• Smart Structures and Systems
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• v.3 no.3
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• pp.385-403
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• 2007

The effectiveness of the newly developed smart passive control system employing a magnetorheological (MR) damper and an electromagnetic induction (EMI) part for seismic protection of base isolated structures is numerically investigated. An EMI part in the system consists of a permanent magnet and a coil, which changes the kinetic energy of the deformation of an MR damper into the electric energy (i.e. the induced current) according to the Faraday's law of electromagnetic induction. In the smart passive control system, the damping characteristics of an MR damper are varied with the current input generated from an EMI part. Hence, it does not need any control system consisting of sensors, a controller and an external power source. This makes the system much simpler as well as more economic. To verify the efficacy of the smart passive control system, a series of numerical simulations are carried out by considering the benchmark base isolated structure control problems. The numerical simulation results show that the smart passive control system has the comparable control performance to the conventional MR damper-based semiactive control system. Therefore, the smart passive control system could be considered as one of the promising control devices for seismic protection of seismically excited base isolated structures.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.50-55
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• 2008

In general, the swing motion of the crane is controlled and suppressed by activating the trolley motion. In many papers reported by us, we suggested a new type of anti-sway control system of the crane. In the proposed control system, a small auxiliary mass(moving-mass) is installed on the spreader and the swing motion is controlled by moving the auxiliary mass. The actuator reaction against the auxiliary mass applies inertial control forces to the container in order to reduce the swing motion in the desired manner. Futhermore the measuring systems based on image sensor have been proposed also. To obtain the robustness for our control system, $H_{\infty}$ based control techniques and other approach have been applied to suppress swing motion. As well known, the robust control technologies based on $H_{\infty}$ control need complicated and difficult process. In the result, the obtained closed-loop system becomes to high order system which may give us many difficulties to apply it to the real plants. Therefore, we introduce an easy approach which is based on LQ control theory. In this approach, we introduce the frequency dependent weighting matrices which give the system filters to shape frequency characteristics of the controlled system and guarantee the control performance.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.218-224
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• 1990

A motor group control system is developed for continuous manufacturing processes such as rolling process or electrolytic tinning process. The control system consists of four subsystems ; Multi-Function Controller (MFC), Flexible Motor Drive (FMD), Bulky Input/Output (BIO), Graphic Console and Simulator (GCS). A graphic control language, called Function Block Language, is used to configure the control algorithms for each subsystem. All subsystem are linked together thru a field bus to communicate data with each other.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1318-1326
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• 2014

The purpose of a tracking control system is to track a moving target and to find the exact information of the target. If the platform of the tracking control system is equipped on a moving vehicle such as a ship, the tracking control system will treat even the additional platform motion. In order to avoid the complexity comprising the tracking control system, a process to treat the platform motion, named stabilizing system, must be separated from the tracking control system. In this paper, a method to comprise an attitude control system for the platform stabilization is proposed using an adaptive fuzzy control which is applicable to the system with structural and parametric uncertainty. The suggested adaptive fuzzy control algorithm is the 2nd/1st-type indirect adaptive fuzzy control algorithm using the advantages of 1st-type and 2nd-type indirect adaptive fuzzy control algorithm. Several experiments using the implemented stabilizing system are executed for verifying the effectiveness of the suggested method.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1008-1011
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• 1996

Most control systems of power plants are using classical PID controllers for their process control. In order to get the desired control performances, the correct tuning of PID controllers is very important. Sometimes, it is necessary to retune PID controllers after the change of system operating condition and system design change, etc. Commercial auto-tuning controllers such as relay feedback controller can be used for this purpose. However, using these controllers to the safety-critical systems of nuclear power plants may be cause of unsafe operation, because they are using test signals for tuning. A new system identification auto-tuning method without using test signal has been developed in this paper. This method uses process input/output signals for system identification of unknown control process. From the model information of control process which was obtained from system identification approach, the optimal PID parameters can be calculated. The method can be used in the safety-critical systems because it is not using test signals during system modeling process.

