PhD defence by Tong Hui

Abstract

With the growing interest in using aerial robots for contact-based industrial applications to enhance labor safety and reduce costs, the development of aerial systems with physical interaction capabilities has significantly advanced over the past decades. Two critical aspects of evaluating aerial robots’ physical interaction capabilities are their wrench generation ability and contact interface handling.

While various aerial platforms have been introduced to enhance wrench generation compared to underactuated Commercial-Off-The-Shelf (COTS) multirotors, maximizing the potential of COTS multirotors in aerial applications remains limited. Additionally, although substantial force generation is often required for industrial tasks, existing approaches to achieving high-force interactions with aerial robots face practical limitations.

In terms of contact interface handling, challenges persist in modeling and controlling interactions, particularly under real-world conditions and with the increased complexity of advanced manipulation tasks. This thesis addresses these challenges to further improve the physical interaction capabilities of aerial robots. It introduces a framework to identify the limitations of underactuated COTS-based aerial manipulators and ensures their safe utilization in industrial environments.

A novel aerial vehicle design with dynamically adjustable Center of Mass (CoM) locations is presented to tackle the high-force interaction problem, enabling the system to exert interaction forces comparable to its gravitational force.

To address sliding tasks with active wheels under real-world contact conditions, the thesis investigates friction modeling, wheel actuation limits, and the control constraints of the aerial platform. This comprehensive study aims to ensure successful task execution while considering the practical challenges encountered during development.

The handling of passive End-Effector (EE)s with multiple contact points is further investigated through a static pushing task and a push-and-slide task.

For the former, a modification of the baseline controller with reduced attitude control stiffness is proposed to achieve stable contact. For the latter, both hardware and control solutions are developed to provide more reliable task performance.

The proposed methods and concepts are validated through extensive experiments and simulations. The thesis concludes with a comprehensive discussion of the challenges encountered, key lessons learned, and perspectives on addressing physical interaction problems with aerial robots. By combining theoretical insights with practical solutions, this work aims to advance the field of aerial manipulation for industrial applications.

Supervisors

• Main supervisor: Associate Professor Matteo Fumagalli, Department of Electrical and Photonics Engineering, DTU
• Co-supervisor: Professor Ole Ravn, Department of Electrical and Photonics Engineering, DTU

External examiners

• Professor Stjepan Bogdan, University of Zagreb, Croatia
• Professor Hyoun Jin Kim, Seoul National University, Korea

Chair of assessment committee

• Associate Professor Roberto Galeazzi, Department of Electrical and Photonics Engineering, DTU

Master of the Ceremony

• Associate Professor Dimitrios Papageorgiu, Department of Electrical and Photonics Engineering, DTU