Design and Control of a Fully-Actuated Hexrotor for Aerial Manipulation Applications

This paper addresses the issue of controller complexity for multirotor aerial manipulator (AM) implementation by utilizing a special class of fully actuated hexrotor within the framework of a firmware, which allows standard multirotor actuation modes. Using this platform, manipulator and vehicle dynamics are decoupled, making the airframe inherently more robust than standard multirotor for trajectory tracking in AM applications. Furthermore, its unique design allows for the implementation of modular control strategies. The proposed rotor orientation model makes it possible to decouple the dynamics, allowing full analytical development of the optimal solution. A methodology for analysis, control allocation, and design of this special class of hexrotor is presented, and the implementation of a custom flight stack is demonstrated using a hexrotor prototype in closed-loop flight testing. The flight stack developed is compliant with the open-source ArduPilot Mega (APM) firmware, allowing it to take advantage of all generic multirotor control algorithms. Experimental results are presented to demonstrate feasibility of the system.