• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.95-100
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• 2013

This paper presents a new state feedback control approach for communication networks based control systems in which control input and output observation time-delay natures are generally occurred in practice. We first establish a generic state feedback control framework based on well-known linear system theory. A maximum time-delay value which allows critical stability of whole control system are defined to make a positive definite Lyapunov function which is mathematically composed of controlled system states. We analytically derive its control parameters by using a steepest descent optimization method in order to guarantee a stability condition through Lyapunov theory. Computer simulation is numerically carried out for demonstrating reliability of the proposed NCS algorithm and a comparative study is accomplished to prove its superiority for which the traditional control approach for NCS is made use of under same simulation scenarios.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.107.6-107
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• 2002

$\textbullet$ An autonomous mobile robot was controlled through the Internet. $\textbullet$ For the direct control, the feedback data should be provided properly. $\textbullet$ Therefore, an efficient communication scheme should be defined. $\textbullet$ To overcome the transmission delay, the highly abstracted message format was used. $\textbullet$ As the feedback data, the real image sequences may suffer the transmission delay or loss of content. $\textbullet$ To resolve this, the feature information was used to construct the synthetic feedback information. $\textbullet$ By doing this, the operator could feel the hands-on control with an Internet-based robot.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1887-1891
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• 2005

Despite significant advances in multimedia transferring technologies in various fields of robotics, it is sometimes quite difficult for the operator to fully understand the context of 3D remote environments from 2D image feedback. Particularly, in the remote control of mobile robots, the recognition of the object associated with the task is very important, because the operator has to control the robot safely in various situations not through trial and error. Therefore, it is necessary to provide the operator with 3D volumetric models of the object and object-related information as well such as locations, shape, size, material properties, and so on. Thus, in this paper, we propose a vision-based human interface system that provides an interactive, information-rich map through network-based information brokering. The system consists of an object recognition part, a 3D map building part, a networked knowledge base part, and a control part of the mobile robot.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.8
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• pp.768-773
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• 2012

Packet loss compensation techniques are increasingly important to stable remote control over wireless communication in WNCS (Wireless Networked Control Systems). Its time varying channels, limited bandwidth, interference, and poor signal not only leads to packet loss or latency, but also can negatively affect performance and system stability. This paper presents a compensation technique exploiting an EWMA (Exponentially Weighed Moving Average)-based value estimator to clarify the influence of packet loss on the overall WNCS behavior. As an example of actuator to be remotely controlled, a rotary-type inverted pendulum has been considered, and modeled. Performance evaluation results through Matlab/Simulink and Truetime co-simulation confirm the superiority of the proposed value estimation method over previous approaches.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.106.3-106
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• 2001

Financial institutions survive on the ability to collect and react to data. Today´s financial community is bombarded by massive amounts of information from real time data-feeds, risk management systems, and other intelligent sources. The large quantities of numerical data are virtually impossible to understand quickly. Humans have the ability to understand pictures instantaneously. Thus, by converting data into pictures, and using colour, size, shape, and pattern to define relationships, individuals can rapidly process complex Information.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1599-1600
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• 2007

The DTL water skid cooling system and Resonant Control Cooling Systems (RCCS) will employ a control system that can be operated by a local, programmable logic controller (PLC), interfaced through a touch screen interface, mobile alarm SMS server system, or it can be operated through the PEFP global control system network. The RCCS is implemented using Experimental Physics and Control System (EPICS) based hardware and software and is integrated with other networked PEFP EPICS systems. This presentation discusses the features of the local control system.

• Korean Journal of Computational Design and Engineering
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• v.9 no.3
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• pp.212-219
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• 2004

This paper presents the visualization method of the KAIST interactive bicycle simulator. The simulator consists of two bicycles of 6 DOF and 4 DOF platforms, force feedback handlebars and pedal resistance systems to generate motion feelings; a real-time visual simulator, a HMD and a beam projection system; and a 3D sound system. The system has an integrating control network with the server-client network structure for multiple simulators. The visual simulator generates dynamic images in real-time while communicating with other modules of the simulator. The operator of the simulator can have realistic visual experience of riding on a velodrome or through the KAIST campus, while being able to watch the other bicycle with an avatar.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.988-991
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• 2010

This paper presents a control design for networked control systems (NCS) with uncertain time delay using model matching. The dynamics of the time delay are approximated through the Pade linearization and the uncertain delay term is recursively estimated by the recursive least square (LS) algorithm. Computer simulation illustrates that the proposed control compares favorably with a recently published control approach.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.9
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• pp.227-234
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• 2018

Guaranteeing the end-to-end delay deadline is an important issue for quality of service (QoS) of delay sensitive systems, such as real-time system, networked control system (NCS), and cyber-physical system (CPS). Most routing algorithms typically use the mean end-to-end delay as a performance metric and select a routing path that minimizes it to improve average performance. However, minimum mean delay is an insufficient routing metric to reflect the characteristics of the unpredictable wireless channel condition because it only represents average value. In this paper, we proposes a deadline-aware routing algorithm that maximizes the probability of packet arrival within a pre-specified deadline for CPS by considering the delay distribution rather than the mean delay. The proposed routing algorithm constructs the end-to-end delay distribution in a given network topology under the assumption of the single hop delay follows an exponential distribution. The simulation results show that the proposed routing algorithm can enhance QoS and improve networked control performance in CPS by providing a routing path which maximizes the probability of meeting the deadline.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.250-253
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• 2005

A Programmable Automation Controller (PAC) has been developed by Turbotek Co., Ltd. The developed system has multi-domain functionality-including sequence control, motion control and HMI- on a single platform. The PAC also has a common development platform for the design and integration of multi-domain automated systems. Since hardware of the developed system has modular architectures, performance and specification of the controller are determined by combination of specific modules. The developed system employs de facto standards such as OPC interface that allow users to easily exchange data as part of networked multi-vendor systems.