• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.301-303
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• 2018

This paper describes a robot control system and control method of a human arm type redundant manipulator. The control of a redundant manipulator suffer from computational complexity and singularity problem because of numerical inverse kinematics. To deal with such problems, analytical methods for a redundant robot arm have been researched to enhance the performance of inverse kinematics. In this research, we propose a numerical control method and weighted pseudo inverse kinematics algorithm. Using this algorithm, it is possible to generate a trajectory passing through the singular points and intuitively move the elbow without regard to the end-effector pose. Performance of the proposed algorithm was verified by various simulations. It is shown that the trajectory planning and using this algorithm provides correct results near the singular points and can utilize redundancy intuitively. We proved this system's validity through field test.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5A
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• pp.382-388
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• 2005

An OFDM system may be a good candidate for a next-generation wireless communication system which requires high-speed and high-rate data transmission. In OFDM systems, guard intervals are inserted to mitigate the effects of ISI (Inter-Symbol Interference). But guard interval insertion degrades the system performance from the standpoint of data rate and bandwidth efficiency. In this paper, a new method to improve the performance of an OFDM system without guard interval. First, PIC (Parallel Interference Cancellation) scheme which can reduce ISI by subtracting the estimated multi-path components from the received signal will be considered. And the proposed system with Pseudo-Decorrelator estimates transmitted signals by using the inverse matrix of cross-correlation matrix relating to interference components. The performance of the proposed system is evaluated through computer simulations and compared with that of the PIC system and an OFDM system without guard interval.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.7
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• pp.658-668
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• 2004

This paper is concerned with a control allocation strategy using the dynamic inversion and the pseudo inverse control which generates the nominal control input trajectories. In addition, an autopilot design method is proposed by using time-varying control technique which is time-varying version of the pole placement of linear time-invariant system for an agile missile with aerodynamic fin and thrust vectoring control. The control allocation proposed in this paper is capable of extracting the maximum performance by combining each control effector, aerodynamic fin and thrust vectoring control. The adopted time-varying control technique for the autopilot design enhances the robustness of the tracking performance for a reference command. The main results are validated through the nonlinear simulations with aerodynamic data.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.138-141
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• 2005

In this paper, we propose a watermarking technique of multispectral images. In our method, the Principal Component Analysis (PCA) is preliminarily applied on the multispectral image. The most principal component image is used for embedding with a watermark, which is a pseudo-random number sequence generated with a secret key. The embedding process is performed in the wavelet domain. The resulting image is then reinserted into the principal component images, and the final multispectral image containing the watermark can be produced by the inverse PCA. Experimental results are provided to illustrate the performance of the algorithm against various kinds of attacks.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.41-42
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• 2017

기존의 다중 코일을 이용한 소형 자성체를 제어하는 시스템에서 전류 벡터 지령은 구동 매트릭스의 pseudo-inverse를 사용하여 계산되었다. 본 논문에서는 기존의 전류 지령에 null space 전류 벡터 지령을 더하는 방법을 이용하여 현재 전류 벡터값과 목표 전류 벡터 지령 사이의 전류 변화량이 최소화 되는 전류 지령 수정 방식을 제안한다. 제한된 전압 정격 내에서 제안된 방식을 적용할 경우 전류 지령 벡터값에 도달하는 시간이 짧아짐으로, 기존 방식에 비해 빠른 반응성을 얻을 수 있다. 제안된 방법은 Matlab(R) Simulink(R)를 통해 검증하였다.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.80-84
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• 2000

Network parameters in power systems are indispensable for all of power system engineering studies, including the power flow calculation and the state estimation. The network parameters required for the studios, in general, are estimated by using several estimation techniques, since it Is very difficult to measure. To improve the estimation accuracy of the network parameters, this paper adopt the synchronized phasor measurements which are acquired from the Phasor Measurement Unit with built-in GPS receiver. In this paper, the parameter estimation problem is formulated with over-determined nonlinear measurement equations and solved with Newton-Raphson method and pseudo-inverse. The effectiveness of the proposed parameter estimation with the synchronized phasor measurements is verified through some case studies with IEEE sample system. The results are very promising.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.679-684
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• 1993

This article presents an approach to estimate the general 3D motion of a polyhedral object using multiple, sensory data some of which may not provide sufficient information for the estimation of object motion. Motion can be estimated continuously from each sensor through the analysis of the instantaneous state of an object. We have introduced a method based on Moore-Penrose pseudo-inverse theory to estimate the instantaneous state of an object. A linear feedback estimation algorithm is discussed to estimate the object 3D motion. Then, the motion estimated from each sensor is fused to provide more accurate and reliable information about the motion of an unknown object. The techniques of multisensor data fusion can be categorized into three methods: averaging, decision, and guiding. We present a fusion algorithm which combines averaging and decision.

• Journal of Mechanical Science and Technology
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• v.14 no.2
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• pp.131-140
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• 2000

For a walking robot with high constant body speed, the dynamic effects of the legs on the transfer phase are dominant compared with other factors. This paper presents a new force distribution algorithm to maximize walkable terrain without slipping considering the dynamic effects of the legs on the transfer phase. Maximizing the walkable terrain means having the capability of walking on more slippery ground under the same constraint, namely constant body speed. A simple force distribution algorithm applied to the proposed walking model with a pantograph leg shows an improvement in the capability of preventing foot-slippage compared with one using a pseudo-inverse method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.896-901
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• 2008

This paper addresses the foot force distribution problem for quadruped robots with a failed leg. The quadruped robot has fault-tolerant straight-line gaits with one leg in locked-joint failure, and has discontinuous motion with respect to the robot body. The proposed method is operated in two folds. When the robot body stands still, we use the feature that there are always three supporting legs, and by incorporating the theory of zero-interaction force, we calculate the foot forces analytically without resort to any optimization technique. When the robot body moves, the conventional pseudo-inverse algorithm is applied to obtain the foot forces for supporting legs. Simulation results show the validity of the proposed scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.756-765
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• 2001

An effective dexterous motion control method of redundant robot manipulators based on neural optimization network is proposed to satisfy multi-criteria such as singularity avoidance, minimizing energy consumption, and avoiding physical limits of actuator, while performing a given task. The method employs a neural optimization network with parallel processing capability, where only a simple geometric analysis for resolved motion of each joint is required instead of computing of the Jacobian and its pseudo inverse matrix. For dexterous motion, a joint geometric manipulability measure(JGMM) is proposed. JGMM evaluates a contribution of each joint differential motion in enlarging the length of the shortest axis among principal axes of the manipulability ellipsoid volume approximately obtained by a geometric analysis. Redundant robot manipulators is then controlled by neural optimization networks in such a way that 1) linear combination of the resolved motion by each joint differential motion should be equal to the desired velocity, 2) physical limits of joints are not violated, and 3) weighted sum of the square of each differential joint motion is minimized where weightings are adjusted by JGMM. To show the validity of the proposed method, several numerical examples are illustrated.