Journal of Aerospace System Engineering (항공우주시스템공학회지)

The Society for Aerospace System Engineering (항공우주시스템공학회)
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Improvement of Transfer Alignment Performance for Airborne EOTS

항공용 전자광학추적장비의 전달정렬 성능 개선

  • Received : 2022.05.12
  • Accepted : 2022.06.26
  • Published : 2022.08.31
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Abstract

An Electro-Optical Tracking System (EOTS) is an electric optical system with EO/IR cameras, laser sensors, and an IMU. The EOTS calculates coordinates of targets, using attitude and acceleration measured by the IMU. In particular for an armed aircraft, the performance of the weapon system depends on how quickly and accurately it acquires the target coordinates. The IMU should be operated after alignment is complete, to meet the coordinate accuracy required by the weapon system so the initial stabilization time of the IMU should be reduced, by quickly measuring the attitude and acceleration. Alignment is the process of determining the initial attitude by resolving the attitude error of the IMU, and the IMU of mission equipment such as an airborne EOTS, uses velocity matching based on the velocity from GPS/INS for aircraft navigation. In this paper, a method is presented to improve the transfer alignment performance of the airborne EOTS, by maneuvering aircraft and the mission equipment. First, the performance factor of the alignment was identified, as a heading error through the velocity matching model and simulation results. Then acceleration maneuvers and attitude changes were necessary, to correct the error. As a result of flight tests applied to an EOTS on a OOO aircraft system, the transfer alignment performance was improved as the duration time was decreased, by more than five times when the aircraft accelerated by more than 0.2g and the EOTS was moving until 6.7deg/s.

일반적인 항공기의 전자광학추적장비(Electro-Optical Tracking System, EOTS)는 EO/IR, 레이저 센서 등의 구성품으로 구성된다. 표적 획득 시 요구되는 표적 좌표는 내부 구성품인 관성측정장비(Inertial Measurement Unit, IMU)에서 측정되는 자세와 가속도 측정값을 이용하여 획득된다. 특히 무장시스템을 운용하는 항공기의 경우, 무장 발사를 위한 표적 좌표를 얼마나 신속하고 정확하게 획득하는가에 따라 무장시스템의 성능이 좌우된다. 무장시스템에서 요구하는 좌표 정확도를 충족하기 위해서는 IMU가 정렬 완료 상태에서 운용되어야 하므로 신속하게 자세와 가속도를 측정하여 IMU 초기 안정화 시간을 단축하여야 한다. IMU의 정렬은 IMU의 자세 오차를 해소하여 초기 자세를 결정하는 과정이며, 항공용 EOTS와 같은 임무장비의 IMU는 항법용 GPS/INS의 속도 정보를 기준으로 하는 속도정합 전달정렬을 수행한다. 본 논문에서는 이러한 속도정합 전달정렬 시간 단축을 위해 항공기와 임무장비의 자세 변화를 통한 전달정렬 성능 개선방안을 제시하였다. 먼저 전달정렬 모델과 시뮬레이션 결과를 통해서 EOTS의 전달정렬이 지연되는 요소가 방위각 오차임을 식별하였다. 그리고 EOTS의 방위각 오차 해소를 위해 항공기의 가속도 기동 및 EOTS의 자세 변화가 요구됨을 확인하였다. 최종적으로 OOO 항공기 체계에 적용한 비행시험 결과, 항공기 가속도 약 0.2g 이상이 발생하면서 EOTS가 6.7deg/s 각속도로 고각 운동 시 그렇지 않을 때보다 5배 이상 빠르게 정렬이 완료되어 전달정렬 성능이 개선되었다.

Keywords

References

  1. J. E. Kain and J. R. Cloutier, "RAPID TRANSFER ALIGNMENT FOR TACTICAL WEAPON APPLICATION", Proc. of Guidance, Navigation and Control Conference, pp.1290-1300, 1989
  2. C. Yang, K. Park, H. Kim and D. Shim, "Transfer Alignment Using Velocity Matching/Parameter Tuning and Its Performance and Observability Analysis " , Journal of Advanced Navigation Technology, Vol.19, No. 5, pp.389-394, 2015 https://doi.org/10.12673/JANT.2015.19.5.389
  3. Y. Lim, K. Ma, M. Kim, and J. Lee, " A Transfer Alignment Algorithm Study for an Aircraft", Proc. of the 2010 KSAS Fall Conference, pp. 726-729, 2010
  4. C. Kin, I. Lee, J. Oh, H. Yu and H. Park, "A Study on Specification and Design of In-Flight Transfer Alignment", Proc. of the Korea Institute of Military Science and Technology Conference, pp. 159-160, 2019.
  5. K.Song, C.Bae, and J. Lyou, "A Transfer Alignment Algorithm Using Velocity and Quaternion Partial Matching Methods", Journal of Control, Automation and Systems Engineering, Vol. 3, No.3, pp. 238-243, 1997
  6. Z. Shiler and S. Dubowski, "Time optimal paths and acceleration lines of robotic manipulators", Proc. of the 26th Conf. Decision and Control, pp. 98-99, 1987.
  7. J. Farrell, M. Barth, The Global Positioning System and Inertial Navigation, McGraw-hill, New York, 1998
  8. D. Titterton and J. Weston, Strapdown Inertial Navigation System, 2nd Ed., IET, London, 2004
  9. W. Chen, Z. Yang, S. Gu, Y. Wang, and Y. Tang, "Adaptive transfer alignment method based on the observability analysis for airborne pod strapdown inertial navigation system", Scientific Reports, Vol. 12, No. 1, pp. 1-14, 2022 https://doi.org/10.1038/s41598-021-99269-x
  10. J. Son, W. Choi, S. Kim, S. Oh, S.Lee and D. Hwang, "Measurement Time-Delay Compensation and Initial Attitude Determination of Electro-Optical Tracking System Using Augmented Kalman Filter", Journal of Korea Multimedia Society, Vol. 24, No. 12, pp. 1589-1597, 2021 https://doi.org/10.9717/KMMS.2021.24.12.1589
  11. P. Groves, "Navigation Using Inertial Sensors", IEEE Aerospace and Electronic Systems Magazine, Vol. 30, No. 2, pp. 42-69, 2014 https://doi.org/10.1109/MAES.2014.130191