• 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.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.2
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• pp.89-93
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• 2004

Supervisory Control And Data Acquisition(SCADA) of electric power system refersto the system that displays, monitors and executes the control commands for remote electric power system. KNR's existing electric power control system is built on UNIX platform such that it costs more for system construction, and people with UNIX skills can only be an operator who controls and manages the system. Moreover, since the system is mainly operated in local offices, system operators must communicate with local operators to investigate the cause of the accident and react the accident every time the system fails. As a new integrated SCADA system is constructed, establishment of small-unit electric power control system, that alters local electric power control system in designated stations, is required. In this study, the electric power control system, which accommodates all functions of UNIX-based SCADA system and facilitates operation and even maintenance for local operators, is to be developed. In order to develop small-unit electric power control system, the industrial automation program, "Cimon", is used. The small-unit electric power control system that accommodatesRTU and newly installed electronic switchboard is being developed and tested at Chulam station of KNR.

• Journal of Biosystems Engineering
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• v.27 no.2
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• pp.79-88
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• 2002

This study was conducted to develop system for high speed rice transplanting machines. The control system includes a sensor detecting the tilt angle of the seedling bed, a micro-controller and a hydraulic system consisting of a double acting cylinder, a four-way three-position solenoid valve, a relief valve and a hydraulic pump. The levelling system shared the pump with the existing steering control, resulting in a tandem center circuit for the steering and levelling control systems. Using the input signal from the sensor, the micro-controller determined and generated the output signal to control the cylinder through the solenoid valve to keep the seedling bed always parallel to the water surface regardless of soil unevenness during the transplanting operations. Both an ON/OFF and a PWM control schemes were tested. When the flow rate was more than 1 ι/min in the ON/OFF control, the system showed unstable rolling. However, in the PWM control, the system worked stably although the flow rate was more than 1 ι/min. The PWM control showed a better performance when a large difference between the angle and the dead band of the control system occurred. The characteristics of tile system response to given tilt angles were predicted by a computer simulation. Both the ON/OFF and the PWM control systems worked well providing that the operating and waiting times were properly adjusted.

• Korean Journal of Agricultural Science
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• v.37 no.1
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• pp.123-130
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• 2010

A steering control system based on CAN(Controller Area Network) for autonomous tractor was developed to reduce duty of a central processing computer and to improve performance of steering control in terms of reduced control interval and error. The steering control system consisted of a SCU (Steering Control Unit), an EHPS system, and a potentiometer. The SCU consisted of an MCU (Micro Controller unit), an A/D converter, and a DC-DC converter, and a PID controller was used to control steering angle. The steering control system was communicated with the computer by CAN-bus. Each actuator and implement was connected to a multi-function board interfacing with the computer through a USB cable. Without CAN, control interval of the autonomous tractor was 1.5 seconds. When the CAN-based steering control system was combined with the autonomous tractor, however, control interval of the integrated system was reduced to those less than 0.05 seconds. When the autonomous tractor was operated with 1.5-s and 0.05-s control cycles at a 0.63-m/s travelling speed, the trajectories were close to straight lines for both of the control cycles. For a 1.34-m/s traveling speed, tractor trajectory was close to sine wave with a 1.5-s control cycle, but was straight line with a 0.05-s control cycle.

• Structural Engineering and Mechanics
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• v.82 no.4
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• pp.445-458
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• 2022

Some of the control systems used in engineering structures that use sensors and decision systems have some time delay reducing efficiency of the control system or even might make it unstable. In this research, in addition to considering the effect of the time delay in vibration control process, predictive control is used to compensate the time delay. A semi-active vibration control approach with the help of magneto-rheological dampers is implemented. In addition to using fuzzy inference system to determine the appropriate control voltage for MR damper, structural behavior prediction system and specifying future responses are also used such that the time delays occurring within control process are overcome. For this purpose, determination of prediction horizon is conducted for one, five, and ten steps ahead for single degree of freedom structures with periods ranging from 0.1 to 4 seconds, subjected to twenty earthquake excitations. The amount of time delay applied to the control system is 0.1 seconds. The obtained results indicate that for 0.1 second time delay, average prediction error values compared to the case without time delay is 3.47 percent. Having 0.1 second time delay in a semi-active control system reduces its efficiency by 11.46 percent; while after providing the control system with structure behavior prediction, the difference in the results for the control system without time delay is just 1.35 percent on average; indicating a 10.11 percent performance improvement for the control system.