Earticle

The most important role of air defense system is to attack the air target of enemy to defend the important military unit or facilities. In order to attack the target as soon as it is detected, fast and precise fire signal transfer using the fire control stick is very important. However, it was found that firing is not conducted in the test for fire control stick. In order to find the reason of such problem and improve life cycle of fire control stick, the test was conducted and it was found that chattering occurred and this led to malfunction of signal transfer from control stick to fire control unit of air defense system. In order to draw resolution for this problem, two contact plate made of beryllium copper is suggested to add to the control stick to enhance the contact and reduce chattering effect. The four fire switch prototypes were tested for 100,000 times and it showed its reliability of use.

The main milling cutter used for typical arthroplastic surgery robot, ROBODC system is 7.8 mm milling cutter. this cutter was used in case of traditional total knee arthroplasty, but 7.8mm milling cutter is not appropriate for newest surgical technique, MIS(minimally invasive Surgery). Generally, cutting method for MIS is tunnel cutting and cutter of cantilever type and small diameter is must be developed for MIS. Generally, Main problem of cutting system is chattering due to vibration of cutter by rotation and numerical analysis using finite element method was used for identifying chattering problems in this study. shaft length, cutter length, diameter and so on were proposed by axis displacement, stress, strain analysis through numerical analysis.

A Study of Images of Foreign Women in Minyeodrui Sooda(Chattering of The Beauties). Journal of the International Network for Korean Language and Culture. Vol. 7-2. 47-70. The way of storytelling of talk shows and real variety shows is that give the facts, and create an impression. But until mow some views of Minyeodrui Sooda(Chattering of The Beauties) have been focusing more on sexuality. So this study started from doubt whether it is right. We feel the necessity of taking an objective view of the this problem and for this reason carry out a survey and focus group interview for foreigner. The results of this research are as in the following. This program didn't use chattering although it operates as a social skills. That’s because this program was concentrated toward sexuality by Koreans's distorted perceptions of sexuality. In addition, this program didn't change in spite of that it's about time this program has to move toward 'unity' from 'separation'. That’s because production crew are just busy making anything new to say, forgetting their purpose. Until now, we have ignored and devalued television, but television is necessary to settle multi-cultural Society in Korea why it has a powerful influence on the public. Therefore we need to meditate on meaning of <Minyeodrui Sooda>. (Kyunghee University)

Minyeodrui Sooda(Misooda) is a talk show program of KBS(Korean Broadcasting System) started at 2006. It is a program that foreign women who live in Korea talked together on the Korea and Korean cultures. The levels of Korean language use of them are various, but the experiences of living in Korea are all enough. Misooda is a very popular program in Korea. It's popularity depends on the contents, the expressions, the roles of speaker and listener and the contexts of dialogue.(In this point, it is similar to general communication model.) Korean television viewers laugh on, evaluate and sympathize to performer's chat during program. It depends on the relationship between foreign performers and Korean viewers. Misooda had taken enquetes on difficulties of learning Korean language for foreigners at 2007 August. As a result, it was ranked the 1st to Konglish(Korean style English dialect) use, the 2nd to the methods of naming a person, and the 3rd to complicated honorific. This result is to come out from the experiences of living in Korea as a stranger. Education of language and culture aims to improve the communicative skills of foreign language users on the surface. However, the in-depth goal is to improve the abilities of understanding cross-culture and to enlarge the multi-cultural vision of both of teachers and learners. The education of Korean language and culture must try to deepen comprehensions between Korean and foreigner as a Korean language and culture's owner. It can be selected to contents of education onto Korean language and culture by contents based, supplier based and user based methods. During that time the Korean language education has been taught in contents/ supplier oriented methods, but it needs to have more consideration on the user oriented method. The Korean language education is a sort of recursive and mutual process because we could reflect on myself through the other's sight. Also, the many sides of language culture education would change founded on the improvement of education of Korean language and culture like this.

Virtual axis machine tool is widely used in the machining process of complicated curved surface, pointing on the uncertain factors that exists in the virtual axis machine tool system will affect the process accuracy of the virtual axis machine tool, also take the problem that the upper bound of the interference of the actual system are unable to be measured into considering, in this paper, a sliding model control scheme with upper bound adaptive learning based on RBF networks, and the proposed scheme is realized in the MATLAB platform. The simulation results revealed that compared with the traditional sliding model control, the proposed control algorithm has the good performance on position tracking, the error upper bound prediction, chattering reducing, fasting convergence and so forth.

