Decoupled Controllers for Mobile Manipulation with Aerial Robots : Design, Implementation and Test

Abstract: This work considers an aerial robot system composed of an Unmanned Aerial Vehicle (UAV) and a rigid manipulator, to be employed in mobile manipulation tasks. The strategy adopted for accomplishing the aerial manipulation is a decomposition of the previous system in two decoupled subsystems: one concerning the center of mass of the aerial robot; and another concerning the manipulator's orientation. Two Lyapunov-based controllers are developed, using a back stepping procedure, for solving the trajectory tracking problems related to the two subsystems. In the controller design, three inputs are assumed available: a translational acceleration along a body direction of the UAV; an angular velocity vector of this body rotation; and, finally, a torque at the spherical, or revolute, joint connecting the UAV and the manipulator. The first two inputs are generated by the same controller in order to drive the center of mass on a desired trajectory; while a second controller drives, through the third input, the manipulator's orientation to track a desired orientation. Formal stability proofs are provided that guarantee asymptotic trajectory tracking. Finally, the proposed control strategy is experimentally tested and validated.