Hyeung-Sik Choi - Academia.edu (original) (raw)
Papers by Hyeung-Sik Choi
In this study, we designed and developed an underwater LED communication system composed of an LE... more In this study, we designed and developed an underwater LED communication system composed of an LED and a photo sensor. In addition, we experimented with video data transmission in a water tank. Two communication modules were installed in the 3 m water tank, and the image data transmission test was successfully performed at a rate of 20 frames per second(FPS), image resolution of 480 × 272, and data communication speed of 4 Mbps.
Journal of Marine Science and Engineering
Underwater vehicles are a powerful tool that can assist oceanologists with measuring the state of... more Underwater vehicles are a powerful tool that can assist oceanologists with measuring the state of oceans on a large scale. The heading control is essential for the underwater vehicle to follow a specific path. This study describes the general decoupled dynamics of underwater vehicles, which is a nonlinear second-order differential equation considering linear and quadratic damping hydrodynamics. A novel aspect of this study is the development of a new analytical solution for the second-order nonlinear differential equation, which involves the heading motion of the underwater vehicle. In this study, the time-optimal trajectory is formulated as the closed-form solution for the heading dynamics of the underwater vehicle. The concept of this trajectory is based on the shortest arrival time when the maximum force from the thrusters is applied to the underwater vehicle. Finally, a simulation of the time-optimal trajectory and evaluation of the robustness of the controller were demonstrated...
Applied Sciences
The twin hybrid autonomous underwater vehicle (THAUV) is a novel type of unmanned underwater plat... more The twin hybrid autonomous underwater vehicle (THAUV) is a novel type of unmanned underwater platform that consists of a twin torpedo-shaped hull and is actuated by two buoyancy engines and two thrusters proposed in this paper. The THAUV was designed to have faster speed generated by the two buoyancy engines and two thrusters. The two buoyancy engines on each hull and the airfoil are mainly responsible for the diving and surfacing motion, and the thrusters drive the THAUV along the horizontal plane. The THAUV is capable of carrying more instrumentation and energy than a conventional hybrid autonomous underwater vehicle (HAUV) with a single buoyancy engine such that the THAUV can perform more exploration tasks and operate for a longer period in a one-time operation. Different from other unmanned underwater vehicles (UUVs) with two airfoils or wings, the THAUV has a single airfoil connecting the twin hull such that it does not require connecting bars and additional airfoils. For this ...
Journal of Marine Science and Engineering
A typical structure of an underwater glider (UG) includes a pair of fixed wings, and the hydrodyn... more A typical structure of an underwater glider (UG) includes a pair of fixed wings, and the hydrodynamic force driving the glider forward as descending or ascending in the water is generated primarily by the fixed wings. In this paper, a simplified glider motion model was established to analyze the dynamics in an easier way, and whose simulation results do not differ from the original one. Also, in the paper, the effects of the wing position and wing shape on the UG to the motion were studied. Since no direct analytic approach cannot be performed, the case study of the effects of six different wing positions and three wing shapes on gliding performances which are gliding speed, gliding angle and gliding path were performed through computer simulation. The simulation results revealed that when the fixed wing is located far from the buoyancy center to the tail end, more traveling range is achieved with less energy. Also, effect of the shape difference of the wings were analyzed. Shape ch...
In this paper, we examine controller design for pitch-axis motion of an underwater robotic vehicl... more In this paper, we examine controller design for pitch-axis motion of an underwater robotic vehicle in the vertical plane. First, an AUV mathematical model is established, Next, the control synthesis includes the ∞ H loop-shaping design. Then, the resulting controller has been evaluated extensively in both the frequency and the time-domains. Finally, it is found that the proposed vehicle system provides good maneuverability over a wide range of operating conditions, even under model uncertainties.
Journal of Institute of Control, Robotics and Systems, 2016
This paper presents the kinematic and dynamic analysis of the robot arm for inspection and rescue... more This paper presents the kinematic and dynamic analysis of the robot arm for inspection and rescue operations. The inspection robot arm has Pitch–Pitch–Pitch–Yaw motion for an optimal and stable view of the camera installed at the end of the manipulator. The rescue operation robot arm has Yaw–Pitch–Pitch–Roll motion to handle heavy tools. Additionally, both robot arms are waterproof, as they use the triple-layer O-ring. Furthermore, the dynamic equation including the damping force due to the mechanical seal for waterproofness was derived by using the Newton–Euler method. A control system using the ARM processor was developed and introduced in this paper, and its performance was verified through experiments.
