• Geomechanics and Engineering
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• 제20권3호
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• pp.267-273
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• 2020

Solutions of the water pressure and groundwater inflow distribution along the tunnel perimeter in a half-infinite aquifer were investigated considering the conditions of the constant head and constant water pressure. It is assumed that the circular tunnel is buried in a fully saturated, homogeneous, isotropic and half-infinite space. Coordinate transformation technique was adopted, the problem of solving the control equations of water pressure in the Cartesian coordinate was transformed to that in the bipolar coordinate system, which can significantly simplify the derivation procedure of the water pressure and inflow distribution. The validation results show the accuracy and advantage of the proposed approach.

• 전기학회논문지
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• 제63권1호
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• pp.162-172
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• 2014

A three-dimensional dynamic model for simulating various motions of full vehicle is presented. The model has 16 independent degrees of freedom (DOF) consisting of three kinds of components; a vehicle body of 6 DOF, 4 independent suspensions equipped at every corner of the body, and 4 tire models linked with each suspension. The dynamic equations are represented in six coordinate frames such as world fixed coordinate, vehicle fixed coordinate, and four wheel fixed coordinate frames. Then these lead to the approximated prediction model of vehicle posture. Both lateral and longitudinal dynamics can be computed simultaneously under the conditions of which various inputs including steering command, driving torque, gravity, rolling resistance of tire, aerodynamic resistance, etc. are considered. It is shown through simulations that the proposed 3D model can be useful for precise design and performance analysis of any full vehicle control systems.

• Journal of Mechanical Science and Technology
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• 제16권6호
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• pp.762-769
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• 2002

This paper presents how effective it is to use many features for improving the speed and accuracy of visual servo systems. Some rank conditions which relate the image Jacobian to the control performance are derived. The focus is to describe that the accuracy of the camera position control in the world coordinate system is increased by utilizing redundant features in this paper. It is also proven that the accuracy is improved by increasing the number of features involved. Effectiveness of the redundant features is evaluated by the smallest singular value of the image Jacobian which is closely related to the accuracy with respect to the world coordinate system. Usefulness of the redundant features is verified by the real time experiments on a Dual-Arm robot manipulator made by Samsung Electronic Co. Ltd..

• 대한인간공학회지
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• 제9권2호
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• pp.21-28
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• 1990

The robot motion control in the industrial robot is generally executed by the teach pendant. But, it requires much teaching time and workload to the operators. This study suggests the use of the robot motion control method by the computed keyboard in the industrial robot instead of the teach pendant. TES/CCS(Teaching Expert System/Cartesian Coordinate System) and TES/WCS(Teaching Expert System/World Coordinate System) that have been proposed to improve the robot motion control are applied for this concept. This study is intended to improve the robot motion control in TES/CCS. Parameter limitation problems in getting the motion data on position and posture of the robot in macro motion control are solved by proposed geometric algorithm. This result demonstrates reduction of the average teaching task time to the teaching position.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권1호
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• pp.31-37
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• 2003

A robust tracking control for nonholonomic dynamic systems is proposed in this paper. Since nonholonomic dynamic systems have constraints imposed on motions that are not integrable, i.e., the constraints cannot be written as time derivatives of some functions of generalized coordinates, advanced techniques are needed for their control. It is shown that if the state of nonholonomic systems is mapped into a bounded space by a coordinate transformation, a robust controller for dynamic models of nonholonomic systems with input disturbances can be designed using sliding mode control. Stability and robustness of the proposed controller are proved in the Lyapunov sense. Numerical simulations on the trajectory tracking of a two-wheeled mobile robot are conducted to validate the effectiveness of the proposed controller.

• 한국운동역학회지
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• 제13권1호
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• pp.1-12
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• 2003

The purpose of this study was to design the method of 3D space calibration to reduce RMSE by statistical analysis when using the DLT algorithm and control frame. Control frame for 3D space calibration was consist of $1{\times}3{\times}2m$ and 162 contort points adhere to it. For calculate of 3D coordination used two methods about 2D coordination on image frame, 2D coordinate on each image frame and mean coordination. The methods of statistical analysis used one-way ANOVA and T-test. Significant level was ${\alpha}=.05$. The compose of methods for reduce RMSE were as follow. 1. Use the control frame composed of 24-44 control points arranged equally. 2. When photographing, locate control frame to center of image plane(image frame) o. use the lens of a few distortion. 3. When calculate of 3D coordination, use mean of 2D coordinate obtainable from all image frames.

