• 대한전기학회논문지:시스템및제어부문D
• /
• 제49권9호
• /
• pp.526-537
• /
• 2000

This paper deals with a sliding mode controller with integral compensation in a magnetic suspension system The control scheme comprises an integral controller which is designed for achieving zero steady-steate error under step disturbance input and a sliding mode controller which is designed for enhancing robustness under plant parametric variations. A procedure is developed for determining the coefficients of the switching plane and integral control gain such that the overall closed-loop system has stable eigenvalues. A proper continuous design signal is introduced to overcome the chattering problem. The performance of a magnetically suspended balance beam using the proposed integral sliding mode controller is illustrated. Simulation and experimental results also show that the proposed method is effective under the external step disturbance and input channel parametric variations.

• 한국결정성장학회지
• /
• 제17권1호
• /
• pp.6-10
• /
• 2007

R-plane 사파이어 위에 a-plane GaN층이 성장된 기판에 혼합소스 HVPE(mixed-source hydride vapor phase epitaxy) 방법으로 GaN/InGaN의 이종접합구조(heterostructure)를 구현하였다. GaN/InGaN 이종접합구조는 GaN, InGaN, Mg-doped GaN 층으로 구성되어 있다. 각 층의 성장온도는 GaN층은 $820^{\circ}C$, InGaN 층은 $850^{\circ}C$, Mg-doped GaN 층은 $1050^{\circ}C$에서 성장하였다. 이때의 $NH_3$와 HCl 가스의 유량은 각각 500 sccm, 10 sccm 이었다. SAG-GaN/InGaN 이종접합구조의 상온 EL (electroluminescence) 특성은 중심파장은 462 nm, 반치폭(FWHM : full width at half maximum) 은 0.67eV 이었다. 이 결과로부터 r-plane 사파이어 기판위에 multi-sliding boat system의 혼합소스 HVPE 방법으로 이종접합구조의 성장이 가능함을 확인하였다.

• Structural Engineering and Mechanics
• /
• 제26권5호
• /
• pp.517-544
• /
• 2007

This study shows a fuzzy tuning scheme to fuzzy sliding mode controller (FSMC) for seismic isolation of earthquake-excited structures. The sliding surface can rotate in the phase plane in such a direction that the seismic isolation can be improved. Since ideal sliding mode control requires very fast switch on the input, which can not be provided by real actuators, some modifications to the conventional sliding-mode controller have been proposed based on fuzzy logic. A superior control performance has been obtained with FSMC to deal with problems of uncertainty, imprecision and time delay. Furthermore, using the fuzzy moving sliding surface, the excellent system response is obtained if comparing with the conventional sliding mode controller (SMC), as well as reducing chattering effect. For simulation validation of the proposed seismic response control, 16-floor tall building has been considered. Simulations for six different seismic events, Elcentro (1940), Hyogoken (1995), Northridge (1994), Takochi-oki (1968), the east-west acceleration component of D$\ddot{u}$zce and Bolu records of 1999 D$\ddot{u}$zce-Bolu earthquake in Turkey, have been performed for assessing the effectiveness of the proposed control approach. Then, the simulations have been presented with figures and tables. As a result, the performance of the proposed controller has been quite remarkable, compared with that of conventional SMC.

• Smart Structures and Systems
• /
• 제5권3호
• /
• pp.209-221
• /
• 2009

A control algorithm for seismic protection of building structures based on the theory of variable structural control or sliding mode control is presented. The paper focus in the design of sliding surface. A method for determining the sliding surface by pole assignment algorithm where the poles of the system in the sliding surface are obtained on-line, based on the frequency content of the incoming earthquake signal applied to the structure, is proposed. The proposed algorithm consists of the following steps: (i) On-line FFT process is applied to the incoming part of the signal and its frequency content is recognized. (ii) A transformation of the frequency content to the complex plane is performed and the desired location of poles of the controlled structure on the sliding surface is estimated. (iii) Based on the estimated poles the sliding surface is obtained. (iv) Then, the control force which will drive the response trajectory into the estimated sliding surface and force it to stay there all the subsequent time is obtained using Lyapunov stability theory. The above steps are repeated continuously for the entire duration of the incoming earthquake. The potential applications and the effectiveness of the improved control algorithm are demonstrated by numerical examples. The simulation results indicate that the response of a structure is reduced significantly compared to the response of the uncontrolled structure, while the required control demand is achievable.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1998년도 사면안정 학술발표회 논문집
• /
• pp.99-110
• /
• 1998

