• 제어로봇시스템학회논문지
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• 제15권9호
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• pp.952-958
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• 2009

This article presents a combined structure of serial and parallel mechanisms for a humanoid robot. The 3 DOF parallel structure is designed and added to the waist of the humanoid robot arm to give flexible bending and rotating motions. Forward and inverse kinematics of a serial and parallel robot have been analyzed to generate motions. Simulation studies of verifying kinematics solutions of the parallel robot have been done. Experimental studies of mimicking shake-hands motion have been conducted to show the feasibility and usability of the combined structure.

• 생물환경조절학회지
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• 제13권1호
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• pp.1-7
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• 2004

본 연구는 오이수확기의 매니퓰레이터 개발을 위한 기구학적 분석을 하는 것이다. 매니퓰레이터의 정방향 기구학 및 역방향 기구학 분석을 한 후 실제 장치의 반복오차 측정실험을 통해 이론 값을 검증하였다. 매니퓰레이터는 총 세 개의 링크로서 한 개의 수직링크와 두 개의 호전링크로 구성되어져 있으며, 세 개의 스테핑 모터가 각 관절에 장착되어 링크에 동력을 전달한다. 주요 연구결과를 요약하면 다음과 같다. D-H Parameter를 이용하여 정방향 기구학에 의한 매리퓰레이터의 변환 연산자를 얻었다. 역방향 기구학의 해는 두가지로 나타났으며 삼각함수를 이용하여 해를 구하였다. 매리퓰레이터의 반복오차를 측정한 검증 실험에서는 X, Y, Z축에 대하여 반복 오차가 최대 2.60mm, 2.05mm, 1.55mm로 나타났으며, 정방향 및 역방향 기구학에서 오차의 최대지점 및 최소지점의 실제 좌표는 일치하였다. 반복오차 측정 결과는 매리퓰레이터의 목표지점인 오이의 직경에 비해 비교적 작게 나타났다. 측정오차는 실험중 발생한 실험오차로 판단된다. 매니퓰레이터의 오차를 줄이고 작업능률의 향상을 위해서는 링크의 수를 줄이고 오이의 품종 및 재배환경을 고려하여야 하며, 경량이면서도 견고한 재료를 사용하여 하중을 줄여야 한다.

• 로봇학회논문지
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• 제10권3호
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• pp.139-145
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• 2015

This paper proposed a method of cooperative control of three mobile robots for carrying an object placed on a floor together. Each robot moves to the object independently from its location to a pre-designated location for grasping the object stably. After grasping the common object, the coordination among the robots has been achieved by a master-slave mode. That is, a trajectory planning has been done for the master robot and the distances form the master robot to the two slave robots have been kept constant during the carrying operation. The localization for mobile robots has been implemented using the encoder data and inverse kinematics since the whole system does not have the slippage as much as a single mobile robot. Before the carrying operation, the lifting operations are implemented using the manipulators attached on the top of the mobile robots cooperatively. The real cooperative lifting and carrying operations are implanted to show the feasibility of the master-slave mode control based on the kinematics using the mobile manipulators developed for this research.

• 로봇학회논문지
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• 제15권3호
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• pp.212-220
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• 2020

This paper deals with a strategy of gain optimization for the kinematic control algorithm of a wire-driven surgical robot. The proposed controller consists of the closed-loop inverse kinematics with the back-calculation method. The closed-loop inverse kinematics has 18 PID control gains, and the back-calculation method has 6 gains. An efficient strategy is designed to optimize 18 values first and then the remaining 6 values. The optimal gain sets are searched under the step input with performance indices. In this gain optimization, the objective function is defined as the minimum value of signal-to-noise ratio of the performance indices for 6 DoF (Degree-of-Freedom) motion that is based on the Taguchi method, and the constraints are applied to obtain stable responses for each motion evenly. The gain sets obtained are verified by simulations using the test trajectories. In comparative results, the optimal gain value based on the performance index combined with ISE (integral of square error) and settling time showed the best control performance.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.28-31
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• 1996

We propose an estimator design method of Stewart platform, which gives the 6DOF, positions and velcities of Stewart platform from the measured cylinder length. The solution of forward kinematics is not solved yet as a useful realtime application tool because of the complexity of the equation with multiple solutions. Hence we suggest an nonlinear estimator for the forward kinematics solution using Luenberger observer with nonlinear error correction term. But the way of residual gain selection of the estimator is not clear, so we suggest an algebraic Riccati equation for gain matrix using Lyapunov method. This algorithm gives the sufficient condition of the stability of error dynamics and can be extended to general nonlinear system.

