• 센서학회지
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• 제16권3호
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• pp.211-219
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• 2007

This paper describes the development of 6-axis force/moment sensor for a humanoid robot. In order to walk on uneven terrain safely, the robot's foot should perceive the applied forces Fx, Fy, Fz and moments Mx, My, Mz to itself, and be controlled by the foot using the forces and moments. Also, in order to grasp unknown object safely, the robot's hand should perceive the weight of the object using the mounted 6-axis force/moment sensor to its wrist, and be controlled by the hand using the forces and moments. Therefore, 6-axis force/moment sensor should be necessary for a humanoid robot's hand and foot. In this paper, 6-axis force/moment sensor for a humanoid robot was developed using many PPBs (parallel plate-beams). The structure of the sensor was newly modeled, and the sensing element of the sensor was designed using theoretical analysis. Then, 6-axis force/moment sensor was fabricated by attaching strain-gages on the sensing elements, and the characteristic test of the developed sensor was carried out. The rated outputs from theoretical analysis agree well with the results from the experiments.

• 한국정밀공학회지
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• 제31권2호
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• pp.113-117
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• 2014

Laser Assisted Machining (LAM) was often used in process of difficulty-to-cut materials. In previous study, Laser assisted machining was a straight path processing using 1-axis manipulator in laser module. But 1-axis manipulator in laser module was able to process only straight path. So, in this study, laser module in laser assisted machining equipped to 2-axis manipulator. 2-axis manipulator has two motors. First motor is machining direction motor and second motor is Vertical Motor. Machining direction motor rotates in the direction of machining and vertical motor rotates vertical direction in the direction of machining. Machining path of laser assisted machining was considered diagonal path and curved path of laser heat source. This study calculated the 2-axis manipulator's rotation angle in diagonal path and curved path.

• 한국정밀공학회지
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• 제30권12호
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• pp.1313-1320
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• 2013

An ultraprecision multi-axis machine tool has been designed and developed in our laboratory. The machine tool has four moving axes which are composed of three linear axes and one rotational axis. It has a gantry type structure and the Z-axis is on the X-axis and the C-axis, on which a workpiece is located, is inside the Y-axis. This paper shows control performance improving method and procedure for the ultra-precision positioning control of a hydrostatic bearing guided linear axis. Through improvements of electrical and mechanical components for the control system such as control electronics and oil pumping systems, the control disturbing noise is decreased. Also by the frequency domain analysis of control system those problem-making system components are identified and modified with analytical methods. The controller is analyzed and designed from frequency domain data and system information. In the experimental control results the nanometer order control result is successfully presented.

• 천문학회지
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• 제43권5호
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• pp.169-181
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• 2010

We develop a proto-model of an off-axis reflective telescope for infrared wide-field observations based on the design of Schwarzschild-Chang type telescope. With only two mirrors, this design achieves an entrance pupil diameter of 50 mm and an effective focal length of 100 mm. We can apply this design to a mid-infrared telescope with a field of view of $8^{\circ}{\times}8^{\circ}$. In spite of the substantial advantages of off-axis telescopes in the infrared compared to refractive or on-axis reflective telescopes, it is known to be difficult to align the mirrors in off-axis systems because of their asymmetric structures. Off-axis mirrors of our telescope are manufactured at the Korea Basic Science Institute (KBSI). We analyze the fabricated mirror surfaces by fitting polynomial functions to the measured data. We accomplish alignment of this two-mirror off-axis system using a ray tracing method. A simple imaging test is performed to compare a pinhole image with a simulated prediction.

• 한국CDE학회논문집
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• 제15권5호
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• pp.354-361
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• 2010

The paper presents an efficient computation of optimal tool length for 5-axis mold & die machining. The implemented procedure processes an NC file as an initial input, where the NC data is generated by another commercial CAM system. A commercial CAM system generates 5-axis machining NC data which, in its own way, is optimal based on pre-defined machining condition such as tool-path pattern, tool-axis control via inclination angles, etc. The proper tool-length should also be provided. The tool-length should be as small as possible in order to enhance machinability as well as surface finish. A feasible tool-length at each NC block can be obtained by checking interference between workpiece and tool components, usually when the tool-axis is not modified at this stage for most CAM systems. Then the minimum feasible tool-length for an NC file consisting of N blocks is the maximum of N tool-length values. However, it can be noted that slight modification of tool-axis at each block may reduce the minimum feasible tool-length in mold & die machining. This approach can effectively be applied in machining feature regions such as steep wall or deep cavity. It has been implemented and is used at a molding die manufacturing company in Korea.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.53-60
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• 2002

Recently, the development of aerospace and automobile industries brought new technological challenges, related to the growing complexity of products and new geometry models. High speed machining using 5-Axis milling machine is widely used for 3D sculptured surface parts. 5-axis milling of turbine blade generates the vibration, deflection and twisting caused from thin and cantilever shape. So, the surface roughness and the waviness of workpiece are not good. In this paper, The effects of cutter orientation and lead/tilt angle in 5-Axis high speed ball end-milling of turbine blade were investigated to improve the geometric accuracy and surface integrity. The experiments were performed at lead/tilt angle $15^{\circ}$ of workpiece with four cutter directions such as horizontal outward, horizontal inward, vertical outward, and vertical inward. Workpiece deflection, surface roughness and machined surface were measured with various cutter orientations such as cutting direction, and lead/tilt angle. The results show that when 5-axis machining of turbine blade, the best cutting strategy is horizontal inward direction with tilt angle. The results show that when 5-axis machining of turbine blade, the best cutting strategy is horizontal inward direction with tilt angle.