Aiming at the inaccurately modeling and some uncertain existing in servo system seriously affected the control quality and the instability problem, sliding mode control algorithm with improved reaching law is proposed in this paper. The improved reaching law is used to weaken the chattering problem existing in the sliding mode control. Also the kalman filter is used to inhibit the interference, which makes the servo system have strong anti-interference ability and the ability of weakening the chattering problem existing in the sliding mode control. The method of sliding mode control is the basis of a number of patents and patents pending. The simulation results show that the algorithm can effectively inhibit the external disturbance and noise existing in the system, and make the system have strong anti-interference ability. At the same time, the chattering also is obviously inhibited, and the method makes the system stability and control quality been further improved.

The DC motor is a key element for servo system, and the control quality of control system would be seriously affected by the nonlinear, the parameter uncertain, the inaccurately modeling and some uncertain existing in servo system. So it is very difficult to satisfy control requirements by using the traditional control method. In this paper, the sliding mode control algorithm with reaching law is proposed. By using the reaching law to weaken the chattering phenomenon existed in the SMC, also by using the SMC method can enhance the anti-interference ability of the servo system. In order to test and verify the effectiveness of the proposed SMC with reaching law for the DC motor, the designed controller was dynamically simulated by using the MATLAB. It is shown from the simulation results that the proposed controller offers several advantages such as good chattering inhibition capability, fast response, good disturbance rejection capability, good position tracking capability and so forth. It is also revealed that the proposed control strategy is valid for the DC servo system from simulation results. The results also provide the certain theoretical basis and application value for engineering practice.

Uncertain or complicated systems are difficult to control. Modeling the system uncertainties is an especial topics in most of engineering field. On the other hand, since system has uncertainty, design stable and robust controller is crucial importance in control engineering. To solve this challenge nonlinear control technique is the best choice. Sliding mode control is one important type of robust control. Model imprecision may come from actual uncertainty about the plant or from a purposeful simplification of the system's dynamics. Modeling inaccuracies can cause strong adverse effects on the control design of nonlinear systems. For the class of systems to which it applies, sliding mode controller design provides a systematic approach to the problem of maintaining stability and consistent performance in the face of modeling imprecision. However, sliding mode controller is a robust and stable controller but it has an important challenge called, chattering phenomenon. This research focuses on the comparative between three methods to eliminate/reduce the chattering.

Design of a robust controller for multi input-multi output (MIMO) nonlinear uncertain dynamical system can be a challenging work. This research focuses on the design and analysis of a high performance chattering free PD plus PD partly sliding mode controller in presence of uncertainties. In this research, sliding mode controller is a robust and stable nonlinear controller, which selected to control of robot manipulator. The proposed approach effectively combines of design methods from switching sliding mode controller, and linear Proportional-Derivative (PD) control to improve the performance, stability and robustness of the sliding mode controller. To reduce the chattering with respect to stability and robustness; linear controller is added to the switching part of the sliding mode controller. The linear controller is to reduce the role of sliding surface slope and switching (sign) function. To improve the flexibility, design high speed and low cost controller, micro-electronic device (FPGA-Based) controller is introduced in this research. The proposed design is 30-bits FPGA-based controller for inputs and 35-bits for output. All joints of robot are used to test the controller in simulation environments, using VHDL code for the purpose of simulation in Xilinx. The maximum frequency in FPGA-based design is about 63.6 MHz and the delay time in this design is about 15.7 ns. It is observed that this controller is able to make as a fast response at 15.716 𝑛𝑠 clock period with 63.6 𝑀𝐻𝑍 of a maximum frequency and 4.407 𝑛𝑠 for minimum input arrival time after clock. From investigation and synthesis summary, 30.286 𝑛𝑠 for maximum input arrival time after clock with 33.018 𝑀𝐻𝑍 frequencies, this design has 15.716 𝑛𝑠 delays for each controller to 46 logic elements and the offset before CLOCK is 55.773 𝑛𝑠 for 132 logic gates.

