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Sensor Signal Processing for Estimating Gradient Values using Perturbation Input (섭동 입력을 사용한 구배 값 추정용 센서 신호 처리)

  • Lee, Sooyong
    • Journal of Sensor Science and Technology
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    • v.26 no.4
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    • pp.251-258
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    • 2017
  • According to recent studies by scientists about how to search for food, homes and the mates, it is found that the gradient information plays a key role. From cells to insects and large animals, they mostly either have special sensing organism or use a strategy to measure the gradient. Use of a perturbation as an additional input is introduced for sensor signal processing in order to get the gradient information. Different from typical approach, which calculates the gradient from differentiation, the proposed processing is done by a form of integration, thus it is very robust to noise. Discrete time domain analyses are given for one, two and three input functions for the estimation of the gradients. The amplitude and the frequency of the perturbation are two important parameters for this approach. A quantitative index to measure the effects of the amplitude is developed based on the linear regression analysis. The frequency of the perturbation is to be selected high enough to finish one period of the perturbation before the property is changed significantly with respect to time. Another quantitative index is proposed for guiding the selection of the frequency.

Optimal Control Design-based Gain Selection of an LCL-filtered Grid-connected Inverter in State-Space under Distorted Grid Environment

  • Tran, Vi-Thuy;Yoon, Seung-Jin;Kim, Kyeong-Hwa
    • Proceedings of the KIPE Conference
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    • 2018.07a
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    • pp.344-345
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    • 2018
  • In order to alleviate the negative impacts of harmonically distorted grid condition on grid-connect inverters, an optimal control design-based gain selection scheme of an LCL-filtered grid-connected inverter and its ability to compensate selective harmonics are presented in this paper. By incorporating resonant terms into the control structure in the state-space to provide infinity gain at selected frequencies, the proposed control offers an excellent steady-state response even under distorted grid voltage. The proposed control scheme is achieved by using a state feedback controller for stabilization purpose and by augmenting the resonant terms as well as intergral term into a control structure for reference tracking and harmonic compensation. Furthermore, the optimal linear quadratic control approach is adopted for choosing an optimal feedback gain to ensure an asymptotic stability of the whole system. A discrete-time full state observer is also introduced into the proposed control scheme for the purpose of reducing a total number of sensors used in the inverter system. The simulation results are given to prove the effectiveness and validity of the proposed control scheme.

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Data Rate Condition for Quantizer Achieving Practical Stability (실용적 안정성을 보장하는 양자화기 데이터 율 조건)

  • Yang, Janghoon
    • Journal of Advanced Navigation Technology
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    • v.22 no.3
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    • pp.228-232
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    • 2018
  • Dealing with quntization error in a control system properly becomes much more important as many devices are connected through network and controlled. Thus, in this paper, we study a data rate condition on quantizer to achieve practical stability in a discrete time linear time invariant system with state feedback control. First, required data rate is shown to depend on eigenvalue of the closed loop system, the size of the initial state vector, the magnitude of initial quantization error, and control gain in the absence of process noise. It additionally depends on the maximum magnitude of process noise when noise is not zero. Asymptotic analysis shows that a new design method may be needed to reduce the date rate for a networked control in the presence of quantization error and noise.. We provide a simple numerical evaluation of uniform quantizer and logarithmic qunatizer to assess their characteristics of practical stability depending on data rate in the presence of noise.

System Identification of Quadrotor IT Convergence UAV using Batch and RLS Estimation Methods (배치추정기법과 RLS추정기법을 사용한 쿼드로터 IT융합 무인항공기 시스템식별)

  • Jung, Sunghun
    • Journal of the Korea Convergence Society
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    • v.8 no.4
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    • pp.9-18
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    • 2017
  • UAVs began to be actively applied to so-called 3D jobs, including the autonomous exploration, investigation, mapping, search and rescue, etc. since the mid-2000s. With this global trend, having a precise controllability of the UAV will certainly revolutionize the life of the modern human in the aspect of tremendous applications of the UAV. In the first part, a simplified dynamic model of the UAV identified using system identification techniques is compared with the previously built time-discrete linear model. In the second part, the three parameters of the dynamic model are estimated using the batch and RLS methods. Angular acceleration data of the quadrotor UAV at the hovering maneuver are analyzed and shown to be converging at all time. Also, according to the quadrotor flight data from both experiments and MATLAB simulations, the batch estimation method turns out to be more accurate than the RLS estimation method based on the comparison of final parameter values.

Modelling Gas Production Induced Seismicity Using 2D Hydro-Mechanical Coupled Particle Flow Code: Case Study of Seismicity in the Natural Gas Field in Groningen Netherlands (2차원 수리-역학적 연계 입자유동코드를 사용한 가스생산 유발지진 모델링: 네덜란드 그로닝엔 천연가스전에서의 지진 사례 연구)

  • Jeoung Seok Yoon;Anne Strader;Jian Zhou;Onno Dijkstra;Ramon Secanell;Ki-Bok Min
    • Tunnel and Underground Space
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    • v.33 no.1
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    • pp.57-69
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    • 2023
  • In this study, we simulated induced seismicity in the Groningen natural gas reservoir using 2D hydro-mechanical coupled discrete element modelling (DEM). The code used is PFC2D (Particle Flow Code 2D), a commercial software developed by Itasca, and in order to apply to this study we further developed 1)initialization of inhomogeneous reservoir pressure distribution, 2)a non-linear pressure-time history boundary condition, 3)local stress field monitoring logic. We generated a 2D reservoir model with a size of 40 × 50 km2 and a complex fault system, and simulated years of pressure depletion with a time range between 1960 and 2020. We simulated fault system failure induced by pressure depletion and reproduced the spatiotemporal distribution of induced seismicity and assessed its failure mechanism. Also, we estimated the ground subsidence distribution and confirmed its similarity to the field measurements in the Groningen region. Through this study, we confirm the feasibility of the presented 2D hydro-mechanical coupled DEM in simulating the deformation of a complex fault system by hydro-mechanical coupled processes.

