Loon Copter: Implementation of a hybrid unmanned aquatic–aerial quadcopter with active buoyancy control

Abstract

Aquatic-aerial unmanned vehicles recently became the focus of many researchers due to their various possible applications. Achieving a fully operational vehicle that is capable of aerial, water-surface and underwater operations is a significant challenge considering the vehicle's air-water-air transition, propulsion system and stability underwater. We present in this paper an unconventional unmanned hybrid aquatic-aerial quadcopter with active buoyancy control that is capable of aerial flight and water-surface operation, as well as subaquatic diving. We report on the first successful prototype of the vehicle, named the Loon Copter, to provide initial evaluation results of its performance in both mediums. The Loon Copter uses a single set of motors and propellers for both air and underwater maneuvering. It utilizes a ballast system to control vehicle buoyancy and depth underwater, as well as to perform seamless air-to-water and water-to-air transitions. A closed loop control algorithm is utilized for the vehicle's aerial and water-surface stability and maneuver while an open loop control algorithm is used for underwater maneuver. The experimental results show a fully operational prototype with six degrees of freedom underwater, stable flight, operation capabilities on water surface, and agile maneuvering underwater.

Attitude and Altitude Control of Unmanned Aerial-Underwater Vehicle Based on Incremental Nonlinear Dynamic Inversion

“…However, due to the huge differences in the physical properties between air and water, it is a great challenge to design a vehicle capable of both air flight and underwater navigation, especially concerning the power system, configuration, dynamics, and control. According to the existing literature, fixed-wing [5][6][7] , variable-swept wing [8,9] , flapping wing [10] , and multi-rotor systems [11][12][13][14][15][16][17][18] for aerial and underwater navigation have been proposed. Paulo [11] et al evaluated the controllability, payload/vehicle volume, environment switch-over, and structure modification of aerial and underwater vehicles.…”

“…For the development of an UAUV prototype with a multi-rotor configuration, Paulo [11] proposed a hybrid unmanned aerial-underwater vehicle with a quad-rotor configuration to verify the feasibility of water-air crossing motion. Hamzeh [12,13] demonstrated the feasibility of single-layer propellers to achieve both air and underwater motion, and designed a prototype named LOON COPTER incorporated with an active buoyancy adjustment device.…”

Global optimization for Cross-domain aircraft based on Kriging model and par-ticle swarm optimization algorithm

“…Another typical design thought is based on multi-rotor technology, which has been widely utilized in Unmanned Aerial Vehicles (UAVs) and Remotely Operated Vehicles (ROVs). Alzu'bi et al in Oakland University improved traditional quadrotors with additional water pumps for buoyancy and depth control underwater [ 10,11]. Based on X-4 configuration, Maia et al in Rutgers University utilized dual air rotors in each vehicle-arm with a column gap between the top and bottom motors, which highly improved effective lift force [11][12][13][14].…”

“…Alzu'bi et al in Oakland University improved traditional quadrotors with additional water pumps for buoyancy and depth control underwater [ 10,11]. Based on X-4 configuration, Maia et al in Rutgers University utilized dual air rotors in each vehicle-arm with a column gap between the top and bottom motors, which highly improved effective lift force [11][12][13][14]. Brazilian researchers Drews et al changed bottom 4 air rotors into water ones in order to obtain better underwater performance [ 15,16].…”

MEDUSA: A Multi-Environment Dual-Robot for Underwater Sample Acquisition

“…Due to their vertical take-off and landing capability, they can land on water and sink, without requiring added design features. Several multirotors have achieved a degree of aerial-aquatic mobility [11], [12], [13], however these vehicles have a short flight time and range when compared to fixed-wing solutions. While underwater propulsion can be achieved using the same propellers as for flight, this comes at a performance cost and does not always lead to effective locomotion.…”