• Journal of Ocean Engineering and Technology
• /
• v.34 no.5
• /
• pp.334-341
• /
• 2020

Most towfish systems do not have propulsive devices and cannot compensate for perturbation motion, which can affect the observation data. This paper discusses attitude control of a towfish with elevators on the left and right tail wings to improve the quality of the observational data. Specifically, we investigate the relationships between the towing point, the center of gravity, and the drag forces produced by the elevators to clarify whether the elevators can control the attitude of the towfish sufficiently for various positions of the towing point and center of gravity. The feasible positions of the towing point and center of gravity are defined by mechanical analyses, and simulations are conducted to verify that the elevators can provide attitude control in these positions. The simulation results show that at some positions, the elevators can control the attitude quickly and sufficiently even if disturbances exist.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.7 no.2
• /
• pp.409-425
• /
• 2015

In this paper, we employ a dynamics modeling method for investigating a multi-body dynamics system of semi-submersible autonomous underwater vehicles consisting of a towing vehicle operated near the water surface, a tow cable, and a towfish. The towfish, which is towed by a marine cable for the purposes of exploration or mine hunting, is modeled with a Six-Degree-of-Freedom (6-DOF) equation of motion that reflects its hydrodynamics characteristics. The towing cable, which can experience large displacements and deformations, is modeled using an absolute nodal coordinate formulation. To reflect the hydrodynamic characteristics of the cable during motion, the hydrodynamic force due to added mass and the drag force are imposed. To verify the completeness of the modeling, a few simple numerical simulations were conducted, and the results confirm the physical plausibility of the model.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.696-699
• /
• 2004

A side scan sonar system uses the towfish installed sonars, It is an equipment that search images of the bottom surface of the sea in real time. It is a typical equipment that is related to a sea investigation such as a geological survey, seabed communication cable and power line cable placing repair investigation, fish breeding ground investigation, sea purification, relic and mineral investigation, and mine and submarine search. It used to fined objects and investigate on the seabed surface. But, recently, it is used to sea purification and geological survey that require information of the correct surface of the seabed. So, it needs various filtering technique and image processing techniques development to acquire high resolution image. therefore, this research develops a side scan sonar using multi-beam sensors that supply various information with the fast scan speed and correct high resolution that is not a simple underwater investigation equipment.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.54 no.10
• /
• pp.581-586
• /
• 2005

The multi-beam side scan sonar system uses the towfish installed sonars, it is an equipment that search images of the bottom surface of the sea in real time. It is a typical equipment that is related to a sea investigation such as a geological survey, seabed communication cable and power line cable placing repair investigation, fish breeding ground investigation, sea purification, relic and mineral investigation, and mine and submarine search. Recently, it is used to sea purification and geological survey that require information of the correct surface of the seabed. Therefore, this research develops multi-beam sensors for a side scan sonar that supply various information with the fast scan speed and correct high resolution that is not a simple underwater investigation equipment.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2006.06a
• /
• pp.317-318
• /
• 2006

The towfish oi a side scan sonar is an equipment that search images of the bottom surface of the sea in real time. It is a typical equipment that is related to a sea investigation such as a geological survey, seabed communication cable and power line cable placing repair investigation, fish breeding ground investigation, sea purification, relic and mineral investigation, and mine and submarine search. It used to find objects and Investigate on the seabed surface. But, recently, it is used to sea purification and geological survey that require information of the correct surface of the seabed. So, it needs various filtering technique and image processing techniques development to acquire high resolution image. Therefore, this research develops a side scan sonar using multi-beam sensors that supply various information with the fast scan speed and correct high resolution that is not a simple underwater investigation equipment.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2011.10a
• /
• pp.121-121
• /
• 2011

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2000.10a
• /
• pp.216-221
• /
• 2000

This paper deals with the Gain Control in the processing of the underwater acoustic image obtained from side scan sonar(SSS) system. At first, this paper describes the principles of SSS that is a surveying equipment for the underground of the rivers or dams as well as sea floor. Then this paper analyzes the cause and effects of the time varying intensity from the view point of transmission loss and beam pattern. At last, the time varying gain filter that is adopted by the towfish is introduced.

• The Journal of the Acoustical Society of Korea
• /
• v.40 no.6
• /
• pp.546-554
• /
• 2021

In the signal processing of synthetic aperture sonar, it is subject that the platform in which the sensor array is installed moves along the straight line path. In practical operation in underwater, however, the sensor platform will have trajectory disturbances, diverting from the line path. It causes phase errors in measured signals and then produces deteriorated SAS images. In this study, in order to develop towed SAS, as tools to remove the phase errors associated with the trajectory disturbances of the towfish, motion compensation technique using Redundant Phase Center (RPC) and also Phase Gradient Autofocus (PGA) method is investigated. The performances of these two approaches are examined by means of a simulation for SAS system having a sway disturbance.