Design and Implementation of a Thrust-Vectored Unmanned Tail-Sitter with Reconfigurable Wings

Abstract

In this paper, we present the development of a reconfigurable hybrid unmanned aerial vehicle (UAV): U-Lion [Ang et al., 11th IEEE Int. Conf. Control Automation (ICCA), pp. 750-755]. U-Lion is a small-scale UAV that is capable of vertical takeoff and landing (VTOL) and fixedwing Cruise modes through its unique mechanical design. Mainly built with carbon fiber and expanded polyolefin (EPO) foam, U-Lion is equipped with an array of avionic components which enable stable control of the UAV both in VTOL and Cruise modes. It was employed by the National University of Singapore (NUS) Unmanned System Research Group to participate in the 2013 UAV Grand Prix (UAVGP) competition held in Beijing, China. Its design adopts a reconfigurable wing and a tail-sitter structure, which combines the advantages of a fixed-wing plane and a rotor helicopter effectively. U-Lion could transit from vertical takeoff to a hovering stage before flying in Cruise mode to realize efficient long duration flight. The propulsion of U-Lion comes from a self-fabricated contra-rotating motor fixed on a gimbal mechanism which can change the direction of the motor for the required thrust. This thrust-vectored propulsion system primarily provides control in the VTOL mode but also enhances flight capabilities in Cruise mode. The maximum thrust provided by the motor can be as high as 40 N and it provides six degree of motion controls in VTOL mode. U-Lion has a few special internal designs to empower its capabilities: (1) Reconfigurable wings allow the U-Lion to adapt to different flying modes. (2) Adaptive center of gravity (CG) by adjusting the battery position to fulfill the different requirements of CG for VTOL mode and Cruise mode. (3) Unique contra-rotating thrust-vectored propulsion system. The detailed design and implementation procedure have been presented in this paper along with our computational fluid dynamics (CFD) simulation results, real flight tests and competition performance.

Research on the Effect Characteristics of Free-Tail Layout Parameters on Tail-Sitter VTOL UAVs

“…Despite significant research efforts dedicated to the flight mechanics and control of tail-sitter VTOL UAVs since their inception in 1944, comparatively little attention has been paid to their takeoff/landing procedures. This paper presents a comprehensive review of the structural configurations of various tail-sitter VTOL UAV designs, focusing on the tailless wing layout adopted by the widely recognized "Google wing" [5]. This layout integrates the vertical tail and fuselage into a single structure to reduce the center of gravity and cruise aerodynamic drag.…”

The hybrid bio-inspired aerial vehicle: Concept and SIMSCAPE flight simulation

“…There have been some types of wings' combinations and configurations in both of the academic research and industrial applications of UAVs. According to the available literatures, heretofore, the hybrid UAVs were all designed based on the fixed wings and rotors without exception [1], [2], [3], [4]. The above representative Hybrid UAVs are differ due to whether the rotors and wings tilted or fixed during their flight mode conversions.…”