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Mathematical Problems in Engineering
Volume 2013, Article ID 856803, 11 pages
Research Article

Lock-In Amplifier Technology in Laser Gyroscope North Finder of Constant Rate Biasing

1School of Mechanical Engineering, Tianjin University, Tianjin 300072, China
2School of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China
3School of Automation, Beijing Institute of Technology, Beijing 100081, China

Received 21 January 2013; Accepted 11 March 2013

Academic Editor: Cristian Toma

Copyright © 2013 Bin Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper presents a new type of strapdown north finder. A simplified configuration is proposed, including three parts: a pendulous force-feedback accelerometer, a ring laser gyroscope, and a single-axis rotating platform. The dynamic northfinding scheme of continuous rotation is adopted to eliminate the lock-in region of the laser gyroscope and to modulate the weak attitude signals; meanwhile the complex leveling process is avoided in this proposed configuration. To suppress the drift noises of the accelerometer and gyroscope, two digital lock-in amplifiers are used to extract the weak attitude signals. Simulation results show that the north finder can determine the heading angle in 72 s, when the rotating rate is /s with the maximum heading error less than 1.0′; meanwhile the horizontal attitude angles as well as the constant drift noises of the inertial components could also be obtained.