• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.795-797
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• 1998

This paper suggests a design method of the optimal PD control system having robust performance. This PD control system is designed by applying genetic algorithm(GA) with reference model to the optimal determination of proportional(P) gain and derivative(D) gain that are given by PD servo controller. These proportional and derivative gains are simultaneously optimized in the search domain guaranteeing the robust performance of closed-loop system. This PD control system is applied to the fuel-injection control system of diesel engine and compared with ${\mu}$ -synthesis control system for robust performance. The effectiveness of this PD control system is verified by computer simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.2
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• pp.121-128
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• 2018

This work proposes a simple control method of a buck-type active power decoupling circuit that can minimize the ripple values in the dc link voltage. The proposed method utilizes a simplified duty calculation method and an optimal compensation gain tracking algorithm with variable-step approach. Thus, the dc link voltage ripple can be effectively reduced through the proposed method along with rapid response in tracking the optimum compensation gain. Moreover, the proposed method has better dynamic responses in the load fluctuation or abnormal situation. MATLAB/Simulink simulation and hardware-in-the-loop-simulation(HILS)-based experimental results are presented to validate the effectiveness of the proposed control method.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.892-895
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• 1996

An unknown input observer is proposed that can be used in wheelbase preview control of commercial vehicles. The preview and state information, required to calculate actuator force, are reconstructed from the measurement variables such as heave and pitch acceleration. Gain matrix of observer is optimally selected so that influence of system and measurement noises on the estimation error can be minimized. Estimated preview information requires low pass filtering to eliminate high frequency components resulting from differentiation of noisy output signals. Effectiveness of the proposed method is demonstrated by numerical simulation of half car model.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.209-211
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• 1986

The continuous time linear quadratic problem (LQP) has been applied to the control of a 8-tray distillation column using the code VASP. The weighting matrices for the state variables and control variables were adjusted iteratively. The simulation results of the optimal control with 2 inputs and 2 outputs showed that the LQP method is very satisfactory for a rapid response and feedback control, and any desired response could be obtained by adjusting the weighting matrices Q under = and R under =. The feedback gain matrix K under = was also determined.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.442-448
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• 2008

This paper presents an approach to define an optimal piezoactuator length to actively control structural vibration. The optimal ratio of the piezoactuator length against beam length when a pair of piezoceramic actuator and accelerometer is used to suppress unwanted vibration with direct velocity feedback (DVFB) control strategy is not clearly defined so far. It is well known that direct velocity feedback (DVFB) control can be very useful when a pair of sensor and actuator is collocated on structures with a high gain and excellent stability. It is considered that three different collocated pairs of piezoelectric actuators (20, 50 and 100 mm) and accelerometers installed on three identical clamped-clamped beams (300 * 20 * 1 mm). The response of each sensor-actuator pair requires strictly positive real (SPR) property to apply a high feedback gain. However the length of the piezoactuator affects SPR property of the sensor-actuator response. Intensive simulation and experiment shows the effect of the actuator length variation is strongly related with the frequency range of SPR property. A shorter actuator gave a wider SPR frequency range as a longer one had a narrower range. The shorter actuator showed limited control performance in spite of a higher gain was applied because the actuation force was relatively small. Thus an optimal length ratio (actuator length/beam length) was suggested to obtain relevant performance with good stability with DVFB strategy. The result of this investigation could give important information in the design of active control system to suppress unwanted vibration of smart structures with piezoelectric actuators and accelerometers.

• Journal of Astronomy and Space Sciences
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• v.24 no.4
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• pp.431-450
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• 2007

In the auto-guiding system for obtaining a long exposure astrophotography, CCD camera is usually used for measuring guide errors which are affected by optical dispersion and mechanical disturbances. In this paper, a discrete time dynamic model and a performance index are proposed for analysing the auto-guiding system. The optimal gain for proportional control is derived considering the optical dispersion and the disturbances. Some experiments are provided to illustrate that the optimal control gain is lower as the optical dispersion is higher.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.164-168
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• 1988

This paper utilizes an optimal control law for the accurate tracking servo system design. The devivation of a simple control law implementing microprocessor is made to minimize position and speed error of the controller. The 16 bit microprocessor receives command angular position and calculate the control algorithm for accurate tracking and provides control system gain scheduling to achieve very short settling time. Simulation results and some experimental results of the position controlled tracking using 4.5Kw DC servo motor are shown.

• Design & Manufacturing
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• v.16 no.1
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• pp.15-20
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• 2022

This paper is about elimination the situation in which gas sensor data becomes inaccurate due to temperature control when a semiconductor gas sensor is driven. Recently, interest in semiconductor gas sensors is high because semiconductor sensors can be driven with small and low power. Although semiconductor-type gas sensors have various advantages, there is a problem that they must operate at high temperatures. First temperature control was configured to adjust the temperature value of the heater mounted on the gas sensor. At that time, in controlling the heater temperature, gas sensor data are fluctuated despite supplying same gas concentration according to the temperature controlled. To resolve this problem, gas and temperature are extracted as a data. And then, a relation function is constructed between gas and temperature data. At this time, it is included low pass filter to get the stable data. In this paper, we can find optimal gain and parameters between gas and temperature data by using genetic algorithm.

• Journal of Power System Engineering
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• v.7 no.4
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• pp.38-43
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• 2003

This paper proposes an optimum design problem of structural and control systems. taking a 3-D truss structure as an example. The structure is supposed to be subjected to initial static loads and time-varying disturbances. The structure is controlled by a state feedback $H_{\infty}$ controller to suppress the effect of the disturbances. The design variables are the cross sectional areas of truss members. The structural objective function is the structural weight. As the control objective, we consider two types of performance indices. The first function represents the effect of the initial loads. The second one is the norm of the feedback gain. These objective functions are in conflict with each other. Then, first, two control objective functions are transformed into one control objective by the weighting method. Next, the structural objective is treated as the constraint. By introducing the second control objective which considers the magnitude of the feedback gain, we can per limn the design which is robust in modeling errors.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.211-214
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• 2000

The conventional PI controller has been widely used in industrial application due to the simple control algorithm. But it is very difficult to find the optimal PI control gain. Therefore in this paper to obtain optimal performance fuzzy proportional-plus-integral controller for the vector control system of an induction machine is presented. The simulation model is created in MATLAB/SIMULINK. The simulation results demonstrate the good performance of this system.