Jong Kwang Lee

Bridge‐transported bilateral master–slave servo manipulator system for remote manipulation in spent nuclear fuel processing plant

A bridge-transported bilateral master–slave servo manipulator system called the Bridge-Transported Dual-Arm Servo-Manipulator (BDSM) was developed for remote manipulation at the Pyroprocess Integrated Inactive Demonstration (PRIDE) facility. Its many innovative design concepts include a motion-decoupled, cable-drive mechanism, fully counterbalanced linkage structure, and interface system for easy attachment/detachment of the arms during remote maintenance. In addition, the manipulator is mounted at the end of a novel redundant-drive extensible telescopic boom with a synchronized compact cabling management system. The BDSM is currently installed in the Remote Handling Evaluation Mock-up (RHEM), where it has successfully completed operating tests with a remote control system incorporating a bilateral force-reflection controller. Good tracking performance was confirmed regardless of the payload, allowing highly transparent control. The system is thus expected to achieve its design goals in dexterous remote handling tasks in PRIDE.

Development of an overhead crane for remote handling tasks at nuclear facility

An overhead crane with telescopic motion was developed to transport servo-manipulator for remote handling tasks in the PyRoprocess Integrated inactive DEmonstration facility (PRIDE). The overhead crane consists of a telescope, trolley system, cabling management system, girder and rotation interface. The telescope of the overhead crane was designed as a cylindrical pipe-based tube type in order to increase the bending and twisting rigidity and it has a long extended length and short retracted length. The cabling management system was designed to be compact in size in order to accommodate the changed cable length according to the telescopic motion. All drive modules were designed to have spare modules in order to prepare for emergencies. As design verification process, structural analysis was performed on some important modules. Currently, the overhead crane is installed at a test bay in KAERI, and it is being tested.

Hybrid robust controller design for a two mass system with disturbance compensation

In this paper we describe a robust control method for when a torque or inertia change in a two mass system. There are various controllers that represent a robustness. Especially, the disturbance observer (DOB) and H infin of them are well known for their efficiency with respect to a disturbance rejection. Actually, there is method to make use of two controllers together as a cascade type. But the performance of this control is not efficient due to a fault in that the system degree increases when it designs a controller. In this paper, a hybrid type disturbance compensation is proposed for robust control methods. Basically, a hybrid robust controller is driven by the H infin controller, and a H infin control of the limited scope of a control for a disturbance when compared with the disturbance observer (DOB) will be compensated for by the H infin control input. We performed a DOB and H infin comparison simulation to prove the performance of the controller that is proposed in this paper. We performed simulations for a change in the torque and inertia and found that the proposed controller showed a small error. For a verification, we performed simulations by using MATLAB/SIMULINK.

Bridge transported servo manipulator system for remote handling tasks under a radiation environment

Purpose – This paper aims to describe bridge transported servo‐manipulator (BTSM) system, which was developed to overcome the limited workspace of the conventional mechanical master‐slave manipulators in a hot cell.Design/methodology/approach – The BTSM system consists of four components: a transporter with a telescoping tubeset, a slave manipulator, a master manipulator, and a remote control system. The slave manipulator is able to move horizontally, transversely, and vertically by using the transporter.Findings – The performance test of the BTSM system has been carried out in terms of basic functions such as force threshold, bilateral control and force reflection characteristic.Originality/value – With respect to design characteristic, the BTSM system has the novel features in that the individual motor modules or the slave manipulator can be repaired in a fully remote manner in case of catastrophic failure. Also, a 3D viewing camera facilitates remote tasks giving human operators realistic environmental...

Design of Bridge Transport System with Equal Incremental Telescopic Motion

This paper introduces the design of a bridge transport system with a telescopic tube for positioning equipment to perform remote handling tasks in a radioactive facility. It consists of an extensible and retractable telescopic tube assembly for z-direction motion, a cabling system for management of power and signal cables, and a trolley system for transverse motion and accommodating servo drives. The working environment for the bridge transport system with the telescopic tube requires strict geometrical constraints, including a short height, short telescopic tube length when retracted, and a long stroke. These constraints were met by solving a nonlinear programming problem involving the optimal dimensions. This paper introduces a cabling system for effective management of cables with changeable lengths to accommodate telescopic motions and a selection guide for servo drives that are sufficient to drive the system.

