• Title/Summary/Keyword: Cavity Dither

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A study on the dither-stripping with dither motion sensor of a ring laser gyroscope (링레이저 자이로의 몸체진동 검출센서를 이용한 dither-stripping 연구)

  • Sim, Gyu Min;Im, Hu Jang
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.5
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    • pp.63-71
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    • 2003
  • In this paper we dicuss the dither-stripping methods by V-F(voltage to frequency) conversion of the output of angular velocity sensor which is for detecting the dither motion of the ring laser cavity. In this case, it is very important to evaluate the pulse-to-pulse scale factor between the ring lase output pulse and V-F output pulse, and also to compensate the zero offset of the V-F output pulse. In the case of the dither-stripping by the V-F conversion of angular velocity sensor output, there is a big angle uncertainty in the process of compensating the zero offset due to the dither noise for compensating the V-F output. By differential, the phase of the V-F output is changed. So, to compensate it, we change 90deg of the phase of angular velocity sensor output and delay half sampling time of the phase of ring laser output in advance. In this case the pulse-to-pulse scale factor can be evaluated by the standard deviation of each pulse. We can get the good result of the dither-stripping output by this angle differential method.

Numerical Research on the Lock-in Compensation Method of a Ring Laser Gyroscope for Reducing INS Alignment Time (관성항법장치 초기정렬시간 단축을 위한 링레이저 자이로 lock-in오차 보상방법의 수치해석적인 분석)

  • Shim, Kyu-Min;Jang, Suk-Won;Paik, Bok-Soo;Chung, Tae-Ho;Moon, Hong-Key
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.3
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    • pp.275-282
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    • 2009
  • Generally, the sinusoidal cavity dither is adopted to ring laser gyroscope for eliminating the lock-in which is non-linear effect at the small rotation input. Despite this method, there are some remained errors which are generated at the dither turnaround, and those errors produce random walk which is a general character of a ring laser gyroscope. As one of the numerous research results for compensating these errors, there is a special lock-in compensation method which is the method of error estimation and compensation by comparing the beat signal periods of before and after the dither turnarounds. In this paper, by ring laser gyroscope modeling and numerical analysis, we verified the theoretical validity and confirmed the effectiveness of this method in expectation of the possible beat signal measurement time resolution. As a result, we confirmed the random walk decreases from a-half to a-third by this lock-in compensation method. So, it is expected to be a remarkable method for reducing the INS alignment time.