• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.2
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• pp.175-179
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• 2003

Convergence condition determines performance of iterative learning control (ILC), for example, convergence speed, remaining error, etc. Hence, the performance can be elevated and a feasible set of learning controllers grows if a less conservative condition is obtained. In the frequency domain, the $H_{\infty}$ norm of the transfer function between consecutive errors has been currently used to test convergence of a learning system. However, even if the convergence condition based on the $H_{\infty}$ norm has a clear property about monotonic convergence, it has a few drawbacks, especially in MIMO plants. In this paper, the relation between the condition and the monotonicity of convergence is clarified and a modified convergence condition is found out using a frequency domain Lyapunov equation, which supersedes the conventional one in the frequency domain.

• Journal of Drive and Control
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• v.16 no.4
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• pp.16-22
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• 2019

The electro-hydraulic training device (TP511) provided by Festo Didactic are widely used, but teaching materials do not include mathematical modeling. Thus, there is a limit for full-scale learning about the electro-hydraulic servo system by using this equipment. In this study, for the purpose of improving students' understanding of the classical control and modern control Festo's electro-hydraulic servo training device (TP511) was mathematically modeled and parameter values were calculated by examining the characteristics of each component. And P, PI, PD, and PID controllers highly used in the industrial field, were designed by using the root locus method to achieve the optimal gains and used for simulation and experiments using the Festo's electro-hydraulic servo training apparatus. The validity of the derived mathematical model and the calculated parameter values were verified through simulation and experiment. It was found that the p control can achieve the control target more effectively than the pid control for Festo's electro-hydraulic servo training system by using the root locus method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1727-1736
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• 2006

In a fuzzy control system to vocess fuzzy data in high-speed for intelligent systems, one of the important problems is the improvement of the execution speed in the fuzzy inference and defuzzification stages. Especially, it is more important to have high-speed operations in the consequent Pan and defuzzification stage. Therefore, in this paper, to improve the speedup of the fuzzy controllers for intelligent systems, we propose novel integer fuzzy operation method without mulitplications and divisions by only integer addition to convert real values in the fuzzy membership functions in the consequent part to integer grid pixels $(400{\times}30)$ without [0, 1] real operations. Also we apply the proposed system to the truck backer-upper control system. As a result, this system shows a real-time very high speed fuzzy control as compared as the conventional methods. This system will be applied to the real-time high-speed intelligent systems such as robot arm control.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.236-247
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• 2002

We propose a cell－multiplexing scheme for the real－time communication service in ATM network and a new service discipline guarantee end-to-end delay based on pseudo-isochronous cell switching. The proposed scheme consists of two level frame hierarchy, upper and lower frame, which is used to assign the bandwidth and to guarantee the requested delay bound, respectively. Since the Proposed algorithm employs two level frame hierarchy, it can overcome the coupling problem which is inherent to the framing strategy It can be comparatively reduce the complexity, and still guarantee the diverse delay bounds of end-to-end. Besides, it consists of two components, traffic controller and scheduller, as the imput traffic description model and regulates the input traffic specification. The function of the traffic controller is to shape real -time traffic to have the same input pattern at every switch along the path. The end-to-end delay is bounded by the scheduller which can limit the delay variation without using per-session jitter controllers, and therefore it can decrease the required buffer size. The proposed algorithm can support the QoS's of non-real time traffic as well as those of real time traffic.

• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.747-753
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• 2005

In this paper, as an anti-sway control strategy of container cranes, we investigate a variable structure control in which the moving load follows a given trajectory, whereas both the trolley and hoist controllers achieve their positioning problems. It is crucial, in an automated container terminal, that collisions should be avoided during the transference of containers from one place to another. It is also necessary, in the case of a quay crane, to select suitable loading and unloading trajectories of containers, so that possible collisions with surrounding obstacles are avoided. After a brief introduction of the mathematical model, a robust control scheme (i.e., a second-order sliding mode control that guarantees a fast and precise transference and a suppression of the resulted swing) is presented. Despite model uncertainties and unmodeled actuators dynamics, the swing suppression from the given trajectory is obtained by constraining the system motion on suitable sliding surfaces, which include both the desired path and the swing angle. The proposed controller has been tested with a laboratory-size pilot crane. Experimental results are provided.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.43-59
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• 2019

