• 대한조선학회논문집
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• 제42권4호
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• pp.299-306
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• 2005

To determine a guidance law which is suitable for Target Tracking System(TTS) of an underwater vehicle, the performance (hitting probability) of TTS were calculated with four different guidance schemes, considering underwater vehicle's manoeuvrability and characteristics of seeking equipment such as sonar To evaluate the performance of TTS with each guidance law, numerous target-tracking simulations of underwater vehicle were performed under the condition of target's various motion scenario. Furthermore, the effect of sonar characteristics to the performance of guidance law in TTS was studied by changing parameters of sonar such as frequency of ping and detecting error of target. The pursuit-tail guidance law showed the best performance among four different guidance laws. Complex motion of target from straight line to turning circle and zigzag movement, low frequency of sonar ping and large detecting error of target decreased the hitting probability.

• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.756-767
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• 2005

This paper presents a decentralized motion control method of welding mobile manipulators which use for welding in many industrial fields. Major requirements of welding robots are accuracy, robust, and reliability so that they can substitute for the welders in hazardous and worse environment. To do this, the manipulator has to take the torch tracking along a welding trajectory with a constant velocity and a constant heading angle, and the mobile-platform has to move to avoid the singularities of the manipulator. In this paper, we develop a kinematic model of the mobile-platform and the manipulator as two separate subsystems. With the idea that the manipulator can avoid the singularities by keeping its initial configuration in the welding process, the redundancy problem of system is solved by introducing the platform mobility to realize this idea. Two controllers for the mobile-platform and the manipulator were designed, respectively, and the relationships between two controllers are the velocities of two subsystems. Control laws are obtained based on the Lyapunov function to ensure the asymptotical stability of the system. The simulation and experimental results show the effectiveness of the proposed controllers.

• Geomechanics and Engineering
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• 제8권6호
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• pp.811-828
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• 2015

Proper modelling of the basal resistance terms is key in simulating the motion of fluidized granular flow. In this paper, standard depth-averaged governing equations of granular flow are used together with the classical Coulomb, Voellmy, and velocity dependent friction models (VDFM). A high-resolution modified TVDLF method is implemented to solve the partial differential equations without numerical oscillations. The effects of basal resistance terms on the motion of granular flows such as geometric shape evolution, travel times and final deposits are analyzed. Based on the numerical results, the predictions of the front and rear end positions and developing length of granular flow with Coulomb friction model show excellent agreements with experiment results reported by Hutter et al. (1995), and illustrate the validity of the numerical approach. For the Voellmy model, the higher value of turbulent coefficient than reality may obtain more reasonable predicted runout for the small-scale avalanche or granular flow. The energy exchange laws indicate that VDFM is different from the Coulomb and Voellmy models, although the flow characteristics of both three models fit the measurements and observations very well.

• 한국산업융합학회 논문집
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• 제19권1호
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• pp.18-30
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• 2016

In this paper, we propose a new technique to the design and real-time control of an adaptive controller for robotic manipulator based on digital signal processors. The Texas Instruments DSPs(TMS320C80) chips are used in implementing real-time adaptive control algorithms to provide enhanced motion control performance for dual-arm robotic manipulators. In the proposed scheme, adaptation laws are derived from model reference adaptive control principle based on the improved Lyapunov second method. The proposed adaptive controller consists of an adaptive feed-forward and feedback controller and time-varying auxiliary controller elements. The proposed control scheme is simple in structure, fast in computation, and suitable for real-time control. Moreover, this scheme does not require any accurate dynamic modeling, nor values of manipulator parameters and payload. Performance of the proposed adaptive controller is illustrated by simulation and experimental results for a dual arm robot manipulator with eight joints. joint space and cartesian space.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.324-327
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• 1996

This paper describes the robust controller design methods applied to the problem of an automatic system for tow-vehicle/trailer combinations. This study followed an inverse Linear Quadratic Regulator(LQR) approach which combines pole assignment methods with conventional LOR methods. It overcomes two concerns associated with these separate methods. It overcomes the robustness problems associated with pole placement methods and trial and error required in the application of the LQR problem. Moreover, a Kalman filter is used as the observer, but is modified by using the loop transfer recovery (LTR) technique with modified transmission zero assignment. The proposed inverse LQG,/LTR controllers enhances the forward motion stability and maneuverability of the combination vehicles. At high speeds, where the inherent yaw damping of the vehicle system decreases, the controller operates to maintain an adequate level of yaw damping. At backward moton, both 4WS (2WS tow-vehicle, 2WS trailer) and 6WS (4WS tow-vehicle, 2WS trailer) control laws are proposed by using inverse LQG/LTR method. To evaluate the stability and robustness of the proposed controllers, simulations for both forward and backward motion were conducted using a detailed nonlinear model. The proposed controllers are significantly more robust than the previous controllers and continues to operate effectively in spite of parameter perturbations that would cause previous controllers to enters limit cycles or to loose stability.

