• Earthquakes and Structures
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• 제24권1호
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• pp.1-9
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• 2023

A model for calculating structure interacted mechanics is proposed. A structural interaction model and controller design based on tuned mass damping (TMD) was developed to control the induced vibration. A key point is to introduce a new analytical model to evaluate the properties of the TMD that recognizes the motion-dependent nonlinear response observed in the simulations. Aiming at the problem of increased current harmonics and low efficiency of permanent magnet synchronous motors for electric vehicles due to dead time effect, a dead time compensation method based on neural network filter and current polarity detection is proposed. Firstly, the DC components and the higher harmonic components of the motor currents are obtained by virtue of what the neural network filters and the extracted harmonic currents are adjusted to the required compensation voltages by virtue of what the neural network filters. Then, the extracted DC components are used for current polarity dead time compensation control to avert the false compensation when currents approach zero. The neural network filter method extracts the required compensation voltages from the speed component and the current polarity detection compensation method obtains the required compensation voltages by discriminating the current polarity. The combination of the two methods can more precisely compensate the dead time effect of the control system to improve the control performance. Furthermore, based on the relaxed method, the intelligent approach of stability criterion can be regulated appropriately and the artificial TMD was found to be effective in reducing cross-wind vibrations.

• 센서학회지
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• 제12권2호
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• pp.79-87
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• 2003

본 논문에서는 비선형 특성을 갖는 센서 배열을 사용하는 시스템에서, 센서 배열에 soft computing을 이용하여 선형적인 특성을 얻고, 배열의 특성을 이용하여 외란의 영향을 감소시켜 시스템의 성능을 향상시키는 방법을 제안한다. 대표적인 예로 배열에 사용된 광전도 센서인 CdS는 단일 CdS 셀 조차도 비선형적인 특성을 갖고 있기 때문에 비선형 특성을 소속 함수로 표현하는 퍼지 변수를 사용한다. 배열로 사용되는 센서에 각 단일 센서의 소속 함수와 특성을 이용하는 퍼지 논리를 적용하여 전체적으로 선형화된 센서 특성을 얻는다. 각 센서의 비선형적 요소를 표현하는 소속함수의 파라미터들에 유전 알고리즘을 사용하여 최적화 된 선형 특성을 얻어 시스템의 성능을 향상시킬 수 있다. 또한 보정을 위한 센서를 추가하지 않고 센서 배열의 특성을 이용하여 광전도 센서가 민감한 영향을 받는 외란을 보정하여 시스템의 외란 제거 성능을 향상시킬 수 있다. CdS 센서 배열의 자체 비선형성 뿐만 아니라 입력되는 물체의 그림자는 경계가 뚜렷하지 않고 흐릿하므로 퍼지 논리를 이용하는 방법이 거리측정과 외부 광원에 의한 외란에 대해 향상된 결과를 보인다. 제안된 방법을 적용한 센서 배열을 자기부상(Magnetic Levitation System)에서 볼의 거리 측정에 적용하여 성능을 검증한다.

• 한국지능시스템학회논문지
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• 제8권2호
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• pp.50-59
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• 1998

This paper presents stabilization and adaptive control of flexible single link robot manipulator system by self-recurrent neural networks that is one of the neural networks and is effective in nonlinear control. The architecture of neural networks is a modified model of self-recurrent structure which has a hidden layer. The self-recurrent neural networks can be used to approximate any continuous function to any desired degree of accuracy and the weights are updated by feedback-error learning algorithm. When a flexible manipulator is rotated by a motor through the fixed end, transverse vibration may occur. The motor toroque should be controlled in such a way that the motor rotates by a specified angle, while simultaneously stabilizing vibration of the flexible manipuators so that it is arresed as soon as possible at the end of rotation. Accurate vibration control of lightweight manipulator during the large changes in configuration common to robotic tasks requires dynamic models that describe both the rigid body motions, as well as the flexural vibrations. Therefore, a dynamic models for a flexible single link robot manipulator is derived, and then a comparative analysis was made with linear controller through an simulation and experiment. The results are proesented to illustrate thd advantages and imporved performance of the proposed adaptive control ove the conventional linear controller.

