• Journal of Advanced Marine Engineering and Technology
• /
• v.26 no.5
• /
• pp.581-588
• /
• 2002

A fuzzy learning control algorithm is proposed in this paper. In this method, two fuzzy controllers are used as a feedback and a feedforward type. The fuzzy feedback controller can be designed using simple knowledge for the controlled system. On the other hand, the fuzzy feedforward controller has a self-organizing mechanism and therefore, it does not need any knowledge in advance. The effectiveness of the proposed algorithm is demonstrated by experiment on the position and force control problem of a parallelogram type robot manipulator with two degrees of freedom. It is shown that the rapid learning and the robustness can be achieved by adopting the proposed method.

• Journal of Advanced Marine Engineering and Technology
• /
• v.18 no.4
• /
• pp.25-32
• /
• 1994

This paper presents a robust impedance controller design to coordinate a robot manipulator under system uncertainties while regulating external forces. By an impedance approach, the relationship between the motion and external forces is defined. Due to the system uncertainties, two kind of sliding mode control schemes based on the impedance approach are derived to ensure that the manipulator end-effector follows a desired trajectory and the force applied to end effector is regulated according to a target impendance. A stability condition is shown according to a sliding condition. To evaluate the devised control scheme, a numerical example is shown.

• Journal of Computational Design and Engineering
• /
• v.1 no.4
• /
• pp.243-255
• /
• 2014

The present study describes the development of control hardware and software for a mobile welding robot. This robot is able to move and perform welding tasks in a double hull structure. The control hardware consists of a main controller and a welding machine controller. Control software consists of four layers. Each layer consists of modules. Suitable combinations of modules enable the control software to perform the required tasks. Control software is developed using C programming under QNX operating system. For the modularizing architecture of control software, we designed control software with four layers: Task Manager, Task Planner, Actions for Task, and Task Executer. The embedded controller and control software was applied to the mobile welding robot for successful execution of the required tasks. For evaluate this imbedded controller and control software, the field tests are conducted, it is confirmed that the developed imbedded controller of mobile welding robot for shipyard is well designed and implemented.

• The Journal of Korea Robotics Society
• /
• v.13 no.2
• /
• pp.79-85
• /
• 2018

This study focuses on autonomous exploration based on map expansion for an underwater robot equipped with acoustic sonars. Map expansion is applicable to large-area mapping, but it may affect localization accuracy. Thus, as the key contribution of this paper, we propose a method for underwater autonomous exploration wherein the robot determines the trade-off between map expansion ratio and position accuracy, selects which of the two has higher priority, and then moves to a mission step. An occupancy grid map is synthesized by utilizing the measurements of an acoustic range sonar that determines the probability of occupancy. This information is then used to determine a path to the frontier, which becomes the new search point. During area searching and map building, the robot revisits artificial landmarks to improve its position accuracy as based on imaging sonar-based recognition and EKF-SLAM if the position accuracy is above the predetermined threshold. Additionally, real-time experiments were conducted by using an underwater robot, yShark, to validate the proposed method, and the analysis of the results is discussed herein.

• Journal of Ocean Engineering and Technology
• /
• v.26 no.6
• /
• pp.59-65
• /
• 2012

In this research, a novel mater arm was studied as a teaching device for an underwater revolute robot arm used as a slave arm. The master arm was designed to be a seven-degree-of-freedom (DOF) structure, with a structure similar to that of the slave arm, and to be desktop size to allow it to be worn on a human arm. The master arm with encoders on the joints was used as an input device for teaching a slave robot arm. In addition, small electric magnets were installed at the joints of the master arm to generate the haptic force. A control system was designed to sense excessive force and torque in the joints of the master arm and protect it by controlling the position and velocity of the slave arm through the encoder signal of the master arm.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.25 no.4
• /
• pp.342-348
• /
• 2015

Recently, many waste is getting into the ocean because of natural disasters and trash of illegality. These destroy the marine ecosystem and the great views around the ocean. Many methods are used for the removal of the waste in the ocean and one of the main waste forms is floating debris. In order to remove the waste, the nets are mostly used and the ships are recently used. However, many problems are occurred due to low number of people and techniques in the ship-based removal. To solve this problem, a surface robot for floating debris removal is developed. To verify the performance of the developed robot, tests of surge, yaw, and floating debris removal are executed. The test results show the possibility of real applications and the need for additional studies.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.12
• /
• pp.106-113
• /
• 1996

This paper presents a modeling of undersea robot manipulators and a control scheme appropriate for manipulating the manipulators working under the unstrcuctured sea water environment. Under the sea, the added mass and added moment of inertia, buoyancy, and drag forces should be considered in modeling the dynamics of the robot manipulators. Due to the complexity of them, the desired dynamics of manipulators can not be accomplished by the conventional control schemes. Hence, a sliding mode control is applied to control the modeling error.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.1
• /
• pp.121-128
• /
• 2016

A furan mold design and machining system for marine propeller casting was developed. In general, a large marine propeller is produced by casting in a foundry, where the upper and lower molds are constructed of cement or other materials like furan. Then, the cast workpiece is machined and manually ground. Currently, furan mold construction requires a series of manual tasks. This introduces a fairly large amount of stock allowances, which require a considerable number of man-hours for later machining and grinding, and also increase the work processes. A mold design and off-line robot programming software tool with a six-axis robot hardware system was developed to enhance the shape accuracy and productivity. This system will be applied in a Korean ship building company.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.291-292
• /
• 2011

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.13 no.3
• /
• pp.223-228
• /
• 2007

This paper investigated on mechanical characteristic of Al alloy for ship's welded with various welding techniques such as TIG, MIG welding and welding by robot. The yield strength, tensile strength and elongation in TIG welding present 83.9%, 64.6% and 21.9% compare to those in base metal, respectively. The MIG welding is carried out with welding eletrode of ER5183 and ER5356. The mechanical characteristics in ER5356 are improved at approximately 2-4% for ER5183. The mechanical properties of 5083O in welding by robot are better than those of 5456-H116.