• 한국정밀공학회지
• /
• 제26권4호
• /
• pp.64-71
• /
• 2009

A 3-D rehabilitation robot system is developed in this paper. The robot system is for the rehabilitation of upper extremities, especially the shoulder and elbow joints, and has 3-D workspace for enabling occupational therapy to recover physical functions in activities of daily living(ADL). The rehabilitation robot system, which is driven by actuators, has 1 DOF in horizontal rotational motion and 2 DOF in vertical rotational motion, where all actuators are set on the ground. Parallelogram linkage mechanisms lower the equivalent inertia of the control elements as well as control forces. Also the mechanisms have high mechanical rigidity for the end effector and the handle. Passive motion mode experiments have been performed to evaluate the proposed robot system. The results of the experiments show and excellent performance in simulating spasticity of patients.

• Journal of Biosystems Engineering
• /
• 제25권2호
• /
• pp.141-150
• /
• 2000

This study was carried out to de develop a control strategy of a fruit harvesting redundant robot. The method of generating a safe trajectory, which avoids collisions with obstracles such as branches or immature fruits, in the 3D(3-dimension) space using artificial potential field technique and virtual plane concept was proposed. Also, the method of setting reference velocity vectors to follow the trajectory and to avoid obstacles in the 3D space was proposed. Developed methods were verified with computer simulations and with actual robot tests. Fro the actual robot tests, a machine vision system was used for detecting fruits and obstacles, Results showed that developed control method could reduce the occurrences of the robot manipulator located in the possible collision distance. with 10 virtual obstacles generated randomly in the 3 D space, maximum rates of the occurrences of the robot manipulator located in the possible collision distance, 0.03 m, from the obstacles were 8 % with 5 degree of freedom (DOF), 8 % with 6-DOF, and 4% with 7-DOF, respectively.

• 로봇학회논문지
• /
• 제5권2호
• /
• pp.102-109
• /
• 2010

In this study, an anthropomorphic robot Hand, called "SKKU Hand III" is presented. The hand has thirteen DOF(Degree-Of-Freedom) and is designed based on the skeletal structure of the human hand. Each finger module(except thumb module) has three DOF and four joints with a saddle joint mechanism which has two DOF at the base joint. Two distal joints of the finger module are mechanically coupled by a timing belt and pulleys. The thumb module is composed of a finger module and an additional actuator, which makes it possible to realize the opposition between the thumb and the other fingers. In addition, the palm DOF of the human hand is mimicked with a spatial link mechanism between the index finger and the thumb. Thus, it can grasp objects more stably and more strongly. For the modularization of the robotic hand all the driving circuits are embedded in the hand, and only the communication lines supporting CAN protocol with DC power cable are given as an interface. Therefore, it is possible to apply it to any robot system the interface. To validate the feasibility of the SKKU Hand III, a series of the representative grasp experiments such as power, precision, intermediate grasp etc. are carried out with the object around us and its operation is demonstrated.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 춘계학술대회논문집
• /
• pp.675-680
• /
• 2001

In this study, a fluid/structure coupled analysis system using computational fluid dynamics and computational structural dynamics has been developed. The unsteady flow fields are predicted using unstructured Euler code. Coupled time-integration method (CTIM) was applied to computer simulation of the flow-induced vibration phenomena. To investigate the interaction effect of shock motions, 2-DOF airfoil systems have been studied in the subsonic and transonic flow region. Also, aeroelastic analyses for the airfoil with an arbitrary object are performed to show the analysis capability and interference effects for the complex geometries. The present results show the flutter stabilities and characteristics of aeroelastic responses with moving shock effects.

• 한국소음진동공학회논문집
• /
• 제14권11호
• /
• pp.1182-1194
• /
• 2004

This paper addresses the application of an active magnetic bearing (AMB) system to levitate the elevation axis of an electro-optical sight mounted on a moving vehicle. In this type of system, it is desirable to retain the elevation axis in an air-gap between magnetic bearing stators while the vehicle is moving. To eliminate disturbance responses, a disturbance observer based sliding mode control is developed. This control can decouple disturbance observation dynamics from sliding mode dynamics and preserves the robustness of the sliding control. The sliding surfaces are designed in the consideration of scattering of received image. The proposed control is applied to a 2-DOF active magnetic bearing system subject to base motion. Along with experimental results, the feasibility of the proposed technique is illustrated.

