• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권2호
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• pp.109-114
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• 2002

Various inverted pendulum systems have been frequently used as a model for the performance test of the proposed control system. We first identify a rotary-type inverted pendulum system by the Euler-Lagrange method and then design a FLC (Fuzzy Logic Controller) fur the plant. FLC`s are one of useful control schemes fur plants having difficulties in deriving mathematical models or having performance limitations with conventional linear control schemes. Many FLC`s imitate the concept of conventional PD (Proportional-Derivative) or PI (Proportional-Integral) controller. That is, the error e and the change-of-error are used as antecedent variables and the control input u the change of control input Au is used as its consequent variable for FLC`s. In this paper we design a simple-structured FLC for the rotary inverted pendulum system. We also perform some computer simulations to examine the tracking performance of the closed-loop system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1833-1838
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• 1991

This paper presents a stabilization technique for unstable systems. An inverted pendulum, which is a typical unstable mechanical system, is considered and stabilized by a nonlinear control. The stabilization problem in this system is related to that in postural control of human being. In this paper, the variable structure control (VSC) is applied to the stabilization problem. Robustness by the VSC and that by a conventional linear feedback controller are compared.

• Smart Structures and Systems
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• 제4권6호
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• pp.741-757
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• 2008

The research field of structural control has evolved from the development of passive devices since 1970s, through the intensive investigation on active systems in 1980s, to the recent studies of semi-active control systems in 1990s. Currently semi-active control is considered most promising in civil engineering applications. However, actual implementation of semi-active devices is still limited due mainly to their system maintenance and associated long-term reliability as a result of power requirement. In this paper, the concept of functionally upgraded passive devices is introduced to streamline some of the state-of-the-art researches and guide the development of new passive devices that can mimic the function of their corresponding semi-active control devices for various applications. The general characteristics of this special group of passive devices are discussed and representative examples are summarized. Their superior performances are illustrated with cyclic and shake table tests of two example devices: mass-variable tuned liquid damper and friction-pendulum bearing with a variable sliding surface curvature.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권8호
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• pp.467-472
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• 2000

A three-level decoupled sliding mode controller is developed to achieve asymptotic stability for a class of sixth-order nonlinear systems. The sixth-order system is decoupled into three subsystems according to the structure of the whole system. Each subsystem has a separate control target in the form of a sliding surface. The information of the third sliding surface is transferred to the second one through an intermediate variable and the information of the second sliding surface is transferred to the first one through another intermediate variable. Consequently, the controller designed on the basis of the first sliding surface can make three subsystems move toward their sliding surfaces, respectively. The three-level decoupled sliding mode controller is applied to the double-inverted pendulum problem where the zero stable states are required.

• Wind and Structures
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• 제32권4호
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• pp.341-354
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• 2021

Articulated towers are one of the class of compliant offshore structures that freely oscillates with wind and waves, as they are designed to have low natural frequency than ocean waves. The present study deals with the dynamic response of a double-pendulum articulated tower under hydrodynamic and aerodynamic loads. The wind field is simulated by two approaches, namely, single-point and multiple-point. Nonlinearities such as instantaneous tower orientation, variable added mass, fluctuating buoyancy, and geometrical nonlinearities are duly considered in the analysis. Hamilton's principle is used to derive the nonlinear equations of motion (EOM). The EOM is solved in the time domain by using the Wilson-θ method. The maximum, minimum, mean, and standard deviation and salient power spectral density functions (PSDF) of deck displacement, bending moment, and central hinge shear are drawn for high and moderate sea states. The outcome of the analyses shows that tower response under multiple-point wind-field simulation results in lower responses when compared to that of single-point simulation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.425-428
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• 1998

This paper proposes a new fuzzy controller using variable structure control theory. In this paper, after the time-varying fuzzy sliding surface is designed, the fuzzy rules are defined based on the variable structure control theory. This design method makes the fuzzy controller design more structured and can guarantee the stability and robustness of the fuzzy controller and overcome the shortcoming of the variable structure system. Through computer simulation and experiment of nonlinear inverted pendulum system, this thesis demonstrate that system has the robustness against disturbance and modelling error, and the tracking performance of it is improved.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1470-1473
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• 2003

In this paper the networked control systems (NCS) problem is discussed where plants and controllers are distributed and interconnected by a common network. NCS is designed with LQ regulator and applied to an inverted pendulum accounting for the multiple time delays. We are to deals with a networked control system with a single controller, multiple sensors and multiple actuators. Since these parts are distributed, they are interconnected by communication networks. An NCS with LQ regulator is designed and applied to an inverted pendulum as a benchmark plant to check its performance under time delays induced by the network. Network induced delays are composed of two parts. One is the delay from controller to plant, and another is from plant to controller. They are assumed to be constant in this paper, and the plant and controller are discretized. To apply the LQ regulator the NCS model is transformed to a standard model with delayed states as state variable. And real network induced delay is measuring in TCP/IP network assuming that two delays are constant.

