Theory And Design Issues Of Underwater Manipulator.

In this paper we discuss the theory and implementation issue that is faced by underwater manipulators designers

A survey on uninhabited underwater vehicles (UUV)

ASME Early Career Technical Conference, ASME ECTC, October 2-3, 2009, Tuscaloosa, Alabama, USAThis work presents the initiation of our underwater robotics research which will be focused on underwater vehicle-manipulator systems. Our aim is to build an underwater vehicle with a robotic manipulator which has a robust system and also can compensate itself under the influence of the hydrodynamic effects. In this paper, overview of the existing underwater vehicle systems, thruster designs, their dynamic models and control architectures are given. The purpose and results of the existing methods in underwater robotics are investigated

Hydrodynamic Coefficients for Various Postures of the Underwater Manipulator

The hydrodynamic coefficients of underwater manipulators constantly change during their operation. In this study, the hydrodynamic coefficients of an underwater manipulator were calculated using the finite volume method to better explain its hydrodynamic performance. The drag, lift, and moment coefficients and the Strouhal number of an underwater manipulator for different postures were investigated. The results indicated that in each motion range, the coefficients first increase and then decrease.  Meanwhile, when the attitude of the underwater manipulator is axis-symmetric or origin-symmetric, the hydrodynamic coefficients and the Strouhal number obtained are approximately the identical. The drag coefficient, lift coefficient and moment coefficient reach their maximum values of 3.59, 3.29, and 1.78 at angles of 30°, 150°, and 150°, respectively， with minimum values at 90°, 50° and -30°. Furthermore, the leading-edge shape of the underwater manipulator had a significant effect on the hydrodynamic coefficient. Maximum reductions of 44%, 25%, and 50.5% were obtained in the drag, lift, and moment coefficients, respectively, by comparing the semicircular leading edge with the right-angle leading edge. A maximum Strouhal number of 0.219 was obtained when the semicircular leading edge of the underwater manipulator was the upstream surface. This study will provide theoretical guidance to reveal the hydrodynamic performance of the underwater manipulators. It also serves as a reference for the structural design of the underwater manipulators

Hovering-mode control of the glider-type unmanned underwater vehicle

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2011Includes bibliographical references (leaves: 104-107)Text in English; Abstract: Turkish and Englishxiii, 109 leavesResearch on the underwater robotics has attracted the interest of many researchers over the years. The primary reasons are the need to perform underwater intervention tasks that are dangerous for a diver and the need to perform underwater survey tasks that last for longer periods of time. Unmanned underwater vehicles can be divided into two categories. Most of the systems, today, that require a certain level of precision and dexterity are built as Remotely Operated Vehicles (ROV). On the other hand, the systems that perform repetitive tasks are configured as Autonomous Underwater Vehicles (AUV). The objective of the thesis is to design a novel, cost-efficient, and fault-tolerant ROV that can hover and be used for shallow water investigation. In order to reduce the cost, the numbers of thrusters are minimized and internal actuators are used for steering the vehicle and stability in hovering mode. Also, the design is planned to be open for modification for further improvements that will enable the use of the vehicle for intervention tasks and studies. In this work, previously developed unmanned underwater vehicles are reviewed. Following this, the conceptual designs are created for the underwater vehicle and internal actuator designs are developed. Designed mechanisms are modeled in SolidWorks© and transferred to MATLAB© Simulink for hovering-mode control studies. Afterwards, to verify the simulation results, experiments are conducted with a seesaw mechanism by using LabVIEW© programming. Finally, results are given, discussed and future works are addressed

Underwater Vehicles

For the latest twenty to thirty years, a significant number of AUVs has been created for the solving of wide spectrum of scientific and applied tasks of ocean development and research. For the short time period the AUVs have shown the efficiency at performance of complex search and inspection works and opened a number of new important applications. Initially the information about AUVs had mainly review-advertising character but now more attention is paid to practical achievements, problems and systems technologies. AUVs are losing their prototype status and have become a fully operational, reliable and effective tool and modern multi-purpose AUVs represent the new class of underwater robotic objects with inherent tasks and practical applications, particular features of technology, systems structure and functional properties