In digital closed-loop interferometric fiber optic gyroscopes (IFOGs), electrical cross-coupling errors significantly affect measurement accuracy, especially at low angular velocities. This limitation restricts application of IFOGs in high-precision environments. Addressing these errors is crucial for enhancing the gyroscope’s performance and reliability. This study aims to explore the mechanisms of electrical cross-coupling errors and develop effective techniques to suppress these errors, thereby improving the overall accuracy and reliability of IFOGs.

We begin with a comprehensive analysis of the generation mechanisms of electrical cross-coupling errors in IFOGs. Classical four-state modulation is used as a case study to examine the influence of these errors during different phases of modulation. The four-state modulation method obtains angular velocity information by demodulating four discrete states. However, the reset operations during various modulation phases affect the output differently, leading to dead zone effects at low angular velocities. We propose two methods to address this issue. 1) Analog adding feedback method. This method minimizes reset operations by resetting only the feedback phase during modulation. This reduction in reset operations maintains the modulation consistently in the same phase, thus suppressing the dead zone. Nonetheless, due to the inherent influence of electrical cross-coupling, this method introduces an additional bias that must be accounted for in the overall system accuracy. 2) Ratio four-state demodulation method. By adjusting the demodulation ratio of the feedback signal, this method mitigates correlation between modulation and demodulation sequences, enhancing measurement accuracy. This technique, combined with the analog adding feedback method, not only addresses the dead zone issue but also helps in reducing the additional biases introduced by electrical cross-coupling. We conduct detailed experiments in a digital closed-loop IFOG system specifically designed to monitor electrical cross-coupling errors under controlled conditions, analyzing the system’s response to low angular velocities and quantifying the dead zone effects caused by these errors.

The results present a detailed analysis of the influence of electrical cross-coupling errors on IFOG performance. These errors cause significant deviations in the gyroscope’s output, particularly at low angular velocities, leading to the dead zone effect where the output remains zero despite of changes in input angular velocity (Fig. 7). The anglar velocity of experimentally tested dead zone is 0.2 (°)/h, demonstrating the critical need for effective error suppression methods. The analog adding feedback method significantly reduces the number of reset operations, resulting in a substantial decrease in the dead zone. Experimental data (Fig. 8) show that this method reduces the dead zone to below the measurement threshold of 0.022 (°)/h, thereby improving the gyroscope’s performance. Nonetheless, due to electrical cross-coupling, this method inevitably introduces an additional bias of approximately -0.06 (°)/h, which must be carefully managed to ensure accurate measurements. Further analysis (Fig. 9) reveals that the combined method of analog adding feedback and ratio four-state demodulation provides a significant improvement in measurement accuracy. By minimizing the correlation between modulation and demodulation sequences, this approach ensures that the gyroscope can operate accurately even at low angular velocities. Experimental results (Table 2) indicate that this method effectively suppresses electrical cross-coupling errors, resulting in more reliable and precise measurements.

Our study demonstrates the feasibility and effectiveness of the proposed methods in suppressing electrical cross-coupling errors in digital closed-loop IFOGs. The combination of the analog adding feedback method with the ratio four-state demodulation method shows significant improvements in measurement accuracy, particularly at low angular velocities. These techniques mitigate the dead zone effects and guarantee the overall stability and reliability of the gyroscope’s performance. The findings have significant implications for the design and operation of high-precision IFOGs. By addressing the critical issue of electrical cross-coupling errors, the proposed methods pave the way for developing more accurate and reliable gyroscopes, essential for various high-precision applications. Future research will focus on further refining these techniques.