This paper expands a sliding mode fuzzy controller which sliding surface gain is optimized by Gradient Descent Optimization Algorithm (GDOA). The main goal is to guarantee acceptable trajectories tracking between the second order nonlinear system (robot manipulator) actual and the desired trajectory. The fuzzy controller in proposed sliding mode fuzzy controller is based on Mamdani’s fuzzy inference system (FIS) and it has one input and one output. The input represents the function between sliding function, error and the rate of error. The outputs represent torque, respectively. The GDOA is the most prominent iterative method for solving sparse systems of nonlinear equations. The GDOA is a composite of simple, elegant ideas that almost anyone can understand. Pure sliding mode fuzzy controller has difficulty in handling unstructured model uncertainties. To solve this problem applied GDOA to sliding mode fuzzy controller for adjusting the sliding surface gain ( ). Since the sliding surface gain ( ) is adjusted by GDOA, it is nonlinear and continuous. GDOA sliding mode fuzzy controller is stable model-free controller which eliminates the chattering phenomenon without to use the boundary layer saturation function. Lyapunov stability is proved in GDOA sliding mode fuzzy controller based on switching (sign) function. This controller has acceptable performance in presence of uncertainty (e.g., overshoot=0.1%, rise time=0.6 second, steady state error = 1.1e-9 and RMS error=1.8e-9).

Fuel ratio (FR) is the mass ratio of air and fuel trapped inside a cylinder before combustion begins, and it affects engine emissions, fuel economy, and other performances. For a dual fuel engine equipped with both port-fuel-injection (PFI) and direct injection (DI) systems, the fuel ratio is the ratio of the first fuel and total fuel masses. In this research, a multi-input-multi-output baseline chattering free sliding mode methodology scheme is developed with guaranteed stability to simultaneously control fuel ratios to desired levels under various air flow disturbances by regulating the mass flow rates of engine PFI and DI injection systems. A baseline estimator with varying parameter gain is designed with guaranteed stability to allow implementation of the proposed state feedback sliding mode methodology into a MATLAB simulation environment, where the sliding mode strategy is implemented into a model engine control module (“software”). The baseline sliding methodology performance was compared with a well-tuned baseline multi-loop PID controller through MATLAB simulations and showed improvements, where MATLAB simulations were conducted to validate the feasibility of utilizing the developed controller and state estimator for automotive engines. A baseline sliding mode tracking methodology is developed to regulate the transient and steady state FR based upon a control oriented model of the engine PFI wall wetting dynamics. The proposed tracking method is designed to optimally track the desired FR by minimizing the error between the trapped in-cylinder mass and the product of the desired FR and fuel mass over a given time interval. The performance of the optimal proposed tracking methodology was compared with the conventional fueling control based on the inverse fueling dynamics through simulations and showed improvement over the baseline conventional inverse fueling dynamics methodology.

To reduce the chattering errors of reed switch sensors used for automatic remote measurement of water supply system, a reed switch sensor was analyzed and improved. The operation of reed switch sensors can be described as a mechanical contact by approximation of permanent magnet piece to generate an electrical pulse. The reed switch sensors are used in measurement application by detecting the rotational or translational displacement. To apply for flow measurement devices, the reed switch sensors should keep high reliability. They are applied for the electronic digital type of water flow meters. The reed switch sensor is just installed simply on the mechanical type flow meter. A small magnet is attached on a pointer of the water meter counter rotor. Inside the reed sensor, two steel leaf springs make mechanical contact and apart as rotation of flow meter counter. The counting electrical contact pulses can be converted as the water flow amount. The MCU sends the digital flow rate data to the server using the wireless communication network. But it occurs data difference or errors by chattering noise. The reed switch sensor contains chattering error by it self at the force equivalent position. The vibrations such as passing car near to the switch sensor installed location. In order to reduce chattering error, most system uses just software methods for example using filter and also statistical calibration methods. The chattering errors were reduced by changing leaf spring structure using mechanical hysteresis characteristics.

This paper deals with "chattering" problem in variable structure control system. For digital computer control, chattering reduction algorithm in Analog-VSC is extended to Discrete-VSC. The proposed algorithm is applied to position control of D.C Servo Motor by using 6502 .mu.-processor. The improved transient response, as well as a considerable reduction of chattering, is illustrated experimentally.imentally.

In this paper, a hyperstable cascade control scheme for servo drive systems is proposed to reduce the chattering, which is an undesirable property in discontinuously controlled systems. First, a discontinuously controlled hyperstable MRAC scheme is designed with respect to PI speed control system using only output variables, and then a linear position controller is cascaded. It is shown that the above system is asymptotically stable and the chattering is greatly reduced at a constant speed provided that the disturbance torque satisfies a certain condition.

