• Journal of Mechanical Science and Technology
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• 제16권8호
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• pp.1053-1063
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• 2002

This paper presents a robust nonlinear controller for a f degree of freedom (DOF) parallel manipulator in the task space coordinates. The proposed control strategy requires information on orientations and translations in the task space unlike the joint space or link space control scheme. Although a 6 DOF sensor may provide such information in a straightforward manner, its cost calls for a more economical alternative. A novel indirect method based on the readily available length information engages as a potential candidate to replace a 6 DOF sensor. The indirect approach generates the necessary information by solving the forward kinematics and subsequently applying alpha-beta-gamma tracker With the 6 DOF signals available, a robust nonlinear task space control (RNTC) scheme is proposed based on the Lyapunov redesign method, whose stability is rigorously proved. The performance of the proposed RNTC with the new estimation scheme is evaluated via experiments. First, the results of the estimator are compared with the rate-gyro signals, which indicates excellent agreement. Then, the RNTC with on-line estimated 6 DOF data is shown to achieve excellent control performance to sinusoidal inputs, which is superior to those of a commonly used proportional-plus-integral-plus-derivative controller with a feedforward friction compensation under joint space coordinates and the nonlinear controller under task space coordinates.

• 한국학교수학회논문집
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• 제19권4호
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• pp.357-371
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• 2016

본 연구는 수학적 모델링의 과제공간을 설정하고 이를 기반으로 모델링 과제의 복잡성을 나타내는 평가척도(rating scheme)를 설계하여 예비 수학교사를 대상으로 두 가지의 실험연구 결과를 얻었다. 첫째는 종전의 문제구조를 표현한 문제공간을 발전시켜 모델링 과제에 맞는 과제공간을 설정하고, 모델링 과제의 복잡성을 수치로 나타내는 계량적인 평가척도를 설계하여 의미 있는 타당도를 확인하였다. 둘째는 모델링의 과제 복잡성에 대한 평가척도, 학생 성취수준, 과제 특수 발견 전략의 개수 사이의 일관된 패턴이 있음을 발견하였다.

• International Journal of Control, Automation, and Systems
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• 제6권1호
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• pp.101-108
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• 2008

The transposed Jacobian is proposed to transform the control space from task space to joint space, in this paper. Instead of inverse Jacobian, the transposed Jacobian is preferred to avoid singularity problem, short real time calculations and its generality to apply for rectangular Jacobian. On-line Jacobian identification is proposed to cancel parametric errors produced by D-H parameters of manipulator. To identify Jacobian, the joint angles and the end-effector position are measured when tracking a desired trajectory in task space. Stability of control system is analyzed. The control system is simulated for position control of a two-link manipulator driven by permanent magnet dc motors. Simulation results are shown to compare the roles of inverse Jacobian and transposed Jacobian for transforming the control space.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.411-413
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• 1992

This paper proposes a simple and high performance hybrid position/force control of robots based on disturbance compensation by using the disturbance observer in task coordinate space. The disturbance observer linealizes system of robot manipulators in task coordinate space and realizes acceleration control. To realize the strict acceleration control, the disturbance observer whose input is a position signal by simple computation, works as if it were a disturbance detector. The inverse kinematics can be simplified, because the disturbance observer in task coordinate space compensates not only the disturbance but also the error due to the simplification of the inverse kinematics. The new strategy is applied to a three-degrees-of freedom direct drive robot. The robust and simple hybrid position/force control is realized experimentally.

• 로봇학회논문지
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• 제1권2호
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• pp.107-116
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• 2006

We propose a planning algorithm to automatically generate a robust behavior plan (RBP) with which mobile robots can achieve their task goal from any initial states under dynamically changing environments. For this, task description space (TDS) is formulated, where a redundant task configuration space and simulation model of physical space are employed. Successful task episodes are collected, where $A^*$ algorithm is employed. Interesting TDS state vectors are extracted, where occurrence frequency is used. Clusters of TDS state vectors are found by using state transition tuples and features of state transition tuples. From these operations, characteristics of successfully performed tasks by a simulator are abstracted and generalized. Then, a robust behavior plan is constructed as an ordered tree structure, where nodes of the tree are represented by attentive TDS state vector of each cluster. The validity of our method is tested by real robot's experimentation for a box-pushing-into-a-goal task.

