TrofyBot: A Transformable Rolling and Flying Robot with High Energy Efficiency

Image credit: FAST-FIRE

Abstract

Terrestrial and aerial bimodal vehicles have gained significant interest due to their energy efficiency and versatile maneuverability across different domains. However, most existing passive-wheeled bimodal vehicles rely on attitude regulation to generate forward thrust, which inevitably results in energy waste on producing lifting force. In this work, we propose a novel passive-wheeled bimodal vehicle called TrofyBot that can rapidly change the thrust direction with a single servo motor and a transformable parallelogram linkage mechanism (TPLM). Cooperating with a bidirectional force generation module (BFGM) for motors to produce bidirectional thrust, the robot achieves flexible mobility as a differential driven rover on the ground. This design achieves 95.37% energy saving efficiency in terrestrial locomotion, allowing the robot continuously move on the ground for more than two hours in current setup. Furthermore, the design obviates the need for attitude regulation and therefore provides a stable sensor field of view (FoV). We model the bimodal dynamics for the system, analyze its differential flatness property, and design a controller based on hybrid model predictive control for trajectory tracking. A prototype is built and extensive experiments are conducted to verify the design and the proposed controller, which achieves high energy efficiency and seamless transition between modes.

Publication
2025 IEEE International Conference on Robotics and Automation (ICRA 2025)
Mingwei Lai 赖明威
Mingwei Lai 赖明威
Master

My research interests include model predictive control and trajectory planning.

Qiuyu Ren 任秋予
Qiuyu Ren 任秋予
Ph.D. student

My research interests include UAV tracking, motion planning and Model Predictive Control (MPC)

Chao Xu 许超
Chao Xu 许超
Full Professor

My research interests include Geometries and Control of Mechanical Systems, Kinematic Agents and Cybernetics, Multi-Physics Driven Robotics, AI-Driven Science.

Fei Gao 高飞
Fei Gao 高飞
Associate Professor

My research interests include aerial robotics, autonomous navigation, swarm cooperation, and embodied intelligence.

Yanjun Cao 曹燕军
Yanjun Cao 曹燕军
Research Professor

My research interests focuse on key challenges in multi-robot systems, such as collaborative localization, perception, communication, and system organization.