• 제어로봇시스템학회논문지
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• 제9권10호
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• pp.798-807
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• 2003

We propose a blind mobile robot force control algorithm that uses force information as a guidance toward to the goal position. Based on the mobile robot dynamics, the control law is formed from explicit force errors. Simulation studies are conducted based on the kinematics and the dynamics of the mobile robot. Simulation results show that good force tracking can be achieved. In order to confirm simulation results, experiments are performed. The robot is commanded to follow unknown environment with maintaining a certain desired force. Experimental results show that the blind mobile robot successfully maintains contact with a regulated desired force and arrives at the goal position.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.869-874
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• 2004

The inverse kinematics of five-axis milling machines produce large errors near stationary points of the required surface. When the tool travels cross or around the point the rotation angles may jump considerably leading to unexpected deviations from the prescribed trajectories. We propose three new algorithms to repair the trajectories by adjusting the rotation angles in such a way that the kinematics error is minimized. Given the tool orientations and the inverse kinematics of the machine, we first eliminate the jumping angles exceeding ${\pi}$ by using the angle adjustment algorithm, leaving the jumps less than ${\pi}$ to be further optimized. Next, we propose to apply an angle switching algorithm to compute the rotations and identify an optimized sequence of rotations by the shortest path scheme. Further error reduction is accomplished by the angle insertion algorithm based an o special interpolation to obtain the required rotations near the singularity. We have verified the algorithms by five-axis milling machines, namely, MAHO600E at the CIM Lab of Asian Institute of Technology and HERMLE UWF902H at the CIM Lab of Kasetsart University.

• 한국지능시스템학회논문지
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• 제17권7호
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• pp.862-868
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• 2007

일반적으로 인간손에 있는 검지 손가락의 평면운동은 3개의 관절운동에 의해 이루어진다. 이러한 운동을 위해서는 기본적으로 역기구학 문제를 풀어야 하는데, 이것은 로봇 손을 이용한 파지나 조작행위에 있어서 필수적이다. 따라서 본 논문에서는 이러한 로봇 손가락의 역기구학 문제를 지능적으로 해결할 수 있는 뉴럴 러닝에 기반한 방법을 제안하고자 한다. 제안된 방법은 뉴럴 러닝에 있어서 동적인 학습율을 적용함으로써 보다 빠른 학습이 가능하고, 생체모방에 근거한 인간 손가락의 운동특성을 고려하는 것이 특징이다. 제안된 방법의 유용성을 입증하기 위하여 시뮬레이션을 수행한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.296-301
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• 2005

This paper describes the kinematics, dynamics and control of a 6-DOF shaking table with a bell crank structure, which converts the direction of reciprocating movements. In this shaking table, the bell crank mechanism is used to reduce the amount of space needed to install the shaking table and create horizontal displacement of the platform. In kinematics, joint design is performed using $Gr{\ddot{u}}bler's$ formula. The inverse kinematics of the shaking table is discussed. The derivation of the Jacobian matrix is presented to evaluate singularity conditions. Considering the maximum stroke of the hydraulic actuator, collision between links and singularity, workspace is computed. In dynamics, computations are based on the Newton-Euler formulation. To derive parallel algorithms, each of the contact forces is decomposed into one acting in the direction of the leg and the other acting in the plane orthogonal to the direction of the leg. Applying the Newton-Euler approach, the solution of inverse dynamics is almost completely parallel. Only one of the steps-the application of the Newton-Euler equations to the platform-must be performed on one single processor. Finally, the efficient control scheme is proposed for the tracking control of the motion platform.

• 전자공학회논문지
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• 제50권3호
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• pp.203-211
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• 2013

본 논문에서는 바닥작업용 서비스 로봇을 위한 두 팔 매니퓰레이터의 개발 및 제어에 관한 연구를 기술하였다. 6자유도의 매니퓰레이터를 설계하였으며, 그 중 5자유도 매니퓰레이터를 제작하였다. 제작된 매니퓰레이터의 순기구학과 역기구학을 해석하고 시뮬레이션을 수행하여 기구학을 검증하였다. 실제로 역기구학을 바탕으로 로봇 팔을 제작하여 제어하였다. 양팔의 동작 성능을 확인하기 위해 오른쪽 팔과 왼쪽 팔을 각각 따로 제어하여 서로 다른 경로를 추종하는 실험을 수행하였다. 실험결과를 통해 기구학 분석을 검증하였으며, 시스템의 동작 여부를 확인할 수 있었다.