A Bionic Flexible-bodied Underwater Glider with Neutral Buoyancy

The buoyancy of traditional Underwater Glider(UG)with a rigid hull is aff ected by the changing marine parameters,making it difficult for the vehicle to dive deeper with good motion characteristics.In the present work,the development of a novel UG for neutral buoyancy,which is equipped with a Flexible-Liquid-Rigid(FLR)composite hull,is presented.The innovative hull that imitates the buoyancy regulation mechanism of marine organisms is easily adaptable to the changing marine environment.The rigid part of the composite hull withstands hydrostatic pressure for inner function modules of the vehicle.The liquid of the composite hull mainly serves as a buoyancy compensation to mitigate the eff ect of buoyancy variation caused by the changing marine parameters.The flexible covering provides a good hydrodynamic shape for the vehicle under the internal liquid pressure.The buoyancy variation due to the composite hull compression as well as changes of seawater density and temperature was comprehensively considered in the design process and integrated to the dynamic model.In addition,sea trials were performed to verify the motion characteristics of the proposed vehicle.The results reveal that the Flexible-bodied Underwater Glider(FUG)has a better gliding performance in practice.