Aerial tool operation system using quadrotors as Rotating Thrust Generators

We propose a new aerial tool operation system consisting of multiple quadrotors connected to a tool by spherical joints to perform tool operation tasks. We model the system and show that the attitude dynamics of each quadrotor is decoupled from the tool dynamics, so that we can consider the quadrotors as thrusters and control the tool by adjusting the orientation and magnitude of these thrusters. We also show that the 6-DOF tool dynamics could be under-actuated or fully-actuated, depending on the number of quadrotors attached to the tool and the geometric configuration of their attachments. We then design control laws for the tool-tip position/orientation tracking of the (under-actuated) tool system with two quadrotors and the (fully-actuated) tool system with three quadrotors. We use Lyapunov approach to find the desired thrust command for each quadrotor while also taking into account the spherical joint limits in a form of constrained optimization. Simulation and implementation results are performed to support the theory.