Generalized Modeling of Overactuated Aerial Manipulators: Theory and Application

Abstract

This paper proposes a unified dynamic model for aerial robots which encompasses all known actuation principles including tilting propellers and centroid variation methods such as moving masses or robotic manipulators. Of course, one can envision a wide variety of vehicles, all with different combinations of actuation principles. Therefore, a generalized modeling methodology for such vehicles is developed and presented in this paper. The modeling approach is verified through a comparative analysis of MATLAB simulations and laboratory experiments with a tilting propeller aerial manipulator vehicle, named Toucan. Finally, in order to fully explore and exploit the capabilities of the designed aerial manipulator, contact-based experiments with force tracking are performed using the proposed adaptive impedance controller. To demonstrate the advantages of such a vehicle, the adaptive impedance control method is used to generate position and orientation commands and achieve end-effector force tracking on a flat surface while the aerial manipulator maintains a neutral attitude. This greatly increases the stability and safety of contact-based operations, as the vehicle does not require changes in attitude to meet the force requirements. Note to Practitioners—This paper was motivated by a surge of different configurations of aerial vehicles emerging. A modeling method for generalized aerial vehicles is presented to determine which vehicle configurations are best suited for a specific application. This approach considers vehicles with additional actuators such as tilting propellers and robotic manipulators. The effectiveness of the proposed method is validated on a custom-designed quadrotor with four moving masses emulating centroid variation of a generic robotic manipulator. This original design is augmented with tilting propellers, yielding a truly generalized experimental platform. The generalized modeling algorithm and the experimental platform are tested both in free flight and in a scenario that demonstrates applying the desired force to a flat surface. Overall, we showcase the proposed generalized modeling is a useful tool for the rapid prototyping and design of aerial manipulators, paving the way for more advanced and capable systems in the future. With this approach, practitioners can gain a better understanding of the potential and limitations of their aerial vehicles, and ultimately improve their performance and effectiveness in specific applications.