An Underwater Gliding Robot Using an Origami-Inspired Buoyancy Regulator

Abstract Underwater robots require sophisticated buoyancy regulators for efficient three-dimensional motion. Conventional buoyancy control techniques include ballast-based and pressurized air bladders, which often disturb the surrounding water and are noisy. This paper introduces TOD-UWG, an underwater gliding robot equipped with a noiseless and fixed-mass buoyancy regulating mechanism. This technique employs a swim bladder made with origami. The origami-based swim bladder is compressed using a thread and pulley mechanism actuated by a servo motor, while the stretching takes place when the tension in the thread is relieved. The study focuses on the feasibility of buoyancy control using a soft origami structure, ensuring efficient actuation while reducing energy consumption. We also present the details of selecting suitable materials with a focus on durability and compatibility with the origami design principles, guaranteeing the long-term functionality and reliability of the entire system against water seepage for shallow water applications. Experimental characterization of buoyancy force generated by the origami mechanism has been performed, and it is used to calibrate the robot. We envisage that the developed approach can impart buoyancy regulation-based energy-efficient depth control capabilities to underwater robots that can reduce environmental impact.