• 한국정밀공학회지
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• 제32권7호
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• pp.643-651
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• 2015

Multi-axis magnetic and accelerometer sensor are widely used in consumer product such as smart phones. The vector output of multi-axis sensors have errors on each axis such as offset error, scale error, non-orthogonality. These errors cause many problems on the performance of the applications. In this paper, we designed the effective inline compensation algorithm for calibrating of 3 axis sensors using ellipsoid for mass production of multi-axis sensors. The outputs with those kinds of errors can be modeled by ellipsoid, and the proposed algorithm makes sequential mappings of the virtual ellipsoid to perfect sphere which is calibrated function of the sensor on three-dimensional space. The proposed calibrating process composed of four main stages and is very straightforward and effective. In addition, another imperfection of the sensor such as the drift from temperature can be easily inserted in each mapping stage. Numerical simulation and experimental results shows great performance of the proposed compensation algorithm.

• 대한수의학회지
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• 제33권2호
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• pp.189-198
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• 1993

The present study was undertaken to provide basic data on endochondral ossification for the axis in developing Miniature Schnauzers. This study was determined to the morphological features and development of growth plast in the axis of this experimental animals by histological and histochemical methods. The axis from 2 healthy Miniature Schnauzers(postnatal 6hr, 5week) was used. The obtained results were as follows : 1. In 5-week-old Miniature Schnauzer, the axis consisted of 4 separate ossification centers : centrum l, intercentrum 2, centrum 2 and epiphysis. Intercentrum 2 was intercalated between centrum 1 cranially, centrum 2 caudally. 2. The space of centrum 1 was more broader than the other ossification centers. 3. The zone of reserved chondrocytes was more extensive than the zone of proliferative chondrocytes, trabeculation was weakly observed, however, the proximal epiphyseal plate of axis was actively trabeculation observed in the zone of calcified chondrocytes. 4. Eighteen columns of chondrocytes were observed in the centrum 1 and five to seven columns of chondrocytes were observed in the centrum 2 of Miniature Schnauzer(postnatal 5 week) 5. A positive reaction to alcianophility was observed in all the territorial matrix at the zone of hypertrophic chondrocytes in this experimental animals.

• 융합신호처리학회논문지
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• 제11권3호
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• pp.183-188
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• 2010

본 논문에서는 LoG scale-space를 이용한 그레이스케일 영상에서 연속패턴 라인 중심축 검출 기법을 제안한다. 제안된 기법은 LoG의 스케일 크기를 적응적으로 가변하여 라인 중심축을 검출하는 방법이다. 작은 스케일의 LoG 연산자는 라인의 에지점에서 영교차 특성이 나타나며, 영교차점을 중심으로 좌우에 +/- 극성을 가진 극점이 존재하게 된다. 즉 일정한 폭을 가지는 라인은 양쪽 가장자리에서 2개의 +극점을 가지게 된다. LoG의 확산동작을 반복함에 따라 스케일을 증가시키면 +극점은 라인 양쪽 에지영역에서 중심영역으로 이동하여 점진적으로 가까워져서 최종적으로 하나의 극점으로 중첩되어진다. 연속패턴 라인 중심축은 2개의 +극점이 중심영역에서 중첩되는 점이다. 제안하는 방법은 기존의 이진영상에서 적용되는 세선화 방법보다 강인하게 연속패턴 라인 중심축을 검출함을 확인하였다.

• 한국기계가공학회지
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• 제10권2호
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• pp.9-15
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• 2011

In order to develop a practical postprocessor for 5-axis machining, the general equations of numerically controlled (NC) data for 5-axis configurations with not only non-orthogonal rotary axes but also orthogonal rotary axes were exactly expressed by the inverse kinematics, and a Windows-based postprocessor written in Visual Basic was developed according to the proposed algorithm. The developed postprocessor is a general system that suitable for all kinds of 5-axis machine tool with orthogonal and non-orthogonal rotary axes. Through implementation of the developed postprocessor and verification by a cutting simulation and machining experiment, the effectiveness of the proposed algorithm is confirmed. Compatibility is improved by allowing exchange of data formats such as rotational tool center position (RTCP) controlled NC data, vector post NC data, and program object file (POF) cutter location (CL)data, and convenience is increased by adding the function of work-piece origin offset. Consequently, the technology of practical post-processor for 5-axis machining is developed.