Transactions of the Korean Society of Mechanical Engineers B, 2004
Journal of Advanced Research in Ocean Engineering, 2016
Journal of the Korean Society of Marine Engineering, 2011
An experimental study was carried out to measure the heat transfer coefficient in flow boiling to... more An experimental study was carried out to measure the heat transfer coefficient in flow boiling to deionized water in a microchannel having a hydraulic diameter of 500m. Tests were performed in the ranges of heat fluxes from 100 to 400 kW/㎡, vapor qualities from 0 to 0.2 and mass fluxes of 200, 400 and 600 kg/m 2 s. From the experimental results, it is found that the measured heat transfer coefficients is independent of mass flux and quality, and is somewhat dependent of heat flux. Measured data of heat transfer are compared to a few available correlations proposed for macroscale. The previous correlations for macroscale overpredicted the flow boiling heat transfer coefficient for the test conditions considered in this work.
International Journal of Precision Engineering and Manufacturing-Green Technology, 2016
In this paper, an underwater glider (UG) has been studied and developed for observing the ocean e... more In this paper, an underwater glider (UG) has been studied and developed for observing the ocean environment. The design and control of a new underwater glider (UG) having a high horizontal speed of the maximum 2.5 (Knots) was studied. For this, the capacity of buoyancy engine which performs 2.5 (Knots) horizontal speed was designed. Also, a controllable buoyancy engine to regulate the amount of buoyancy was developed for control of the pitching angle of UG. The mass shifter carrying the battery was designed for controlling pitching and yawing motion of the UG and the control system to control them was constructed. A mathematical modeling based on six degree-of-freedom dynamics equation including the buoyancy engine and mass shifter dynamics was performed to find the optimal pitching angle of the UG for maximum speed. Using the mathematical model, a simulation representing the vertical and horizontal speed of the UG with respect to pitching angles is developed and is presented. A number of experiments was performed to verify the accuracy of the simulation and the performance of the developed UG.
Lecture Notes in Electrical Engineering
Underwater Glider is now the powerful tool for ocean sampling using torpedo shape. Inspired by th... more Underwater Glider is now the powerful tool for ocean sampling using torpedo shape. Inspired by the manta ray with their effective maneuverability, the ray-type underwater glider is developed with a dual buoyancy engine and a movable mass. The shape of this platform allows for larger payload of battery and sensors. The analysis of fluid resistance performance is carried out through Computational Fluid Dynamics (CFD) for the optimum shape. Simulation of gliding dynamics of ray-type glider is studied for understanding the advantage of what nature has already done for the shape of the manta ray.
Journal of Marine Science and Technology, 2017
In this paper, we propose a novel global sliding mode controller (SMC) for an uncertain linear ti... more In this paper, we propose a novel global sliding mode controller (SMC) for an uncertain linear time-varying second order system. The proposed controller was implemented on the underwater vehicle (UV) with uncertainty of bounded parameters and disturbances within limited control input. By applying the proposed controller to the second-order UV system, the arrival time at the reference position and the maximum allowable acceleration are expressed in a closed-form equation if ranges of parametric uncertainties and reference inputs are specified. The closed-form equation can be utilized in designing the capacity of vehicle systems with the condition of the minimum arrival time to the target position. The superior performance of the proposed control scheme is validated through computer simulation. The simulation results show that this proposed controller forces the UV to track the designed time optimal trajectory very well, even with uncertainties. Its robustness can be guaranteed if bounds of the uncertainties are known.
2017 IEEE Underwater Technology (UT)
This paper introduces the GPS(Global Positioning System)-aided localization algorithm designed es... more This paper introduces the GPS(Global Positioning System)-aided localization algorithm designed especially for improvement for position error due to dead reckoning using DVL(Doppler Velocity Logger) and TCM(Tilt-compensated Compass Module). In order to verify fundamental performance of proposed algorithm, dynamic simulation was performed. As a result, it was verified that locational error is bounded with modest distance, after estimating the heading bias error of TCM and position of AUV(Autonomous Underwater Vehicle) using GPS positional data, which is received when surfaced.
