• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.5
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• pp.55-61
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• 2004

Chatter monitoring is also important for realizing an unmanned machining system. while many researches were done on this area, it is still a difficult job to detect very small amplitude amount of chattering. A monitoring system using a capacitive spindle displacement sensor was developed to monitor cutting vibration in turning in this research. The variance of the measured spindle displacement signals using the developed sensor was calculated and utilized to quantify the small vibration in machining. The results were compared with variance obtained using a tool dynamometer. The result showed that the developed system could be utilized in monitoring the subtle changes of cutting vibrations with high sensitivity confidence.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.516-522
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• 2003

Monitoring chattering is also important for realizing an unmanned machining system While many researches were done on this area, it is still a difficult job to detect very small amplitude amount of chattering. A monitoring system using a capacitive spindle displacement sensor was developed to monitor cutting vibration in turning in this research. The variance of the measured spindle displacement signals using the developed sensor was calculated and utilized to quantity the small vibration in machining. The results were compared with variance obtained using a tool dynamometer. The result showed that the developed system could be utilized in monitoring the subtle changes of cutting vibrations with high sensitivity confidence.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.27-32
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• 2002

The intensity modulated type (reflective method) optical fiber sensor is a well -known method and widely applied to the displacement measurements and other industrial purposes. This type sensor has the advantages of relatively cheap cost, small sensor size and easiness of operation. The sensitivity of the sensor is very dependent of several error terms; the variation in the intensity of the light source and the changes in the surface reflectivity of the object. An optical fiber coupled displacement probe with a new compensation method is presented in this paper. The proposed displacement sensor can measure the displacements of the target surface independent of surface reflectivity error that is caused by the materials and surface processing grade.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1250-1251
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• 2022

Measuring management is an important part of preventing the collapse of retaining walls in advance by evaluating their stability with a variety of measuring instruments. The current work of measuring management requires considerable human and material resources since measurement companies need to install measuring instruments at various places on the retaining wall and visit the construction site to collect measurement data and evaluate the stability of the retaining wall. It was investigated that the applicability of the current work of measuring management is poor at small and medium-sized urban construction sites(excavation depth<10m) where measuring management is not essential. Therefore, the purpose of this study is to develop a laser sensor-based hardware to support the wall displacement measurements and their control software applicable to small and medium-sized urban construction sites. The 2D lidar sensor, which is more economical than a 3D laser scanner, is applied as element technology. Additionally, the hardware is mounted on the corner strut of the retaining wall, and it collects point cloud data of the retaining wall by rotating the 2D lidar sensor 360° through a servo motor. Point cloud data collected from the hardware can be transmitted through Wi-Fi to a displacement analysis device (notebook). The hardware control software is designed to control the 2D lidar sensor and servo motor in the displacement analysis device by remote access. The process of analyzing the displacement of a retaining wall using the developed hardware and software is as follows: the construction site manager uses the displacement analysis device to 1)collect the initial point cloud data, and after a certain period 2)comparative point cloud data is collected, and 3)the distance between the initial point and comparison point cloud data is calculated in order. As a result of performing an indoor experiment, the analyses show that a displacement of approximately 15 mm can be identified. In the future, the integrated system of the hardware designed here, and the displacement analysis software to be developed can be applied to small and medium-sized urban construction sites through several field experiments. Therefore, effective management of the displacement of the retaining wall is possible in comparison with the current measuring management work in terms of ease of installation, dismantlement, displacement measurement, and economic feasibility.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.257-258
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• 2006

This paper presents the displacement sensor based on astigmatic method that has a small measurement range. The sensor has the characteristic that the measuring range is changed easily by exchanging a objective lens or distance between a objective lens and a collimator lens. The measuring range and resolution is evaluated by a laser interferometer.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.12
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• pp.1267-1271
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• 2014

There have been many autonomous robot calibration methods which form closed loop structures through the various attached sensors and mechanical fixtures. Single point calibration among them has been used for on-site calibration due to its convenience of implementation. The robot can reach a single point with infinitely many configurations so that single point calibration algorithm can be set up and easily implemented relative to the other methods. However, it is not still easy to drive the robots' sharp edge to its corresponding edge of the fixture. This is error-prone process. In this paper, we propose a 3 dimensional small displacement measuring sensor and a robot calibration algorithm based on this sensor. This method relieves the difficulty of matching two edges in the single point calibration and improves the resulting robot accuracy. Simulated study is carried out on a Hyundai HA06 robot to show the effectiveness of the proposed method over the single point calibration. And also, the resulting robot accuracy is compared with that from 3D laser tracker based calibration to show the dependency of robot accuracy on range of the workspace where the measurement data are collected.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1959-1965
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• 2011

Measuring the movement of joint angle of human body is very important clinically. Human joint angle displacement can be used to evaluate the degree of disease and disability. Also, we can determine the rehabilitation process with angular information. Conventional methods for measuring angular displacement are many weakness. The purpose of this study is to overcome the limitations of existing equipments by using optical method. For this reason, optical sensor system was used to correlate detected light signal with joint angle. Experimental results of the applied joint model in this study showed that joint angular displacement can be measured by optical signals. The suggested method is simple, durable, small, lightweight, convenient, and cost effective.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.8 s.173
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• pp.42-49
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• 2005

Our purpose is to develop a precision magnetic displacement sensor that has sub-micron resolution and small size probe. To achieve this, we first have tried to establish mathematical models of a magnetic sensor in this paper. The inductance model that presents basic measuring principle of a magnetic sensor is based on equivalent magnetic circuit method. Especially we have concentrated on modeling of magnetic flux leakage and magnetic flux fringing. The induced model is verified by experimental results. The model, including the magnetic flux leakage and flux fringing effects, is in good agreement with the experimental data. Subsequently, based on the augmented model, we will design magnetic sensor probe in order to obtain high performances and to scale down the probe.

• Korean Journal of Construction Engineering and Management
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• v.23 no.1
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• pp.64-72
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• 2022

The retaining wall structure is essential for construction work that performs underground excavation. Displacement management of the retaining wall structure is important regardless of the size of the construction. However, in the case of small-scale construction sites with an excavation depth of less than 10m, displacement management of retaining wall structure not properly performed due to problems such as 1) companies' smallness, 2) lack of capacity of construction managers, 3) complexity of installation, dismantling and displacement of measuring instruments. As a result of analyzing previous research, it was analyzed that it is difficult to apply this to a small - scale construction site because most of the previous research has problems in using an expensive 3D scanner or installing many measuring instruments. This study aims to propose a conceptual design of a displacement measurement system for retaining wall structure based on laser sensor and to verify the displacement recognition performance of core technology applied to the conceptual design. A conceptual design was proposed using a 2D laser scanner. As a result of verifying the displacement recognition of the 2D laser scanner, a displacement of 15mm was analyzed to be sufficiently understandable. In the future, if the proposed conceptual design is developed and applied to the small-scale construction site, it is thought that it will contribute to the reduction of safety accidents at small-scale construction sites.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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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.