• 한국지능시스템학회논문지
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• 제14권3호
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• pp.363-368
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• 2004

In this paper, the robustness property of 2nd-order iterative learning control(ILC) method for a class of linear and nonlinear discrete-time dynamic systems is studied. 2nd-order ILC method has the PD-type learning algorithm based on both time-domain performance and iteration-domain performance. It is proved that the 2nd-order ILC method has robustness in the presence of state disturbances, measurement noise and initial state error. In the absence of state disturbances, measurement noise and initialization error, the convergence of the 2nd-order ILC algorithm is guaranteed. A numerical example is given to show the robustness and convergence property according to the learning parameters.

• International Journal of Control, Automation, and Systems
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• 제4권1호
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• pp.124-135
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• 2006

In this paper, we propose a switching control method for a class of 2nd order nonlinear systems with single input. The main idea is to switch the control law before the trajectory of the solution arrives at singular hyperplanes which are defined by the denominator of the control law. The proposed method can handle a class of nonlinear systems which is difficult to be stabilized by the existing methods such as feedback linearization, backstepping, control Lyapunov function, and sliding mode control.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.122-124
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• 2005

In this paper, we propose a switching control method for 2nd order nonlinear systems. The main idea behind the method is changing the control law before the trajectory of the solution arrives at the singularities imposed on the denominator of the control law. We show that the control system is asymptotically stable from the fact that the sector consisting of the singular hyperplanes is an invariant set. Illustrative examples are given.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.451-454
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• 1998

This paper proposes a new method of Model Predictive Control (MPC) of nonlinear process by us-ing the measured Volterra kernels as the nonlinear model. A nonlinear dynamical process is usually de-scribed as Volterra kernel representation, In the authors' method, a pseudo-random M-sequence is ar plied to the nonlinear process, and its output is measured. Taking the crosscorrelation between the input and output, we obtain the Volterra kernels up to 3rd order which represent the nonlinear characteristics of the process. By using the measured Volterra kernels, we can construct the nonlinear model for MPC. In applying Model Predictive Control to a nonlinear process, the most important thing is, in general, what kind of nonlinear model should be used. The authors used the measured Volterra kernels of up to 3rd order as the process model. The authors have carried out computer simulations and compared the simulation results for the linear model, the nonlinear model up to 2nd Volterra kernel, and the nonlinear model up to 3rd order Vol-terra kernel. The results of computer simulation show that the use of Valterra kernels of up to 3rd order is most effective for Model Predictive Control of nonlinear dynamical processes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.395-397
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• 2007

In this paper, a Gauss-Seidel fast affine projection (GS-FAP) algorithm developed for the linear active noise control (ANC) is further utilized for nonlinear ANC of a 2nd-order Volterra systems with a nonlinear primary path and a noisy secondary path. The simulation results, obtained by applying adaptive Volterra filtering, show that the proposed approach yields more stable and faster nonlinear AN.C, compared with the conventional methods for the nonlinear ANC in case of noisy plant models.

• 제어로봇시스템학회논문지
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• 제14권11호
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• pp.1130-1138
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• 2008

A mobile robot should be designed to navigate with collision avoidance capability in the real world, coping with the changing environment flexibly. In this paper, a novel navigation method is proposed for fast moving mobile robots using limit-cycle characteristics of the 2nd-order nonlinear function. It can be applied to robots in dynamically changing environment such as the robot soccer. By adjusting the radius of the motion circle and the direction of the obstacle avoidance, the mobile robot can avoid the collision with obstacles and move to the destination point. To demonstrate the effectiveness and applicability, it is applied to the robot soccer. Simulations and real experiments ascertain the merits of the proposed method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1993년도 추계학술대회 논문집
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• pp.90-92
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• 1993

PM3 semiempirical calculations ions have performed on the three aromatic heterocyclic polymers. The dipole moment (${\mu}$7), static 1st-orders(${\alpha}$), 2nd-order (${\beta}$), and 3rd-order polarizabilities(${\gamma}$) were investigated to study the nonlinear optical properties of the polythiophene, polyfuran, and polypyrrole systems. As a function of n, ${\alpha}$ and ${\gamma}$ increases much more rapidly for the polythiophene systems than for the polyfuran and Polypyrrole systems due to the pi-electron delocalization.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.673-677
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• 1986

This paper deals with the state observer-controller which observes unmeasurable state variables of the system and then uses the estimated values as feedback signals. The linearized model is deduced from the nonlinear electrohydraulic servo system. The 4th order analog linear observer-controller and the 2nd order digital one are modelled and implemented using OP amplifiers and IBM PC/XT, respectively. The two observer are experimentally used in the control of an electrohydraulic system. The results are satisfactory in estimation performance and in tracking performance to command signal.

• 한국지진공학회논문집
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• 제9권3호
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• pp.33-42
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• 2005

비선형 함수로 모델링되는 동적 시스템의 비선형 파라미터를 결정하기 위하여 주파수 영역 볼테라 모델을 적용하는 연구를 수행하였다. 시간영역의 1차, 2차, 3차 전달함수에 해당하는 주파수 영역의 볼테라 핵함수를 비선형 파라미터 산정 과정에 3차 비선형 항까지 포함시켰다. Schetzen의 방법으로 시스템의 비선형 미분방정식에 적합한 볼테라 급수 표현식을 정하고, 이로부터 유도되는 비선형 전달함수를 입력 출력 관계식에 사용하였다. 관찰된 입력을 비선형 주파수 영역 모델에 대입하여 계산한 출력과 관찰된 출력의 차이로 오차를 정의한 후 오차를 최소화 시키는 시스템 파라미터의 값을 구하였다. 예제를 통하여 선형 주파수 구간 뿐만 아니라 2차 혹은 3차 비선형이 지배적인 주파수 범위 대에서 볼테라 모델이 충분한 정확성과 수렴성을 가지며 인식된 파라미터는 실제 값과 잘 일치함을 확인할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.315-318
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• 2003

This paper proposes a switching control method applicable to any affine, 2nd order nonlinear system with single input. The key contribution is to develop a control design method which uses a piecewise continuous Lyapunov function non-increasing at every discontinuous point. The proposed design method requires no restrictions except full state availability. To obtain a non-increasing, piecewise continuous Lyapunov function, we change the sign of off-diagonal term s of the positive definite matrix composing the former Lyapunov function according to the sign of the Inter-connection term. And we use the solution of inequalities which guarantee each Lyapunov function is non-increasing at any discontinuous point.