Implementation of MDCT core in Digital-Audio with Micro-program type vector processor

  • Ku Dae Sung;Choi Hyun Yong;Ra Kyung Tae;Hwang Jung Yeun;Kim Jong Bin
    • Proceedings of the IEEK Conference
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    • 2004.08c
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    • pp.477-481
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    • 2004
  • High Quality CD, OAT audio requires that large amount of data. Currently, multi channel preference has been rapidly propagated among latest users. The MPEG(Moving Picture Expert Group) is provides data compression technology of sound and image system. The MPEG standard provides multi channel and 5.1 sounds, using the same audio algorithm as MPEG-l. And MPEG-2 audio is forward and backward compatible. The MDCT (Modified Discrete Cosine Transform) is a linear orthogonal lapped transform based on the idea of TDAC(Time Domain Aliasing Cancellation). In this paper, we proposed the micro-program type vector processor architecture a benefit in MDCT/IMDCT of MPEG-II AAC. And it's reduced operating coefficient by overlapped area to bind. To compare original algorithm with optimized algorithm that cosine coefficient reduced 0.5%multiply operating 0.098% and add operating 80.58\%$. Algorithm test is used C-language then we designed hardware architecture of micro-programmed method that applied to optimized algorithm. This processor is 20MHz operation 5V.

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Analytical study of house wall and air temperature transients under on-off and proportional control for different wall type

  • Han, Kyu-Il
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.46 no.1
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    • pp.70-81
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    • 2010
  • A mathematical model is formulated to study the effect of wall mass on the thermal performance of four different houses of different construction. This analytical study was motivated by the experimental work of Burch et al. An analytical solution of one -dimensional, linear, partial differential equation for wall temperature profiles and room air temperatures is obtained using the Laplace transform method. Typical Meteorological Year data are processed to yield hourly average monthly values. These discrete data are then converted to a continuous, time dependent form using a Fast Fourier Transform method. This study is conducted using weather data from four different locations in the United States: Albuquerque, New mexico; Miami, Florida; Santa Maria, California; and Washington D.C. for both winter and summer conditions. A computer code is developed to calculate the wall temperature profile, room air temperature, and energy consumption loads. Three sets of results are calculated one for no auxiliary energy and two for different control mechanism -- an on-off controller and a proportional controller. Comparisons are made for the cases of two controllers. Heavy weight houses with insulation in mild weather areas (such as August in Santa Maria, California) show a high comfort level. Houses using proportional control experience a higher comfort level in comparison to houses using on-off control. The result shows that there is an effect of mass on the thermal performance of a heavily constructed house in mild weather conditions.

Real-Time Prediction of Streamflows by the State-Vector Model (상태(狀態)벡터 모형(模型)에 의한 하천유출(河川流出)의 실시간(實時間) 예측(豫測)에 관한 연구(研究))

  • Seoh, Byung Ha;Yun, Yong Nam;Kang, Kwan Won
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.2 no.3
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    • pp.43-56
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    • 1982
  • A recursive algorithms for prediction of streamflows by Kalman filtering theory and Self-tuning predictor based on the state space description of the dynamic systems have been studied and the applicabilities of the algorithms to the rainfall-runoff processes have been investigated. For the representation of the dynamics of the processes, a low-order ARMA process has been taken as the linear discrete time system with white Gaussian disturbances. The state vector in the prediction model formulated by a random walk process. The model structures have been determined by a statistical analysis for residuals of the observed and predicted streamflows. For the verification of the prediction algorithms developed here, the observed historical data of the hourly rainfall and streamflows were used. The numerical studies shows that Kalman filtering theory has better performance than the Self-tuning predictor for system identification and prediction in rainfall-runoff processes.

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Optimal Fuzzy Filter for Nonlinear Systems with Variance Constraints (분산 제약을 갖는 비선형 시스템의 최적 퍼지 필터)

  • Noh, Sun-Young;Park, Jin-Bae;Joo, Young-Hoon
    • Journal of the Korean Institute of Intelligent Systems
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    • v.22 no.5
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    • pp.549-554
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    • 2012
  • In this paper, we consider the optimal fuzzy filter of nonlinear discrete-time with estimation error variance constraint. First, the Takagi and Sugeno(T-S) fuzzy model is employed to approximate the nonlinear system. Next, the error state is mean square bounded, and the steady state variance of the estimation error of each state is not more than the individual predefined value. It is shown that, the addressed problem can be carried out by solving linear matrix inequality(LMI) and some algebraic quadratic matrix inequalities. Finally, some examples are provided to illustrate the design procedure and expected performance through simulations.

Estimation of Uncertain Past and Future Locations of Moving objects (이동 객체의 불확실한 과거 및 미래의 위치 추정)

  • 안윤애;류근호
    • Journal of KIISE:Databases
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    • v.29 no.6
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    • pp.441-452
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    • 2002
  • If continuous moving objects are managed by conventional database, it is not possible for them to store all position information changed over time in the database. Therefore, a time period of regular rate is determined and position information of moving objects are discretely stored in the system for every time period. However, if continuous moving objects are managed as discrete model, we will have problems which cannot properly answer to the query about uncertain past or future position information. To solve this problem, in this paper, we propose the method and algorithm which use the history information stored in the same database, to estimate the past or future location of moving objects. The cubic spline interpolation is used to estimate the past location and the mean movement value of the history information is used to predict the future location of moving objects. Finally, from the location estimation experimentation of using virtual trajectory and location sample, we proved that the proposed cubic spline function has less error than the linear function.