• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.772-775
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• 1992

It is necessary to estimate hydrodynamic coefficients to design the auto-pilot system and motion simulator of submersible vehicle. In this paper, an algorithm was designed to estimate hydrodynamic coefficients of submersible vehicle. Using this algorithm, the hydrodynamic coefficients were estimated from measurements of full scale trial. The estimated hydrodynamic coefficients were used for the design of an auto-depth controller(ADC) of submersible vehicle, and the resulting ADC are proved to have a better performance than the previous one.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.7
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• pp.661-667
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• 2010

This paper presents a failure diagnosis and accommodation strategy which is capable of tolerating faulty actuators of a submersible vehicle. The proposed method is mainly based on a sliding mode control technique. The primary ideas include a performance index to describe the effectiveness of actuators, and a controller reconfiguration strategy using the actuator effectiveness index. The actuator effectiveness proposed in this work is defined as the relationship between the sliding surface and the controlled system behavior. The resulting actuator effectiveness is then used in reconfiguring the controller in order to counteract for the deteriorated control performance in the presence of a faulty actuator. The effectiveness of the proposed method is demonstrated by means of numerical simulations with a submersible vehicle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.3
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• pp.850-860
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• 1996

This paper considers a sliding mode controller for a depth and course control of a class of submersible Vehicles. Since the vehicle used here shows complex dynamic characteristics sensitive to speed variation and buoyancy, robustness in control of vertical and horizontal plane motions of the vehicle is achieved by using the sliding mode controller of which a structure varies according to a pre-designed principle, so called the variable structure control. To compare this controller with another in robustness, PID controller for the same model of vehicle is designed. From various simulations for two controllers, it is shown that the sliding mode controller is the more robust anainst to modeling errors and disturbances.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.776-779
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• 1992

This paper describes the auto-depth control system with depth control tank for low speed submersible vehicle that can be used for both near surface and deeply submerged keeping operations. The PDA control algorithm is used to design controller and adaptive notch filter is designed to eliminate the dominant frequency of seaway. The computer simulations demonstrate the excellent depth keeping performance of the controller under seaway effects.

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

• IEMEK Journal of Embedded Systems and Applications
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• v.13 no.2
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• pp.65-71
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• 2018

In order to make the underwater vehicle carry out the mission in a submarine environment, it is needed to plan a safe and efficient route to a given destination and prevent the autonomous submersible from colliding with obstacles while moving along the planned route. The function of collision avoidance makes the travel distance of the autonomous submersible longer. Moreover, it should move slowly near to obstacles against their moving disturbance. As a result, this invokes the degradation of the navigation efficiency in the process of collision avoidance. The side effect of the collision avoidance is not ignorable in the case of high congested environments such as the coast with many obstacles. In this paper, we suggest a path planning method which provides the route with minimum travel time considering collision avoidance in congested environment. For the purpose, we define environmental congestion map related to geometric information and obstacles. And we propose a method to consider the moving cost in the RRT scheme that provides the existing minimum distance path. We verified that the efficiency of our algorithm with simulation experiments.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.6
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• pp.389-394
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• 2018

Remotely operated vehicle(ROV) and autonomous underwater vehicle(AUV) have been used for underwater surveys, underwater exploration, resource harvesting, offshore plant maintenance and repair, and underwater construction. It is hard for people to work in the deep sea. Therefore, we need a vision control system of underwater submersible that can replace human eyes. However, many people have difficulty in developing a deep-sea image control system due to the deep sea special environment such as high pressure, brine, waterproofing and communication. In this paper, we will develop an Ethernet based remote image control system that can control the image mounted on ROV.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.4
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• pp.50-60
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• 2014

Many countries are paying efforts to the research and development of water-breathing ramjet propulsion for submersible vehicle with the super-cavitation which makes traveling at high speed in underwater possible. In this study, a conceptual design of an underwater vehicle with water-breathing ramjet was carried out. Mission profiles and operating conditions are determined by examining the operation environment. Drag is estimated based on the theories of super-cavitation and fluid mechanics. The sizing and performance analysis of the components were performed using thrust required, thrust and specific impulse of designed engine were verified.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.6
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• pp.550-558
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• 2019

The roll motion of a general vessel, which is more influenced by resonance as compared to other motions, adversely affects the passenger and hull. Therefore, reducing the roll motion through an anti-rolling system is critical, and most ships use various devices such as anti-rolling tanks, bilge keels, and fin stabilizers to accomplish this. In this study, a simplified model is developed for the application of an anti-rolling device for unmanned semi-submersible vessels. The applied anti-rolling device is installed on the stern and stem of a ship using a pair of servo motors with added weight, and the motor is controlled through the Arduino. The moment of the motor is designed and implemented based on a mathematical model such that it is calculated through the restoring force according to the heel angle of the ship. The performance of the proposed system was verified by utilizing the roll damping coefficient calculated by the free-roll decay test and logarithmic decrement method and was validated by a towing tank test. The system is expected to be used for unmanned vessels to perform sustainable missions.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.1-8
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• 2002

When a body enters waters, its original kinetic energy or momentum is distributed among the body and surrounding water in the form of added mass. Due to the transfer of the energy or momentum, the bode is subjected to the hydrodynamic impact forces and acceleration. This impact behavior can be an important criterion of submersible vehicle launched to the air. In this paper, based on Life-boat model, an approximate method is proposed for the evaluation of the forces and responses of cylindrical rigid bode by water entry impact. The impact forces are calculated by yon Karman's momentum theory and motion responses the body, especially acceleration, are calculated by a numerical integration of the motion equations derived by hydrodynamic force equilibrium. The proposed method is expected to be a simple but efficient tool lot the preliminary design or motion analysis of a body subjected to water entry impact.