• Journal of Institute of Control, Robotics and Systems
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• v.18 no.8
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• pp.713-718
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• 2012

Lumber spine range of motion has been used to measure of physical and functional impairment by various tools from a ruler to 3D kinematic devices. However, pre-existing tools have problems in either movement or accuracy and reliability limitations. Accurate devices are limited by fixed space whereas simple devices are limited in measuring complex movements with less accuracy. In order to solve the location, movement and accuracy limitations at once, we have developed a novice measurement device equipped with accelerometer sensor and gyroscope sensor for getting three-dimensional information of motion. Furthermore, Kalman filter was applied to the algorithm to improve accuracy. In addition, RF wireless communication was added for the user to conveniently check measured data in real time. Finally, the measurement method was improved by considering the movement by a reference point. An experiment was conducted to test the accuracy and reliability of the device by conducting a test-retest reliability test. Further modification will be conducted to used the device in various joints range of motion in clinical settings in the future.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1299-1307
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• 2014

In this work, an appropriate analysis model of a precise foot sensor with low detection pressure capability under a low range of variation in the dimensional variables was proposed. With a simple two-dimensional model, it was found that a remarkably high error level sometimes occurred between the analysis and experimental results. In order to overcome the error and improve the performance, a three-dimensional model was introduced, and the detection pressure and sensor characteristics were compared with those of the experimental results, which showed its enhanced performance with less error and higher precision.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.123.1-123
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• 2001

For Autonomous navigation of the mobile robots, the robots' capability to recognize 3D environment is necessary. In this paper, an on-line 3D map building method for autonomous mobile robots is proposed. To get range data on the environment, we use an sensor system which is composed of a structured light and a CCD camera based on optimal triangulation. The structured laser is projected as a horizontal strip on the scene. The sensor system can rotate $\pm$ $30{\Circ}$ with a goniometer. Scanning the system, we get the laser strip image for the environments and update planes composing the environment by some image processing steps. From the laser strip on the captured image, we find a center point of each column, and make line segments through blobbing these center poings. Then, the planes of the environments are updated. These steps are done on-line in scanning phase. With the proposed method, we can efficiently get a 3D map about the structured environment.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.123.5-123
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• 2001

For autonomous navigation of the mobile robots, the robots' capability to recognize 3D environment is necessary. In this paper, an on-line 3D map building method for autonomous mobile robots is proposed. To get range data on the environment, we use a sensor system which is composed of a structured light and a CCD camera based on optimal triangulation. The structured laser is projected as a horizontal strip on the scene. The sensor system can rotate$\pm$30$^{\circ}$ with a goniometer. Scanning the system, we get the laser strip image for the environments and update planes composing the environment by some image processing steps. From the laser strip on the captured image, we find a center point of each column, and make line segments through blobbing these center points. Then, the planes of the environments are updated. These steps are done on-line in scanning phase. With the proposed method, we can efficiently get a 3D map about the structured environment.

• Electronics and Telecommunications Trends
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• v.29 no.1
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• pp.11-20
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• 2014

동작인식(gesture recognition) 기술은 입력 영상으로부터 영상에 포함된 사람들의 동작을 인식하는 기술로써 영상감시(visual surveillance), 사람-컴퓨터 상호작용(human-computer interaction), 지능로봇(intelligence robot) 등 다양한 적용분야를 가진다. 특히 최근에는 저비용의 거리 센서(range sensor) 및 효율적인 3차원 자세 추정(3D pose estimation)기술의 등장으로 동작인식은 기존의 어려움들을 극복하고 다양한 산업분야에 적용이 가능할 정도로 발전을 거듭하고 있다. 본고에서는 그러한 거리영상(range image) 기반의 동작인식 기술에 대한 최신 연구동향을 살펴본다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9C
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• pp.573-580
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• 2011

