• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.369-372
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• 1998

In this research a fault-tolerant and bumpless switching control is proposed for boiler systems used in the power plants. Firstly, three operating points are selected to control the nonlinear boiler through the full operational range, and the $H_{\infty}$ loop shaping controller and the model-based predictive controller(MBPC) are designed. To prevent the windup and bump problems which are caused by the actuator saturation and the controller switching, an anti-windup and bumpless transfer technique is adopted to the $H_{\infty}$ loop shaping controller. Also the constrained gain-scheduling technique is applied to MBPC to achieve the same objective. Secondly, the fault-tolerant control technique is proposed to continue the control action without stopping the boiler operation even in case of some faults. Through various simulation studies, the performances of the proposed control techniques are demonstrated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5409-5415
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• 2012

Piezo ceramic actuator is used for various industrial products such as spray, dispenser, and valve control etc. Since the deflection of the piezo ceramic element depends on the applied voltage, it is required a power amplifier with high voltage supply for driving the piezo ceramic actuators. In this paper, we develop a simple H-bridge type power amplifier and a compact flyback type high voltage switching mode power supply for piezo ceramic actuators. It is easy to adjust the amount of energy input to piezo ceramic actuator by pulse-width-modulation with H-bridge type power amplifier.

• Journal of Sensor Science and Technology
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• v.14 no.1
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• pp.1-6
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• 2005

This paper describes a novel concept of a chemically sensitive scanning force microscope (CS-SFM). It consists of the conventional SFM and the time-of-flight mass spectrometer (TOF-MS). A switchable cantilever (SC) fabricated by the micromachining technology combines each advantage of two completely different systems, SFM and TOF-MS. The CS-SFM offers to produce both images of topography and chemical information simultaneously. First we employed a rotatable tip holder based on 4 piezotube actuators for demonstration of the possibility of the CS-SFM concept. Second the CS-SFM concept is optimized with the micromachining technology. The micromachined SC with an integrated bimorph actuator and a piezoresistive strain sensor provides a reasonable switching speed of ${\sim}10$ ms which is very attractive for the CS-SFM application. The SC is currently being integrated in an ultra-high-vacuum system to perform various experiments.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1152-1157
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• 2005

This paper is concerned with the construction of an improved sliding mode control for the active suspension system of a one-wheel car model subject to the excitation from a road profile. The active control is composed of the equivalent and the switching controls where an improved sliding surface is proposed. The active control force is generated by operating a pneumatic actuator due to the control signal that constructed by measuring the state variables of the car model and by estimating the excitation from the road profile using the VSS observer. The experimental result indicates that the proposed active suspension system is relatively effective in the vibration suppression of the car model.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.330-335
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• 1995

The actuator's response delay, disturbance and measurement noise can often cause a significant error in the target tracking of an underwater vehicle. The first purpose of this paper is error analysis about motion of an underwater vehicle when the closed loop system has actuator and disturbance and noise. The underwater vehicle is simulated for cases of various disturbances. The second purpose is robust controller design for the underwater vehicle with parameter uncertainty. So, two robust control methods are applied for the underwater vehicle. One is standard $H_{\infty}$ control, and the other is time-varying sliding mode control with modified saturation function. Suboptimal design parameters for $H_{\infty}$ control, and design parameters for time-varying switching surfaces are provided Simulations for the two controllers are carried out and their performances are analyzed.lyzed.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.65.2-65
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• 2002

This paper is concerned with the accurate position control of a rodless pneumatic cylinder using On/Off solenoid valve. A novel Intelligent Modified Pulse Width Modulation(MPWM) is newly proposed. The control performance of this pneumatic cylinder depends on the external loads. To overcome this problem , switching of control parameter using artificial neural network is newly proposed, which estimates external loads on rodless pneumatic cylinder using this training neural network. As an underlying controller, a state feedback controller using position, velocity and acceleration is applied in the switching control the system. The effectiveness of the proposed control algorithms are demonstrated...on/off solenoid valve, load estimation, MPWM, Artificial neural network.

• Journal of KSNVE
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• v.7 no.2
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• pp.273-279
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• 1997

Reduction of number of actuators for independent modal space control In this paper, a new modified independent modal space control (IMSC), which relaxes the fundamental hardware limitation of IMSC, is suggested to handle the vibration and attitude control problem for flexible large structures. This method has adapted a new switching algorithm between controlled modes and a novel design technique for modal control force. The main advantage of this method is to minimize the discontinuity of the modal control forces and to assure the asymptotic stability of the closed-loop systems. This process is shown to be simple and efficient in a realistic example of vibration control of a cantiloever beam. It has been found that the modified IMSC suggested in this paper, which can reduce the number of actuators, is highly excellent compared to other previous methods in terms of the performance and stability of the vibration control systems.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.2
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• pp.103-108
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• 2005

Loading/Unloading task in the real industry is performed by crane, but most of the loading/unloading task with the weight of 5kg∼30kg is done by human workers and this kind of work causes industrial disaster of workers. Therefore it is necessary to develop low cost loading/unloading manipulator system to prevent this kind of industrial accidents. This paper is concerned with the design and fabrication of 2 axis pneumatic manipulators using on/off solenoid valves and accurate position control without respect to the external load and low damping in the pneumatic rotary actuator. To overcome the change of external load, switching of control parameter using LVQNN (Learning Vector Quantization Neural Network) is newly applied, which estimates the external loads in the pneumatic cylinder. As an underlying controller, a state feedback controller using position, velocity and acceleration is applied to the switching control system. The effectiveness of the proposed control algorithms are demonstrated through experiments of pneumatic cylinder with various loads.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.4
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• pp.82-90
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• 2009

Pneumatic cylinder is one of the low cost actuation sources which have been applied in industrial and prosthetic application since it has a high power/weight ratio, a high-tension force and a long durability However, the control problems of pneumatic systems, oscillatory motion and compliance, have prevented their widespread use in advanced robotics. To overcome these shortcomings, a number of newer pneumatic actuators have been developed such as McKibben Muscle, Rubber Actuator and Pneumatic Artificial Muscle (PAM) Manipulators. In this paper, one solution for position control of a robot arm, which is driven by two pneumatic artificial muscles, is presented. However, some limitations still exist, such as a deterioration of the performance of transient response due to the changes in the external load of the robot arm. To overcome this problem, a switching algorithm of the control parameter using a learning vector quantization neural network (LVQNN) is proposed in this paper. This estimates the external load of the pneumatic artificial muscle manipulator. The effectiveness of the proposed control algorithm is demonstrated through experiments with different external working loads.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.12
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• pp.639-647
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• 2001

We present an integrated optical microswitch, composed of silicon waveguides, gold-coaled silicon micromirrors, and electrostatic contact actuators, for applications to the optical signal transceivers. For a low switching voltage, we modify the conventional curled electrode microactuator into a electrostatic microactuator with touch-down beams. We fabricate the silicon waveguides and the electrostatically actuated micromirrors using the ICP etching process of SOI wafers. We observe the single mode wave propagation through the silicon waveguide with the measured micromirror loss of $4.18\pm0.25dB$. We analyze major source of the micromirror loss, thereby presenting guidelines for low-loss micromirror designs. From the fabricated microswitch, we measure the switching voltage of 31.74V at the resonant frequency of 6.89kHz. Compared to the conventional microactuator, the present contact microactuator achieves 77.4% reduction of the switching voltage. We also discuss a feasible method to reduce the switching voltage to 10V level by using the electrode insulation layers having the residual stress less than 30MPa.