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

摘要

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 107s 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.