• Proceedings of the KIEE Conference
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.325-326
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• 2007

인간형 로봇(Humanoid)은 인간과 유사한 구조를 갖고 있는 로봇으로, 이족 보행이 가능하고 양 손이 자유롭기 때문에 인간 생활 환경에 적용이 가능하다. 인간형 로봇은 이족 보행 로봇의 형태를 지니며 보통 20 자유도(DOF : Degree of freedom) 이상의 높은 자유도와 직렬형 링크 구조로 인해 로봇의 안정도를 해석하고 움직임을 제어하기가 어렵다. 이러한 이유로 이족 보행 로봇 동작의 안정도를 증가시키기 위해 로봇의 최적화된 동작 패턴 생성과 자세 제어 등이 연구 되고 있다. 본 논문에서는 범용 근사자의 특징을 갖는 신경망을 이용하여 이족 보행 로봇의 동작 패턴 생성 방법에 대하여 제안하였다. 실제로 계획된 동작을 토대로 6가지의 동작 패턴을 생성하였으며 컴퓨터 모의실험과 상용 이족 보행 로봇을 이용하여 생성된 동작 패턴의 안정도를 확인해보고 제안된 방법에 타당성을 검증하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제37권2호
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• pp.192-198
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• 2013

This paper presents the stabilization and design of a pan-tilt control part for the directional pan-tilt system for shipboard directional equipment. In order to control each control axis with compensation for ship motion, the 2 degree of freedom(2DOF) PID controller is designed and its parameters are tuned using a real-coded genetic algorithm(RCGA). Simulation demonstrates the effectiveness of the 2 DOF PID controller tuning.

• The Journal of the Acoustical Society of Korea
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• 제24권1E호
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• pp.7-15
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• 2005

This paper addresses issues encountered in measuring the general, 6-degree-of-freedom motion of a human head, A complete mathematical description for measuring the head motion using the six-accelerometer configured bite-bar is suggested, The description shows that the six-axis vibration cannot be completely obtained without the roll, pitch and yaw angular velocity components, A new method of estimating the three orthogonal (roll, pitch and yaw) angular velocities from the six acceleration measurements is introduced. The estimated angular velocities are shown to enable further quantitative error analysis in measuring the translational and angular accelerations at the head. To make this point clear, experimental results are also illustrated in this paper. They show that when the effects of angular velocities are neglected in the head vibration measurement the maximum percentage errors were observed to be more than $3 \%$ for the angular acceleration of the head and to be close to $5 \%$ for its translational acceleration, respectively. It means that the inclusion of all the angular velocity dependent acceleration components gives more accurate measurement of the head vibration.

• Journal of the Society of Naval Architects of Korea
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• 제36권1호
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• pp.1-14
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• 1999

The simulation results of a small racing boat racing in steady wind and encountering waves are investigated by Nakato & Ha. The simulation of the race running is realized by referring the measured data of boats and the motions are described by a set of equations of motion in six degree of freedom as generals used in the aerodynamics. In this report, Nakato & Ha's motion equations are modified by equipping the flaps to generate the lift. The flaps of the racing boat could restrain considerably the boat from capsizing caused by superposed external disturbances, wind and encountering waves.

• Transactions on Control, Automation and Systems Engineering
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• 제3권2호
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• pp.117-123
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• 2001

To improve control performance of a non-linear system, many other reserches have used the sliding model control algorithm. The sliding mode controller is known to be robust against nonlinear and unmodeled dynamic terms. However, this algorithm raises the inherent chattering caused by excessive switching inputs around the sliding surface. Therefore, in order to solve the chattering problem and improve control performance, this study has developed the sliding mode controller with a perturbation estimator using the observer-based fuzzy adaptive network. The perturbation estimator based on the fuzzy adaptive network generates the control input of compensating unmodeled dynamics terms and disturbance. And the weighting parameters of the fuzzy adaptive network are updated on-line by adaptive law in order to force the estimation errors converge to zero. Therefore, the combination of sliding mode control and fuzzy adaptive network gives rise to the robust and intelligent routine. For evaluation control performance of the proposed approach, tracking control simulation is carried is carried out for the hydraulic motion simulator which is a 6-degree of freedom parallel manipulator.

