Design and Control of Multibody Multirotor for Faster Flight and Manipulation

A novel multibody octorotor UAV is developed to increase the controllability and flight performance of the multirotor UAV. A conventional multirotor is underactuated since only four states for the rigid body dynamics can be controlled independently, although it has a number of rotors than four. Pitch and roll motions are coupled with xy position. Therefore, additional actuators of a camera gimbal are necessary to control the orientation of the camera. In addition, aerodynamic performance, such as flying speed, is not as good as a fixed-wing UAV because an attitude of the multirotor should be changed along with its speed, which causes increasing aerodynamic drag. The multibody multirotor (MBMR) UAV developed in this paper is able to decouple the pitch angle of the multirotor from position control of the main fuselage, which improves controllability as well as aerodynamic performance. Independence of the pitch angle can be achieved by dividing the multirotor to three frames using rotational joints. Control structure and control allocation are designed for the MBMR. Aerodynamic analysis and flight simulation are implemented for validation of the MBMR and control.