Modeling and Control of a Fully-actuated Quadrotor Manipulator with Tiltable Rotors

In this paper, a fully-actuated quadrotor manipulator with four tiltable rotors is introduced. A 2-DOF manipulator is attached to the bottom of the body of quadrotor, which means that the quadrotor manipulator system has 10 actuator inputs. In contrast, the DOF of the quadrotor body and manipulator is 8. The end effector of the quadrotor manipulator is capable of tracking an arbitrary 6-DOF trajectory. In order to control the nonlinear quadrotor manipulator system, a feedback linearization is applied to the system. For the reason that the body of quadrotor is overactuated, the solution to control allocation problem is not unique. To solve the control allocation problem quickly, a pseudoinverse method is adopted. Due to redundancy of the quadrotor manipulator, the number of the solutions to the inverse kinematics is infinite. In this paper, the inverse kinematics problem is solved numerically by using damped least squares method. It's confirmed that the end effector of the quadrotor manipulator can track an arbitrary desired 6-DOF trajectory timely by a simulation.