| Author Name | Affiliation | Postcode | | Shuai Chen* | School of Information and Control Engineering, Liaoning Shihua University, Fushun 113001 , China | 113001 | | Xinzhi Liu | Department of Applied Mathematics, University of Waterloo, Waterloo N2L3G1 , Canada | N2L3G1 | | Qian Sun | College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001 , China | 150001 | | Ya Zhang | School of Electrical Engineering & Automation, Harbin Institute of Technology, Harbin 150001 , China | 150001 |
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| Abstract: |
| Owing to the weak observability of the azimuth misalignment angle, alignment accuracy and time are always the contradictory issues in the initial alignment process of Strapdown Inertial Navigation System (SINS), which requires a compromise between them. In this paper, a combined alignment mechanism is proposed to construct an observable and controllable system model, which can effectively achieve higher azimuth alignment accuracy during the fixed time period. First, the Reduced Order Kalman Filter (ROKF) alignment algorithm was utilized to calculate the misalignment angles in parallel with the classical gyrocompass alignment algorithm. Then, the misalignment angles calculated by the gyrocompass alignment method were used to formulate the augmented measurement model with zero velocity models. Finally, the zero velocity model of the ROKF method was switched into the augmented measurement model when the azimuth misalignment angle of the gyrocompass alignment method was close to steady situation. The combined alignment method was analyzed reasonably by the observability and the mathematical deduction. The comparison results of the numerical simulation and the experimental data test showed that the combined method had good performance in terms of estimation accuracy and consistency of the alignment results. |
| Key words: inertial navigation instrumentation and measurement gyroscopes accelerometers Kalman filter measurement errors |
| DOI：10.11916/j.issn.1005-9113.2019019 |
| Clc Number:U666.12; V249.32+2; V324.2+3 |
| Fund: |
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| Descriptions in Chinese: |
| Owing to the weak observability of the azimuth misalignment angle, alignment accuracy and time are always the contradictory issues in the initial alignment process of Strapdown Inertial Navigation System (SINS), which requires a compromise between them. In this paper, a combined alignment mechanism is proposed to construct an observable and controllable system model, which can effectively achieve higher azimuth alignment accuracy during the fixed time period. First, the Reduced Order Kalman Filter (ROKF) alignment algorithm was utilized to calculate the misalignment angles in parallel with the classical gyrocompass alignment algorithm. Then, the misalignment angles calculated by the gyrocompass alignment method were used to formulate the augmented measurement model with zero velocity models. Finally, the zero velocity model of the ROKF method was switched into the augmented measurement model when the azimuth misalignment angle of the gyrocompass alignment method was close to steady situation. The combined alignment method was analyzed reasonably by the observability and the mathematical deduction. The comparison results of the numerical simulation and the experimental data test showed that the combined method had good performance in terms of estimation accuracy and consistency of the alignment results. |