A manipulator workspace generation algorithm using a singular value decomposition

This paper presents a manipulator workspace boundary generation algorithm that can be easily implemented as a computer algorithm. The algorithm searches the workspace boundary on the basis of slice curves which are defined as the cross-section of the workspace boundary with planes parallel to XY , YZ, or XZ plane. The collection of these slice curves represents a tomographic view of the workspace boundary. The proposed workspace boundary searching algorithm is composed of two stages. First stage is for estimating the boundary by using a linearization model of the forward kinematic equation, which searches the feasible direction vector at a current point while considering both the kinematic condition and the joint limits. The other is for correcting the estimated boundary point to an exact boundary point by solving an optimization problem that maximizes a fuzzy set like cost function.

Simultaneous Intrinsic and Extrinsic Parameter Identification of a Hand-Mounted Laser-Vision Sensor

In this paper, we propose a simultaneous intrinsic and extrinsic parameter identification of a hand-mounted laser-vision sensor (HMLVS). A laser-vision sensor (LVS), consisting of a camera and a laser stripe projector, is used as a sensor component of the robotic measurement system, and it measures the range data with respect to the robot base frame using the robot forward kinematics and the optical triangulation principle. For the optimal estimation of the model parameters, we applied two optimization techniques: a nonlinear least square optimizer and a particle swarm optimizer. Best-fit parameters, including both the intrinsic and extrinsic parameters of the HMLVS, are simultaneously obtained based on the least-squares criterion. From the simulation and experimental results, it is shown that the parameter identification problem considered was characterized by a highly multimodal landscape; thus, the global optimization technique such as a particle swarm optimization can be a promising tool to identify the model parameters for a HMLVS, while the nonlinear least square optimizer often failed to find an optimal solution even when the initial candidate solutions were selected close to the true optimum. The proposed optimization method does not require good initial guesses of the system parameters to converge at a very stable solution and it could be applied to a kinematically dissimilar robot system without loss of generality.

Development of a control system for master-slave operation

A prototype of a master-slave servo manipulator system has been developed for the use in the PRIDE (PyRoprocess Integrated inactive DEmonstration) facility where the integrated performance of full pyroprocess flow will be verified. The PRIDE facility is designed to have an argon-atmosphere cell which prohibits direct access by human operators. Therefore, all the operation and maintenance of the process equipment is performed remotely through a master-slave manipulation. In this work, we present the development of a remote control system for a bridge transported dual arm servo-manipulator.

ERGONOMIC ANALYSIS OF A TELEMANIPULATION TECHNIQUE FOR A PYROPROCESS DEMONSTRATION FACILITY

In this study, remote handling strategies for a large-scale argon cell facility were considered. The suggested strategies were evaluated by several types of field test. The teleoperation tasks were performed using a developed remote handling system, which enabled traveling over entire cell area using a bridge transport system. Each arm of the system had six DOFs (degrees of freedom), and the bridge transport system had four DOFs. However, despite the dexterous manipulators and redundant monitoring system, many operators, including professionals, experienced difficulties in operating the remote handling system. This was because of the lack of a strategy for handling the installed camera system, and the difficulty in recognizing the gripper pose, which might fall outside the FOV (field of vision) of the system during teleoperation. Hence, in this paper, several considerations for the remote handling tasks performed in the target facility were discussed, and the tasks were analyzed based on ergonomic factors such as the workload. Toward the development of a successful operation strategy, several ergonomic issues, such as active/passive view of the remote handling system, eye/hand alignment, and FOV were considered. Furthermore, using the method for classifying remote handling tasks, several unit tasks were defined and evaluated.

Development of a Remote Handling System in an Integrated Pyroprocessing Facility

Over the course of a decade-long research programme, the Korea Atomic Energy Research Institute (KAERI) has developed several remote handling systems for use in pyroprocessing research facilities. These systems are now used successfully for the operation and maintenance of processing equipment. The most recent remote handling system is the bridge-transported dual arm servo-manipulator system (BDSM), which is used for remote operation at the worlds largest pyroprocess integrated inactive demonstration facility (PRIDE). Accurate and reliable servo-control is the basic requirement for the BDSM to accomplish any given tasks successfully in a hotcell environment. To achieve this end, the hardware and software of a digital signal processor-based remote control system were fully custom-developed and implemented to control the BDSM. To reduce the residual vibration of the BDSM, several input profiles, including input shaping, were carefully chosen and evaluated. Furthermore, a time delay controller was employed to achieve good tracking performance and systematic gain tuning. The experimental results demonstrate that the applied control algorithms are more effective than conventional approaches. The BDSM successfully completed its performance tests at a mock-up and was installed at PRIDE for real-world operation. The remote handling system at KAERI is expected to advance the actualization of pyroprocessing.