Expanding the Mission Capabilities of a Quadrotor Biplane Tail-sitter with Morphing Winglets

摘要

Multi-mode air vehicles with hover and high cruise speed capabilities can meet a wide range of mission requirements but are limited in their performance in either mode due to the design compromises that come from operating across a wide speed range. This paper describes and evaluates mission-planning strategies for a quadrotor biplane tail-sitter vehicle with a folding winglet system. The winglets offer two configurations that improve aerodynamic efficiency at different airspeeds at the cost of increased airframe mass. Flight data from a prototype vehicle developed at the University of Maryland is used to form an empirical model for power consumption in the two modes. Autonomous flight planning profiles designed to leverage these improvements in aerodynamic performance are implemented in simulation for three representative scenarios. Homogenous teams of morphing-capable vehicles are used in a search and rescue mission, a counter-poaching pursuit-evasion scenario, and in a perimeter defense application. Statistics are gathered from simulated tests with randomly generated objectives to assess mission performance. Current results show that when operated with the same deployment strategies, quadrotor biplane teams enjoy improvements in target acquisition speed and energy consumption over conventional rotorcraft platforms due to their improved aerodynamic efficiency in cruise. Quadrotor biplanes that are able to reconfigure in flight enjoy only modest improvements compared to a fixed box configuration in a search-and-rescue role, and a more significant improvement in a counter-poaching mission. Wing morphing offers more significant advantages in a perimeter defense scenario that requires a wider range of flight speeds; Simulation results show that in this capacity, the morphing elements can offer the operational effectiveness of a high-speed platform along with the improved efficiency enjoyed by a dedicated low-speed wing configuration. In the base defense trials simulated, this translated to a larger defendable perimeter with the same number of vehicles, power savings that allow a bigger team to be fielded for the same power, or the same mission effectiveness of having one less intruder attacking the perimeter.