• Journal of Institute of Control, Robotics and Systems
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• v.9 no.12
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• pp.969-976
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• 2003

A remote control strategy for vehicles in Intelligent Vehicle Highway System (IVHS) is considered. An optimal scheduling of a limited communication channel is proposed for lead vehicle control in a platoon. The optimal scheduling problem is to find the optimal communication sequence that minimizes the cost obtained inherently by an optimal control without the communication constraint. In this paper, the PID control law which guarantees the string stability is used for the lead vehicle control. The fact that the PID control law is equivalent to the approximately linear quadratic tracker allows to obtain the performance measure to find an optimal sequence. Simulations are conducted with five maneuvering platoons to evaluate the optimality of the obtained sequence.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.109-114
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• 2005

Fiber optic sensors hold a great potential for structural monitoring due to their stability and durability. This paper deals with the applicability of long-gage deformation fiber optic sensors to prestressed concrete structures. Two sets of 3 m long-gage sensors are attached to the prestressed concrete girder with parallel topology. Using the quadratic regression of measured deformations over the length of sensors it is possible to extrapolate the deflection of the girder. The static response based on the developed method is compared with the results using conventional strain gages and LVDTs.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.6
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• pp.689-694
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• 1998

본 논문에서는 상태와 제어입력에 시간지연을 가지는 이산 불확실성 시스템의 견실 H/sub ∞/ 상태궤환 제어기 설계문제를 다룬다. 동일한 제어기에 대해서, 파라미터 불확실성을 가지는 시간지연 시스템이 자승적 안정성(quadratic stability)과 폐루프 시스템의 H/sub ∞/ 노옴의 한계를 유지하면서 파라미터 불확실성이 없는 등가의 시스템으로 변형된다. 그리고 주어진 이산 불확실성 시간지연 시스템의 견실 H/sub ∞/ 상태궤환 제어기가 존재할 충분조건과 제어기 설계 알고리듬을 제시한다. 또한 변수치환과 Schur 여수(complement) 정리를 이용하면 구한 충분조건은 LMI(linear matrix inequality) 형태로 쓸 수 있다. 예제를 통하여 제시한 결과의 타당성을 보인다.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.1
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• pp.15-18
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• 2007

We consider the problem of designing a static output feedback sliding mode control law for linear dynamical systems with mismatched uncertainties in the state matrix. We assume that an output dependent sliding surface guaranteeing the quadratic stability of the sliding mode dynamics is given, the reachability condition is not required to be satisfied globally, and the output feedback sliding mode control law complises both linear and discontinuous parts. We reduce the problem of designing the linear part of the sliding mode control law to a simple LMI problem which offers design flexibility for combining various useful convex design specifications. Our approach does not require state transformation and it can be applied to mismatched uncertain systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.451-458
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• 2012

This paper addresses the problem that policy iteration (PI) for continuous-time (CT) systems requires explorations of the state space which is known as persistency of excitation in adaptive control community, and as a result, proposes a PI scheme explorized by an additional probing signal to solve the addressed problem. The proposed PI method efficiently finds in online fashion the related CT linear quadratic (LQ) optimal control without knowing the system matrix A, and guarantees the stability and convergence to the LQ optimal control, which is proven in this paper in the presence of the probing signal. A design method for the probing signal is also presented to balance the exploration of the state space and the control performance. Finally, several simulation results are provided to verify the effectiveness of the proposed explorized PI method.

• Communications of the Korean Mathematical Society
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• v.23 no.2
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• pp.191-199
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• 2008

We investigate the relation between the vector variable bi-additive functional equation $f(\sum\limits^n_{i=1} xi,\;\sum\limits^n_{i=1} yj)={\sum\limits^n_{i=1}\sum\limits^n_ {j=1}f(x_i,y_j)$ and the multi-variable quadratic functional equation $$g(\sum\limits^n_{i=1}xi)\;+\;\sum\limits_{1{\leq}i<j{\leq}n}\;g(x_i-x_j)=n\sum\limits^n_{i=1}\;g(x_i)$$. Furthermore, we find out the general solution of the above two functional equations.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.1
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• pp.10-18
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• 1998

불확실한 변수와 비선형성을 가지는 유연조인트 로봇의 견실제어 방안을 제시한다. 그리고 본 시스템에서 불확실구조는 일치성을 유지하지 않는 불일치성 불확실 시스템이다. 제어기는 리아노프의 방안에 근거를 두고있다. 견실제어는 연산토크법을 사용하고 삽입제어기법을 통하여 좌표변환을 통해 구성된다. 제어기 설계과정은 우선 연산토크방법에 의해 시스템 동역학에서 정격부분을 선형으로 2개의 부분시스템으로 구성한다. 이후 좌표변환을 이용하여 각 부분시스템에 제어기를 구축한다. 이 방안을 통하여 관성 행렬이 알려진 값인 경우 이 행렬의 상위한계 조건없이 제어기를 설계할 수 있다. 따라서 임의의 형태의 로봇에도 적용 가능한 제어알고리즘이 된다. 설계된 견실제어는 변환된 시스템이나 원시스템 모두 실용적 안정성을 보장한다. 이 변환은 단지 불확실변수의 최대 한계값의 정보만을 요구한다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.1
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• pp.30-38
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• 2013

This paper describes the design optimization of Unmanned Aerial Vehicles(UAVs). An optimization framework has been developed and implemented for the conceptual design of UAVs. An integrated design analysis program was developed with several analysis modules such as propulsion, performance, mission, weight, and stability and control. A UAV configuration design optimization was performed by implementing the integrated analysis to enhance the endurance of UAVs. A SQP optimizer was utilized to build an optimization module for this program and sensitivity analysis was performed to determine the trends of shape variables for developing optimization objective. In conclusion, the results indicate that the resulting optimized UAVs configurations show performance improvements over the baseline design and reliable analysis results.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.3 no.1
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• pp.58-65
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• 2003

In this paper, a new model, which is a Takagi-Sugeno fuzzy model, for mobile robot is presented. A controller, consisting of two loops the one of which is the inner state feedback loop designed for stability and the outer loop is a PI controller designed for tracking the reference input, is suggested. Because the robot dynamics is nonlinear, it requires the controller to be insensitive to the nonlinear term. To achieve this objective, the model is developed by well known T-S fuzzy model. The design algorithm of inner state-feedback loop is regional pole-placement. In this paper, regions, for which poles of the inner state feedback loop are lie in, are formulated by LMI's. By solving these LMI's, we can obtain the state feedback gains for T-S fuzzy system. And this paper shows that the PI controller is equivalent to the state feedback and the cost function for reference tracking is equivalent to the LQ(linear quadratic) cost. By using these properties, it is also shown in this paper that the PI controller can be obtained by solving the LQ problem.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1309-1313
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• 2010

In this paper, we propose a novel guidance law for controlling an UAV(Unmanned Air-Vehicle) to follow a reference line in vertical plane. A kinematics model representing the relative motion of the UAV to the reference line is derived. And then LQR(Linear Quadratic Regulator) theory is applied to the model to derive the VLFG(Vertical Line Following Guidance) law. The resultant guidance law forms a gain-scheduling controller scheduled by a simple parameter $\sigma$ which is a function of the UAV's velocity, axial acceleration, gravity, and the slope of the reference line. Also derived is a stability condition for the $\sigma$ variation based on Lyapunov theory. Simulation results show that the proposed guidance law can be applied effectively to UAV guidance algorithm design.