Development of underwater electric manipulator based on interventional autonomous underwater vehicle (AUV)

In applications such as marine rescue,marine science,archaeology,and offshore industries,autonomous underwater vehicles(AUVs)are frequently used for survey missions and monitoring tasks,with most operations being performed by manned submersibles or remotely operated vehicles(ROVs)equipped with robotic arms,as they can be operated remotely for days without problems.However,they require expensive marine vessels and specialist pilots to operate them.Scientists exploring oceans are no longer satisfied with the use of manned submersibles and ROVs.There is a growing desire for seabed exploration to be performed using smarter,more flexible,and automated equipment.By improving the field operation and intervention capability of AUVs,large-scale and long-range seafloor exploration and sampling can be performed without the support of a mother ship,making it a more effective,economical,convenient,and rapid means of seafloor exploration and sampling operations,and playing a critical role in marine resource exploration.In this study,we explored the integration technology of underwater electric robotic arms and AUVs and designed a new set of electric manipulators suitable for water depths greater than 500 m.The reliability of the key components was analyzed by finite element analysis and,based on the theory of robot kinematics and dynamics,simulations were performed to verify the reliability of the key components.Experiments were conducted on land and underwater,trajectory tracking experiments were completed,and the experimental data in air and water were compared and analyzed.Finally,the objectives for further research on the autonomous control of the manipulator underwater were proposed.

Real-time localization for underwater equipment using an extremely low frequency electric field

A new real-time underwater equipment location method adopting an electric field induced by a standard current source is proposed.Our goals were real-time tracking and location of stationary or moving underwater equipment both in shallow and deep seas,under noisy conditions.The main features of this method are as follows:(1)a standard current source on the water surface,which can be towed by a vehicle,consisting of two electrodes,a signal generator,and a GPS unit;(2)measurement of the extremely low frequency(ELF)electric field emitted by the current source,made possible by electric field sensors on the underwater equipment;(3)position of the underwater equipment is estimated in real time based on a progressive update extended Kalman filter(PUEKF),which is carried out using the propagation model of an ELF electric field because the electric field at the position of the underwater equipment and the current source position are known.We verified the accuracy of our method and confirmed real-time location feasibility through numerical,physical scale,and real-time sea experiments.Through numerical experiments,we verified that our method works for underwater equipment location in real-world conditions,and the location error can be less than 0.2 m.Next,real-time location experiments for stationary underwater measuring equipment in water tank were conducted.The result shows that the location error can be less than 0.1 m.We also confirmed real-time location feasibility through the use of offshore experiment.We expect that our method will complement conventional underwater acoustic location methods for underwater equipment in acoustically noisy environments.

Development of A Deep Ocean Electric Autonomous Manipulator

This paper describes an underwater 3500 m electric manipulator （named Huahai-4E, stands for four functions deep ocean electric manipulator in China）, which has been developed at underwater manipulation technology lab in Huazhong University of Science and Technology （HUST） for a test bed of studying of deep ocean manipulation technologies. The manipulator features modular integration joints, and layered architecture control system. The oil-filled, pressure-compensated joint is compactly designed and integrated of a permanent magnet （PM） brushless motor, a drive circuit, a harmonic gear and an angular feedback potentiometer. The underwater control system is based on a network and consisted of three embedded PC/104 computers which are used for servo control, task plan and target sensor respectively. They communicate through User Datagram Protocol （UDP） multicast communication in Vxworks OS. A supervisor PC with a virtual 3D GUI is fiber linked to underwater control system. Furthermore, the manipulator is equipped with a sensor system including a unique ultra-sonic probe array and an underwater camera. Autonomous grasp strategy based multi-sensor is studied. The results of watertight test in 40 MPa, joint＇s efficiency test and autonomous grasp experiments in tank are also presented.