OCEANS 2017 – Anchorage, 2017
The underwater vehicle-manipulator system (UVMS) generally has more degrees of freedom than those... more The underwater vehicle-manipulator system (UVMS) generally has more degrees of freedom than those required to perform a given task. Because of these extra of degrees of freedom, UVMS has infinite combinations of joint velocities. In this paper, in order to generate the joint angle trajectories of the manipulator, a redundancy resolution is performed to minimize the distance between the position of ZMP and the mass center of the underwater vehicle. Proposed algorithm helps the whole system to keep the dynamic stability while the UVMS conduct a given task. To evaluate the proposed ZMP algorithm and redundancy resolution method, a testbed composed of redundant manipulator was developed. The results show that ZMP algorithm helps the stability of the UVMS while the end-effector of the manipulator tracks the desired trajectory accurately.
Journal of the Korean Society of Marine Engineering, 2011
Abstract: In this paper, a temperature control for LED(Light Emitting Diode) lamp using a cooling... more Abstract: In this paper, a temperature control for LED(Light Emitting Diode) lamp using a cooling fan isstudied. An efficient temperature control scheme for the LED lamp using the fan wind at the lowest soundnoise is studied. Also, for minimization study of sound noise and temperature control of an LED lamp, asequential control algorithm using the cooling fan at the lowest sound noise is presented. For the study, after measurement of the minimum sound noise of the fan and related temperature of the LED lamp through tests, experiments on temperature control of the LED lamp using the fan was performed. Key words: Heat sink, Cooling fan, Cooling system, Sound noise control †교신저자(한국해양대학교기계공학과 hchoi@hhu.ac.kr, Tel: 051-410-4297)1 한국해양대학교 기계 에너지 시스템 공학부2 한국해양대학교 기관시스템 공학부 1. 서 론 화석에너지의 고갈 및 환경문제로 인해 에너지를 효율적으로 사용하는 것이 중요한 이슈가 되고 있다. 전기 에너지 중 조명에 사용되는 에너지의 양이 총 전기에너지 사용량의 약 20%를 차지한다. 현재 사용하는 조명으로는 형광등 외에도 백열등, 할로겐 등이 있으나 이들을 대체하는 조명원으로 LED가 있다. LED는 저 소비전력, 뛰어난 내구성, 경제성, 고응답성 및 수명이 반영구적이라...
Machines
Unmanned Surface Vessels (USVs) have witnessed an increasing growth in demand for development due... more Unmanned Surface Vessels (USVs) have witnessed an increasing growth in demand for development due to their compactness, mobility and maneuverability, which make them well-suited for environmental monitoring on narrow water in Vietnam in particular and in general at several similar tropical regions. However, current surface vessels are limited to operation on open water only. In this paper, we design a USV, namely, VIAM-USV2000, equipped with advanced autonomous capabilities to satisfactorily carry out missions in confined riverine environments. More specifically, our prototype is designed to follow a smooth B-Spline path that is self-planned to meet the limiting curvature and avoid static obstacles. Moreover, the vessel is capable of avoiding dynamic obstacles by an advanced Set-based Guidance mechanism. Simulated and experimental results at a local lake prove the effectiveness of the proposed capabilities, thereby paving the way for the extensive deployment of USVs in many real-wor...
In this paper, an analysis on the design and mechanics of the underwater tracked vehicle (UTV) wi... more In this paper, an analysis on the design and mechanics of the underwater tracked vehicle (UTV) with a rock crusher (RC) tool for rock excavation has to be considered and performed. The objective of this paper is to analyze the mechanics of the UTV system that are affected by the RC force and torque for underwater rock cutting. For this, the forces and moments on the RC tool based on the analysis of the mechanics of the individual cutter tool are determined. Also, a mathematical expression is derived for the forces and moment of the combined UTV system with RC tool for rock excavation. For the design of the UTV system, the required tractive thrust and down thrust force were analysed, and the moment to the rotor carriage caused by the cutting system is studied. To support the validity of the analyses, a number of numerical simulations are performed using the derived equations.