The Traffic controller currently used in Korea is a switch control system that directly transfers 220V of high voltage to traffic lights one to one. This method requires a lot of cables, and there are concerns about electric shock. Accordingly, Korea Road Traffic Authority added the digital communication signal controller standard using digital communication method to the standard specification of the communication signal controller of the National Police Agency. Based on these specifications, this paper intended to develop digital communication call controllers. In addition, it was verified that even if the digital communication signal controller and analogue communication call controller were mixed, they could operate in the signal control system currently in operation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.698-707
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• 2017

This paper deals with predictive control methods of mobile robots for reference trajectory tracking control. Predictive control methods using predictive model are known as effective schemes that minimize the future errors between the reference trajectories and system states; however, the amount of real-time computation for the predictive control are huge so that their applications were limited to slow dynamic systems such as chemical processing plants. Lately with high computing power due to advanced computer technologies, the predictive control methods have been applied to fast systems such as mobile robots. These predictive controllers have some control parameters related to control performance. But these parameters have not been optimized. In this paper we employed the genetic algorithm to optimize the control parameters of the predictive controller for mobile robots. The improved performances of the proposed control method are demonstrated by the computer simulation studies.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.1
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• pp.25-31
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• 2011

These days, almost all of the embedded systems have microprocessors or micro-controllers in them as their brains. So microprocessor related subjects become very important and most engineering departments have those kinds of subjects in their curriculums with practice hours. However, in most universities in Korea, the number of students in a class is more than 40 and only one teaching assistant is assigned to the class. So it is very hard job to find out an appropriate method to evaluate the students' achievements in their practice hours fairly. In this study, the author introduces some suggestions for the evaluation of the students' achievements in microprocessor practice courses. In addition to it, the author also introduces some guidelines for contents of microprocessor related subjects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.445-453
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• 2002

We propose a cell-multiplexing scheme for the real-time communication service in ATM network and a new service discipline guarantee end-to-end delay based on pseudo-isochronous cell switching. The proposed scheme consists of two level frame hierarchy, upper and lower frame, which is used to assign the bandwidth and to guarantee the requested delay bound, respectively. Since the proposed algorithm employs two level frame hierarchy, it can overcome the coupling problem which is inherent to the framing strategy. The proposed scheme consists of two components, traffic controller and scheduller, as the imput traffic description model and regulates the input traffic specification. The function of the traffic controller is to shape real-time traffic to have the same input pattern at every switch along the path. The end-to-end delay is bounded by the scheduller which can limit the delay variation without using per-session jitter controllers, and therefore it can decrease the required buffer size. The proposed algorithm can support the QoS's of non-real time traffic as well as those of real time traffic

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.12
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• pp.511-517
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• 2006

The key issues in high power, high energy applications such as electromagnetic launchers include safety, reliability, flexibility, efficiency, compactness, and cost. To explore some of the issues, a control scheme for a large current wave-forming was designed, built and experimentally verified using a 2.4MJ pulse power system (PPS). The PPS was made up of eight capacitors bank unit, each containing six capacitors connected in parallel. Therefore there were 48 capacitors in total, with ratings of 22kV and 50kJ each. Each unit is charged through a charging switch that is operated by air pressure. For discharging each unit has a triggered vacuum switch (TVS) with ratings of 200kA and 250kV. Hence, flexibility of a large current wave-forming can be obtained by controlling the charging voltage and the discharging times. The whole control system includes a personal computer(PC), RS232 and RS485 pseudo converter, electric/optical signal converters and eight 80C196KC micro-controller based capacitor-bank module(CBM) controllers. Hence, the PC based controller can set the capacitor charging voltages and the TVS trigger timings of each CBM controller for the current wave-forming. It also monitors and records the system status data. We illustrated that our control scheme was able to generate the large current pulse flexibly and safely by experiments. The our control scheme minimize the use of optical cables without reducing EMI noise immunity and reliability, this is resulting in cost reduction. Also, the reliability was increased by isolating ground doubly, it reduced drastically the interference of the large voltage pulse induced by the large current pulse. This paper contains the complete control scheme and details of each subsystem unit.