• 한국수자원학회논문집
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• 제53권12호
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• pp.1049-1057
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• 2020

본 연구는 드론을 이용하여 홍수기 하천에서의 유량측정방법 개발을 위해 수행하였다. 홍수기 유량측정은 예산, 인력, 안전 및 하천공사 등의 문제로 매년 모든 지점에서 유량 측정을 실시하지 못하는 어려움이 있다. 특히 태풍 등 큰 호우사상 발생 시 수위-유량관계 변화 검토가 필요하지만 앞에서 언급한 문제 등으로 인하여 측정에 어려움이 있다. 이런 문제점을 개선하기 위해 최소 인력이 단시간 간편하게 측정할 수 있는 방법을 개발하였다. 항공사진측량 개념으로 접근하여 의정부시(신곡교) 지점과 영동군(영동제2교) 지점 하도 주변에 확인 가능한 위치에 지상기준점(GCP, Ground Control Points) 4개점을 선점하고 VRS DGPS 장비를 이용하여 좌표측량을 수행하였다. 드론을 일정높이의 정지상태(Hovering)에서 하도 내 수 표면을 카메라의 인터벌 기능으로 3초 간격 정사영상을 촬영하였다. 정사 촬영된 항공사진의 좌표계를 평면지각좌표계인 GRS80 TM좌표계로 정의한 후 GCP 좌표를 활용하여 보다 정밀하게 정사보정을 실시하였다. 수표면에 유하하는 부유물의 3초 간격 위치를 X, Y좌표 분석을 통해 이동거리를 평균유속으로 산정하고 유하경로에 따른 통수단면적을 적용하여 유량을 산정하였다. 따라서 항공사진측량 기법을 적용하여 홍수기에 드론을 이용한 유량측정방법에 대한 적용성을 확인하였다.

• 전기학회논문지
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• 제67권2호
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• pp.314-324
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• 2018

This paper proposes a linear distributed target tracking filter for multiple unmanned aerial vehicles(UAVs) sharing their passive sensor measurements through communication channels. Different from the conventional nonlinear filtering schemes, the distributed passive target tracking problem is newly formulated within the framework of a linear robust state estimation theory incorporated with a linear uncertain measurement equation including the coordinate transform uncertainty. To effectively cope with the performance degradation due to the coordinate transform uncertainty, a linear consistent robust Kalman filter(CRKF) theory is devised and applied for designing a distributed passive target tracking filter. Through the simulations for typical UAV surveillance mission, the superior performance of the proposed method over the existing schemes of distributed passive target tracking are demonstrated.

• 제어로봇시스템학회논문지
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• 제16권4호
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• pp.346-352
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• 2010

This paper presents an intuitive interface scheme for controlling a hydraulic backhoe, which is a piece of excavating equipment consisting of a digging bucket on the end of a two-part articulated arm, and typically mounted and rotated on the back of a tractor or front loader. The passive levers/joysticks for actuator operations of a hydraulic backhoe are replaced into electric joysticks with a robotic controller, which will generate the end-effecter command trajectories of the backhoe through joystick rate control in cylindrical coordinate. The developed backhoe with the hydraulic control system showed the maxim position error of 3 cm with intuitive coordinate operations, which would be helpful for conveniently performing various excavating tasks with natural and effective ways.

• 대한기계학회논문집A
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• 제32권5호
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• pp.437-443
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• 2008

In this paper, analysis and control of the flexible multibody system using MATLAB is presented. The equations of motion of a flexible body are derived in terms of the modal coordinate. The rigid-flexible multibody dynamic solver is developed. Finite element information required to analyze motion of flexible bodies is imported from ANSYS. The modified finite element data, such as modal mass matrix, modal stiffness matrix and constraint mode shapes, is calculated in the solver. Since the solver is developed using MATLAB, it is very easy to connect with SIMULINK which is widely used to control motion of the multibody system. Several simulations are implemented to verify the developed solver. A control example is carried out and the usefulness of the developed solver is demonstrated.