Research on the Static Magnetic Field of Ships with Corrosion and Anticorrosion Efficacy Using Electric Dipole Model

In the case of three-layered(air-seawater-seabed)model,the analytical expressions of the static electric and static magnetic field produced by the static electric dipole located in seawater were derived by using the mirror image theory.Combined with the distribution of the underwater electric potential measured in laboratory,an electric dipole model for physical scale of ship was established and the distribution characteristics of an actual ship' s corrosion related magnetic field were obtained.Based on established models,theoretical analysis and calculation were made to catch out the distribution characteristics of static magnetic field related with corrosion and anticorrosion,which can not be measured directly in seawater.The results show that the static magnetic field related with corrosion and anticorrosion is a kind of noteworthy obstacle signal for degaussed ships.

Decoloration of Azo Dye Sunset Yellow by a Coaxial Insulated-Rod-to-Cylinder Underwater Streamer Discharge System

A coaxial insulated-rod-to-cylinder underwater streamer discharge system capable of injecting plasma into a large volume of water was developed and employed to decolorize azo dye sunset yellow. The rod type anode was covered by an insulator tube with a wall thickness of 0.4 mm. A series of slits with a width of 20 μm to 80 μm and a length of about 4 mm were cut onto the wall of the insulator tube. Depending on the solution conductivity, a cylindrical discharge region with a length of 60 mm and a wall thickness of 5 mm to 11 mm forms in the reactor. The influence of the solution conductivity, pH and pulse frequency on the decoloration of sunset yellow was investigated. The results show that the solution conductivity has little effect, while the solution pH and the pulse frequency have significant influence on the decoloration rate of sunset yellow. The decoloration rate of sunset yellow is increased with the increase in pulse frequency. A lower pH in solution promotes the decoloration of sunset yellow while a higher pH inhibits it.

Advancing Scientific Rigor: Towards a Universal Informational Criterion for Assessing Model-Phenomenon Mismatch

The escalating costs of research and development, coupled with the influx of researchers, have led to a surge in published articles across scientific disciplines. However, concerns have arisen regarding the accuracy, validity, and reproducibility of reported findings. Issues such as replication problems, fraudulent practices, and a lack of expertise in measurement theory and uncertainty analysis have raised doubts about the reliability and credibility of scientific research. Rigorous assessment practices in certain fields highlight the importance of identifying potential errors and understanding the relationship between technical parameters and research outcomes. To address these concerns, a universally applicable criterion called comparative certainty is urgently needed. This criterion, grounded in an analysis of the modeling process and information transmission, accumulation, and transformation in both theoretical and applied research, aims to evaluate the acceptable deviation between a model and the observed phenomenon. It provides a theoretically grounded framework applicable to all scientific disciplines adhering to the International System of Units (SI). Objective evaluations based on this criterion can enhance the reproducibility and reliability of scientific investigations, instilling greater confidence in published findings. Establishing this criterion would be a significant stride towards ensuring the robustness and credibility of scientific research across disciplines.

Effect of the Circuit and Wire Parameters on Exploding an Al Wire in Water

The underwater electrical explosion of an aluminum wire is influenced by many factors, such as wire parameters, pulsed power energy, etc. In this paper, underwater electrical explosion of an aluminum wire was investigated with pulsed voltage in the time scale of a few microseconds. A self-integrated Rogowski coil and a voltage divider were used for the measurements of current and voltage at the wire load, respectively. The deposited energy before breakdown was calculated based on experimental waveforms of current and voltage by mathematical method. Effects of the applied voltage, circuit inductance and sion and energy deposition were analyzed by means parameters of Al wire on the electrical exploof experiments and calculation. The results show that the current rise rate has an important influence on explosion process, such as the energy deposition before breakdown, the electrical power as well as the various explosion stages. A higher current rise rate can be achieved by increasing applied voltage and decreasing circuit inductance. The inhomogeneity of the energy deposition will result in prematured breakdown as well as lowered energy deposition, making the explosion process of wire more complicated.