• Title/Summary/Keyword: Continuous-Time Model

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Intelligent Digital Redesign of a Fuzzy-Model-Based Controllers for Nonlinear Systems with Uncertainties (불확실성을 갖는 비선형 시스템을 위한 퍼지 모델 기반 제어기의 지능형 디지털 재설계)

  • Jang Kwon-Kyu;Kwon Oh-Shin;Joo Young-Hoon
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.3
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    • pp.227-232
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    • 2006
  • In this paper, we propose a systematic method for intelligent digital redesign of a fuzzy-model-based controller for continuous-time nonlinear system which may also contain system uncertainties. The continuous-time uncertain TS fuzzy model is first contructed to represent the uncertain nonlinear system. A parallel distributed compensation(PDC) technique is then used to design a fuzzy-model-based controller for both stabilization. The designed continuous-time controller is then converted to an equivalent discrete-time controller by using a globally intelligent digital redesign method. This new technique is designed by a global matching of state variables between analog control system and digital control system. This new design technique provides a systematic and effective framework for integration of the fuzzy-model-based control theory and the advanced digital redesign technique for nonlinear systems with uncertainties. Finally, Chaotic Lorenz system is used as an illustrative example to show the effectiveness and the feasibility of the developed design method.

Input Dimension Reduction based on Continuous Word Vector for Deep Neural Network Language Model (Deep Neural Network 언어모델을 위한 Continuous Word Vector 기반의 입력 차원 감소)

  • Kim, Kwang-Ho;Lee, Donghyun;Lim, Minkyu;Kim, Ji-Hwan
    • Phonetics and Speech Sciences
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    • v.7 no.4
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    • pp.3-8
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    • 2015
  • In this paper, we investigate an input dimension reduction method using continuous word vector in deep neural network language model. In the proposed method, continuous word vectors were generated by using Google's Word2Vec from a large training corpus to satisfy distributional hypothesis. 1-of-${\left|V\right|}$ coding discrete word vectors were replaced with their corresponding continuous word vectors. In our implementation, the input dimension was successfully reduced from 20,000 to 600 when a tri-gram language model is used with a vocabulary of 20,000 words. The total amount of time in training was reduced from 30 days to 14 days for Wall Street Journal training corpus (corpus length: 37M words).

Event-Triggered Model Predictive Control for Continuous T-S fuzzy Systems with Input Quantization (양자화 입력을 고려한 연속시간 T-S 퍼지 시스템을 위한 이벤트 트리거 모델예측제어)

  • Kwon, Wookyong;Lee, Sangmoon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.9
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    • pp.1364-1372
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    • 2017
  • In this paper, a problem of event-triggered model predictive control is investigated for continuous-time Takagi-Sugeno (T-S) fuzzy systems with input quantization. To efficiently utilize network resources, event-trigger is employed, which transmits limited signals satisfying the condition that the measurement of errors is over the ratio of a certain level. Considering sampling and quantization, continuous Takagi-Sugeno (T-S) fuzzy systems are regarded as a sector bounded continuous-time T-S fuzzy systems with input delay. Then, a model predictive controller (MPC) based on parallel distributed compensation (PDC) is designed to optimally stabilize the closed loop systems. The proposed MPC optimize the objective function over infinite horizon, which can be easily calculated and implemented solving linear matrix inequalities (LMIs) for every event-triggered time. The validity and effectiveness are shown that the event triggered MPC can stabilize well the systems with even smaller average sampling rate and limited actuator signal guaranteeing optimal performances through the numerical example.

Alternative Derivation of Continuous-Time Model for Current-Mode Control (전류모드제어를 위한 연속시간모델의 새로운 유도 방법)

  • Jung Dong-Yeol;Hong Sung-Soo;Choi Byung-Cho;Sakong Sug-Chin
    • Proceedings of the KIPE Conference
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    • 2002.11a
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    • pp.218-222
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    • 2002
  • Two existing continuous-time models for the current-mode control have presented noticeable differences in their small-signal predictions. As an attempt to clarify the origin of these disparities, this paper presents an alternative way of deriving a continuous-time model for the current-model control. The results of this paper would provide insights to comprehend the dissimilarity in the modeling method and final results of the earlier models of current-mode control.

