An Agile, Coaxial, Omnidirectional Rotor Module: On the Development of Hybrid, All Terrain Robotic Rotorcrafts

Abstract

Unmanned Aerial Vehicles (UAV) are typically based on rotorcraft designs and have been extensively used to perform mechanical interaction tasks that could involve inspection as well as search-and-rescue operations in critical unstructured and dynamic environments. UAV based aerial manipulation has also received an increased interest and it has attracted considerable research effort in the robotics community. However, the state-of-the-art control approaches that are being applied to traditional underactuated UAVs show critical stability issues during the execution of manipulation tasks. This is due to the fact that these tasks require the exertion of significant forces with respect to the vehicle-weight ratio. Designs of fully-actuated and overactuated systems show better suitability for such tasks but are still specific to certain functions and tasks, lacking the needed agility and flexibility. In this paper, we propose a novel design of an agile, coaxial, omnidirectional rotor module that can move and exert forces in all directions, without limitations on orientation and wiring. This independent rotor unit presents high mobility and maneuverability, high fight autonomy, and offers high potential for all terrain robotic manipulation applications. In this work, the proposed rotor module has been employed to develop an unconventional, hybrid, all terrain robotic rotorcraft that can act both as a drone and as a mobile robot.