• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.27-28
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• 2010

• 로봇학회논문지
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• 제4권4호
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• pp.298-304
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• 2009

This paper describes an algorithm that improves 3D reconstruction result using a multi-sensor fusion disparity map. We can project LRF (Laser Range Finder) 3D points onto image pixel coordinatesusing extrinsic calibration matrixes of a camera-LRF (${\Phi}$, ${\Delta}$) and a camera calibration matrix (K). The LRF disparity map can be generated by interpolating projected LRF points. In the stereo reconstruction, we can compensate invalid points caused by repeated pattern and textureless region using the LRF disparity map. The result disparity map of compensation process is the multi-sensor fusion disparity map. We can refine the multi-sensor 3D reconstruction based on stereo vision and LRF using the multi-sensor fusion disparity map. The refinement algorithm of multi-sensor based 3D reconstruction is specified in four subsections dealing with virtual LRF stereo image generation, LRF disparity map generation, multi-sensor fusion disparity map generation, and 3D reconstruction process. It has been tested by synchronized stereo image pair and LRF 3D scan data.

• Smart Structures and Systems
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• 제15권6호
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• pp.1543-1567
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• 2015

In this study, a wireless crack sensor is developed for monitoring cracks propagating in two dimensions. This sensor is developed by incorporating a laser-based optical navigation sensor board (ADNS-9500) into a smart wireless platform (Imote2). To measure crack propagation, the Imote2 sends a signal to the ADNS-9500 to collect a sequence of images reflected from the concrete surface. These acquired images can be processed in the ADNS-9500 directly (the navigation mode) or sent to Imote2 for processing (the frame capture mode). The computed crack displacement can then be transmitted wirelessly to a base station. The design and the construction of this sensor are reported herein followed by some calibration tests on one prototype sensor. Test results show that the sensor can provide sub-millimeter accuracy under sinusoidal and step movement. Also, the two modes of operation offer complementary performance as the navigation mode is more accurate in tracking large amplitude and fast crack movement while the frame capture mode is more accurate for small and slow crack movement. These results illustrate the feasibility of developing such a crack sensor as well as point out directions of further research before its actual implementation.

• 제어로봇시스템학회논문지
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• 제18권6호
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• pp.601-607
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• 2012

The recognition of elevator door is needed for mobile service robots to moving between floors in the building. This paper proposed the sensor fusion approach using LRF (Laser Range Finder) and camera to solve the problem. Using the laser scans by the LRF, we extract line segments and detect candidates as the elevator door. Using the image by the camera, the door candidates are verified and selected as real door of the elevator. The outliers are filtered through the verification process. Then, the door state detection is performed by depth analysis within the door. The proposed method uses extrinsic calibration to fuse the LRF and the camera. It gives better results of elevator door recognition compared to the method using LRF only.

• 한국CDE학회논문집
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• 제17권3호
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• pp.156-163
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• 2012

Real-time three-dimensional shape measurement is becoming increasingly important in various fields, including medical sciences, high-technology industry, and microscale measurements. However, there are not so many 3D profile tools specially designed for specifically narrow space, for example, to scan the tooth shape of a human jaw. In this paper, a real-time 3D intraoral scanner is proposed for the measurement of tooth profile in the mouth cavity. The proposed system comprises a laser diode beam, a micro charge-coupled device, a graticule, a piezoelectric transducer, a set of optical lenses, and a polhemus device sensor. The phase-shifting technique is used along with an accurate calibration method for the measurement of the tooth profile. Experimental and theoretical inspection of the phase-to-coordinate relation is presented. In addition, a nonlinear system model is developed for collimating illumination that gives the more accurate mathematical representation of the system, thus improves the shape measurement accuracy. Experiment results are presented to verify the feasibility and performance of the developed system. The experimental results indicate that overall measurement error accuracy can be controlled within 0.4 mm with a variability of ${\pm}0.01$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.285-286
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• 2006

The essential tasks to operate the welding robot are the acquisition of the position and/or shape of the parent metal. For the seam tracking or the robot automation, many kinds of contact and non-contact sensors are used. Recently, the vision sensor is most popular. In this paper, the development of the system which measures the profile of the welding part is described. The total system will be assembled into a compact module which can be attached to the head of welding robot system. This system uses the line-type structured laser diode and the vision sensor It implemented Direct Linear Transformation (DLT) for the camera calibration as well as radial distortion correction. The three dimensional shape of the parent metal is obtained after simple linear transformation and therefore, the system operates in real time. Some experiments are carried out to evaluate the performance of the developed system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.263-266
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• 2002

An optical method for surface roughness estimation based on statistical analysis of the light intensity of a scattered laser beam pattern. The method is very simple but has a disadvantage that no more information than the averaged roughness is estimated. In this study a new try was conducted to derive more advanced surface information from the details of the light intensity distribution. Some periodic ripples among the light intensity distribution being assumed to relate with scratch left on the machined surface, a corresponding surface profile is estimated from the ripples using FFT and IFFT algorithm. IFFT technique is used to extract some dominant signal components among the intensity distribution. Compared to the measured profiles by a stylus type surf-tester, the profiles obtained through the proposed method are probably acceptable in a sense of the profile shape. Calibration of the amplitude needs more works in the future.

• 소성∙가공
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• 제7권4호
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• pp.382-392
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• 1998

Computer simulations and test trials were carried out to obtain the optimal stamping conditions of the die design of the laser welded automotive body. The stamping process including gravity deflection bead calibration binder wrap, forming and spring back was simulated and compared with the results obtained from test trials. The production variables were determined from a preliminary operation and they were investigated in the simulation and the test trials. The formability was tested under the various conditions, such as the initial position of blank, blank holding force, corner radius and the shape of drawbead. Sound products without fracture, wrinkling and excessive weldline movement were produced by applying results obtained this investigation.

• 제어로봇시스템학회논문지
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• 제2권3호
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• pp.200-208
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• 1996

This paper describes the mechanism, guidance, sensor system, and navigation algorithm of METRO, a free ranging mobile robot. METRO is designed for use in structured surroundings or factory environments rather than unstructured natural environments. An overview of the physical configuration of the mobile robot is presented as well as a description of its sensor system, an omnidirectional laser range finder. Except for the global path planning algorithm, a guidance and a navigation algorithm with a local path planning algorithm are used to navigate the mobile robot. In METRO the computer support is divided into a supervisor with image processing and local path planning and a slave with motor control. The free ranging mobile robot is self-controlled and all processing being performed on board.

• 전기전자학회논문지
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• 제22권3호
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• pp.605-612
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• 2018

본 논문에서는 선형으로 스위핑하는 파장 스위핑 레이저를 구현하기 위한 새로운 방식을 제안하였으며, 레이저 제작 및 실험을 통하여 1kHz 속도, 80nm 구간의 선형 스위핑 특성을 확인하였다. 제안된 방식은 FFP-TF 인가 파형에 대한 초기 한번의 선 보정만을 필요로 한다. 따라서 기존의 비선형 스위핑 레이저에서 불가피한 후 보정 과정의 번거로움 및 시간 소모문제를 해결해 준다.