• International Journal of Precision Engineering and Manufacturing
• /
• 제8권2호
• /
• pp.3-8
• /
• 2007

A machining system that generates accurate relative motions between the tool and workpiece is required to realize ultra precise machining or measurements. Accuracy improvements for each element of the machine are also required. This paper proposes a machining system that uses a compensation device for the six-degree-of-freedom (6-DOF) motion error between the tool and workpiece. The compensation device eliminates elastic and thermal errors of the joints and links due to temperature fluctuations and external forces. A hexapod parallel kinematics mechanism installed between the tool spindle and surface plate is passively actuated by a conventional machine. Then the parallel mechanism measures the 6-DOF motions. We describe the conception and fundamentals of the system and test a passively extensible strut with a compensation device for the joint errors.

• 한국항공우주학회지
• /
• 제34권12호
• /
• pp.75-81
• /
• 2006

민간항공안전국 등급 2를 만족하는 헬리콥터 시뮬레이터에 사용되는 6자유도 운동구현장치 개발에 관해 기술하였다. 운동판과 제어 구동장치의 기구학적 및 구조적 해석을 통해 설계 제작된 운동구현장치의 시험 평가로부터 규정에 만족하는 결과를 보였고 이로부터 실제 헬리콥터 시뮬레이터로의 적용 타당성을 확보하였다. 또한 동품의 개발 결과로 인해 그간 유압 구동체계를 사용한 운동구현장치의 단점을 전기식 구동장치 적용을 통해 새롭게 개선함과 동시에 국내 최초로 10 톤급의 적재하중 능력을 보유한 6자유도 운동구현장치를 보급하게 되는 계기를 마련하였다.

• 대한기계학회논문집A
• /
• 제36권2호
• /
• pp.237-244
• /
• 2012

이 논문은 목표치 정형화 필터와 외란관측기를 활용하여 연속 냉간압연 시스템의 스트립 두께 및 장력에 대한 2-자유도 최적 제어기 설계에 관한 연구를 수행한다. 먼저 게이지 미터식과 후크 법칙을 이용하여 스트립 두께 및 장력에 관한 동적모델을 각각 구축한다. 다음에는 동적모델을 기반으로 2-자유도 제어기를 설계한다. 여기서 피드포워드 제어기는 목표치 정형화 필터와 외란 관측기를 활용한 제어기로 구성되며, 피드백 제어기는 역 최적 제어기로 설계된다. 끝으로 컴퓨터 시뮬레이션을 통하여 이 논문에서 제안한 2-자유도 최적 제어기가 연속 냉간압연 시스템의 기존 제어기보다 스트립 두께 및 장력에 대한 목표치 추종성능과 외란 제거성능이 매우 우수함을 보인다.

• 한국정밀공학회지
• /
• 제29권10호
• /
• pp.1128-1136
• /
• 2012

In this paper, the states and parameters in a dynamic system are estimated by applying an Unscented Kalman Filter (UKF). The UKF is widely used in various fields such as sensor fusion, trajectory estimation, and learning of Neural Network weights. These estimations are necessary and important in determining the stability of a mobile system, monitoring, and predictions. However, conventional approaches are difficult to estimate based on the experimental data, due to properties of non-linearity and measurement noises. Therefore, in this paper, UKF is applied in estimating the states and parameters needed. An experimental dynamic system has been set up for obtaining data and the experimental data is collected for parameter estimation. The measurement noises are primarily reduced by applying the Low Pass Filter (LPF). Given the simulation results, the estimated error rate is 39 percent more efficient than the results obtained using the Least Square Method (LSM). Secondly, the estimated parameters have an average convergence period of four seconds.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 춘계학술대회 논문집
• /
• pp.273-277
• /
• 1995

Many hudraulic components have nonlinearities to some extent. These nonlinearities often cause the time delay, thus degrading the performance of the hydraulic control systems and making it difficult to modelthem. In this paper, a new vibration isolation control algorithm that eliminates the necessity of a sophiscated modeling of hydraulic system was proposed. The algotithm is a hybrid type control shecheme consisting of a linear controller and a hetero-synaptic neural network controller. Using this control scheme, simulations and experiments were performed for 1 DOF(Degree of freedom) and 2 DOF vibration isolation. The hybrid type control algorithm can isolate the base vibration signifcantly rather than linear control algorithm. And from the weights in hetero-synaptic neural network, we can get the 2nd equivalent differentialmodel of the hydraulic control system with on-line control operation. This equivalent model provides us with much information, such as stability and the characteristics of the control system.