Underwater glider (UG) is the only marine equipment in the field of ocean observation that can realize unmanned autonomous, all-weather and wide-area continuous 3-D observation. The rapid individualized design (RID) and full lifecycle management (FLM) make two difficulties to be solved in the industrialization development of UGs since the UG system involves interdisciplinary multiphysics and there exists multisource uncertainties in complex ocean environment. With the application of new information technologies in industry, the above problems can be effectively solved by the digital twin (DT)-driven methodology. In this article, an architecture of DT-driven RID and FLM for UGs is first put forward based on our previous theoretical research and technique development. Then, the proposed architecture of DT-driven methodology is researched in detail in terms of its digital modeling, design optimization, virtual verification and practical application. Finally, Petrel developed by China is introduced, and a typical preliminary application of DT-driven methodology is presented based on petrel to verify its feasibility. The architecture proposed in this article is also appropriate for other types of autonomous underwater vehicles.

With recent developments in battery technology and low power technology, biofouling, a process referring to the gradual accumulation of organisms on underwater surfaces, has gained a foothold as the primary adversary in long-duration underwater glider flights (C. D. Haldeman, D. K. Aragon, T. Miles, S. M. Glenn, and A. G. Ramos, “Lessening biofouling on long-duration AUV flights: Behavior modifications and lessons learned,” in Proc. OCEANS MTS/IEEE Conf., Monterey, CA, USA, 2016, pp. 1-8). Not only can biofouling increase the drag of the glider, but also it can add the buoyancy discrepancies, which changes the flight characteristics of the glider. Thus, it is necessary to adjust the flight parameters of underwater gliders accordingly for long-duration flights. In this article, the problems of a Petrel-L glider caused by biofouling are introduced. Several critical parameters including the hydrodynamic coefficients, the thermal expansion coefficient, the compressibility, and the net buoyancy compensation of the glider are optimized by an inner penalty function method based on the glider data and the dynamic model of Petrel-L. The effect of these parameters influenced by biofouling on the gliding range is analyzed. The results indicate that the changed hydrodynamic coefficients and net buoyancy compensation decrease the gliding range by 14.64% when the hotel load, including the power of the control system and the sensors, is 0.2 W. The gliding range loss can be decreased to 7.11% by adjusting the flight parameters. This article provides a reference of flight parameter adjustment for other types of biofouled underwater gliders.

This paper proposes a bio-inspired hull shape (BHS) for AUV by studying and modeling the body shape of humpback whales. Among factors affecting hydrodynamic characteristics, this paper considers both the hull drag and displacement volume to optimize the BHS, which profitably improve the space utilization and voyage of the AUV. The optimization is conducted by a surrogate model using response surface methodology (RSM), during which the translational propagation Latin hypercube design (TPLHD) is adopted to obtain sampling points. In order to verify the optimization results of BHS, the drag computations for BHS and eight typical hull shapes of existing typical or bionic AUVs are performed for comparison under conditions of similar volume, wet surface area, body length and attachments. A scaled-down model of BHS with attachments is then designed, manufactured and carried out a towing tank test. The drag measured in the towing tank test is basically the same as the simulation result, with the average relative error of 3.68% at 4m/s. The result of the shape optimization performed with the RSM is effective. Furthermore, the proposed BHS is highly suitable for underwater vehicles with requirements for longer distance, higher speed or better sensor carrying capacity.