Two original designs of the landing gear for the module of interest have been modeled and analyzed in this study. Two new designs have also been developed, modeled, and analyzed. A limited analysis of the forces that occur in the legs/struts has also been performed, to account for possible failure of the members due to buckling. The model incorporates a sloped surface of deformable terrain for stability analysis of the landing scenarios, and unilateral constraints to model the ground reaction forces upon contact. The lift forces on the UAV are modeled as mathematical relations dependent on the speed of the ducted fan to enable the variation of the impact velocities and the different landing scenarios. The simulations conducted illustrate that initial conditions at landing have a big impact on the stability of the module. The two new designs account for the worst possible scenario, and; for the material properties given, end with a larger weight than the one of the original design with three legs and a ring. Simulation data from several landing scenarios are presented in this paper, with analysis of the difference in performance among the different designs.