Modeling and Control of a Class of Modular Aerial Robots Combining Under Actuated and Fully Actuated Behavior

The design, modeling, and control of a new class of modular aerial robots, obtained by rigidly interconnecting a number of ducted-fan aircraft, are presented in this paper. A remarkable feature of the proposed class of vehicles is the fact that different dynamical behaviors, ranging from underactuated to fully actuated, can be obtained by adopting a suitable interconnection topology. To exploit this variety of actuation scenarios, a combination of control allocation and feedback control algorithms is proposed. The control allocation module exploits actuator redundancy by identifying the directions in the input space that affect the vehicle dynamics, whereas the feedback controller provides stabilization of the actuated degrees of freedom over desired attitude and position trajectories. A physical prototype, realized by interconnecting two ducted-fan vehicles, is employed to experimentally demonstrate the effectiveness of the proposed methodology.