• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1811-1812
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• 2008

This paper represents a absolute position tracking system with sensor fusion and PD-gain. this paper presents an accurate localization method by relative and absolute sensor fusion and PD control for position tracking of mobile robot. we developed a sensor based absolution position tracking and smooth moving algorithm using this algorithm.

• Current Optics and Photonics
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• 제5권4호
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• pp.362-369
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• 2021

Absolute position sensors are widely used in machine tools and precision measuring instruments because measurement errors are not accumulated, and position measurements can be performed without initialization. The laser speckle-based absolute position sensor, in particular, has advantages in terms of simple system configuration and high measurement accuracy. Unlike traditional absolute position sensors, it does not require an expensive physical length scale; instead, it uses a laser speckle image database to measure a moving surface position. However, there is a problem that a huge database is required to store information in all positions on the surface. Conversely, reducing the size of the database also decreases the accuracy of position measurements. Therefore, in this paper, we propose a new method to measure the surface position with high precision while reducing the size of the database. We use image stitching and approximation methods to reduce database size and speed up measurements. The absolute position error of the proposed method was about 0.27 ± 0.18 ㎛, and the average measurement time was 25 ms.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.156-160
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• 1997

This paper introdues the development of hydraulic cylinder with magnetic sensor detecting absolute and precise position for automation of excavator. The system which is developed can detect absolute position witha little displacement by using algorithm for recognizing datum points, 1/4 divider algorithm and high precision algorithm improved position precision and robustness to noise etc. The solenoid valve and PWM control using saw-toothed wave are used for absolute position control of cylinder, respectively

• 제어로봇시스템학회논문지
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• 제13권10호
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• pp.970-977
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• 2007

Absolute position detector which is one of the major equipment in the field of factory automation, not only perceives the absolute position of the rotary machine but also outputs switch data according to the given angle. Absolute position detector is composed of sensor module and its controller. In this paper, a sensor driver is implemented using FPGA with VHDL. This chip has a less form factor than conventional circuit. A test shows reliable precision within THD(total harmonic distortion) of 0.2% which can be applicable commercially. Also, FPGA-based phase error compensation methods were newly discussed. In the future, more research will be conducted to enhance the precision by the introduction of 3-phase transformer.

• 대한전자공학회논문지SD
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• 제41권2호
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• pp.27-32
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• 2004

Absolute optical angle 센서는 디지털 광학 장치의 핵심적인 부분이라고 말할 수 있으며, 이 장치의 목적은 Pseudorandom-code와 Geometry-code를 이 용하여 코드화된 원판(coded disk)의 상대적/절대적 변위 (Relative/Absolute angle position)를 해결하기 위함이다. 이 기술에서 디스크의 각 위치(Angular position)는 먼저 Pseudorandom-code에 의해 "Coarse" angle이 검출되어 결정되어지며, 그런 다음 Geometry-code의 Pixel 계산에 의해서 얻어지는 "Fine" angular position 데이터는, 7㎛의 Line image 센서를 사용 시, 시스템의 0.006°분해능 결과를 구할 수 있다. 제안된 기술은 비접촉 반사 특성, 시스템의 높은 분해능, 상대적으로 간단한 코트 패턴 그리고 센서의 고유한 디지털 성질을 갖는 등 많은 면에서 새로운 방식이다 더 나아가서 시스템은 두 개의 코드화된 원판에 적용하여 얻어진 절대 자의 변형(Absolute angular displacement)을 관찰하는 방식으로 쉽게 토크 센서로 변경할 수 있다. 제안된 센서의 디지털 광전 특성은 토크와 각을 동시에 측정함으로써 자동 차량 시스템에 사용 시 이상적인 시스템을 만든다. 본문에서는 코드화된 원판의 정확한 각 위치(Angular position)를 결정하기 위하여 Pseudo random-code와 Geometry-code를 활용한 기술을 제안하며, 아이디어의 실행 가능성을 구현하는 실험 결과를 제시하였다.

