| Increasing maneuverability of internally actuated Underwater Gliders (UGs) is inevitable due to high demands in underwater surveillance and reconnaissance missions where agility and stealthiness are the keys to success. High maneuverability is needed to provide the opportunity for optimal trajectory planning, planar motion smoothness, and re-planning adapting to the dynamic environments.;This work explores extending the maneuverability of underwater gliders through coupled improvement in mechanical design, efficient use of internal actuation, and motion planning strategy utilizing flight concatenation. The existence of five flight patterns ``advanced flight", inspired by air gliders, enabled solely by utilizing internal actuation are investigated: Circle, Oval Turn, U-turn, S-Turn, and Figure-8. A feedforward-feedback switching controller is utilized to connect the steady state flights through transition stages that features a neutrally buoyant state.;These advanced flights are categorized into two main groups: 1) continuous curvature and 2) switching curvature maneuvers. Circle, Oval Turn, and U-Turn belong to continuous curvature family maintaining a continuous increasing or decreasing heading angle. S-turn and Figure-8 are classified as switching curvature since the heading angle of the vehicle changes in transition points, switching into opposite convex or concave outlines.;The advanced flights can be completed by any underwater glider that is mechanically capable of tight helical motion as long as the controller is capable of performing a smooth transition between steady-state flights. Advance flights will increase the capability of underwater glider system in tracking optimized complicated paths in 3D space and improve fleet cooperative navigation and coordination. |
