Characteristic Analysis of Noise in a Resonator Optic Gyroscope (ROG) Using a Feedback Loop
D. Ying, Q. Li, Y. Ren, H. Ma, Z. Jin and W. Wu
We set up a broadened resonator optic gyroscope (ROG) feedback loop model with the noise sources including a standard data acquisition (DAQ) board induced electric circuit noise, photo-detector (PD) noise and laser frequency noise, to predict, explain, and further optimize the system performance. Based on this model and combining with experimental tests, the characteristics of these three noises in ROG is analysed and optimized, and how the noises transfer in feedback state is discussed. The system with feedback loop shows strong rejection to electric circuit noise and laser frequency noise in the system output bandwidth, but nearly no effect on the power of PD noise. For the whole noise power spectrum, larger loop delay and system output bandwidth induces more power for all the three noise sources, and larger loop gain induces less power for both electric circuit and laser frequency noises but more power for PD noise. The sum of the three noises equivalent rotation is predicted and optimized by choosing different loop gain, loop delay and output bandwidth, and it is concluded that for a resonator micro-optic gyroscope (RMOG) with a 7.9 cm perimeter resonator, if the system loop delay decreases to 1 μs and gain increases to 1.6 × 107, the noise equivalent rotation caused by laser frequency noise and PD noise will be down to 2.66°/h with 10.00 Hz output bandwidth.
Keywords: Resonator optic gyroscope (ROG), feedback loop, electric circuit noise, photo-detector