Journal of IKEEE (전기전자학회논문지)

Institute of Korean Electrical and Electronics Engineers (한국전기전자학회)
권호 표지
DOI QR코드

DOI QR Code

An Implementation of High-precision Three-phase Linear Absolute Position Sensor

고정도 3상 직선형 절대 위치 센서의 구현

  • Received : 2015.07.14
  • Accepted : 2015.08.27
  • Published : 2015.09.30
Download PDF
⟨ Previous Next ⟩

Abstract

Recently a demand for high precision absolute position transducer is increasing in order to control thickness in steel industry. LVDT (linear variable differential transformer) is widely used to measure the absolute position in the linearly moving cylinder under poor factory environment. In this paper we implement the three phase LVDT with a high resolution of one micron and L/D (LVDT to digital) converter. First we designed U, V, and W three phase signaling using FPGA. Second a pulse output algorithm is designed for position information with A and B phase waveforms. Finally the performance is compared with previous sensors. Experiments show that the linearity deviation error is 0.009788 [mm] and the average sinusoidal THD is 0.0751%, which means 2.2% and 33% more improved result than the previous sensors respectively.

최근 들어 철강의 두께 제어를 위해 고정밀도의 절대 위치 검출 센서에 대한 필요성은 증가하고 있다. 열악한 공장 환경 하에서 직선 운동하는 실린더의 절대 위치를 측정하기 위해서는 LVDT가 널리 사용된다. 본 논문에서는 1 미크론의 고해상도를 가지는 3상 LVDT 및 L/D (LVDT to digital) 변환기를 구현하였다. 이를 위하여 첫째 U, V, W 3상 정현파에 대한 시그널링을 FPGA로 설계하였다. 둘째 위치 정보에 대한 A상, B상 펄스 파형 출력 알고리즘을 구현하였다. 마지막으로 성능 평가를 위하여 기존의 센서들과 비교하였다. 실험 결과 직선성 편이 오차는 0.009788 [mm] 로써 2.2% 향상된 결과를 얻었고 정현파의 왜곡률은 평균 0.0751%로 기존보다 33%의 향상된 결과를 얻어 우수한 센서임을 입증하였다.

Keywords

References

  1. E. E. Herceg, Handbook of Measurement and Control-An Authoritative Treatise on the Theory and Application of the LVDT, Schaevitz, 1976.
  2. F. Yassa and S. Garvericks, "Multichannel digital demodulator for LVDT/RVDT position sensors," IEEE J. Solid-State Circuits, vol. 25, pp. 441-445, Apr. 1990. https://doi.org/10.1109/4.52168
  3. Y. T. Park, S. W. Kwon, J. H. Gang, "Study on Improvement of a LVDT for Displacement Measurements" Journal of Sensor Science and Technology, vol. 5, no. 3, pp. 1-8, May 1996.
  4. D. Crescini, A. Flammini, D. Marioli, and A. Taroni, "Application of an FFT-Based Algorithm to Signal Processing of LVDT Position Sensors" IEEE Transactions on Instrumentation and Measurement, Vol. 47, pp. 1119-1123, 1998. https://doi.org/10.1109/19.746567
  5. TMS320F240 DSP Solution for Obtaining Resolver Angular Position and Speed, Texas Instruments Corp, 2000.
  6. Encoder Technology Corp, A Discussion of Encoder Technology's Converter and Impedance Detector Technology, 2000.
  7. D. S. Nyce, Linear Position Sensors - Theory and Application, Wiley, 2004.
  8. DongYun Shin, Yungi Yang, Chang-Su Lee, "RVDT Phase Error Compensation for Absolute Displacement Measurement" Journal of Control, Automation and Systems Engineering, Vol. 12, No. 7, pp. 658-665, Jul. 2006. https://doi.org/10.5302/J.ICROS.2006.12.7.658
  9. Dong-Yoon Shin, Chang-Su Lee, "A Study on Error Analysis of the Rotational Absolute Position Detector", Control, Automation, and Systems Symposium CASS-2006, pp. 338-343, KINTEX Jun. 1-3, 2006.
  10. Ji-hye Jeon, Dong-Yoon Shin, Yoon-Gi Yang, Jin-Kwon Hwang, Chang-Su Lee, "A FPGA Implementation of Resolver-based Absolute Position Detector", International Conference on Control, Automation and Systems 2007, COEX, Seoul, Korea, pp. 2375-2378, Oct. 17-20, 2007.
  11. LEVEX, Products Guide, Jun. 2009.
  12. NSD, CYLNUC Cylinder Selection Guide for Iron and Steel Industry Applications, 2000.
  13. NSD, ABSCODER Specifications Guide for Iron and Steel Industry Applications, 2001.
  14. R. Pallas-Areny and J. G. Webster, Sensors and Signal Conditioning. New York: Wiley, 1991.
  15. F. S. Tse, I. E. Morse, Measurement and Instrumentation in Engineering, Dekker, 1989.