• 한국산학기술학회논문지
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• 제15권12호
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• pp.7277-7282
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• 2014

본 연구에서는 gradient descent 알고리즘을 퍼지제어기의 동조를 위해 멤버십함수의 폭을 해석하는데 이용하였으며 이 해석은 퍼지 제어규칙의 전건부와 후건부 퍼지변수들을 변화시켜 보다 개선된 제어 효과를 얻기 위해 사용된다. 이 방법은 제어기의 파라미터들이 gradient descent 알고리즘의 반복 과정에서 제어변수를 선택하는 것이다. 본 논문에서는 궤환 목표치 제어를 위해 7개의 멤버십함수와 49개의 규칙 그리고 2개의 입력과 1개의 출력을 갖는 FLC을 사용하였다. 추론은 Min-Max 합성법을 이용하였고 멤버십함수는 13개의 양자화 레벨에 대한 삼각 형태를 채택하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1314-1317
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• 1999

In this paper, we design an Adaptive Neuro-Fuzzy Inference System(ANFIS) Precompensator for the performance improvement of conventional proportional integral derivative (PID) controller that the governor system of power plant constantly maintains the load frequency of two-area power system. The ANFIS Precompensator is expressed as the membership functions of premise parameters and the linear combination of consequent parameters by Sugeno's fuzzy if-then rules using nonlinear input-output relation for the set point automatic modification maintaining conventional PID controller. The proposed compensation design technique is hoped to be satisfactory method overcome difficulty of exact modelling and arising problems by the complex nonlinearities of power system, and our design shows merit that is easily implemented by adding an ANFIS precompenastor to an existing PID controller without replacement.

• Smart Structures and Systems
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• 제23권5호
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• pp.449-466
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• 2019

Cable-stayed bridges are attractive due to their beauty, reducing material consumption, less harm to the environment and so on, in comparison with other kinds of bridges. As a massive structure with long period and low damping (0.3 to 2%) under many dynamic loads, these bridges are susceptible to fatigue, serviceability disorder, damage or even collapse. Tuned Mass Damper (TMD) is a suitable controlling system to reduce the vibrations and prevent the threats in such bridges. In this paper, Multi Tuned Mass Damper (MTMD) system is added to the Ahvaz cable stayed Bridge in Iran, to reduce its seismic vibrations. First, the bridge is modeled in SAP2000 followed with result verification. Dead and live loads and the moving loads have been assigned to the bridge. Then the finite element model is developed in OpenSees, with the goal of running a nonlinear time-history analysis. Three far-field and three near-field earthquake records are imposed to the model after scaling to the PGA of 0.25 g, 0.4 g, 0.55 g and 0.7 g. Two MTMD systems, passive and active, with the number of TMDs from 1 to 8, are placed in specific points of the main span of bridge, adding a total mass ratio of 1 to 10% to the bridge. The parameters of the TMDs are optimized using Genetic Algorithm (GA). Also, the optimum force for active control is achieved by Fuzzy Logic Control (FLC). The results showed that the maximum displacement of the center of the bridge main span reduced 33% and 48% respectively by adding passive and active MTMD systems. The RMS of displacement reduced 37% and 47%, the velocity 36% and 42% and also the base shear in pylons, 27% and 47%, respectively by adding passive and active systems, in the best cases.

