Optimizing Endurance and Stability of a Modular UAV Design

Abstract

This paper presents the stability-integrated design of a modular quadrotor (QR) unmanned aerial vehicle (UAV) that comprises four rotor ducts attached pairwise on a rectangular fuselage. Design optimization is performed, by varying the fuselage dimensions, rotor duct spacing, forward flight angle, and number of batteries, with the objective to maximize the round-trip distance travelled by the UAV subject to stability constraints. The latter is defined in terms of settling time. The design framework comprises simplified aerodynamic models, a QR dynamics model (formulated to suit an asymmetric QR design, as opposed to typical X designs), a PD control system implemented in Simulink, and integration with a CAD modeling software (for in-situ mass and inertia computations). Op- timizations are performed using a genetic algorithm. For the defined mission envelop, the QR UAV accomplishes a roundtrip distance coverage of 29 km, with a settling time of 6.9 s, where optimum designs are found to favor more symmetric rotor spacing in the XY plane. Further parametric studies provide insights into the sensitivity of the QR performance to forward flight angle and number of batteries.