• Transactions of the Korean Society of Automotive Engineers
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• 제6권4호
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• pp.76-85
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• 1998

Recently, Genetic Algorithm(GA) is widely adopted into a search procedure for structural optimization, which is a stochastic direct search strategy that mimics the process of genetic evolution. This methods consist of three genetics operations maned selection, crossover and mutation. Contrast to traditional optimal design techniques which use design sensitivity analysis results, GA, being zero-order method, is very simple. So, they can be easily applicable to wide area of design optimization problems. Also, owing to multi-point search procedure, they have higher probability of converge to global optimum compared to traditional techniques which take one-point search method. In this study, a method of finding the optimum values of suspension parameters is proposed by using the GA. And vehicle is modelled as planar vehicle having 5 degree-of-freedom. The generalized coordinates are vertical motion of passenger seat, sprung mass and front and rear unsprung mass and rotate(pitch) motion of sprung mass. For rapid converge and precluding local optimum, share function which distribute chromosomes over design bound is introduced. Elitist survival model, remainder stochastic sampling without replacement method, multi-point crossover method are adopted. In the sight of the improvement of ride comfort, good result can be obtained in 5-D.O.F. vehicle model by using GA.

• Earthquakes and Structures
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• 제20권4호
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• pp.457-471
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• 2021

This study aims at providing a simple and effective methodology to define a meaningful characteristic period for special class of earthquake records named "pulse-like ground motions". In the proposed method, continuous wavelet transform is employed to extract the large pulse of ground motions. Then, Fourier amplitude spectra obtained from the original ground motion and the residual motion is simply compared. This comparison permits to define a threshold pulse-period (Tp∗) as the threshold period above which the pulse component has negligible contributions to the Fourier amplitude spectrum. The effect of pulse on frequency content of motions was discussed on the light of this definition. The advantage and superior features of the new definition were related to the inelastic displacement ratio (IDR) for single-degree-of-freedom systems with period equal to one half of the threshold period. Analyses performed for the proposed period at three ductility levels u=2,4,6 were compared with the results obtained at half of pulse period derived from wavelet analysis, peak-point method and the peak of product of the velocity and the displacement response spectra (Sv x Sd). According to the results, pulse effects on inelastic displacement ratio seem to be more important when $\frac{T_p^*}{T}=2$ (T is the fundamental vibration period of system). The results showed that utilizing of the proposed definition could facilitate an enhanced understanding of pulse-like records features.

• Journal of Broadcast Engineering
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• 제25권5호
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• pp.672-684
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• 2020

Restoring a low resolution and motion blurred light field has become essential due to the growing works on parallax-based image processing. These tasks are known as light-field enhancement process. Unfortunately, only a few state-of-the-art methods are introduced to solve the multiple problems jointly. In this work, we design a framework that jointly solves light field spatial super-resolution and motion deblurring tasks. Particularly, we generate a straight-forward neural network that is trained under low-resolution and 6-degree-of-freedom (6-DOF) motion-blurred light field dataset. Furthermore, we propose the strategy of local region optimization on the adversarial network to boost the performance. We evaluate our method through both quantitative and qualitative measurements and exhibit superior performance compared to the state-of-the-art methods.

• Journal of Institute of Control, Robotics and Systems
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• 제22권8호
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• pp.585-589
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• 2016

Recently, the robotic assist system for cardiovascular intervention gets continuously growing interest. The robotic cardiovascular intervention systems are largely two folds, systems for cardiac ablation procedure assist and systems for vascular intervention assist. For the systems, the clinician controls the catheter inserted through blood vessel to the heart via a master console or master manipulator. Most of the current master manipulators have structure of joystick-like pivoting 2 degree of freedom (DOF) handle in the core, which is used in parallel with other sliding switches and input devices. It however is desirable to have customized and optimized design manipulator that can provide clinician with intuitive control of the catheter motion fully utilizing the advantage of the use of robotic structure. A 6 DOF kinematic mechanism that can capture the motion control intention of the clinician in translational 3 DOF and rotational 3 DOF is proposed in this paper. Also, a master-slave motion relationship specially designed for the cardiac catheter manipulation motion is proposed and implemented in an experimental prototype. Design revision for implementation of more efficient motion and experiment in combination with an experimental slave robot system for catheter manipulation are underway.

• Journal of Biomedical Engineering Research
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• 제25권6호
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• pp.505-510
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• 2004

In this article, we present an automated system for adjusting the 6 degree of freedom (D.O.F.) circular fixator. The system includes a scheduling software to adjust the Hexapod Circular Fixator (HCF) and an automated strut with the ability of the multiple synchronized motion and independent motion. The HCF was designed to control a 6 D.O.F. Ilizarov fixator and it's mechanism. The HCF adjustment software evaluates each value of altered length of the HCF struts to correct the complex skeletal deformity by using the X-ray data of the patient. The data of HCF adjustment software feed into the automated strut system which provides the scheduled adjustment. Then, the automated strut is synchronized by input data. Also the data of HCF adjustment software can be used to adjust HCF without automated struts. The proposed HCF system was verified by experiments.