• 대한기계학회논문집A
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• 제21권8호
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• pp.1209-1217
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• 1997

This paper proposes the modeling of the dynamics of two cooperating robot manipulators performing the assembly job such as peg-in-hole while coordinating the payload along the desired path. The mass and moment of inertia of the manipulators and the payload are assumed to be unknown. To control the uncertain system, a robust control algorithm based on the computed torque control is proposed. Usually, the robust controller requires high input torques such that it may face input saturation in actual application. In this reason, the robust control algorithm includes fuzzy logic such that the magnitude of the input torque of the manipulators is controlled not to go over the hardware saturation while keeping path tracking errors bounded. A numerical example using dual three degree-of-freedom manipulators is shown.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.112-117
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• 1997

This paper presents a GA(Genetic Algorithms)-Optical control strategy for the control of the swing motion and the transverse position of the overhead crane. The overhead crane system is defined uncertain due to unknown system parameters such as payload and trolly mass. To control the overhead crane. the GA-Optimal control scheme is suggested. which transfers a trolly to a desired place as fast as possible and minimizes the swing of the payload during the transfer. The genetic algorithms are applied to fine digital optimal feedback gains. A computer simulation demonstrate the performance of the proposed the GA-digital optimal controller for the overhead crane.

• 동력기계공학회지
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• 제9권2호
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• pp.65-72
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• 2005

A new approach is presented to design a robust sampled-data controller for an experimental flexible beam carrying an unknown payload at its free end. The purpose of this paper is to move the free end of the beam to a desired position in the specified time under vibration suppression. We derive a transfer function nominal model for the beam and quantitative description of model uncertainties based on experimentally obtained frequency response data. Robust controllers are designed by applying the sampled-data $H_{\infty}$ control and ${\mu}m-theory$, in which two types of uncertainties, structured and unstructured uncertainties, are adopted for satisfactory performance in terms of hinge position regulation and vibration damping, besides obviously asymptotic stability. The effectiveness of the proposed method is confirmed through simulation and experimentation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.381-385
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• 1992

In this paper, dynamic modeling and adaptive control problems for a space robot system are discussed. The space robot consist of a robot manipulator mounted on a free-floating base where no attitude control is applied. Using an extended robot model, the entire space robot can be viewed as an under-actuated robot system. Based on nonlinear control theory, the extended space robot model can then be decomposed into two subsystems: one is input-output exactly linearizable, and the other is unlinearizable and represents an internal dynamics. With this decomposition, a normal form-augmentation approach and an augmented state-feedback control are proposed to facilitate the design of adaptive control for the space robot system against parameter uncertainty, unknown dynamics and unmodeled payload in space applications. We demonstrate that under certain conditions, the entire space robot can be represented as a full-actuated robot system to avoid the inclusion of internal dynamics. Based on the dynamic model, we propose an adaptive control scheme using Cartesian space representation and demonstrate its validity and design procedure by a simulation study.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 춘계학술대회 논문집
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• pp.131-136
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• 1997

This paper represent the variable structure adaptive mode control technique which is new approach to implement the robust control of industrial robot manipulator with external disturbances and parameter uncertainties. Sliding mode control is a well-known technique for robust control of uncertain nonlinear systems. The robustness of sliding model controllers can be shown in contiuous time, but digital implementation may not preserve robustness properties because the sampling process limits the existence of a true sliding mode. the sampling process often forces the trajectory to oscillate in the neighborhood of the sliding surface. Adaptive control technique is particularly well-suited to robot manipulators where dynamic model is highly complex and may contain unknown parameters. Adaptive control algorithm is designed by using the principle of the model reference adaptive control method based upon the hyperstability theory. The proposed control scheme has a simple sturcture is computationally fast and does not require knowledge of the complex dynamic model or the parameter values of the manipulator or the payload. Simulation results show that the proposed method not only improves the performance of the system but also reduces the chattering problem of sliding mode control, Consequently, it is expected that the new adaptive sliding mode control algorithm will be suited for various practical applications of industrial robot control system.

• Journal of Astronomy and Space Sciences
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• 제20권1호
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• pp.1-10
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• 2003

A precise kinematic orbit determination (P-KOD) procedure for Low Earth Orbiter(LEO) using the GPS ion-free triple differenced carrier phases is presented. Because the triple differenced observables provide only relative information, the first epoch's positions of the orbit should be held fixed. Then, both forward and backward filtering was executed to mitigate the effect of biases of the first epoch's position. p-KOD utilizes the precise GPS orbits and ground stations data from International GPS Service (IGS) so that the only unknown parameters to be solved are positions of the satellite at each epoch. Currently, the 3-D accuracy off-KOD applied to CHAMP (CHAllenging Min-isatellite Payload) shows better than 35 cm compared to the published rapid scientific orbit (RSO) solution from GFZ (GeoForschungsZentrum Potsdam). The data screening for cycle slips is a particularly challenging procedure for LEO, which moves very fast in the middle of the ionospheric layer. It was found that data screening using SNR (signal to noise ratio) generates best results based on the residual analysis using RSO. It is expected that much better accuracy are achievable with refined prescreening procedure and optimized geometry of the satellites and ground stations.

• 스마트미디어저널
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• 제8권1호
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• pp.19-26
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• 2019

2018년 평창 동계 올림픽 개막식에서 출처를 알 수 없는 사이버공격이 발생하였다. 해당 공격에서 사용된 악성코드는 인 메모리 악성코드로 기존 악성코드와 은닉하는 장소가 다르며, 140개 이상의 은행, 통신, 정부 기관에서 발견될 정도로 빠르게 확산되고 있다. 인 메모리 악성코드는 전체 악성코드의 15%이상을 차지하며 매우 심각한 피해를 주고 있다. 비휘발성 저장장치로 알려진 하드디스크에 자신의 정보를 저장하는 것이 아닌 휘발성 저장장치 인 램의 특정 메모리영역인 프로세스에 삽입하여 악성행위를 일으키는 악성코드를 인 메모리 악성코드라고 지칭한다. 결과적으로 자신의 정보를 남기지 않아 메모리 탐지 도구를 우회하여 악성코드 분석가들의 분석을 어렵게 한다. 또한 현대 메모리는 갈수록 크기가 증가해 메모리 탐지 도구를 사용하여 메모리전체를 보기 힘들다. 따라서 본 논문에서는 인 메모리 악성코드인 Dorkbot과 Erger를 대상으로 IDA Pro 디버거를 통해 인젝션을 언 패킹하여 효율적으로 페이로드를 산출하는 방법을 제안한다.