Towards a Gliding Robotic Dolphin: Design, Modeling, and Experiments

This paper presents the mechatronic design and implementation of a gliding robotic dolphin. To pursue both high maneuverability and long endurance simultaneously, the gliding robotic dolphin novelly integrates propulsion modes of real dolphins and traditional underwater gliders, through importing a practical buoyancy-driven mechanism on the basis of a bio-inspired robotic dolphin. The hybrid mechatronic design for actual application environments is first holistically provided. In comparison with traditional underwater gliders, the robotic dolphin particularly possesses a pair of controllable flippers and a flatten flukes, which can effectively assist in regulating the gliding attitude. Consequently, a full-state dynamic model with particular consideration of these controllable fins for three-dimensional (3-D) gliding motion is established. Meanwhile, two typical controllers are built to realize these two propulsive modes, e.g., an active disturbance rejection control-based controller for the gliding motion and a central pattern generator-based controller for dolphin-like swimming. Numerical simulations are conducted to analyze 3-D gliding motions of the robotic dolphin as well as the gliding maneuvers based on the controllable fins. Finally, extensive experiments involving gently gliding motion and several dolphin-like propulsive modes illustrate the great locomotion ability of the developed gliding robotic dolphin and also validate the effectiveness of the formulated dynamic model. These hybrid motion modes offer promising prospects of robot applications in complex deep-sea conditions.