2012 12th International Conference on Control, Automation and Systems, 2012
This paper presents a design of self-tuning gain depth controller for the autonomous underwater v... more This paper presents a design of self-tuning gain depth controller for the autonomous underwater vehicle KAUV-1 which has been under development at the Intelligent Robot & Automation Lab, Korea Maritime University (KIAL). The vehicle is shaped like a torpedo with light weight and small size and used for marine exploration and monitoring. The KAUV-1 has a unique ducted propeller located at aft end with yawing actuation acting as a rudder. For depth control, the KAUV-1 uses a mass shifter mechanism to change its center of gravity, consequently, can control pitch angle and depth of the vehicle. A design of classical PD depth controller for the KAUV-1 was presented and analyzed in [11]. However, it has inherent drawback of gains, that is their values are fixed. Meanwhile, in different operation modes, vehicle dynamics might have different impacts on the behavior of the vehicle, for example, ones in modes of diving and moving up as mentioned in [11]. This requires a set of flexible or sel...
Underwater Glider is now the powerful tool for ocean sampling using torpedo shape. Inspired by th... more Underwater Glider is now the powerful tool for ocean sampling using torpedo shape. Inspired by the manta ray with their effective maneuverability, the ray-type underwater glider is developed with a dual buoyancy engine and a movable mass. The shape of this platform allows for larger payload of battery and sensors. The analysis of fluid resistance performance is carried out through Computational Fluid Dynamics (CFD) for the optimum shape. Simulation of gliding dynamics of ray-type glider is studied for understanding the advantage of what nature has already done for the shape of the manta ray.
Journal of the Korean Society for Precision Engineering, 2000
A design of the global optimal sliding mode control is presented to control the second order unce... more A design of the global optimal sliding mode control is presented to control the second order uncertain time varying system with torque limit. With specified ranges of parametric uncertainties and torque limit, the minimum arrival time to reference inputs can be calculated. The proposed control scheme is applied to the motor system carrying loads. The merit of the proposed control scheme is that the arriving time at the reference input, which is the revolution angle, and the maximum allowable acceleration are expressed in a closed form solution. The superior performance of the proposed control scheme is validated by the computer simulation and experiments comparing with other sliding mode controllers.
In this study, we designed and developed an underwater LED communication system composed of an LE... more In this study, we designed and developed an underwater LED communication system composed of an LED and a photo sensor. In addition, we experimented with video data transmission in a water tank. Two communication modules were installed in the 3 m water tank, and the image data transmission test was successfully performed at a rate of 20 frames per second(FPS), image resolution of 480 × 272, and data communication speed of 4 Mbps.
Journal of Marine Science and Engineering
Underwater vehicles are a powerful tool that can assist oceanologists with measuring the state of... more Underwater vehicles are a powerful tool that can assist oceanologists with measuring the state of oceans on a large scale. The heading control is essential for the underwater vehicle to follow a specific path. This study describes the general decoupled dynamics of underwater vehicles, which is a nonlinear second-order differential equation considering linear and quadratic damping hydrodynamics. A novel aspect of this study is the development of a new analytical solution for the second-order nonlinear differential equation, which involves the heading motion of the underwater vehicle. In this study, the time-optimal trajectory is formulated as the closed-form solution for the heading dynamics of the underwater vehicle. The concept of this trajectory is based on the shortest arrival time when the maximum force from the thrusters is applied to the underwater vehicle. Finally, a simulation of the time-optimal trajectory and evaluation of the robustness of the controller were demonstrated...
Applied Sciences
The twin hybrid autonomous underwater vehicle (THAUV) is a novel type of unmanned underwater plat... more The twin hybrid autonomous underwater vehicle (THAUV) is a novel type of unmanned underwater platform that consists of a twin torpedo-shaped hull and is actuated by two buoyancy engines and two thrusters proposed in this paper. The THAUV was designed to have faster speed generated by the two buoyancy engines and two thrusters. The two buoyancy engines on each hull and the airfoil are mainly responsible for the diving and surfacing motion, and the thrusters drive the THAUV along the horizontal plane. The THAUV is capable of carrying more instrumentation and energy than a conventional hybrid autonomous underwater vehicle (HAUV) with a single buoyancy engine such that the THAUV can perform more exploration tasks and operate for a longer period in a one-time operation. Different from other unmanned underwater vehicles (UUVs) with two airfoils or wings, the THAUV has a single airfoil connecting the twin hull such that it does not require connecting bars and additional airfoils. For this ...
