• 제어로봇시스템학회논문지
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• 제22권11호
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• pp.952-959
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• 2016

This paper proposes a novel indoor positioning system (IPS) that uses a calibrated camera sensor network and dense 3D map information. The proposed IPS information is obtained by generating a bird's-eye image from multiple camera images; thus, our proposed IPS can provide accurate position information when objects (e.g., the mobile robot or pedestrians) are detected from multiple camera views. We evaluate the proposed IPS in a real environment with moving objects in a wireless camera sensor network. The results demonstrate that the proposed IPS can provide accurate position information for moving objects. This can improve the localization performance for mobile robot operation.

• 제어로봇시스템학회논문지
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• 제6권12호
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• pp.1093-1098
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• 2000

This paper presents an efficient algorithm for including the kinematic calibration data into the motion controller to improve the positioning accuracy of the manipulators. Rather than spending several iterations for finding the inverse solution of the calibrated kinematics, our approach requires only the nominal inverse solution and the calibrated forward kinematics for providing a better position command promptly. Thus, real-time application is guaranteed whenever the manipulators nominal inverse solution can be expressed in a closed form. Experimental results show that the line tracking performances can be remarkably improved by employing our algorithm.

• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1279-1286
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• 1999

In conventional GPS/DR integration schemes, the GPS position (or pseudo-range) information is used in calibrating DR sensors. In those schemes, however, an inaccurate calibration may degrade the position accuracy when the GPS measurement is not available. This paper presents a new integration scheme where the GPS velocity information is used in calibrating DR sensors. Also proposed is a new error model of DR sensors for calibrating the bias error and the tilt error in dynamic environments. The proposed model makes it possible that the errors of both the DR sensor parameters and the velocity are calibrated using the GPS carrier-based velocity(or the pseudo-range rate) measurement while the DR position error is calibrated using the GPS position measurement. Since the DR sensors are calibrated accurately, the positioning accuracy is drastically improved when the GPS measurements are unavailable.

• 한국정보통신학회논문지
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• 제21권10호
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• pp.1917-1922
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• 2017

WPS는 현실세계에 산재한 무선 신호를 활용하여 측위를 수행한다. 측위 위치의 무선 신호 정보를 수집하여 radio map을 구성하는 구축단계, 구성된 정보와 수집된 무선 신호를 비교하는 측위 단계로 나누어진다. WPS는 측위 시 수집된 신호에 변화가 나타날 경우 측위 정확도의 하락을 가지고 온다. PDR은 관성 센서들을 활용하여 보행자의 걸음걸이 수, 이동거리, 방향을 분석하여 최종 이동지를 분석하는 시스템이다. WPS의 측위 결과가 두 개 이상의 위치로 나타날 경우 측위 정확도의 문제로 판단할 수 있다. 몇몇의 조건에서 문제가 발생하게 된다. 본 논문에서는 앞서 언급한 문제점이 발생하는 상황에 대하여 분석하고 이를 PDR을 통해서 보정하는 시스템에 대하여 제안한다. 이 복합측위를 적용할 경우 WPS에 문제가 발생할 경우에도 측위 정확도를 유지하거나 향상 시킬 수 있을 것으로 사료된다.

• 한국정밀공학회지
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• 제20권12호
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• pp.64-72
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• 2003

This paper presents a small loading and positioning device using VCM (voice coil motor). The developed device consists of a VCM-based linear actuating system, a capacitance displacement sensor and a cantilever deflection sensing system. The trust force of the VCM proportional to applied current moves the column supported on two pairs of parallel leaf springs. The infinitesimal displacement of moved column is detected by capacitance displacement sensor with a resolution of 0.1nm and a repeatability of 1nm. Also, a micro cantilever with known stiffness (200N/m), which is mounted on the end of the column, is used as a force sensor to detect the load applied to a specimen. After the cantilever contacts with the specimen, the deflection of cantilever and the load applied to the specimen are measured by using an optical lever system which consists of a diode laser, a mirror and a PSD (position sensitive detector). In this paper, an experimental system was constructed and its actuator and sensing parts were tested and calibrated. Also, the constructed system was applied to the indentation experiment and the load-displacement curve of aluminum was obtained. Experimental results showed that the developed device can be applied for performing nano indentation.