• 한국융합학회논문지
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• 제2권3호
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• pp.25-32
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• 2011

현재의 웹은 표준화된 통합 환경을 지원하지 않는다. 이로 인해 작업 규모가 클 경우 작업 효율을 떨어뜨리는 원인이 될 수 있다. 본 논문에서는 복수의 행위 주체들이 함께 일을 할 때 서로의 일처리 프로세스를 공유하는 것이 가능한 통합 공간(SB공간)을 제안한다. SB공간은 웹 사이트의 하나로 설치될 수 있으며, 웹 공간과의 효율적인 연계사용이 가능하다. 이는 사실상 웹 공간의 확장을 의미하는 바, 이를 통해 웹 공간의 생산성을 현저하게 개선할 수 있다. 본 논문에서는 구체적인 사례 연구를 통해서 이를 입증해 보인다.

• International Journal of Aeronautical and Space Sciences
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• 제12권2호
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• pp.163-174
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• 2011

Task assignments of multiple unmanned aerial vehicles (UAVs) are examined. The phrase "task assignment" comprises the decision making procedures of a UAV group. In this study, an on-line decentralized task assignment algorithm is proposed for an autonomous UAV group. The proposed method is divided into two stages: an order optimization stage and a communications and negotiation stage. A genetic algorithm and negotiation strategy based on one-to-one communication is adopted for each stage. Through the proposed algorithm, decentralized task assignments can be applied to dynamic environments in which sensing range and communication are limited. The performance of the proposed algorithm is verified by performing numerical simulations.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2009년도 학술대회
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• pp.677-684
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• 2009

다양한 센서 네트워크와 유비쿼터스 기술이 제공되는 지능형 협업 환경은 사용자를 위해 확장된 인터랙션을 제공할 수 있다. 기존의 인터랙션이 사용자와 컴퓨터 머신과의 직접적인 인터랙션이 주를 이룬 반면 새로 확장된 인터랙션은 사용자와 공간과의 인터랙션을, 실질적으로 공간을 구성하는, 관리와 제어가 가능한 구성요소와의 인터랙션을 나타낸다. 본 논문은 이러한 공간 인터랙션을 효과적으로 제공할 수 있도록 하기 위해서 공간 오브젝트를 등록, 인식하고, 특히 사용자의 의도에 맞는 태스크를 지원하기 위해 과거의 인터랙션 정보를 이용한 템플릿 기반 맵핑 알고리즘을 설계한다. 제안된 알고리즘을 이용하는 경우, 공간 오브젝트가 증가함에 따라 템플릿을 검색하여 처리하는데 드는 시스템의 비용이 어느 정도 향상되는지 실험을 통해 분석하도록 하며, 진행되는 모든 공간 인터랙션을 시각적으로 보여주기 위한 그래픽 기반의 도시 방법을 소개하고 결론을 맺는다.

• 융복합기술연구소 논문집
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• 제6권2호
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• pp.9-13
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• 2016

Robot usually requires spline motion to move through multiple knots. In this paper, catmull-rom spline method is applied to the trajectory planning of industrial robot in task space. Centripetal catmull-rom is selected to avoid self-intersection and slow motion which can be occurred in uniform and chordal spline. The method to set two control points are proposed to satisfy velocity conditions of initial and final knots. To optimize robot motion, time scaling method is presented to minimize margin between real robot value and maximum value in velocity and acceleration. The simulation results show that the proposed methods are applied to trajectory planning and robot can follow the planned trajectory while robot motion does not exceed maximum value of velocity and acceleration.

• 제어로봇시스템학회논문지
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• 제4권1호
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• pp.105-112
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• 1998

Regarding the measure of dexterity of robot manipulators, two geometric tools, manipulability ellipsoids and manipulability polytopes, are examined and compared with each other. Even though the manipulability ellipsoid approach is the most widely used technique, it is shown that the manipulability ellipsoid transforms the inexact joint velocity constraints into task space and so it may fail to give an exact measure of dexterity and optimal direction of motion in task space. After showing that the polytope approach can handle such problems, we propose a practical polytope method which can be applied to 3-dimensional task space in general. The relation between manipulability ellipsoids and manipulability polytopes are also explored for a redundant case and a non-redundant one.