• 한국통신학회논문지
• /
• 제19권10호
• /
• pp.2043-2052
• /
• 1994

본 논문에서는 근접한 Processing Element(PE)들간의 통신 부담을 경감시켜 영상신호를 실시간 처리할 수 있는 새로운 병렬처리 방식 ASIC 구조를 설계한다. 하나의 Sliding Memory Plane (SliM) Image Processor chip을 병렬처리 방식을 사용 $3\times3$ PE를 격자 형태로 연결한다. 제안하는 Image Processor를 구현할 수 있다. Sliding 개념은 별도의 보조 프로세서나 DMA를 사용치 않고 또한 PE들을 interupt 걸지 않고 모든 화소가 이웃 PE로 이동됨을 의미한다. 따라서 근접 통신과 계산이 동시에 일어나 기존의 격자 연결 병렬 컴퓨터의 결정적 단점인 근접 통신 부담을 경감시킬 수 있다. 또한 하나의 PE에 두 개의 입출력용 레지스터 plane을 사용, buffer를 제공하여 입출력 부담을 감소시킨다. SliM Image Processor에서는 단지 4개의 통신 link만으로 8가지 방향의 통신경로를 제공하는 by-passing path에 의해 통신 부담없이 대각선 통신을 수행할 수 있다. 제안하는 유일한 특성들로 인해 영상 신호 처리시 성능을 향상시킬 수 있다. 영상신호 처리를 위한 알고리즘들을 효율적으로 수행키 위한 PE, Image Processor 구조 및 명령어를 설계한다.

• 대한기계학회논문집
• /
• 제19권1호
• /
• pp.99-110
• /
• 1995

An industrial robot needs a simple and robust control algorithm obtaining high precision control performance in spite of disturbance and parameter's change. In this paper, for solving this problem, a new sliding mode control algorithm is proposed and applied to the trajectory control of a SCARA type robot. The proposed algorithm has diminished the chattering occurring in sliding mode by setting a dead band along the switching line on the phase plane. It shows that we can easily obtain a simple switching control input satisfying sliding mode in spite of regarding nonlinear terms of a manipulator and servo system as disturbance. A guideline for selection of dead-band width is determined by optimal value of cost function presenting magnitudes of chattering and error. By this algorithm, we can expect the high performance of the trajectory tracking of an industrial robot which needs a robust and simple algorithm.

• 대한기계학회논문집
• /
• 제18권4호
• /
• pp.866-875
• /
• 1994

The problem of a rigid rod sliding on a rough horizontal surface in the plane is analyzed, which is commonly cited as an example of the inconsistency of rigid body frictional mechanics. The inconsistency is demonstrated by analyzing the normal reaction force at the contact point with the surface, and the concept of tangential collision is derived to resolve the inconsistency. Using the Poisson's hypothesis for the coefficient of restitution and Coulomb's law for the friction, the general methodology for solving the tangential collision is presented. The problem of the inconsistency generated in the sliding rod is completely resolved, building the concept of the tangential collision and adopting the theory of frictional impact. The result presented in this paper will obviate a generic obstacle to the development of simulation packages for planar rigid body mechanical systems with temporary contacts, and planning efficient motion strategies for robot manipulators.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
• /
• pp.215-218
• /
• 1995

In this paper, a sliding mode controller (SMC) which can be characterized by high accuracy, fast response and robustness is applied to speed control of AC-SERVO motor. The control input is changed to continuous one in the boundary layer to reduce the chattering phenomenon, and the boundary layer converges to zero when the state variables of system reach to steady state values. The integral compensator is added to reduce steady state error and to provide the continuous torque reference. The acceleration which is necessary to get the sliding plane is estimated by an observer. Sliding surface is included in control input to enhance the robustness and transient response without increasing sliding mode controller gain. The proposed controller is implemented by DSP(digital signal processor). The effectiveness of the proposed control scheme for speed controller is shown by the real-time experimental results in the paper.

• 지질공학
• /
• 제10권3호
• /
• pp.205-216
• /
• 2000

이 연구는 집중호우 시에 심한 지표균열이 발생하여 주민의 안전이 우려되는 달성군 다사읍 이천리 배후 산록의 지반활동 원인을 조사하고 대책을 강구하는데 그 목적이 있다. 활동원인을 조사하기 위하여 지표 지질조사, GPR 탐사, 시추조사 및 시험, 강수자료 검토 등이 수행되었으며, 조사결과를 종합하여 활동면은 지하 6~8m 심도에 위치하는 사암과 셰일의 경계를 이루는 경사각 20~25$^{\circ}$의 층리면이 약선대로 작용한 것으로 확인되었다. 활동면의 전단강도는 한계평형해석법에 의한 역해석을 수행하여 지하수위가 상승한 경우에 안전율이 1.0 이하가 되는 값으로 내부마찰각 18$^{\circ}$, 점착력 0 kgf/$\textrm{cm}^2$으로 결정하였다. 이를 바탕으로 도해적 분석, 한계평형해석 및 수치해석 등 일련의 해석을 수행하였으며, 특히, 다양한 조건 하에서 한계평형해석을 수행하여 그 결과로부터 지반활동 방지를 위한 사면보강방안을 제시하였다. 적절한 표면 배수시설과 함께 지반 그라우팅 혹은 앵커공법의 적용이 사면의 장기적인 안전에 적절할 것이다.