DESIGN AND DEVELOPMENT OF A MULTIMODAL UNDERWATER ROBOT: AN ALL-IN-ONE DRIFTER, GLIDER, AND THRUSTER

Abstract Existing underwater robotic platforms are typically designed around a single locomotion modality, such as drifting, gliding, or thruster-driven propulsion, limiting their adaptability across diverse tasks and operating environments. Drifting provides energy-efficient passive transport and is particularly well suited for collecting ambient flow information. Gliding enables long-range locomotion with low power consumption, making it attractive for persistent underwater missions. Thruster-driven propulsion, in contrast, provides agile maneuverability, enabling active navigation in confined environments and recovery from trapped situations. Although these locomotion strategies offer complementary capabilities, existing underwater robots are generally limited to a single mode of operation, restricting their versatility and mission adaptability. This paper presents, to the best of our knowledge, the first compact underwater robot that integrates drifting, gliding, and thruster-driven locomotion within a unified platform while enabling seamless transitions among all three modes. The robot incorporates a buoyancy control module, a moving-mass pitch regulation mechanism, foldable wings for mode transition, and a rear propulsion and steering assembly for active maneuvering. This integrated design enables the robot to exploit the unique advantages of each locomotion mode according to mission requirements. Experimental results from underwater testing demonstrate reliable buoyancy control, stable gliding, thruster-driven maneuvering, and successful transitions among the three locomotion modes, validating the feasibility and effectiveness of the proposed multimodal platform. The proposed robot provides a versatile and adaptive solution for a wide range of underwater applications, including long-term environmental monitoring, adaptive ocean sampling, and autonomous underwater exploration.