• Title, Summary, Keyword: Absolute encoder

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Detection of Absolute Position of Robot Joint Using Incremental Encoders (증분형 엔코더를 이용한 로봇 관절의 절대위치 검출)

  • Lim, Jae Sik;Lee, Young Jin
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.6
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    • pp.577-582
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    • 2015
  • This paper proposes an efficient detection of absolute position of a robot joint using two incremental encoders. We considers a robot joint comprising a motor, a reducer, two encoders, and a motor drive. An incremental(first) encoder provides motor's rotor position or input position of reducer while another incremental(second) encoder does output position of the reducer. A table is made where the relationship between the first and the second encoder counts is recorded. The key point is placed where the table is constructed: when a pulse occurs in the second encoder, there exists a corresponding unique count value of the first encoder. The absolute position is detected using the table by searching the second encoder position corresponding to the first encoder count value when a pulse occurs in the second encoder. The proposed method needs a small rotation, as just one second encoder's pulse angle, for the initial absolute position detection.

Signal Processing Algorithm for High Precision Encoder (초정밀 엔코더를 위한 신호처리기법개발)

  • 정규원
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.9 no.3
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    • pp.103-110
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    • 2000
  • Shaft encoder which encodes the rotational angle of a shaft becomes more important recently due to factory automation and office automation. Although an absolute type encoder is more dsirable due to its convenience an incremental encoder is commonly used because of its cost and technical difficulties Fabricating a high resolution absolute encoder is very diff-cult because the physical size is limited by currently available technology. In order to overcome this difficulty Moire fringe can be used incorporated with gray code. In order to measure the position of fringes which move as the code disk rotates a neural network was developed in this paper. Formerly fringe position is usually measured by a sophisticated software which needs a little long calculation time. However using nerual network method can eliminate such calculation time even though it needs learning job The pro-posed method is verified through several experiments.

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Design and Development of a Novel High Resolution Absolute Rotary Encoder System Based on Affine n-digit N-ary Gray Code

  • Paul, Sarbajit;Chang, Junghwan
    • Journal of Electrical Engineering and Technology
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    • v.13 no.2
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    • pp.943-952
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    • 2018
  • This paper presents a new type of absolute rotary encoder system based on the affine n-digit N-ary gray code. A brief comparison of the existing encoder systems is carried out in terms of resolution, encoding and decoding principles and number of sensor heads needed. Using the proposed method, two different types of encoder disks are designed, namely, color-coded disk and grayscale coded disk. The designed coded disk pattern is used to manufacture 3 digit 3 ary and 2 digit 5 ary grayscale coded disks respectively. The manufactured disk is used with the light emitter and photodetector assembly to design the entire encode system. Experimental analysis is done on the designed prototype with LabVIEW platform for data acquisition. A comparison of the designed system is done with the traditional binary gray code encoder system in terms of resolution, disk diameter, number of tracks and data acquisition system. The resolution of the manufactured system is 3 times higher than the conventional system. Also, for a 5 digit 5 ary coded encoder system, a resolution approximately 100 times better than the conventional binary system can be achieved. In general, the proposed encoder system gives $(N/2)^n$ times better resolution compared with the traditional gray coded disk. The miniaturization in diameter of the coded disk can be achieved compared to the conventional binary systems.

Signal Processing Algorithm for High Precision Encoder (초정밀 엔코더를 위한 신호처리기법 개발)

  • 정규원
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.320-325
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    • 1999
  • An absolute type shaft encoder which utilized moire fringe will be presented in this paper. Linear moire fringe is commonly used to measure the displacement of the linear motion. However, an absolute encoder which measure the rotation angle of a shaft is operated usually with a code disk which the gray code pattern is printed on. Such encoder has inherently resolution limit because of the patterning mechanism and sensing mechanism. In order to measure the position of fringes which move as the code disk rotates, neural network was developed in this paper. Formerly fringe position is usually measured by a sophisticated software, which needs a little long calculation time. However, using neural network method can eliminate such calculation time, even though it needs learning job. The proposed method is verified through several experiments.