Journal of Marine Science and Engineering
A typical structure of an underwater glider (UG) includes a pair of fixed wings, and the hydrodyn... more A typical structure of an underwater glider (UG) includes a pair of fixed wings, and the hydrodynamic force driving the glider forward as descending or ascending in the water is generated primarily by the fixed wings. In this paper, a simplified glider motion model was established to analyze the dynamics in an easier way, and whose simulation results do not differ from the original one. Also, in the paper, the effects of the wing position and wing shape on the UG to the motion were studied. Since no direct analytic approach cannot be performed, the case study of the effects of six different wing positions and three wing shapes on gliding performances which are gliding speed, gliding angle and gliding path were performed through computer simulation. The simulation results revealed that when the fixed wing is located far from the buoyancy center to the tail end, more traveling range is achieved with less energy. Also, effect of the shape difference of the wings were analyzed. Shape ch...
In this paper, we examine controller design for pitch-axis motion of an underwater robotic vehicl... more In this paper, we examine controller design for pitch-axis motion of an underwater robotic vehicle in the vertical plane. First, an AUV mathematical model is established, Next, the control synthesis includes the ∞ H loop-shaping design. Then, the resulting controller has been evaluated extensively in both the frequency and the time-domains. Finally, it is found that the proposed vehicle system provides good maneuverability over a wide range of operating conditions, even under model uncertainties.
Journal of Institute of Control, Robotics and Systems, 2016
This paper presents the kinematic and dynamic analysis of the robot arm for inspection and rescue... more This paper presents the kinematic and dynamic analysis of the robot arm for inspection and rescue operations. The inspection robot arm has Pitch–Pitch–Pitch–Yaw motion for an optimal and stable view of the camera installed at the end of the manipulator. The rescue operation robot arm has Yaw–Pitch–Pitch–Roll motion to handle heavy tools. Additionally, both robot arms are waterproof, as they use the triple-layer O-ring. Furthermore, the dynamic equation including the damping force due to the mechanical seal for waterproofness was derived by using the Newton–Euler method. A control system using the ARM processor was developed and introduced in this paper, and its performance was verified through experiments.
Transactions of the Korean Society of Mechanical Engineers B, 2004
Journal of Advanced Research in Ocean Engineering, 2016
Journal of the Korean Society of Marine Engineering, 2011
An experimental study was carried out to measure the heat transfer coefficient in flow boiling to... more An experimental study was carried out to measure the heat transfer coefficient in flow boiling to deionized water in a microchannel having a hydraulic diameter of 500m. Tests were performed in the ranges of heat fluxes from 100 to 400 kW/㎡, vapor qualities from 0 to 0.2 and mass fluxes of 200, 400 and 600 kg/m 2 s. From the experimental results, it is found that the measured heat transfer coefficients is independent of mass flux and quality, and is somewhat dependent of heat flux. Measured data of heat transfer are compared to a few available correlations proposed for macroscale. The previous correlations for macroscale overpredicted the flow boiling heat transfer coefficient for the test conditions considered in this work.
International Journal of Precision Engineering and Manufacturing-Green Technology, 2016
In this paper, an underwater glider (UG) has been studied and developed for observing the ocean e... more In this paper, an underwater glider (UG) has been studied and developed for observing the ocean environment. The design and control of a new underwater glider (UG) having a high horizontal speed of the maximum 2.5 (Knots) was studied. For this, the capacity of buoyancy engine which performs 2.5 (Knots) horizontal speed was designed. Also, a controllable buoyancy engine to regulate the amount of buoyancy was developed for control of the pitching angle of UG. The mass shifter carrying the battery was designed for controlling pitching and yawing motion of the UG and the control system to control them was constructed. A mathematical modeling based on six degree-of-freedom dynamics equation including the buoyancy engine and mass shifter dynamics was performed to find the optimal pitching angle of the UG for maximum speed. Using the mathematical model, a simulation representing the vertical and horizontal speed of the UG with respect to pitching angles is developed and is presented. A number of experiments was performed to verify the accuracy of the simulation and the performance of the developed UG.
