International Journal of Aeronautical and Space Sciences

The Korean Society for Aeronautical and Space Sciences (한국항공우주학회)
권호 표지
DOI QR코드

DOI QR Code

A Multistage In-flight Alignment with No Initial Attitude References for Strapdown Inertial Navigation Systems

  • Hong, WoonSeon (Department of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Park, Chan Gook (Department of Mechanical and Aerospace Engineering/ Automation and System Research Institute, Seoul National University)
  • Received : 2016.09.28
  • Accepted : 2017.09.04
  • Published : 2017.09.30
Download PDF
⟨ Previous Next ⟩

Abstract

This paper presents a multistage in-flight alignment (MIFA) method for a strapdown inertial navigation system (SDINS) suitable for moving vehicles with no initial attitude references. A SDINS mounted on a moving vehicle frequently loses attitude information for many reasons, and it makes solving navigation equations impossible because the true motion is coupled with an undefined vehicle attitude. To determine the attitude in such a situation, MIFA consists of three stages: a coarse horizontal attitude, coarse heading, and fine attitude with adaptive Kalman navigation filter (AKNF) in order. In the coarse horizontal alignment, the pitch and roll are coarsely estimated from the second order damping loop with an input of acceleration differences between the SDINS and GPS. To enhance estimation accuracy, the acceleration is smoothed by a scalar filter to reflect the true dynamics of a vehicle, and the effects of the scalar filter gains are analyzed. Then the coarse heading is determined from the GPS tracking angle and yaw increment of the SDINS. The attitude from these two stages is fed back to the initial values of the AKNF. To reduce the estimated bias errors of inertial sensors, special emphasis is given to the timing synchronization effects for the measurement of AKNF. With various real flight tests using an UH60 helicopter, it is proved that MIFA provides a dramatic position error improvement compared to the conventional gyro compass alignment.

Keywords

References

  1. Drora, G. M. and Bar-Itzhack, I. Y., "Observability Analysis of Piece-Wise Constant Systems Part I: Theory", IEEE Transaction on Aerospace and Electronic Systems, Vol. 28, No. 4, 1992, pp. 1056-1067. https://doi.org/10.1109/7.165367
  2. Drora, G. M. and Bar-Itzhack, I. Y., "Observability Analysis of Piece-Wise Constant Systems Part II: Application to Inertial Navigation In-Flight Alignment", IEEE Transaction on Aerospace and Electronic Systems, Vol. 28, No. 4, 1992, pp. 1068-1075. https://doi.org/10.1109/7.165368
  3. Salychev, O. S., Applied Inertial Navigation: Problems and Solution, Moscow: BMSTU Press, 2004.
  4. Siouris, G. M., Aerospace Avionics System: A Modern Synthesis, New York: Academic Press, 1993.
  5. Maybeck, P. S., Stochastic Models, Estimation, and Control, New York: Academic Press, Vol. 2, 1979.
  6. Johnson, C, Ohlmeyer, E. J. and Pepitone, T. R. "Attitude Dilution of Precision-A New Metric for Observability on In- Flight Alignment Errors"‚ AIAA Guidance, Navigation, and Control Conference and Exhibit, 2000, AIAA-2000-4277.
  7. Hong, H. S., Lee, J. G. and Park, C. G., "Performance Improvement of In-Flight Alignment for Autonomous Vehicle Under Large Initial Heading Error", IEE proceedings Radar, Sonar and Navigation, Vol. 151, 2004, pp. 57-62.
  8. Jiancheng, F. and Sheng, Y.‚ "Study on Innovation Adaptive EKF for In-Flight Alignment of Airborne POS", IEEE Transaction on Instrumentation and Measurement, Vol. 60, No. 4, 2011, pp. 1378-1388. https://doi.org/10.1109/TIM.2010.2084710
  9. Lee, H. G., Lee, J. G. and Jee, G. I., "Effects of GPS Measurement Delay on SDINS", IEEE 2000 Position Location and Navigation Symposium, 2000, pp. 464-471.