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Frequency-Domain Balanced Stochastic Truncation for Continuous and Discrete Time Systems

  • Shaker, Hamid Reza
    • International Journal of Control, Automation, and Systems
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    • v.6 no.2
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    • pp.180-185
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    • 2008
  • A new method for relative error continuous and discrete time model order reduction is proposed. The reduction technique is based on two recently developed methods, namely frequency domain balanced truncation within a frequency bound and inner-outer factorization techniques. The proposed method is of interest for practical model order reduction because in this context it shows to keep the accuracy of the approximation as high as possible without sacrificing the computational efficiency. Numerical results show the accuracy and efficiency enhancement of the method.

A study of a combined release model using perturbation solutions (섭동해를 이용한 혼합 누출에 관한 연구)

  • Kim, Myungbae
    • Journal of Energy Engineering
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    • v.23 no.4
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    • pp.41-48
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    • 2014
  • Leak of liquid has been categorized conventionally into instantaneous release and continuous release. In this study, the spread of cryogenic liquid due to limited period of release is investigated for the first time to establish a new classification method with recognizing the irrationality of the conventional one. Such physical phenomena are governed by simultaneous equations concerning volume, radius and height of pool of the cryogenic liquid, and major parameters are evaporation rate per unit area, time of release, and spill quantity. The simultaneous governing equations is decoupled to get efficiently perturbation solutions. As the results, for the same spill quantity, in view of release model, combined release model that consists of continuous and consecutive instantaneous model is necessary with small time of release, while continuous model is solely required with large time of release. Also, the combined model is necessary for small spill quantity with the same time of release. These two regimes of release are clearly distinguished using the perturbation solution to provide a clear basis for the new classification of release models.

CONTINUOUS DATA ASSIMILATION FOR THE THREE-DIMENSIONAL SIMPLIFIED BARDINA MODEL UTILIZING MEASUREMENTS OF ONLY TWO COMPONENTS OF THE VELOCITY FIELD

  • Anh, Cung The;Bach, Bui Huy
    • Journal of the Korean Mathematical Society
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    • v.58 no.1
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    • pp.1-28
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    • 2021
  • We study a continuous data assimilation algorithm for the three-dimensional simplified Bardina model utilizing measurements of only two components of the velocity field. Under suitable conditions on the relaxation (nudging) parameter and the spatial mesh resolution, we obtain an asymptotic in time estimate of the difference between the approximating solution and the unknown reference solution corresponding to the measurements, in an appropriate norm, which shows exponential convergence up to zero.

OPTIMAL PORTFOLIO CHOICE IN A BINOMIAL-TREE AND ITS CONVERGENCE

  • Jeong, Seungwon;Ahn, Sang Jin;Koo, Hyeng Keun;Ahn, Seryoong
    • East Asian mathematical journal
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    • v.38 no.3
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    • pp.277-292
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    • 2022
  • This study investigates the convergence of the optimal consumption and investment policies in a binomial-tree model to those in the continuous-time model of Merton (1969). We provide the convergence in explicit form and show that the convergence rate is of order ∆t, which is the length of time between consecutive time points. We also show by numerical solutions with realistic parameter values that the optimal policies in the binomial-tree model do not differ significantly from those in the continuous-time model for long-term portfolio management with a horizon over 30 years if rebalancing is done every 6 months.

A continuous time asymmetric power GARCH process driven by a L$\'{e}$vy process

  • Lee, Oe-Sook
    • Journal of the Korean Data and Information Science Society
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    • v.21 no.6
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    • pp.1311-1317
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    • 2010
  • A continuous time asymmetric power GARCH(1,1) model is suggested, based on a single background driving L$\'{e}$vy process. The stochastic differential equation for the given process is derived and the strict stationarity and kth order moment conditions are examined.

A Design on Robust Model Following Servo System Using $\delta$--Operator ($\delta$-연산자를 이용한 강인한 모델 추종형 서보 제어 시스템의 구성에 관한연구)

  • Kim, Chung-Tek;Hwang, Hyun-Joon
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.2
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    • pp.121-126
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    • 2000
  • In the fast sampling limit the delta operator model tends to the analog system model. This fundamental property of the delta operator model unifies continuous and discrete time control system. In this paper we study robust linear optimal model following servo system in the presence of disturbances and parameter perturbations. A technique to directly design the generalized differential operator based unified control system that covers both differential operator based continuous time and delta operator based discrete time case is presented. The quadratic criterion function for a linear system is used to design the robust unified servo control system The characteristics of the proposed servo system are analysed and simulated to verify the robustness.

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