• International Journal of Computer Science & Network Security
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• 제24권2호
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• pp.169-177
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• 2024

Interacting Spherical tank has maximum storage capacity is broadly utilized in industries because of its high storage capacity. This two tank level system has the nonlinear characteristics due to its varying surface area of cross section of tank. The challenging tasks in industries is to manage the flow rate of liquid. This proposed work plays a major role in controlling the liquid level in avoidance of time delay and error. Several researchers studied and investigated about reducing the nonlinearity problem and their approaches do not provide better result. Different types of controllers with various techniques are implemented by the proposed system. Intelligent Adaptive Neuro Fuzzy Inference System (ANFIS) based Sliding Mode Controller (SMC) with Fractional order PID controller is a novel technique which is developed for a liquid level control in a interacting spherical tank system to avoid the external disturbances perform better result in terms of rise time, settling time and overshoot reduction. The performance of the proposed system is obtained by analyzing the simulation result obtained from the controller. The simulation results are obtained with the help of FOMCON toolbox with MATLAB 2018. Finally, the performance of the conventional controller (FOPID, PID-SMC) and proposed ANFIS based SMC-FOPID controllers are compared and analyzed the performance indices.

• 한국생산제조학회지
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• 제19권1호
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• pp.145-155
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• 2010

This paper presents a new approach to obstacle avoidance for mobile robot in unknown or partially unknown environments. The method combines two navigation subsystems: low level and high level. The low level subsystem takes part in the control of linear, angular velocities using a multivariable PI controller, and the nonlinear position control. The high level subsystem uses ultrasonic and IR sensors to detect the unknown obstacle include static and dynamic obstacle. This approach provides both obstacle avoidance and target-following behaviors and uses only the local information for decision making for the next action. Also, we propose a new algorithm for the identification and solution of the local minima situation during the robot's traversal using the set of fuzzy rules. The system has been successfully demonstrated by simulations and experiments.

• 전기학회논문지
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• 제65권7호
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• pp.1270-1276
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• 2016

This paper proposes the controller design for regulation control of two-link robot arm using sum of squares (SOS) control method that takes into account the input constraint. The existing studies of two link robotic arm system used a linear model of all the non-linearity of the system is linearized. For a linear controller, since the model of the system is simplified, it is possible to design a controller in consideration of constraints on the disturbance. However, there is a limit to the performance using a linearized model for a system with a complex nonlinear properties. To compensate for this in the case of using a fuzzy LMI method, it is necessary to have a large number of linear models and thus there is a disadvantage that the system becomes complicated. To solve these problems, we represents a two-link robot arm system with a polynomial model using a Taylor series expansion and design the controller considering the case where the magnitude of the control input is limited using SOS method. We demonstrate by simulations the feasibility of the proposed algorithm.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.282-286
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• 2000

In this paper, magneto-rheological(MR) damper is studied for vibration control of large infra structures under earthquake. Generally, active control devices need a large control force and a high power supply system to reduce the vibration effectively. Large and miss tuned control force may induce the dangerous situation such that the generated large control force acts to amplify the structural vibration. Recently, to overcome the weaknesses of the active control, the semi-active control method is suggested by many researchers. Semi-active control uses the passive control device of which the characteristics can be modified. Control force of the semi-active device is not generated from the actuator with power supply. It is generated as a dynamic reaction force of the device same as in the passive control case, so the control system is inherently stable and robust. Unlike the case of passive control, control force of semi-active control is adjusted depending on the measured response of the structure, so the vibration can be reduced more effectively against various unknown environmental loads. Magneto-rheological(MR) damper is one of the semi-active devices. Dynamic characteristics of the MR material can be changed by applying the magnetic fields. So the control of MR damper needs only small power. Response time of MR to the input voltage is very short, so the high performance control is possible. MR damper has a high force capacity so it is adequate to the vibration control of large infra structure. Because MR damper has a nonlinear property, normal control method used in active control may not be effective. Clipped optimal control, modified bang-bang control etc. have been suggested to MR damper by many researchers. In this study, sliding mode fuzzy control(SMFC) is applied to MR damper. Genetic algorithm is used for the controller tuning. To verify the applicability of MR damper and suggested algorithm, numerical simulation on the aseismic control is carried out. Simulation model is three-story building structure, which was used in the paper of Dyke, et al. The control performance is compared with clipped optimal control. The present results indicate that the SMFC algorithm can reduce the earthquake-induced vibration very effectively.