• 제어로봇시스템학회논문지
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• 제16권10호
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• pp.991-996
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• 2010

In this paper, a new indoor positioning system based on incident angle measurement of infrared sensor has been suggested. Though there have been various researches on indoor positioning systems using vision sensor or ultrasonic sensor, they have not only advantages, but also disadvantages. In a new positioning system, there are three infrared emitters on fixed known positions. An incident angle sensor measures the angle differences between each two emitters. Mathematical problems to determine the position with angle differences and position information of emitters has been solved. Simulations and experiments have been implemented to show the performance of this new positioning system. The results of simulation were good. Since there existed problems of noise and signal conditioning, the experimented has been implemented in limited area. But the results were acceptable. This new positioning method can be applied to any indoor systems that need absolute position information.

• 한국정밀공학회지
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• 제27권1호
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• pp.125-133
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• 2010

A versatile micro-robotic platform for micro/nano scale assembly has been demanded in a variety of application areas such as micro-biology and nanotechnology. In the near future, a flexible and compact platform could be effectively used in a scanning electron microscope chamber. We are developing a platform that consists of miniature mobile robots and a compact positioning stage with multi degree-of-freedom. This paper presents the design and the implementation of a low-cost and compact multi degree of freedom position sensor that is capable of measuring absolute translational and rotational displacement. The proposed sensor is implemented by using a CMOS type image sensor and a target with specific hole patterns. Experimental design based on statistics was applied to finding optimal design of the target. Efficient algorithms for image processing and absolute position decoding are discussed. Simple calibration to eliminate the influence of inaccuracy of the fabricated target on the measuring performance also presented. The developed sensor was characterized by using a laser interferometer. It can be concluded that the sensor system has submicron resolution and accuracy of ${\pm}4{\mu}m$ over full travel range. The proposed vision-based sensor is cost-effective and used as a compact feedback device for implementation of a micro robotic platform.

• 제어로봇시스템학회논문지
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• 제20권9호
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• pp.914-921
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• 2014

In this paper, an algorithm is suggested to detect an offset angle of the absolute rotor position sensor after the initial assembly of a PMSG. Unlike previous studies in a stationary state, this one is not designed to detect an electrical angle but rather the absolute position of the rotor is detected while operating the generator. Also,a position sensor, current sensors and voltage sensor were used to ensure reliability. This technique completes the detection of the sensor offset in two steps. In the first step, a zero-crossing of the EMF is measured using a voltage sensor to detect the electrical angle offset when the alternator is actuated by the engine. In the second step, a high frequency current is injected along the d-axis on-line during the control of the generation, eventually to obtain the inductance using a DFT (Discrete Fourier Transform), and then to ultimately extract the final electrical angle offset through the comparison of the inductance magnitude. The suggested algorithm was validated with PSIM simulation and, furthermore, was tested with actual experiments on a dynamometer.

• 한국정밀공학회지
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• 제20권4호
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• pp.68-75
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• 2003

This paper introduces the development of hydraulic cylinder with magnetic sensors detecting absolute and precise position for automation of excavator. The system which is developed can detect absolute position with a little displacement by using algorithm for recognizing datum points, 114 divider algorithm and high precision algorithm improved position precision. We alse evaluate the developed system under the load disturbance and add band pass filter to the previous's signal process circuit for the protecting magnetic sensors's saturation.

• 제어로봇시스템학회논문지
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• 제13권10호
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• pp.949-955
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• 2007

This paper proposes an efficient localization algorithm in the RFID sensor space for the precise localization of a mobile robot. The RFID sensor space consists of embedded sensors and a mobile robot. The embedded sensors, that is tags are holding the absolute position data and provide them to the robot which carries a reader and requests the absolute position fur localization. The reader, it is called as antenna usually, gets several tag data at the same time within its readable range. It takes time to read all the tags and to process the data to estimate the position, which is a major factor to deteriorate the localization accuracy. In this paper, an efficient algorithm to estimate the position and orientation of the mobile robot as quickly as possible has been proposed. Along with the algorithm, a new allocation of the tags in the RFID sensor space is also proposed to improve the localization accuracy. The proposed algorithms are demonstrated and verified through the real experiments.