• 한국지능시스템학회논문지
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• 제6권4호
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• pp.71-80
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• 1996

본 논문은 진화연산 중 실수값 탐색에 유리한 진화전략(Evolution Strategies)을 이용하여 대표적인 비선형 시스템인 도립전자(Inverted Pendulum)의 안정화 및 위치제어를 실현한다. 도립진자의 제어입력은 진자의 상태변수 x, $, $, $ 의공간을 나누어 그 공간에해당되는 염색체의 원소가 된다. 일바적으로 염색체의 길이가 길어지면 최적의해를 탐색하기 위한 진화시간은 길어진다. 따라서 본 논문에서는 진화속도를 개선하기 위하여, 서로 대칭이 되는 진자의 구간에 대해서는 제어입력을 따로 구하지 않고 그 제어입력의 부호만 바꾸어 주는 방식을 채용하여 상태공간을 반으로 줄이는 방법을 제안하였으며, 진자의 수레가 제어 목표점에서 멀리 떨어져 있는 경우와 가까이 있는 경우로 나누어, 염색체의 진화과정을 2단계에 걸쳐 수행하게 함으로써 염색체의 진화속도의 개선은 몰룬 시스템 전체의 성능을 향상시켰다. 또 하나의 방법으로 신경회로망과 진화전략을 융합한 방법을 제안하고, 제안한 제어방식은 컴퓨터 시뮬레이션을 통하여 그 유효성을 확인한다.

• Smart Structures and Systems
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• 제13권2호
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• pp.219-233
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• 2014

In a companion paper, Pasala and Nagarajaiah analytically and experimentally validate the Adaptive Length Pendulum Smart Tuned Mass Damper (ALP-STMD) on a primary structure (2 story steel structure) whose frequencies are time invariant (Pasala and Nagarajaiah 2012). In this paper, the ALP-STMD effectiveness on a primary structure whose frequencies are time varying is studied experimentally. This study experimentally validates the ability of an ALP-STMD to adequately control a structural system in the presence of real time changes in primary stiffness that are detected by a real time observer based system identification. The experiments implement the newly developed Adaptive Length Pendulum Smart Tuned Mass Damper (ALP-STMD) which was first introduced and developed by Nagarajaiah (2009), Nagarajaiah and Pasala (2010) and Nagarajaiah et al. (2010). The ALP-STMD employs a mass pendulum of variable length which can be tuned in real time to the parameters of the system using sensor feedback. The tuning action is made possible by applying a current to a shape memory alloy wire changing the effective length that supports the damper mass assembly in real time. Once a stiffness change in the structural system is detected by an open loop observer, the ALP-STMD is re-tuned to the modified system parameters which successfully reduce the response of the primary system. Significant performance improvement is illustrated for the stiffness modified system, which undergoes the re-tuning adaptation, when compared to the stiffness modified system without adaptive re-tuning.

• 생명과학회지
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• 제22권8호
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• pp.1120-1125
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• 2012

국내에 자생 중인 큰엉겅퀴(Cirsium pendulum)를 강원도의 홍천, 원주, 평창, 양양 및 경기도 가평과 충청북도의 충주에서 채취하고, 고려엉겅퀴(Cirsium setidens)를 강원도의 태백 및 경상북도의 봉화에서 채취하였다. 채취된 식물들의 genomic DNA를 분리하여서 18S rDNA, ITS1, 5.8S rDNA, ITS2 및 28S rDNA의 일부를 증폭하고, 그 염기서열을 분석하였다. 이렇게 얻어진 염기서열을 GenBank에 등록하고, 서로 비교해 보았다. 그 결과 큰엉겅퀴는 6개체 모두에서 18S rDNA 및 5.8S rDNA의 염기서열은 서로 완전히 일치하고 있으나, ITS1과 ITS2의 염기서열에서는 약간의 차이를 보였다. 고려엉겅퀴의 경우에는 18S rDNA, ITS1 및 ITS2에서 2개체가 서로 비교적 큰 차이를 보였다. 일본의 홋카이도에서 채취된 큰엉겅퀴와 중국의 안휘성에서 채취된 엉겅퀴(Cirsium japonicum)를 포함하여서 ITS1과 ITS2 염기서열을 비교한 결과, 엉겅퀴, 큰엉겅퀴, 고려엉겅퀴는 확연하게 서로 다른 그룹을 형성하는 것으로 나타났다. 또한 채취된 큰엉겅퀴 및 고려엉겅퀴들의 silymarin 함량을 분석해 본 결과, 모두에서 그 함량이 2 mg/ml가 넘는 것으로 나타났다. 따라서 엉겅퀴뿐만 아니라 큰엉겅퀴나 고려엉겅퀴도 여러 가지 약리작용을 가진 것으로 보고된 silymarin을 상당히 높은 농도로 함유하고 있는 것으로 나타났다.