The sliding mode control is an effective method to establish robustness against parameter variations and disturbance. But, in sliding mode strategy, the control function is discontinuous on the hyperplane. Consequently, the control input chatters at high frequency. When we apply such a control to the induction motor drive system, that causes a torque ripple and current harmonics, which are harmful to the system. In this paper, we introduce a low pass filter between sliding mode control output and driver input to overcome that problem. The band-width of this filter is varied according to the error funtion to improve transient responses.

수동형 진동제어 방식과 같이 시스템이 안정되며, 수동형에 비해 높은 제진 효과가 기대되는 반능동 진동제어 방식은 시스템의 안정화가 요구되는 우주구조물의 제진방법에 유효한 진동제어 방식중 하나이다. On-Off 제어방식에 근거한 반능동 제어는 On-Off 스위칭 시에 전달력의 불연속성으로 인한 chattering을 발생시킬 수 있으며, 이는 탑재체 구조물의 고유진동수와의 커플링으로 인하여 지향성능을 저하시키는 원인으로 작용할 수 있다. 본 논문에서는 chattering 영향 최소화를 통한 지향성능향상을 목적으로 LQ(Linear Quadratic)이론에 기반한 가변 감쇠형 반능동 제어기법을 제안하였다. 시뮬레이션 결과는 본 논문에서 제안한 반능동 제어기법은 기존의 skyhook와 LQ를 기반으로 하는 Bang-Bang 반능동 제어기법과 비교하여 높은 진동절연 성능을 나타내고 있다.

Semi-active vibration control is one of the attractive control methods for space application due to its robustness as passive damping system and much higher damping performance than passive system. However, a chattering induced by the sudden variation of damping force at the time of On-Off switching of semi-active control device degrades pointing performance of the on-board payload. In this paper, to enhance the pointing performance of the on-board payload, we proposed a semi-active vibration isolation with a strategy for attenuating chattering effect. Numerical simulation results using simplified analysis model indicated that the proposed semi-active control strategy produced much better isolation performance than the conventional Bang-Bang control semi-active control laws derived from skyhook and LQ theories.

The input chattering in the sliding mode control (SMC) is alleviated through a low pass filter. When the low pass filter is added to the original system, the overall system including the low pass filter dynamics can not satisfy the matching condition. So the integral SMC is applied for a main controller. A sliding surfaces are designed carefully to make the overall dynamics same with the nominal control system.

Chattering-free sliding mode control is derived from the reaching law method and Lyapunov stability theorem. Its control input Is composed of continuous term and discontinuous term. By the combination of these terms, the robustness and tracking performance can be improved and the chattering can be avoided. But in the reaching mode, the sliding mode control is sensitive to the modeling uncertainties, parameter variations and disturbances, also it needs a large control input. These result in poor transient responses. In this paper, to overcome these problems in the reaching mode, a time-varying sliding surface is proposed. And it is applied to a 2-link SCARA robot manipulator, experimental results show that the transient response is improved and its ...

In this paper, an output chattering attenuation scheme is proposed for two tracking controllers. The controllers have integral actions and are used to eliminate the steady-state tracking errors. By designing a compensator and reducing the discontinuous switching, the output chattering at the switching points can be attenuated significantly. Moreover, combining with the generalized Kalman-Yakubovich-Popov (KYP) lemma and the parameter-dependent Lyapunov function method, this problem can be characterized in terms of linear matrix inequality (LMI) formulation. Finally, the simulation results demonstrate the effectiveness of the proposed method.

This study investigates the effects of operating conditions on the chattering of an automotive disk brake by experimental and computational methods. Design factors, which cause chattering in automobiles, have attracted great attentions for long time; but they are not well understood yet. For this study, we construct a brake dynamometer for measuring the disk surface temperature during chattering, and propose an efficient hybrid algorithm (combining FFT-FEA and traditional FEA program) for analyzing the thermo-elastic behavior of three-dimensional brake system. We successfully measure the judder in a brake system via the dynamometer and efficiently simulate the contact pressure variation by the hybrid algorithm. The three-dimensional simulation of thermo-mechanical interactions on the automotive brake, showing the transient thermo-elastic instability phenomenon, is presented for the first time in this academic community. We also find from the experimental study that the disk bulk temperature strongly influences the brake chattering in the automotive disk brakes.