OBoat: An Agile Omnidirectional Robotic Platform for Unmanned Surface Vehicle Tasks

Platforms for researching and experimenting with challenging aquatic surface tasks have demanding requirements and are expensive, hindering the development, research verification, and thus, widespread adoption of unmanned surface vehicles (USVs). To overcome this drawback, this article describes a low-cost omnidirectional robotic platform, named "OBoat," including its mechanism design, control method, and system architecture. The robot features agile motion by its unique isotropic cylindrical body design and omnidirectional movement with a minimal three-propeller driving setup. First, for the inconsistent water disturbances acting upon the robot from different directions, the cylindrical body isotropic property contributes to its agility. As for the unknown dynamics induced cylindrical body, we performed system identification by designing theoretical and verification experiments. Second, for the omnidirectional propulsion configuration, we explored a minimal three-propeller driving setup (which is seldom addressed on the surface robot designs). Thereafter, we implemented a model predictive controller for omnidirectional motion control based on its unique body shape and propulsion design. After that, we developed a system architecture for various surface applications. Finally, we extensively tested the performance of the platform and system architecture in completing numerous surface tasks, including those deemed challenging by the USV community. Overall, the results indicate the excellent potential of OBoat for rapid prototyping and preliminary evaluations for surface applications, and the robot further provides an option for marine robotics education platform with certain budget.