• Title/Summary/Keyword: Scalar control

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Automatic Surface Generation for Extrusion Die of Non-symmetric H-and U-shaped sections (비축대칭 H-형 및 U-형상의 압출금형 곡면의 자동생성)

  • 유동진;임종훈;양동열
    • Transactions of Materials Processing
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    • v.12 no.6
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    • pp.572-581
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    • 2003
  • In this paper, an automatic surface construction method based on B-spline surface and scalar field theory is proposed to generate the extrusion die surface of non-symmetric H-and U-shaped sections. The isothermal lines and stream lines designed in the scalar field are introduced to find the control points which are used in constructing B-spline surfaces. Intersected points between the isothermal lines and stream lines are used to construct B-spline surfaces. The inlet and outlet profiles are precisely described with B-spline curves by using the centripetal method for uniform parameterization. The extrusion die surface is generated by using the cubic curve interpolation in the u-and v-directions. A quantitative measure for the control of surface is suggested by introducing the tangential vectors at the inlet and outlet sections. To verify the validity of the proposed method, automatic surface generation is carried out for extrusion die of non-symmetric H-and U-shaped sections.

A dominant vibration mode-based scalar ground motion intensity measure for single-layer reticulated domes

  • Zhong, Jie;Zhi, Xudong;Fan, Feng
    • Earthquakes and Structures
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    • v.11 no.2
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    • pp.245-264
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    • 2016
  • A suitable ground motion intensity measure (IM) plays a crucial role in the seismic performance assessment of a structure. In this paper, we introduce a scalar IM for use in evaluating the seismic response of single-layer reticulated domes. This IM is defined as the weighted geometric mean of the spectral acceleration ordinates at the periods of the dominant vibration modes of the structure considered, and the modal strain energy ratio of each dominant vibration mode is the corresponding weight. Its applicability and superiority to 11 other existing IMs are firstly investigated in terms of correlation with the nonlinear seismic response, efficiency and sufficiency using the results of incremental dynamic analyses which are performed for a typical single-layer reticulated dome. The hazard computability of this newly proposed IM is also briefly discussed and illustrated. A conclusion is drawn that this dominant vibration mode-based scalar IM has the characteristics of strong correlation, high efficiency, good sufficiency as well as hazard computability, and thereby is appropriate for use in the prediction of seismic response of single-layer reticulated domes.

Study of New Control Method for Linear Periodic System

  • Jo, Janghyen
    • 제어로봇시스템학회:학술대회논문집
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    • 1999.10a
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    • pp.83-87
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    • 1999
  • The purpose of this study is to provide the new method for selection of a close to optimal scalar control of linear time-periodic system. The case of scalar control is considered, the gain matrix being assumed to be at worst periodic with the system period T. The form of gain matrix may have various kinds but must have same period, for example, one of each element being represented by Fourier series. As the optimal gain matrix I consider the matrix ensuring the minimum value of the larger real part of the Poincare exponents of the system. Finally we present a pole placement algorithm to make the given system be stable. It is possible to determine the stability of the given periodic system without get the analytic solution. The application of the method does not require the construction of the Floquet solution. At present state of determination of the gain matrix for this case will be done only by systematic numerical search procedures.

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Design method of computer-generated controller for linear time-periodic systems

  • Jo, Jang-Hyen
    • 제어로봇시스템학회:학술대회논문집
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    • 1992.10b
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    • pp.225-228
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    • 1992
  • The purpose of this project is the presentation of new method for selection of a scalar control of linear time-periodic system. The approach has been proposed by Radziszewski and Zaleski [4] and utilizes the quadratic form of Lyapunov function. The system under consideration is assigned either in closed-loop state or in modal variables as in Calico, Wiesel [1]. The case of scalar control is considered, the gain matrix being assumed to be at worst periodic with the system period T, each element being represented by a Fourier series. As the optimal gain matrix we consider the matrix ensuring the minimum value of the larger real part of the two Poincare exponents of the system. The method, based on two-step optimization procedure, allows to find the approximate optimal gain matrix. At present state of art determination of the gain matrix for this case has been done by systematic numerical search procedure, at each step of which the Floquet solution must be found.

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Robust Control for Singularly Perturbed Uncertain Systems with State Constraints

  • Lee, Sang-Yup;Kim, Eung-Ju;Kim, Beom-Soo;Lim, Myo-Taeg
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.34.1-34
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    • 2001
  • We deal with robust control problem for singularly perturbed linear systems with norm-bounded structured uncertainty under state constraints. We assume that the norm-bounded uncertainty is composed of repeated scalar-block and full-block forms. In the structured uncertainty, repeated scalar block forms account for uncertain physical parameter value and full-block forms may be some unknown nonlinear dynamics. In order deal with uncertainty and state constraints, we use LMI(Linear Matrix Inequality). The original problem is decomposed into two well behaved reduced order problems. Shinc two LMI problems are completely independent, each solution can be computed simultaneously and work in parallel.

