• Journal of the Society of Naval Architects of Korea
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• v.49 no.5
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• pp.410-415
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• 2012

An experimental study is carried out to investigate the near-wake characteristics of a NACA 0018 foil with a flat plate. Two-frame grey-level cross correlation PIV method is used to measure the local flow characteristic around a pitch damping foil to control the vertical motion of high speed crafts in a circulating water channel. The analysis also includes angles of attack 10 and 20 degrees respectively. Reynolds number $Re{\fallingdotseq}3.5{\times}10^4$ based on the chord length(C=100mm) of NACA0018 has been applied during the whole experiments. The distance between the foil and the flat plate is D/C=0.5, 1.0 and 1.5 respectively. The channel effect according as the distance between the foil and the flat plate has a close relation with the velocity distributions around the foil. In the wake of 20-degree of attack, the complex turbulent flow and a thick boundary layer are formed due to the processes of vortex generation and dissipation.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2575-2580
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• 2005

In this paper, we address two position control scheme; the lead-lag control and the sliding mode control for a stage system, which is levitated and driven by electric magnetic actuators. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal forces. Dynamic equations of the stage system are derived simply. The sliding mode control algorithm is more effective than the lead-lag control algorithm to reduce effects from movements and disturbances of other axis.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.307-312
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• 2010

In this study, advanced computational technique for mechatronic analysis has been developed for the efficient design and test of typical machine tool models. Flexible multi-body dynamic (FMBD) analysis method combined with motion controller including control logics is used to simulate typical operation conditions. The present FMBD machine tool model is composed of flexible column structure, rigid body spindle, vertical motion guide (arm) and screw elements. Driving motor clement with rotating degree-of-freedom is interconnected and governed by the designed Matlab Simulink control logic, and then the position of the spindle is feedback into the control logic. It is practically shown from the results that the investigation of designed machine tools with controller can be effectively conducted and verified.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.671-677
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• 1996

This paper proposes a study on the effects of motion errors for acceleration/ deceleration types. The proposed motion errors are consisted of two errors : one due to transient response of servomechanism and the other due to gain mismatching of positioning servo motor. They are derived from using laplace transformation for the block diagram of general purpose feed drive system. In order to minimize them, the paper proposes second order polynomial regression model by using orthogonal array method which describes one of experimental methodolgies. The validity and reliability of the study was veri lied on a vertical machining center equipped with FANUC 0MC through a series of experiments and analyses.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.11
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• pp.132-142
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• 1996

This paper presents a technique to model and control a manipulator which has a flexible link and moves in a vertical plane. The flexible link is modeled as an Euler-Bernoulli Beam. Elastic deformation of the flexible link is represented using the assumed modes method. A comparison function which satisfies all geometric and natural boundary conditions of a cantilever beam with an end mass is used as an assumed mode shape. Lagrange's equation is utilized for the development of a discretized model. This paper presents a simple technique to improve the correctness of the developed model. The final model including the shortening effect due to elastic deformation correlates very well with experimental results. The free body motion simulation shows that two assumed modes for the representation of the elastic deformation is proper in terms of the model size and correctness. A control algorithm is developed using PID control technique. The proportional, integral and derivative control gains are determined based on dominant pole placement method with a rigid one-link manipulator. A position control simulation shows that the control algorithm can be used to control the position and residual oscillation of the flexible one-link manipulator effectively.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.1
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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.

• Journal of Ocean Engineering and Technology
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• v.23 no.5
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• pp.15-24
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• 2009

The results of a simulation study of variable liquid column oscillations in U-tanks with a novel control scheme are presented. The configuration under investigation is analogous to that of the tuned liquid-column damper used to suppress oscillatory motion in large structures like tall buildings and cargo ships. However, by virtue of an adequate controller, the response of amplitude of the U-tanks becomes larger in a desired frequency range. The motion of wave energy conversion system equipped with a variable liquid column oscillator is described by a series of nonlinear differential equations. The equations describe the motion of body under ocean wave excitation, and the motion of liquid with an air-spring effect caused by the compression and expansion of air in vertical liquid columns and air chambers. It is shown that the effect of the air-spring has a vital role to maintain the natural frequency of oscillation in the system to synchronize with the frequency of the ocean wave, thus the system provides the most effective mode for energy extraction from the ocean.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.167-176
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• 2007

The purpose of this study was to offer suitable model for performing Tippelt motion and data for training Tippelt motion through the quantitative kinematical analysis of Tippelt motion in parallel bars. The results of analysing kinematic variations through three-dimensional reflection analysis of three members of the national team as the objects of the study were shown as follows. 1. It seemed that the shoulder-joints which are stretched as much as possible affects the whole Tippelt motion while one is swinging downward. The time of process of the center of mass for the body reaching to the maximum flection point should be quick and body's moving from the vertical phase to the front direction should be controled as much as possible. 2. While one is swinging upward, the stability of flying motion could be made certain by the control of body's rapid moving to the front direction and stretching shoulder-joints and hip-joint to reverse direction. 3. While one is flying upward, the body should be erected quickly and lessening the angle of the hip-joint affects the elevation of flight. When the powerful counter turn motion is performed, the stable motion could be made. As a result of this study, It seems that sudden fall and the maximum stretch of shoulder-joints is important during performing Tippelt motion in parallel bars. Also, it concludes that the maximum bending of hip-joints at the starting point of upward swing, sudden stretch to the reverse direction of shoulder-joints and hip-joints when one is leaving bars, control of body's moving to the front direction, and lessening the angle of hip-joints at the flying phase is important.

• 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.

• Journal of Ocean Engineering and Technology
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• v.35 no.5
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• pp.313-326
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• 2021

A submerged body with varied control inputs can execute large drift angles and large angles of attack, as well as basic control such as straight movement and turning. The objective of this study is to analyze the dynamic characteristics of a submerged body comprising six thrusters and six control planes, which is capable of a large drift angle and angle of attack motion. Virtual captive model tests via were analyzed via computational fluid dynamics (CFD) to determine the dynamic characteristics of the submerged body. A test matrix of virtual captive model tests specialized for large-angle motion was established. Based on this test matrix, virtual captive model tests were performed with a drift angle and angle of attack of approximately 30° and 90°, respectively. The characteristics of the hydrodynamic force acting on the horizontal and vertical surfaces of the submerged body were analyzed under the large-angle motion condition, and a model representing this hydrodynamic force was established. In addition, maneuvering simulation was performed to evaluate the standard maneuverability and dynamic characteristics of large-angle motion. Considering the shape characteristics of the submerged body, we attempt to verify the feasibility of the analysis results by analyzing the characteristics of the hydrodynamic force when the large-angle motion occurred.