Byung-Suk Park

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.

Robotic virtual manipulations of a nuclear hot‐cell digital mock‐up system

Purpose – Hot‐cells are shielded structures protecting individuals from radioactive materials. The purpose of this paper is to propose a design approach for a hot‐cell simulator using digital mock‐up (DMU) technology and combining Haptic guided complex robotic manipulation for assembly tasks in a virtual environment.Design/methodology/approach – The principal reason for developing a simulator was to explore the feasibility of hot‐cell structure design and collision‐free assembly process. For this, a simulation design philosophy has been proposed that includes DMU facility offering the ability of analyzing the operations and performing complex robotic manipulations in the virtual hot‐cell environment. Furthermore, enhanced Haptic mapping for tele‐manipulation is proposed for training and guidance purposes.Findings – From the analysis and task scenarios performed in virtual simulator, the optimal positions of the manipulators and need of (bridge transport dual arm servo‐manipulators) type were identified. O...

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.

Simulation of remote manipulator using a virtual engineering

This study deals with the design and establishment of a modeling and simulation tool for an evaluation of the accessibility and operability of a remote manipulation in an advanced spent fuel conditioning process facility. This article describes different kinds of modules to analyze and evaluate the behavior of a manipulator and proposes a system architecture which illustrates an interface between its modules. The mathematical background in relation to forward and inverse kinematics for a virtual manipulator to access the devices is explained. To find out if a virtual manipulator by using a 6-DOF haptic device could access a failed part of pyroprocessing devices, and if a human operator could feel the force feedback when it collides with other objects when accessing a device, a case study was carried out.

Design of remotely operated vol-oxidizer for hot-cell application

A high-capacity vol-oxidizer which can handle a several hundred kgHM/batch is being developed to supply U3O8 powders to an electrolytic reduction reactor. In this paper, we deal with the development of remotely operated vol-oxidizer that can convert UO2 pellets to U3O8 powders for hot-cell application. In order to develop this remotely operated vol-oxidizer, we proposed a design process and modular design for the remote operation in hot-cell, and the device has been modified by these modular design points and the design drawings have been presented. The design process consists of steps such as a mechanism device design, an engineering design and thermal analysis. To design the main mechanisms of the 1st step, we evaluated various mechanical (slitting, ball mill, roller straightening) and chemical methods (muffle furnace, rotary kiln). In the engineering design of the 2nd step, we calculated required volumes according to various weights and lengths of rod-cuts to design the reactor size. In the 3rd step, by using the modeling and analysis SWs (SolidWorks, COSMOSWorks), we built a 3D-modeling and performed an analysis of the main mechanisms for the safety design. We have selected the target modules of this devices such as heater, utility, motor, reactor, valve and outlet. The remote assembling and disassembling possibilities of the selected modules have been analyzed from the viewpoints of visibility, interference, approach, weight, and so on. We presented finally modular design suited to the above viewpoints.

Analysis of the Remote Operation in a Digital Mockup of the Advanced Spent Fuel Conditioning Process

Spent nuclear fuel is a high radioactive material and is handled in the hot cell. The ACP equipment is operated in intense radiation fields as well as in a high temperature. Thus, the equipment is operated in a remote manner and should be designed with a consideration for a remote handling and maintenance. Also a suitable remote handling technology needs to be developed along with the design of the process concepts. In this paper, the remote operation of the advanced spent fuel conditioning process (ACP) is analyzed by using 3D graphic simulation tools. For this we developed a digital mockup (DM), which provides the capability of verifying the remote operability of the ACP with the virtual equipment. In other words, by applying a virtual reality to a remote maintenance operation, a remote operation task can be simulated in the DM, not in the physical mockup, that is a real environment. The graphic simulator will substantially reduce the cost of the development of the remote handling and maintenance procedure as well as the process equipment, while at the same time developing a remote maintenance concept that is more reliable, easier to implement, and easier to understand.

Remote manipulator systems for pyroprocessing facility application

In this paper we describe remote manipulator systems for use in pyroprocessing facilities where direct access to an in-cell by human workers is not possible because of the toxicity of argon gas. These remote manipulator systems can be classified into two types, i.e., a BDSM (Bridge transported Dual arm Servo-Manipulators) and a Telemanipulator, depending on the environment they are installed in. The BDSM is an electrically driven manipulator, whereas the Telemanipulator is a mechanically driven manipulator. The remote manipulator systems of the BDSM and Telemanipulator were developed and installed in the pyroprocessing facilities at the Korea Atomic Energy Research Institute, and are currently in use for remote operation and maintenance work of processing equipment and auxiliary devices for pyroprocessing technology development. We present the developments, installation and in-situ operation of remote manipulator systems.

Force reflecting remote robotic mopping system

In this paper, we describe the development of the force reflecting remote robotic mopping system for use in a radioactive zone of a hot-cell. This remote robotic mopping system was designed and developed to clean up the contaminated floor surface of the in-cell by mopping it with a wet cloth in a remote manner. It mainly has three subsystems - a mopping slave to be located inside the hot-cell, a mopping master and a control console to be located outside the hot-cell. A human operator located outside the hot-cell can feel and control the mopping force via the mopping master which, during the operation, the mopping cloth of the mopping slave is pressed against the floor surface to be cleaned, thereby allowing the operator to have a sense of a real mopping. We also present the mechanical design considerations, bilateral controls of the developed force reflecting remote robotic mopping system. Finally, we describe its mopping test results conducted on the simulated contaminated floor.

Uniform Irradiation Systems Using A Rotatable Stage for Test Facilities of PEFP

A new irradiation facility has been developed using not only electric magnets but also a rotatable stage. Generally, the scanning method using magnets has been widely used in most of facilities. However, in this study another new methods have been developed: Two scanning method using a rotatable stage have been proved to make uniform irradiation-as large as 20 cm in diameter with more than 90% uniformity. The mechanical wobbler system makes the same effect as the wobbler system. And the beam is swept along the spiral path with a fixed and variable angular frequency during the scanning in the spiral scanning system.

Optimal Static Output Feedback Control of Tendon Driven Master-Slave Manipulator

In this work, a bilateral control for a master-slave manipulator system which will be used for handling objects contaminated by radioactivity has been addressed. The links of manipulators are driven independently by individual motors installed on the base and the driving torque is transmitted through pre-tensioned tendons. The measurable variables are the positions and rates of master/slave motors. In the consideration of the flexibility of the tendon and available measurements for control, we proposed an optimal static output feedback control for possible bilateral control architecture. By using modal analysis, the system model is reduced to guarantee the detectability which is a necessity for the static output feedback control design. Based on the reduced model, the control gains are determined to attenuate vibration in the sense of optimality. The feasibility of the proposed control design was verified along with some simulation results.