• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1654-1659
• /
• 2003

This paper introduces a fast Fourier transform (FFT)-based spectral analysis method for the transient responses as well as the steady-state responses of linear discrete systems. The force vibration of a viscously damped three-DOF system is considered as the illustrative numerical example. The proposed spectral analysis method is evaluated by comparing with the exact analytical solutions as well as with the numerical solutions obtained by the Runge-Kutta method.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.537-540
• /
• 1987

항공기가 평형상태로 비행하는 도중 돌풍과 같은 외부교란을 만난 교란상태운동은 선형화된 미분방정식으로 표현되며 비교적 짧은 비행시간동안의 비행은 선형시 불변계가 된다. 돌풍은 Gauss-Markov확률과정으로 모델링 되며, 항공기가 돌풍을 만난 교란상태운동은 시스템론적으로 보면 백색잡음이 성형필터를 거쳐 계에 입력되는 것과 같다. 초기의 설계방법은 고전적인 주파수영역에서의 해석방법을 사용하였으나 1960년대에 최적제어이론이 도입되면서 평가함수를 사용하여 원하는 비행특성을 얻는 방법을 사용하게 되었다. 그 후 계에 입력되는 외란과 측정시의 잡음으로 인한 불확실한 측정량으로부터 최적상태변수의 추정을 위해 필터링이론을 도입한 확률제어이론을 적용하여 자동조종장치를 설계하게 되었다. 이때까지는 연속제어계로 설계되었으며 그 후 측정신호를 샘플링하여 연속제어계와 등가의 이산제어계를 사용한 자동조종장치가 등장하였으며 이 경우 설계기법으로는 연속제어계를 사용하고 실현시킬 때는 디지털컴퓨터를 사용하였다. 이는 제어하는 동안 계의 계수와 제어법칙을 바꾸어 줄 수 있는 이산제어계의 장점을 이용하지 못하므로 처음부터 계를 등가의 이산계로 보고 제어계를 설계하는 방법이 도입되었다. 이 때 샘플링간격의 결정과 Quantization 영향이 설계시 고려되어야 한다.

• Proceedings of the KIEE Conference
• /
• 1983.07a
• /
• pp.143-144
• /
• 1983

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.6
• /
• pp.156-164
• /
• 2000

In this study, a discrete time model for a simplified front wheel suspension system which has nonlinear dampling and stiffness property is introduced. The model is estimated from the discrete data which are generated based on the real car parameter. The performance of the proposed method is evaluated through numerical simulation, and the simulation results show that the proposed method can estimate the nonlinear behavior of the suspension system very well.

• 전기의세계
• /
• v.29 no.11
• /
• pp.742-750
• /
• 1980

The problem of nonlinear time-invariant system identification by estimation of Wiener kernels is studied for discrete time systems with inputs having symmetric probability distributions. G-functionals are constructed. It is further shown that under idealized conditions, these seemingly different techniques yield the same results. The results of identification of asimulated second degree system is presented.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.4 s.235
• /
• pp.578-583
• /
• 2005

This paper introduces a fast Fourier transform (FFT)-based spectral dynamic analysis method for the transient responses as well as the steady-state responses of the linear discrete systems subject to non-zero initial conditions. The forced vibration of a viscously damped three-DOF system is considered as the illustrative numerical example. The proposed spectral analysis method is evaluated by comparing its results with the exact analytical solutions and the numerical solutions obtained by the Runge-Kutta method.

• Journal of Advanced Navigation Technology
• /
• v.13 no.5
• /
• pp.756-762
• /
• 2009

As nonlinear friction, stick-slip friction in hydraulic actuators are a problem for accuracy and repeatability. Therefore friction compensation has been approached through various control algorithms. A Adaptive discrete time sliding mode tracking controller has been applied in order to compensate the nonlinear friction characteristics in a hydraulic Actuator. Based on the diophantine equation, a new discrete time sliding function is defined and utilized for the control law which includes a friction and modeling error. Robustness is increased by using both a projection algorithm and a sliding function-based nonlinear feedforward. From the results of simulation and experiment good tracking performance is achieved.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.35 no.11
• /
• pp.511-518
• /
• 1986

An algorithm for block-decomposition of a linear, time-invariant, discrete large-scale systems is presented, based upon the matrix sign function on Z-plane. The block-decomposition is performed by defining a reference circle, a circular stripe and projection operators. Simulation study shows that the presented algorithm is very useful for multivariable control system's analysis and design.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.17 no.6
• /
• pp.38-43
• /
• 1980

For linear discrete-time time-invariant multi-input mufti-output systems, a necessary condition which an optimal output Proportional feedback gains must satisfr is deiived. Quadratic performance index is used. The result is extended to the desi01 problem for determining optimal output proportional plus integral feedback gains. For illustration, an example problem is solved and discussed.

• The Journal of the Acoustical Society of Korea
• /
• v.15 no.1
• /
• pp.23-33
• /
• 1996

In this paper we point out that if the classical principal domain for bispectra is utilized to determine a second-order Volterra model's output, such and output will be incomplete. This deficiency is associated with the periodic nature of the DFT. For this reason, the objective of this paper is to present an "extended" principal domain for Volterra kernels which leads to an improved estimate of the nonlinear system's response. In order to define the extended principal domain, we derive a new discrete frequency-domain Volterra model from a discrete time-domain Volterra model utilizing 2-dimensional DFT and the relationship between the quadratic component of the Volterra model and a square filter. The effect of the extended domain on the model output is interpreted in terms of the periodicity of DFT. Through computer simulations, we demonstrate the effects of the extended principal domain on the Volterra modeling. The simulation results indicate that the extended principal domain plays and important role in computing Volterra model outputs and estimating Volterra model coefficients.