Fault detection method of laser inertial navigation system using dither motion of RLG

A Laser Inertial Navigation System (LINS) is composed of Ring Laser Gyroscopes (RLG) and accelerometers. An RLG has a lock-in region where there exists zero output for input angular rates less than 0.1 degree per second due to imperfections in the mirror. To avoid this, sinusoidal dither motion is applied to the RLG. Under normal LINS operation, the dither motion must be measured by the RLG/accelerometers. In this paper, we propose a method to detect the fault status of LINS by checking the dither motion from RLG/accelerometers utilizing real-time Fast Fourier Transform (FFT). The fault detection method proposed in this paper is verified through stationary and in-vehicle tests.