• 과학교육연구지
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• 제39권3호
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• pp.333-342
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• 2015

이 연구는 단계적 상황 교수자료를 개발하고 대학 물리학 수업에 적용하여 물리 학습에 대한 효과를 조사하는 데 있다. 연구대상은 지방 소재 대학의 사범대학 자연계열 1학년 대학생 총 35명으로 했다. 단계적 상황 교수자료는 상황 이상화하기, 상황 확장하기, 상황 비교하기 단계로 개발하고, 일차원 운동, 이차원 운동, 뉴턴의 운동 법칙 등 6차시 물리 수업에 적용했다. 물리 학습에 대한 효과는 힘 개념 검사지(FCI)와 물리 학습에 대한 신념(MPEX) 설문지를 사용하여 조사했다. 연구결과 단계적 상황 교수자료는 대학생의 힘 개념 변화에는 효과가 있었지만, 물리 학습에 대한 신념에는 유의미한 변화가 없었다. 결론적으로 단계적 상황 교수 학습 전략으로 개발된 교수자료는 학생에게 과학개념을 다양한 상황에 적용하는 기회를 주어 물리 개념 변화를 돕는 데 효과가 있다. 끝으로 연구 결과들을 통해 단계적 상황 물리 수업에 대한 교육적 시사점을 논의했다.

• 한국항공우주학회지
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• 제38권3호
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• pp.221-227
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• 2010

일반적인 전술유도탄에서 표적획득 센서로 사용되는 김발형 탐색기(Gimballed Seeker) 는 탐색기의 표적획득부가 유도탄의 동체운동과는 독립적으로 관성좌표계 상에서 표적을 지향하게 하여 비례항법 유도명령 생성에 필요한 유도탄/표적간의 시선 각속도 정보를 직접 제공한다. 반면 최근에는 탐색기 전체가 유도탄 동체에 고정됨으로써 정비보수 용이, 고장수리 감소, 단가감소 측면 등에서 유리한 동체고정 탐색기(Strapdown Seeker)에 대한 연구가 부분적으로 수행되고 있다. 그런데 동체고정 탐색기에서는 비례항법에 필요한 시선각속도가 직접주어지지 않고 탐색기 영상 평면에 맺힌 표적영상으로부터 유도명령생성에 필요한 정보를 추출하여야 한다. 본 연구에서는 먼저 스트랩다운 탐색기로부터 주어지는 표적정보를 바탕으로 언센티드 칼만필터(Unscented Kalman Filter, UKF)를 적용하여 유도탄과 표적간의 상대운동을 추정한다. 추정된 상대운동 정보를 이용하여 유도명령을 생성하고 유도탄과 표적간의 조우운동을 시뮬레이션을 통하여 검증하였다.

• 한국수학사학회지
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• 제29권4호
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• pp.243-254
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• 2016

This research identifies the elements of the methodologies of Newton's discovery of his dynamics. These methodologies involve the transformation of preceding theoretical concepts and the discovery of common cause. This essay consists of two parts within historical case studies of Newton's works. The elements of the method of discovery consists of the transformation of preceding concepts and the identification of common cause in the formation of the research program's hard cores and protective belts. Newton transformed their predecessors' concepts to find out appropriate common causes in his dynamical theory. The transformed theoretical concepts are synthesized to be constructed as the elements of common cause which provide the foundations of Newtonian research programs.

• Journal of Advanced Marine Engineering and Technology
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• 제27권4호
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• pp.526-534
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• 2003

Motions of animals and gymnasts in the air as well as free flying space robots without thruster are subject to nonholonomic constraints generated by the law of conservation of angular momentum. The interest in nonholonomic control problems is motivated by the fact that such systems can not stabilized to its equilibrium points by the smooth control input. The purpose of this paper is to derive analytical posture control laws for free flying objects in the air. We propose a control method using bang-bang control for trajectory planning of a 3 link mechanical system with initial angular momentum. We reduce the DOF (degrees of freedom) of control object in the first control phase and determine the control inputs to steer the reduced order system from its initial position to its desired position. Computer simulation for a motion planning of an athlete approximated by 3 link is presented to illustrate the effectiveness of the Proposed control scheme.

• Journal of Mechanical Science and Technology
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• 제14권6호
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• pp.666-674
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• 2000

Large deflection dynamic responses of laminated composite cylindrical shells under impact are analyzed by the geometrically nonlinear finite element method based on a generalized Sander's shell theory with the first order transverse shear deformation and the von-Karman large deflection assumption. A modified indentation law with inelastic indentation is employed for the contact force. The nonlinear finite element equations of motion of shell and an impactor along with the contact laws are solved numerically using Newmark's time marching integration scheme in conjunction with Akay type successive iteration in each step. The ply failure region of the laminated shell is estimated using the Tsai- Wu quadratic interaction criteria. Numerical results, including the contact force histories, deflections and strains are presented and compared with the ones by linear analysis. The effect of the radius of curvature on the composite shell behaviors is investigated and discussed.