• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.10
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• pp.678-689
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• 2004

The major concern of networked control system is network uncertainties such as time delay and data loss. Because these uncertainties may degrade the performance of networked control system and destabilize the entire system. Therefore, the performance and the stability variation of networked control system due to network uncertainties must be considered first in designing networked control system. In particular, the stability analysis of networked control system is most important issue since time delay and data loss can make the overall systems unstable. In this paper, we present a new stability analysis method of networked control system with time delay and data loss, which is impossible in previous works. The proposed method can determine maximum time delay and allowable transmission rate that preserve stability performance of networked control system. The results of the simulation validate effectiveness of our stability analysis method.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2383-2385
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• 2004

Network uncertainties can vary the stability property of networked control system. Therefore, the performance and the stability variation of networked control system due to network uncertainties must be considered first in designing networked control system. In this paper, we present a new stability analysis method of networked control system with data loss and time delay. The proposed method can determine maximum allowable time delay and allowable transmission rate that preserves stability performance of networked control system. The results of the simulation validate effectiveness of our stability analysis methods.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2328-2330
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• 2003

This paper presents a new design methodology of networked control system using CAN(Controller Area Network). Feedback control systems having control loops closed through a network are called networked control systems. We design CAN nodes which can transmit control and monitoring data through network bus and apply these to networked control system design. We analyze the variation of stability property according to network-induced delay and determine a proper sampling period of networked control system that preserves stability performance. The results of the experimental example validate effectiveness of our networked control system.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.441-444
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• 2003

Network uncertainties such as data loss and time delay can vary the stability property of networked control system. Therefore, these uncertainties must be considered first in designing networked control system. In this paper, we present a new stability analysis method of networked control system with data loss and time delay. The proposed method can determine maximum allowable time delay and minimum allowable transmission rate that preserves stability performance of networked control system. The results of the simulation validate effectiveness of our stability analysis method.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.3
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• pp.12-20
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• 2002

As numerous sensors and actuators are used in many automated systems, various industrial networks are adopted for real-time distributed control. In order to take advantages of the networking, however, the network implementation should be carefully designed to satisfy real-time requirements considering network induced delays. This paper presents an implementation scheme of a networked control system via Profibus-DP network fur real-time distributed control. More specifically, the effect of the network induced delay on the control performance is evaluated on a Profibus-DP testbed. Also, two conventional PID gain tuning methods are slightly modified fur fouling controllers fur the networked control system. With appropriate choices for gains, it is shown that the networked control system can perform almost as well as the traditional control system.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1235-1239
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• 2003

On the base of network frame and protocol system of Ethernet the networked sensing technology based on Ethernet is studied and the design principles of industrial Ethernet measurement of control system is put forward, and the general structure model is built in the paper. An eight-bit economical MCU scheme is proposed, and a general scheme of distributed intelligent networked measuring and control equipment based on TCP/IP is designed too. A compact TCP/IP protocol stack are successfully implemented in eight-bit MCU. With C51 program language, method of modularized programming is applied in soft design. The problem of in-system modifying measuring and control strategy of its system is solved successfully by assigning memory dynamically and saving parameter with EEPROM, and it makes the intelligent networked measurement and control system can explain and analyses control strategy from PC. Experiment result shows that, the research of intelligent networked measurement and control equipment and system base on TCP/IP is successful, with flexible network, convenient usage, and good commonality.

• IEMEK Journal of Embedded Systems and Applications
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• v.4 no.2
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• pp.97-102
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• 2009

In this paper, the problem of stability analysis for networked control systems with norm-bounded parameter uncertainties is investigated. By construction Lyapunov's functional, a new delay-dependent stability criterion for uncertain networked control system is established in terms of LMIs (linear matrix inequalities) which can be easily by various convex optimization algorithms. One numerical example is included to show the effectiveness of proposed criterion.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.136-138
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• 2006

Recently, network systems are widely used in several areas, and some considerable attentions have been directed to the Networked Control System(NCS). In NCS, network-induced delays are inevitable, and they sometimes degrade the performance of networked control systems to be a source of potential instability. In this paper, We proposes a compensation method for networked control system subject to network-induced delays by using a simple method, which is based on a sort of predictive strategy. To evaluate its feasibility and effectiveness, a real-time NCS for a rotary inverted pendulum is implemented via an Ethernet. Based on the experimental results. we show that the proposed simple method can be a practical and feasible solution to NCS design.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.354-356
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• 2006

In this paper, the position control performance of networked control systems is analyzed when time delay through the network is considered. Integrating a control system into a network has great advantages over the traditional control system which uses point to point connection: it allows remarkable reduction in wiring, makes it easy to install and maintain the system, and improves compability. However, a networked control system has the critical defect that network uncertainties, such as time delay, can degrade the control system's performance. Therefore, the major concern of a networked control system is analyzing the effect of network uncertainties. This paper is concerned with PID controller performance for stability region, critical stability region and unstability region under the time delay in the Controller Area Network.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.598-601
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• 2001

As many sensors and actuators are used in many automated system, various industrial networks are adopted for digital control system. In order to take advantages of the networking, however, the network implementation should be carefully designed to satisfy real-time requirements considering network delays. This paper presents the implementation scheme of a networked control system via Profibus-DP network. More specifically, the effect of the network delay on the control performance was evaluated on a Profibus-DP testbed, and a GA based PID tuning algorithm is proposed to demonstrate the fesibility of the networked control system.