• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1750-1753
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• 1997

This paper describes how the directivity pattern of the back-scattered sound pressure is distributed when a plane acoustic wave is incident on a righid spherical shell underwater. A coupled Finite Element-Boundary Element mehtod is developed as numerical technique. The result of the coupled FE-BE method is agreed with theoretical solution for algorithmic confirmation.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.371-375
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• 1991

The purpose of this paper is the design of a controller of electric actuator for high speed underwater vehicle which is robust against hydro load torque. For this purpose, we design the controller of PD & VSC control schemes. Under proper assumption of the hydro load torque, the tracking performances of these schemes are analyzed through the computer simulation, and the results are presented.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.616-619
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• 1991

This paper describes the design of fuzzy logic controller for underwater vehicle actuator with high hydroload torque disturbance. For real-time processing of the fuzzy rule, the look-up tables including coarse mode and fine mode are used instead of inference engine process. Computer simulations are done in order to analyze the performance of the proposed algorithm and the very useful results are shown to us by comparing with the existing controller.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.850-856
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• 1992

The problem of robust control of a underwater vehicle subject to variation of a real parameter and velocity is considered. The controller set which stabilized perturbed plant is chosen using numerical gradient method and the controller is used for nominal performance and robust performance. Simulation results are presented to show that the precise montion control of the controller is accomplished under perturbation in the system.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.839-844
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• 1992

There are many specific requirements in the actuation, system for high speed underwater vehicle, such as size, weights, power etc.. In this paper, a high performance compact hydraulic actuation system to satisfy such requirements was designed. The controller of the system was designed using both the conventional PID and VSC which were known to have reliability, robustness respectively. The performance analysis was done for the designed actuation system through computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.845-849
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• 1992

The disturbance and time delay can often cause a significant error in the estimation of trajectory of a underwater vehicle. The time delay considered in this study is due to the delayed rudder response to the rudder input from the guidance control part. The simulation tests are performed on maneuver with constant rudder angle, zigzag maneuver, dive-climb maneuver, and corridor pattern maneuver. The results are compared with those of without delay cases.

• The Journal of Korea Robotics Society
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• v.18 no.4
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• pp.472-480
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• 2023

This paper describes the development of a test-equipment for the pre-verification of navigation performance in cluster-based AUVs (Autonomous Underwater Vehicle). In the development of an AUV, conducting hardware and software development sequentially is not efficient due to the limited research and development period. Therefore, in order to reduce the overall development time and achieve successful development results, it is essential to pre-validate the navigation system and navigation algorithms. Accordingly, this paper explains the test-equipment for pre-verification of navigation performance, and ultimately confirms the stability of the navigation system and the performance of the navigation algorithms through the analysis of five types of navigation sensor data stored during real-sea experiments. The results demonstrate that through the development and verification of the test-equipment, it is possible to shorten the overall development period and improvement of product quality in the process of developing multiple AUVs.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.3
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• pp.165-173
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• 2018

Underwater vehicles use Inertial Navigation System (INS) with high-performance Inertial Measurement Unit (IMU) for high precision navigation. However, when underwater navigation is performed for a long time, the INS error gradually diverges, therefore, an integrated navigation method using auxiliary sensors is used to solve this problem. In terms of underwater vehicles, the vertical axis error is primarily compensated through Vertical Channel Damping (VCD) using a depth gauge, and an integrated navigation filter can be designed to perform horizontal axis error and sensor error correction using a speedometer such as Electromagnetic-Log (EM-Log). However, since EM-Log outputs the forward direction relative speed of the vehicle with respect to the sea and sea current, INS correction filter using this may cause a rather large error. Although it is possible to design proper filters if the exact model of the sea current is known, it is impossible to know the accurate model in reality. Therefore, this study proposes an INS/EM-Log integrated navigation filter with the function to estimate sea current using an Interacting Multiple Model (IMM) filters, and the performance of this filter is analyzed through a simulation performed in various environments.

• Journal of IKEEE
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• v.22 no.4
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• pp.1180-1187
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• 2018

This paper had implemented the underwater stage through interaction with fish robots and visitors in the background of traditional fairy tales using 3D floating hologram in an aquarium. The recognition of the object position of the spectator and the underwater robot were performed using the color recognition algorithm. Also, the position tracking algorithm was proposed to follow the object of the visitor and the original fairy tale. This experimental system consists of fish robot, camera, KIOSK for underwater robot control and beam project for underwater imaging. This experiment was carried out by the National Busan Science Museum, and it had satisfied the performance of the underwater stage.

• Journal of the Korean Ceramic Society
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• v.43 no.4 s.287
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• pp.259-263
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• 2006

The applicability of UPT (Ultrasound Pulse Thermography) for real-time defect detection of the ceramic heating plate is described. The ceramic heating plate with superior insulation and high radiation is used to control the water temperature in underwater environment. The underwater temperature control system can be damaged owing to the short circuit, which resulted from the defect of the ceramic heating plate. A high power ultrasonic energy with pulse duration of 280 ms was injected into the ceramic heating plate in the vertical direction. The ultrasound excited vibration energy sent into the component propagate inside the sample until they were converted to the heat in the vicinity of the defect. Therefore, an injection of the ultrasound pulse wave which results in heat generation, turns the defect into a local thermal wave transmitter. Its local emission is monitored and recorded via the thermal infrared camera at the surface which is processed by image recording system. Measurements were Performed on 4 kinds of samples, composed of 3 intact plates and the defect plate. The observed thermal image revealed two area of crack in the defective ceramic heating plate.