A ROV pilot needs to wholly control the behavior of the ROV while it is in execution of object recovery and detection in water. However, most of the commercial ROV operating systems only provide information of video images, depth and orientation. It is difficult for the operator to integrate all information into a vivid picture while steering the vehicle. Besides, limited by the available and expensive operating support, most operators take a lot of practice and field experiences to develop their skill. Therefore, it is necessary to develop a simulator that equips with capabilities of displaying ROV status for real world operation and generating all different operation scenarios for pilot training. This study has developed a multi-function ROV operating virtual environment which integrates all sensory data in real-time to yield a 3D navigation map for operators. Sensory data include GPS, orientation and depth of the ROV, and the acoustic tracking system. In addition to the real physical components connected to the system, a virtual environment for pilot training has constructed. This training environment allows modifying dynamic parameters of the ROV and changing conditions of the ocean environment. Keyboard, joystick and mouse are used as input devices for the system. The developed mathematical model of ROV kinematics and dynamics can generate ROV's corresponding motion according to the commands of the trained-pilot.

Continuing efforts to establish a more continual human presence in the deep ocean are requiring a drastic increase in the number of remotely operated vehicle (ROV) deployments to the ocean floor. Through real-time telemetry afforded by the ROV tether, a human operator can control the ROV, and the vehicle’s robotic manipulators, through haptic and visual interfaces. Given the need for a human presence in the control loop, and the lack of any wireless alternative, the tether is a necessity for ROV operation. While the tether generally maintains a slack or low-tension state, environmental forces that accumulate over the tether can significantly affect ROV motion and complicate the job of the human pilot. The focus of the work presented in this dissertation is the development of a low-tension tether dynamics model for application in the simulation of ROVs.Two methods for modelling the low-tension ROV tether are presented. Both developments include representations of bending and torsional stiffness and are based on a lumped mass approximation to the tether continuum, an approach that has been widely applied in the simulation of taut underwater cables. The first approach appends a bending model to the standard linear lumped mass formulation by applying a discretization scheme to only the bending terms of the governing motion equations. The resulting discrete bending effects are then inserted into the classical linear lumped mass model. Simulated results and an experimental validation showed that the revised linear model captures planar low-tension tether motion very well. In the second approach, a higher-order element geometry is applied that allows the full continuous equations of motion to be discretized producing a new lumped mass formulation. By using a higherorder geometric form for the tether element, a better approximation to the bending terms and a new representation of torsional effects are achieved. The improved bending model is shown to allow element size increases of 35% to 50% over the revised linear lumped mass method. While existing higher-order finite elements could be used to model the ROV tether, it is shown that the choice of element form introduced in this second approach halves the number of variables required to define the tether state as compared to these existing techniques. Applying the higher-order lumped mass model to the simulation of a typical threedimensional ROV maneuver, the importance of torsional effects in the discrete motion equations is evident. Inclusion of a non-zero torsional stiffness produced a resolution of significant tether motions and disturbances on a small ROV that, previous to this work, was not possible with existing cable models. In addition to providing improved bending effects and new torsional considerations, the higher-order element was shown to be an important prerequisite for shorter simulation execution times. Small bends that develop during ROV operation require relatively small elements compared to other marine cable applications. The smaller elements, regardless of the integration technique adopted, constrain allowable time step sizes. By allowing for slightly longer element sizes, the higher-order approach mitigates this negative characteristic of the low-tension tether dynamics. Execution times were reduced by up to 70% over the times incurred when using the element sizes necessary in the linear approach. / Graduate

Unmanned vehicles being used more and more for tasks that need to be done in environ- ments that are hard to access, or dangerous for humans. Because the vehicles are unmanned they need some way of conveying information to the operator about where it is located. In some cases visual feedback to the operator might be enough, but in environments with low visibility other techniques are required. This thesis will address the issue of localization in an underwater environment by means of side-scan sonars and an inertial measurement unit (IMU). It will explore whether it is possible to localize a remotely operated vehicle (ROV) in a known environment by fusing data from the different sensors. A particle filter is applied to the translational motion of the ROV and an extended kalman filter is used to estimate the vehicles attitude. The focus of the thesis lies in statistical mod- eling and simulation of the ROV and its sensors rather than in validation and testing in the physical realm. Results show that a particle filter localization is plausible in environments given varied enough readings. For cases where measurements are similar, such as close to the floor of a pool the filter tends to diverge.