• Imaging Science in Dentistry
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• 제53권4호
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• pp.303-312
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• 2023

Purpose: This study investigated the prevalence of developmental and acquired pathologic conditions associated with impacted third molars (3Ms) in a Southern Brazilian population and evaluated whether demographic and tooth characteristics were correlated with the presence of bone or tooth lesions. Materials and Methods: Panoramic radiographs were assessed for developmental (bone-related) or acquired (tooth-related) pathoses associated with impacted upper or lower 3Ms. Data on tooth positioning, tooth development, and patient demographics were collected. A trained, calibrated postgraduate student evaluated all images. Binary and multivariate logistic regression models were used to assess associations between outcomes and the demographic and radiographic variables. The threshold for statistical significance was set at 5% (P<0.05). Results: The sample comprised panoramic radiographs from 2054 patients, predominantly female (59.2%), with a mean age of 27.2±11.5 years. Overall, 4066 impacted 3Ms were evaluated, revealing 471 (11.6%) developmental and 710 (17.5%) acquired pathoses. Among the developmental pathoses, 460 (95.2%) were indicative of dentigerous cysts. Male sex, lower 3M location, vertical or distoangular positioning, and incomplete root formation were associated with an elevated likelihood of developmental pathology. Lower tooth position, complete root formation, and partial eruption were linked to an increased probability of an acquired pathology in the third or second molar. Conclusion: The prevalence of pathologic conditions associated with impacted 3Ms was low. Male sex, lower 3M placement, horizontal or distoangular positioning, and incomplete root formation were associated with developmental pathoses, while lower tooth position, complete root formation, and partial eruption were related to acquired pathoses.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1832-1835
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• 1997

Off-line programming systems are widely spread in assembly lines of minute electronic products to huge offshore structures. Any OLP system has to be calibrated before the on-line robot tasks are performed because there are inherent differences between the CAD model on OLP and the real robot workspace. This paper uses simple geometric expressions to propose a calibration method applicable to an OLP for SCARA robots. A positioning task on the two-dimensional horizontal surface was used in the error analysis of a SCARA robot and the anaysis shows that the inaccuracy results from the two error sources non-zero offset angles of two rotational joints at the zero return and differences in link lengths. Pen marks on a sheet of plotting paper are used to determine the accurate data on the joint centers and link dimensions. The calculated offset angles and link lengths are fed back to the OLP for the calibration of the CAD model of the robot and task environments.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.632-635
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• 2002

In this paper, a general procedure to determine machine tool errors from the on-machine measurement (OMM) data is described. First, a parameterized error model of a machine tool is illustrated by approximating error components as linear function of axis positions, and a modified error model is proposed which includes backlash effects. To determine the unknown model coefficient vectors of the forward and backward error model, an artifact with 8 cutes is made and calibrated on CMM. Then, lower-left and upper-right cube corners are measured with a touch-trigger probe mounted on the machine tool spindle. Measured error data are used to determine the coefficient vectors. The positioning errors in the XY plane at the fixed z position are simulated for the forward and backward error model.

• 제어로봇시스템학회논문지
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• 제2권3호
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• pp.188-193
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• 1996

In this paper, an integrated navigation system based on GPS(Global Positioning System) and Dead-Reckoning (DR) is designed. For the calibration of DR, a self-calibration method and a GPS-based calibration method are proposed. From the field-test results, it is shown that DR can be successfully calibrated by the two proposed calibration methods. Also, a cascaded filter approach and a mixed-measurement algorithm are employed for GPS/DR integration. By using the newly proposed mixed-measurement algorithm, it is shown in simulation that the position error becomes smaller than by using only DR even if the number of visible GPS satellites is less than 4.

• 융합신호처리학회논문지
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• 제5권4호
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• pp.256-262
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• 2004

로봇이 자율주행을 하는데 있어 중요한 요소는 로봇 스스로 위치를 추정하고 동시에 주위 환경에 대한 지도를 작성하는 것이다. 본 논문에서는 어안렌즈를 이용한 비전 기반 위치 추정 및 매핑 알고리즘을 제안한다. 로봇에 어안렌즈가 부착된 카메라를 천정을 바라볼 수 있도록 부착하여 스케일 불변 특징을 갖는 고급의 영상 특징을 구하고, 이 특징들을 맵 빌딩과 위치 추정에 이용하였다. 전처리 과정으로 어안렌즈를 통해 입력된 영상을 카메라 보정을 행하여 축방향 왜곡을 제거하고 레이블링과 컨벡스헐을 이용하여 보정된 영상에서 천정영역과 벽영역으로 분할한다. 최초 맵 빌딩시에는 분할된 영역에 대해 특징점을 구하고 맵 데이터베이스에 저장한다. 맵 빌딩이 종료될 때까지 연속하여 입력되는 영상에 대해 특징점들을 구하고 맵과 매칭되는 점들을 찾고 매칭되지 않은 점들에 대해서는 기존의 맵에 추가하는 과정을 반복한다. 위치 추정은 맵 빌딩 과정과 맵 상에서 로봇의 위치를 찾는데 이용된다. 로봇의 위치에서 구해진 특징점들은 로봇의 실제 위치를 추정하기 위해 기존의 맵과 매칭을 행하고 동시에 기존의 맵 데이터베이스는 갱신된다. 제안한 방법을 적용하면 50㎡의 영역에 대한 맵 빌딩 소요 시간은 2분 이내, 위치 추정시 위치 정확도는 ±13cm, 로봇의 자세에 대한 각도 오차는 ±3도이다.