WSNs (Wireless Sensor Networks) are becoming more widely used in various fields, and improving localization performance is a crucial and essential issue for sensor network applications. In this paper, we propose a low-complexity localization mechanism for WSNs that operates in 3D (Three-Dimensional) space. The basic idea is to use aerial vehicles or flying objects that are deliberately equipped with the anchor nodes. These anchor nodes periodically broadcast beacon signals containing their current locations, and the unknown nodes receive these signals as soon as they enter the communication range of the anchors. We estimate the locations of the unknown nodes based on the proposed scheme that transforms the 3D problem into 2D computations to reduce the complexity of 3D localization. Simulated results show that our approach is an effective scheme for 3D self-positioning in WSNs.

• Journal of Sensor Science and Technology
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• v.19 no.4
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• pp.285-290
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• 2010

In this paper, a dynamic range(DR) extension technique based on a 3-transistor active pixel sensor(APS) and dual image sampling is proposed. The feature of the proposed APS is that the APS uses two or more photodiodes with different sensitivities, such as a high-sensitivity photodiode and a low-sensitivity photodiode. Compared with previously proposed wide DR(WDR) APS, the proposed approach has several advantages, such as no-external equipments or signal processing, no-additional time-requirement for additional charge accumulation, simple operation and adjustable DR extension by controlling parasitic capacitance and sensitivity of two photodiodes. Approximately 16 dB of DR extension was evaluated from the simulation for the situation of 10 times of sensitivity difference and the same size of parasitic capacitance between those two photodiodes.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.107-113
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• 1997

This paper presents the active control of a flexible cantilever beam vibration. The cantilever beam was excitied by a steady-state harmonic and white noise point force and the control was performed by one piezo ceramic actuator bonded to the surface of the beam. An adaptive controller based on filtered-x LMS algorithm was used and the controller was defined by minimizing the square of the response of error sensor. In the experiment, gap sensor was used as an error sensor while the sinusoidal or white noise was applied as a disturbance. In the case of sinusoidal input, more than 20 dB of vibration reduction was achieved over all range of the natural frequencies and it takes 5 seconds to control the vibration at first natural frequency and 1 second at other natural frequencies. In the case of white noise input, 7 dB of vibration reduction was achieved at the first natural frequency and good control performance was achieved in the considered whole frequency range. Results indicate that the vibration of a flexible cantilever beam could be controlled effectively when the piezo ceramic actuator was used with filtered-x LMS algorithm.

• Journal of Drive and Control
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• v.17 no.4
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• pp.97-102
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• 2020

This paper presents the basic research for the design and fabrication of a 3D-printed load cell made of NCPC (nano-carbon piezo-resistive composite). We designed a structure that can resonate at a low frequency range of about 5-6 Hz with ANSYS using sensitivity analysis and a response surface method. The design was verified by fabricating the device with a low-quality commercial 3D printer and ABS filament. We conducted a feasibility test for a commercial sensor using 1000 cyclic load tests at 0.3 Hz in a material testing system. A manufacturing process for the 3D printer filament based on the NCPC was also developed using the nano-composite process.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1450-1454
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• 2007

A Contact-type Linear Encoder-like Capacitive Displacement Sensor (CLECDiS) has been developed to measure displacements at high accuracy within a long measurement range. In this paper, we have worked on improving the performance and reliability of the sensor. The performance increase can be done by introducing the smaller electrode patterns of $4{\mu}m$ width. In order to improve the reliability of the sensor we have changed the electrode layers from chrome-gold to chrome-gold-chrome and re-design its supporting structure. The newly-designed sensor is fabricated and tested to show that its sensitivity is $35pF/{\mu}m$, which implies that its resolution may be 0.36nm if SNR (Signal-to-Noise-Ratio) is 80.1dB. It is about ten times of that $(3.14pF/{\mu}m)$ of its previous version with 10${\mu}m$ electrodes. The total measurement range remains the same as the previous one; 15mm. The calibration experiments show its improved performance and reliability.