The maneuver of ROV requires considerable pilot skill which is a product of physical and mental practice over a long period of time. However, with the limitations of ROV safety, the availability and high cost of deploying equipment, most of ROV pilots gain the necessary skill through on-the-job training. In this study, we developed a simulation system for ROV pilot training and mission planning. This system is implemented in C++ with the cross-platform OpenGL for 3D graphics. It equips with a scene editor allowing the user to build complex 3D geometric objects from simpler primitives. This editor allows the user to change settings of ambient light intensity, visibility, current speed, and seafloor topography for fulfilling specific training requirements. As well, the user can translate and rotate the entire 3D scene and look at it from different vantage point. Besides, this system provides the user with simple commands for mission planning. For realistically simulating the dynamic behavior of the ROV, the nonlinear hydrodynamic equations of motion of the ROV with six degrees of freedom are applied to describe its motion. Moreover, this system is built with the capability of collision detection for evaluating the collision response of ROV. During the training process, the data engine records all navigation data which can be retrieved and played after conducting a training course. The animation playback function exactly reproduces the scenario that occurs during the period of training. It presents the trainee with the opportunity to review the whole operation scenario. Besides, experiments were designed based on the Taguchi Method to study the effects of different factors on ROV pilot performance. The factors selected for evaluation include ROV trajectory display, underwater visibility, ROV positioning error, and current speed. We found that underwater visibility has the greatest influence on ROV pilot performance, next are ROV positioning error and ROV trajectory display, then the current speed. This result will be helpful in rating the level of difficulty of the training.

Due to the expense and logistics involved with operating real remotely operated vehicles (ROV), training and practice is often difficult to obtain. Therefore, many researches were conducted to increase ROV pilots' experiences through virtual reality. However, most of the training systems that are in use today can only be controlled by a single operator. When two or more ROVs work in a same area, it needs proper concordance among pilots in order to avoid accidents such as collision or cable entanglement. Therefore, this study aims at the development of a ROV operating interface featuring simulated training, remote monitoring, and multiple-user connections. For fulfilling the requirements of remote monitoring, simulated training and multiple-user connections, this study employs JAVA and GL4Java in developing the ROV operating interface. This way we benefit from the 3D description capabilities of GL4Java while JAVA is utilized for the processing and manipulation of web interactions. The developed system architecture includes a server and a client. The client can connect to server by using the web browser through the internet or a LAN with TCP/IP. The server contains required data of sea floor topography and ROV dynamics related parameters. As well, the server is responsible for communicating with the clients. On the client site, it is responsible for sending commands, receiving sensor data and keeping the local information up to date. In remote monitoring, the server periodically integrates and records ROV positioning data and then transmits them to the client. The client receives the updates of ROV status information and displays them on the graphical interface. In simulated training, the equations of motion of ROV are computed on the client-side and only simulated positioning data is reported to the server. In addition, the system allows users to modify underwater visibility, intensity of ambient light and terrain texture for simulating diverse operation conditions.

To expand the ability of collecting underwater targets of "Remotely Operated Vehicle II", developed by National Sun Yat-sen University and National Cheng Kung University, this research will develop an underwater manipulator system which can be integrated with ROV II to have enough degrees of freedom to carry out sampling. The goal will focus on mechanism design and to distinguish the assemble restrictions from other mechanism modules. To avoid use of hydraulic pressure apparatus, the manipulator system will use electric motors as the source of drive, which feeds on ROV II's electricity. In mechanical design, water tightness of underwater manipulator system is first considered to avoid damage of internal electric components. Therefore, in this research, suitable waterproof components will be selected separately for static and dynamic machine parts, and dimension and tolerance of assembly of waterproof components will be analyzed. Then, according to decided design conditions, the number of degrees of freedom of the manipulator and range of length of the arm will be decided. The final design model will be constructed, and selection of motors will be finished by 3D Computer Aided Solid Drawing Software. To have a manipulator system which can deal with different targets, the gripper design needs to consider to easily replacement. In the aspect of systematic control, commercial motor control card and motor driver chip are used to carry out the structure of the entire control system, and develop control interface by C language to easily control each joint of the manipulator system.

For amanipulator to carry outmultiple sampling tasks in a single ROV dive, the samples collected need to be stored temporarily in a secure space to free the gripper for the next sampling. The goal of this research is to design and fabricate a sample holding device to improve the efficient of the ROV which was developed jointly by National Sun Yat-sen University and National Cheng-Kung University. The sample bay mounted on a linear track, moves forward to be in the workspace of the manipulator for the storage service. Upon completion of the sample storage tasks, it retrieves back into the ROV frame to prevent itself from being hit or damaged when the ROV is in motion. The development includes the design for a linear track, an underwater motor and its controller, and sample holder. The design of the sample holder was implemented by decision weighting matrix to choose the most appropriate prototype. The efficacy of the system was verified by several joint tests with the manipulator.

The main focus of this thesis is to design effective trajectories with minimum energy consumption for underwater remotely operated vehicles (ROV) in the environment with ocean current. The complete motion behavior of the ROV includes surge, sway, heave, roll, pitch, and yaw. Both the surge and sway are easy to be influenced by ocean current. The basic mission for the ROV is always from one starting point to a desired target position. An optimum trajectory with the minimum energy consumption not only can make the best use of energy, but also can improve maneuver efficiency for either manual operation or automatic control. In order to solve this problem, the optimal theorem is applied. The Matlab simulation tool is employed to demonstrate the response and performance of the ROV using the proposed trajectories. In addition, the applicably operational range for the ROV can also be determined when thrust limits are considered. Such information presents the extreme maneuver capability of the ROV in the ocean current.

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