AEROBULL: A Center-of-Mass Displacing Aerial Vehicle Enabling Efficient High-Force Interaction

In various industrial sectors, inspection and maintenance tasks using UAV (Unmanned Aerial Vehicle) require substantial force application to ensure effective adherence and stable contact, posing significant challenges to existing solutions. This paper addresses these industrial needs by introducing a novel lightweight aerial platform (3.12kg) designed to exert high pushing forces on non-horizontal surfaces. To increase maneuverability, the proposed platform incorporates tiltable rotors with 5-DoF (Degree of Freedom) actuation. Moreover, it has an innovative shifting-mass mechanism that dynamically adjusts the system's CoM (Center of Mass) during contact-based task execution. A compliant EE (End-Effector) is applied to ensure a smooth interaction with the work surface. We provide a detailed study of the UAV's overall system design, hardware integration of the developed physical prototype, and software architecture of the proposed control algorithm. Physical experiments were conducted to validate the control design and explore the force generation capability of the designed platform via a pushing task. With a total mass of 3.12kg, the UAV exerted a maximum pushing force of above 28N being almost equal to its gravity force. Furthermore, the experiments illustrated the benefits of having displaced CoM by benchmarking with a fixed CoM configuration.

A Center-of-Mass Shifting Aerial Manipulation Platform for Heavy-Tool Handling on Non-Horizontal Surfaces

Aerial vehicles equipped with manipulators can serve contact-based industrial applications, where fundamental tasks like drilling and grinding often necessitate aerial platforms to handle heavy tools. Industrial environments often involve non-horizontal surfaces. Existing aerial manipulation platforms based on multirotors typically feature a fixed CoM (Center of Mass) within the rotor-defined area, leading to a considerable moment arm between the EE (End-Effector) tip and the CoM for operations on such surfaces. Carrying heavy tools at the EE tip of the manipulator with an extended moment arm can lead to system instability and potential damage to the servo actuators used in the manipulator. To tackle this issue, we present a novel aerial vehicle tailored for handling heavy tools on non-horizontal surfaces. In this work, we provide the platform's system design, modeling, and control strategies. This platform can carry heavy manipulators within the rotor-defined area during free flight. During interactions, the manipulator can shift towards the work surface outside the rotor-defined area, resulting in a displaced CoM location with a significantly shorter moment arm. Furthermore, we propose a method for automatically determining the manipulator's position to reach the maximum CoM displacement towards the work surface. Our proposed concepts are validated through simulations that closely capture the developed physical prototype of the platform.