Lecture Notes in Electrical Engineering
Underwater Glider is now the powerful tool for ocean sampling using torpedo shape. Inspired by th... more Underwater Glider is now the powerful tool for ocean sampling using torpedo shape. Inspired by the manta ray with their effective maneuverability, the ray-type underwater glider is developed with a dual buoyancy engine and a movable mass. The shape of this platform allows for larger payload of battery and sensors. The analysis of fluid resistance performance is carried out through Computational Fluid Dynamics (CFD) for the optimum shape. Simulation of gliding dynamics of ray-type glider is studied for understanding the advantage of what nature has already done for the shape of the manta ray.
Journal of Marine Science and Technology, 2017
In this paper, we propose a novel global sliding mode controller (SMC) for an uncertain linear ti... more In this paper, we propose a novel global sliding mode controller (SMC) for an uncertain linear time-varying second order system. The proposed controller was implemented on the underwater vehicle (UV) with uncertainty of bounded parameters and disturbances within limited control input. By applying the proposed controller to the second-order UV system, the arrival time at the reference position and the maximum allowable acceleration are expressed in a closed-form equation if ranges of parametric uncertainties and reference inputs are specified. The closed-form equation can be utilized in designing the capacity of vehicle systems with the condition of the minimum arrival time to the target position. The superior performance of the proposed control scheme is validated through computer simulation. The simulation results show that this proposed controller forces the UV to track the designed time optimal trajectory very well, even with uncertainties. Its robustness can be guaranteed if bounds of the uncertainties are known.
2017 IEEE Underwater Technology (UT)
This paper introduces the GPS(Global Positioning System)-aided localization algorithm designed es... more This paper introduces the GPS(Global Positioning System)-aided localization algorithm designed especially for improvement for position error due to dead reckoning using DVL(Doppler Velocity Logger) and TCM(Tilt-compensated Compass Module). In order to verify fundamental performance of proposed algorithm, dynamic simulation was performed. As a result, it was verified that locational error is bounded with modest distance, after estimating the heading bias error of TCM and position of AUV(Autonomous Underwater Vehicle) using GPS positional data, which is received when surfaced.
OCEANS 2017 – Anchorage, 2017
The underwater vehicle-manipulator system (UVMS) generally has more degrees of freedom than those... more The underwater vehicle-manipulator system (UVMS) generally has more degrees of freedom than those required to perform a given task. Because of these extra of degrees of freedom, UVMS has infinite combinations of joint velocities. In this paper, in order to generate the joint angle trajectories of the manipulator, a redundancy resolution is performed to minimize the distance between the position of ZMP and the mass center of the underwater vehicle. Proposed algorithm helps the whole system to keep the dynamic stability while the UVMS conduct a given task. To evaluate the proposed ZMP algorithm and redundancy resolution method, a testbed composed of redundant manipulator was developed. The results show that ZMP algorithm helps the stability of the UVMS while the end-effector of the manipulator tracks the desired trajectory accurately.
Journal of the Korean Society of Marine Engineering, 2011
Abstract: In this paper, a temperature control for LED(Light Emitting Diode) lamp using a cooling... more Abstract: In this paper, a temperature control for LED(Light Emitting Diode) lamp using a cooling fan isstudied. An efficient temperature control scheme for the LED lamp using the fan wind at the lowest soundnoise is studied. Also, for minimization study of sound noise and temperature control of an LED lamp, asequential control algorithm using the cooling fan at the lowest sound noise is presented. For the study, after measurement of the minimum sound noise of the fan and related temperature of the LED lamp through tests, experiments on temperature control of the LED lamp using the fan was performed. Key words: Heat sink, Cooling fan, Cooling system, Sound noise control †교신저자(한국해양대학교기계공학과 hchoi@hhu.ac.kr, Tel: 051-410-4297)1 한국해양대학교 기계 에너지 시스템 공학부2 한국해양대학교 기관시스템 공학부 1. 서 론 화석에너지의 고갈 및 환경문제로 인해 에너지를 효율적으로 사용하는 것이 중요한 이슈가 되고 있다. 전기 에너지 중 조명에 사용되는 에너지의 양이 총 전기에너지 사용량의 약 20%를 차지한다. 현재 사용하는 조명으로는 형광등 외에도 백열등, 할로겐 등이 있으나 이들을 대체하는 조명원으로 LED가 있다. LED는 저 소비전력, 뛰어난 내구성, 경제성, 고응답성 및 수명이 반영구적이라...