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A Stable Startup Method of V/f Scalar Controlled Permanent Magnet Synchronous Motors (V/f 스칼라 제어 영구자석 동기 전동기의 안정적 초기 구동 기법)

  • Kim, Hyeon-Seong;Lee, Sang-Min;Lee, Kibok
    • The Transactions of the Korean Institute of Power Electronics
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    • v.25 no.5
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    • pp.395-403
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    • 2020
  • This study presents a stable start-up strategy for v/f scalar-controlled permanent magnet synchronous motors (PMSMs). The v/f-controlled PMSMs easily lose synchronism under low-speed conditions if an insufficient stator voltage is applied to the machine due to errors in measured motor parameters and inverter nonlinearity, such as inverter dead time and on-state voltage drop. The proposed method adopts the I/f control method to ensure a stable start at low speeds and then switches to the v/f control method at medium speeds. A smooth transition method from I/f control to v/f control is proposed to minimize the oscillation of the stator current and rotor speed during transition. Moreover, the stability of the I/f and v/f control methods is analyzed using a small-signal model. Simulation and experimental results are provided to verify the performance of the proposed control strategy.

Design of ECC Scalar Multiplier based on a new Finite Field Division Algorithm (새로운 유한체 나눗셈기를 이용한 타원곡선암호(ECC) 스칼라 곱셈기의 설계)

  • 김의석;정용진
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.5C
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    • pp.726-736
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    • 2004
  • In this paper, we proposed a new scalar multiplier structure needed for an elliptic curve cryptosystem(ECC) over the standard basis in GF(2$^{163}$ ). It consists of a bit-serial multiplier and a divider with control logics, and the divider consumes most of the processing time. To speed up the division processing, we developed a new division algorithm based on the extended Euclid algorithm. Dynamic data dependency of the Euclid algorithm has been transformed to static and fixed data flow by a localization technique, to make it independent of the input and field polynomial. Compared to other existing scalar multipliers, the new scalar multiplier requires smaller gate counts with improved processor performance. It has been synthesized using Samsung 0.18 um CMOS technology, and the maximum operating frequency is estimated 250 MHz. The resulting performance is 148 kbps, that is, it takes 1.1 msec to process a 163-bit data frame. We assure that this performance is enough to be used for digital signature, encryption/decryption, and key exchanges in real time environments.

Smoothing and Prediction of Measurement in INS/GPS Integrated Kalman Filter (INS/GPS 결합 칼만필터의 측정치 스무딩 및 예측)

  • Lee, Tae-Gyu;Kim, Gwang-Jin;Je, Chang-Hae
    • Journal of Institute of Control, Robotics and Systems
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    • v.7 no.11
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    • pp.944-952
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    • 2001
  • Inertial navigation system(INS) errors increase with time due to inertial sensor errors, and therefore it is desired to combine INS with external aids such as GPS. However GPS informations have a randomly abrupt jump due to a sudden corruption of the received satellite signals and environment, and moreover GPS can\`t provide navigation solutions. In this paper, smoothing and prediction schemes are proposed for GPS`s jump or unavailable GPS. The smoothing algorithm which is designed as a scalar adaptive filter, smooths abrupt jump. The prediction algorithm which is proved by Schuler error model of INS, estimates INS error in appropriate time. The outputs of proposed algorithm apply stable measurements to GPS aided INS Kalman filter. Simulations show that the proposed algorithm can effectively remove measurement jump and predict INS error.

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Construction of T-S Fuzzy Model for Nonlinear Systems (비선형 시스템에 대한 T-S 퍼지 모델 구성)

  • 정은태;권성하;이갑래
    • Journal of Institute of Control, Robotics and Systems
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    • v.8 no.11
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    • pp.941-947
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    • 2002
  • Two methods of constructing T-S fuzzy model which is equivalent to a given nonlinear system are presented. The first method is to obtain an equivalent T-S fuzzy model by using the sum of linearly independent scalar functions with constant real matrix coefficients. The sum of products of linearly independent scalar functions is used in the second method. The former method is to formulate the procedures of T-S fuzzy modeling dealt in many examples of previous publications; the latter is a new method. By comparing the number of linearly independent functions used in the two methods, we can easily find out which method makes fewer rules than the other. The nonlinear dynamics of an inverted Pendulum on a cart is used as an equivalent T-5 fuzzy modeling example.

Optimal load distribution for two cooperating robot arms using force ellipsoid

  • Choi, Myoung-Hwan;Cho, Hye-Kyung;Lee, Bum-Hee;Ko, Myoung-Sam
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10b
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    • pp.1790-1795
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    • 1991
  • The optimal load distribution for two cooperating robots is studied in this paper, and a new solution approach utilizing force ellipsoid is proposed. The load distribution problem is formulated as a nonlinear optimization problem with a quadratic cost function. The limit on instantaneous power is considered in the problem formulation as the joint torque constraints. The optimal solution minimizing energy consumption is obtained using the concept of force ellipsoid and the nonlinear optimization theory. The force ellipsoid provides a useful geometrical insight into the load distribution problem. Despite the presence of the joint torque constraints, the optimal solution is obtained almost as a closed form, in which the joint torques are given in terms of a single scalar parameter that can be obtained numerically by solving a scalar equation.

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