Song K. Choi

Design of a semi-autonomous underwater vehicle for intervention missions (SAUVIM)

As the research in the autonomous underwater vehicle (AUV) field intensifies and the necessity of underwater robotic vehicles (URVs) increases, the requirements of an URV have expanded from simple fly-by missions to more complex, intervention missions. The Autonomous Systems Laboratory, Department of Mechanical Engineering, University of Hawaii is in the midst of designing and developing a semi-autonomous underwater vehicle for intervention missions (SAUVIM). The proposed open structure AUV possesses a fully functional manipulator, various mission sensors, and composite pressure vessels enclosed in a flooded composite fairing. The vehicle allows human-intervention from a land-based computer system capable of vehicle path-planning and monitoring.

Development of the Omni Directional Intelligent Navigator

The Autonomous Systems Laboratory is in the midst of developing an advanced underwater robotic technology test platform. The platform consists of the Omni-Directional Intelligent Navigator (ODIN) and the Integrated Graphic Workstation (IGW). ODIN is a six degree-of-freedom (dof) underwater vehicle with dual operational modes (autonomous and tethered) and a single dof mechanical manipulator. IGW is a real-time, 3-dimensional graphic monitoring, testing, and evaluation workstation. This paper presents ODINs mechanical and electrical specifications; its vehicle dynamics and depth control system; its recent simulation and experimental results; and IGWs specifications. >

Development of an underwater robot, ODIN-III

During the last decade, the first autonomous underwater robot of the Autonomous Systems Laboratory of the University of Hawaii, ODIN (Omni-Directional Intelligent Navigator) built in 1991 has produced a lot of valuable results in development and control methods [(S.K. Choi et al., July 1994), (Choi, S.K. et al., March 1995), (S.K. Choi et al., April 1996), (Yang, K.C. et al., September 1999), (J. Yuh et al., 2000)]. Recently, ODIN was born again in the 3rd generation with unique features under recent technologies such as abundant system resources owing to a PC104+, new vehicle system software architectures with an object-oriented concept and its implementation, a graphical user interface and an independent algorithm module using a dynamic linking library (DLL) based on the Windows operating system. These give us an ideal environment for developing various algorithms which are needed for developing an advanced underwater robotic vehicle. This paper describes details of the development of ODIN-III and presents initial experimental results for fine motion control.

Design of omni-directional underwater robotic vehicle

Underwater robotic vehicles have been attractive to many applications. Among potential applications of these vehicles include fishery, underwater pollution monitoring, and waste cleaning and handling in the ocean as well as nuclear sites. Over the last decade, there has been increasing R&D effort toward more advanced and intelligent underwater vehicles in support of a variety of applications. In the Autonomous Systems Laboratory, an omni-directional intelligent navigator (ODIN) which has dual (autonomous/remote) operational modes and a mechanical manipulator, was designed as a part of the research in developing a real-time 3D graphic, integrated test platform for advanced vehicle technologies. RSI Research Ltd. manufactured the first model which is described in this paper.<<ETX>>

Fault-tolerant system design of an autonomous underwater vehicle ODIN: An experimental study

This paper describes the design and implementation of a fault-tolerant system for Omni-Directional Intelligent Navigator (ODIN), a six-degree-of-freedom autonomous underwater vehicle (AUV) designed at the University of Hawaii. A fault-tolerant system consists of three areas: fault detection, fault isolation and fault accommodation. Each area is described, and methods discussed in the literaturearebriefly reviewed. The presented design focuses on the thruster (or actuator) and sensor system failures in an AUV. Experimental results show that the presented approach is practical and effective when tolerable failures in actuators and sensors occur. This methodology and concept can be extended to fault-tolerant system design for various AUVs with hardware redundancy.

Experimental study of fault-tolerant system design for underwater robots

Describes the design and implementation of a fault tolerant system for the 6 degrees-of-freedom ODIN autonomous underwater vehicle (AUV). Fault tolerant system design can be divided into three areas: fault detection, fault isolation, and fault accommodation. This paper summarizes previous studies in fault tolerant system design and presents a fault tolerant system design for thruster (actuator) and sensor failure in AUVs. The presented system was implemented in the actual vehicle, ODIN, and its effectiveness was evaluated with experimental results.

Underwater Target Localization

This contribution focuses on the problem, intrinsic to autonomous underwater manipulation, of medium-range target localization for guiding the vehicle toward the target area. Based on the use of the dual-frequency identification sonar (DIDSON) sonar, the goal is to acquire the Earth-referenced Cartesian coordinates of a known target, with the necessary accuracy required for positioning the vehicle, so that the target falls within the manipulator workspace.

Experimental study on an underwater robotic vehicle: ODIN

As underwater application activities mature, the utilization of underwater robotic vehicles becomes more notable. The sophistication required by these URVs have significantly increased, and the development of AUVs are becoming imminent. The Autonomous Systems Laboratory of the University of Hawaii has designed the Omni-Directional Intelligent Navigator (ODIN), its control systems, and its graphic workstation to develop an integrated, real-time, 3-dimensional graphic test platform.

Design of advanced underwater robotic vehicle and graphic workstation

Underwater robotic vehicles (URVs) are the integration of various subsystems such as sensor systems and guidance and control systems. In the Autonomous Systems Laboratory, an autonomous URV was designed and its first model was built as a part of research in developing a test platform for advanced vehicle technologies. Major components of the vehicle and its mechanical and electrical structure are described.<<ETX>>

Experimental validation of model-based thruster fault detection for underwater vehicles

This paper describes a model-based thruster fault detection scheme for an autonomous underwater vehicle. For a vehicle equipped with servo motor based marine thrusters, the velocity and current feedback from the motor controllers can be used to derive two independent thrust approximations. The difference between the two models reveals the presence of fault conditions, and quantifies the error of the output thrust relative to the desired reference. The method is proven effective through experimental validation.