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Detection of Absolute Position for Magneto-Optical Encoder Using Linear Table Compensation (선형 테이블 보상법을 이용한 마그네틱-옵티컬 엔코더의 절대 위치 검출에 관한 연구)

  • Kim, Seul Ki;Kim, Hyeong Jun;Lee, Suk;Park, Sung Hyun;Lee, Kyung Chang
    • Journal of the Korean Society for Precision Engineering
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    • v.33 no.12
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    • pp.1007-1013
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    • 2016
  • This paper presents the development of a magneto-optical encoder for higher precision and smaller size. In general, optical encoders can have very high precision based on the position information of the slate, while their sizes tend to be larger due to the presence of complex and large components, such as an optical module. In contrast, magnetic encoders have exactly the opposite characteristics, i.e., small size and low precision. In order to achieve encoder features encompassing the advantages of both optical and magnetic encoders, i.e., high precision and small size, we designed a magneto-optical encoder and developed a method to detect absolute position, by compensating for the error of the hall sensor using the linear table compensation method. The performance of the magneto-optical encoder was evaluated through an experimental testbed.

Driving Characteristics of Encoder for High Performance Excitation Control of SRM (SRM의 고정도 여자 제어를 위한 엔코더의 운전특성)

  • Kang Yu-Jung;Ahn Jin-Woo;Park Sung-Jun;Kim Cheul-U
    • Proceedings of the KIPE Conference
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    • pp.1-4
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    • 2001
  • SRM(Switched Reluctance Motor) uses reluctance torque by pulse excitation control. SRM drives are much studied in electrical vehicles and industrial application due to the simple, robust mechanical structure and high speed characteristics. For the high performance control of SRM, it is necessary to synchronize the stator phase excitation with the rotor position. This paper proposes a new encoder for high performance excitation control of SRM. The proposed encoder has complex structures of incremental and absolute encoder. An each phase inductance profile can be synchronized with 4-bit absolute position signal and incremental pulses are used for speed detection. Low cost and simple manufacturing of SRM encoder is possible.

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Analysis of the Encoder Composite Signal for a Absolute Position Detection of the Synchronous Motor (동기 전동기의 절대 위치 검출을 위한 엔코더 복합 신호의 분석)

  • Joo, Jae-Hun;Kim, Dong-Hyun;Choi, Jung-Keyng
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.5
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    • pp.1018-1024
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    • 2011
  • For the driving of the sinusoidal type permanent magnet synchronous motor with a maximum continuous torque, the 1200 delayed three phase sinusoidal current inputs which matched with the absolute rotor position are needed at the stator coil. Therefore, the detection of a absolute rotor position is required inevitably. And the right angle relationship between stator magnetic field and rotor magnetic field has to be preserved at a stator by this commutation action. The detection of a absolute position for the commutation can be made generally by the output signal analysis of the encoder attached at a motor shaft. The purposes of this study are to design signal processing logic circuits which could detect the absolute position of motor with a modern encoder system and generate the three reference wave for making sinusoidal current input at a stator coil.

Estimate of walking state of the knee disarticulation prosthesis using position control algorithm of absolute encoder (절대위치 엔코더의 위치제어 알고리즘을 이용한 의지 장치의 보행 상태 추론)

  • Song, H.J.;Park, J.Y.;Shim, J.H.
    • Journal of rehabilitation welfare engineering & assistive technology
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    • v.7 no.2
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    • pp.1-5
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    • 2013
  • In this paper, we proposed how to estimate the walking state in the knee disarticulation prosthesis's knee angle control. In control of the knee disarticulation prosthesis, we can estimate walking state that measurement of knee angle using absolute encoder and measurement of load on the soles using strain gage. We suggested a method of estimating the current walking states which can be divided into four cases and showed the effectiveness of the method via a series of experiments.

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A Design and Construction of Speed Encoder for High Performance Driving of SRM (SRM 고정도 구동을 위한 위치 및 속도엔코더의 설계 및 제작)

  • Kang, Yu-Jung;Oh, Seok-Kyu;Park, Sung-Jun;Ahn, Jin-Woo
    • Proceedings of the KIEE Conference
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    • pp.1191-1193
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    • 2001
  • In switched reluctance motor(SRM) drive, it is necessary to synchronize the stator phase excitation with the rotor position. Therefore, the rotor position information is essential. Usually, optical encoders or resolvers are used to provide the rotor position information. These sensors are expensive and are not suitable for high speed operation. This paper proposes a new encoder for high performance excitation control of SRM. The proposed encoder has complex structures of incremental and absolute encoder. An each phase inductance profile can be synchronized with 4-bit absolute position signal and incremental pulses are used for speed detection. Low cost and simple structure are possible.

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