Machines
Unmanned Surface Vessels (USVs) have witnessed an increasing growth in demand for development due... more Unmanned Surface Vessels (USVs) have witnessed an increasing growth in demand for development due to their compactness, mobility and maneuverability, which make them well-suited for environmental monitoring on narrow water in Vietnam in particular and in general at several similar tropical regions. However, current surface vessels are limited to operation on open water only. In this paper, we design a USV, namely, VIAM-USV2000, equipped with advanced autonomous capabilities to satisfactorily carry out missions in confined riverine environments. More specifically, our prototype is designed to follow a smooth B-Spline path that is self-planned to meet the limiting curvature and avoid static obstacles. Moreover, the vessel is capable of avoiding dynamic obstacles by an advanced Set-based Guidance mechanism. Simulated and experimental results at a local lake prove the effectiveness of the proposed capabilities, thereby paving the way for the extensive deployment of USVs in many real-wor...
In this paper, an analysis on the design and mechanics of the underwater tracked vehicle (UTV) wi... more In this paper, an analysis on the design and mechanics of the underwater tracked vehicle (UTV) with a rock crusher (RC) tool for rock excavation has to be considered and performed. The objective of this paper is to analyze the mechanics of the UTV system that are affected by the RC force and torque for underwater rock cutting. For this, the forces and moments on the RC tool based on the analysis of the mechanics of the individual cutter tool are determined. Also, a mathematical expression is derived for the forces and moment of the combined UTV system with RC tool for rock excavation. For the design of the UTV system, the required tractive thrust and down thrust force were analysed, and the moment to the rotor carriage caused by the cutting system is studied. To support the validity of the analyses, a number of numerical simulations are performed using the derived equations.
2012 12th International Conference on Control, Automation and Systems, 2012
This paper presents a design of self-tuning gain depth controller for the autonomous underwater v... more This paper presents a design of self-tuning gain depth controller for the autonomous underwater vehicle KAUV-1 which has been under development at the Intelligent Robot & Automation Lab, Korea Maritime University (KIAL). The vehicle is shaped like a torpedo with light weight and small size and used for marine exploration and monitoring. The KAUV-1 has a unique ducted propeller located at aft end with yawing actuation acting as a rudder. For depth control, the KAUV-1 uses a mass shifter mechanism to change its center of gravity, consequently, can control pitch angle and depth of the vehicle. A design of classical PD depth controller for the KAUV-1 was presented and analyzed in [11]. However, it has inherent drawback of gains, that is their values are fixed. Meanwhile, in different operation modes, vehicle dynamics might have different impacts on the behavior of the vehicle, for example, ones in modes of diving and moving up as mentioned in [11]. This requires a set of flexible or sel...
Underwater Glider is now the powerful tool for ocean sampling using torpedo shape. Inspired by th... more Underwater Glider is now the powerful tool for ocean sampling using torpedo shape. Inspired by the manta ray with their effective maneuverability, the ray-type underwater glider is developed with a dual buoyancy engine and a movable mass. The shape of this platform allows for larger payload of battery and sensors. The analysis of fluid resistance performance is carried out through Computational Fluid Dynamics (CFD) for the optimum shape. Simulation of gliding dynamics of ray-type glider is studied for understanding the advantage of what nature has already done for the shape of the manta ray.
Journal of the Korean Society for Precision Engineering, 2000
A design of the global optimal sliding mode control is presented to control the second order unce... more A design of the global optimal sliding mode control is presented to control the second order uncertain time varying system with torque limit. With specified ranges of parametric uncertainties and torque limit, the minimum arrival time to reference inputs can be calculated. The proposed control scheme is applied to the motor system carrying loads. The merit of the proposed control scheme is that the arriving time at the reference input, which is the revolution angle, and the maximum allowable acceleration are expressed in a closed form solution. The superior performance of the proposed control scheme is validated by the computer simulation and experiments comparing with other sliding mode controllers.