Analysis of fiber optic gyroscope core indicators

Analysis of fiber optic gyroscope core indicators

1. Zero Bias and Zero Bias Stability

Definition and meaning

Zero Bias: The output equivalent angular velocity of the gyroscope when the input angular velocity is zero, which ideally corresponds to the earth's rotation component.

Zero Bias Stability: the degree of dispersion of zero bias (expressed as standard deviation), which is the core index of accuracy, and strategic products can reach 0.001°/h (1σ).

Influencing factors and optimization

Temperature perturbation: ambient temperature changes lead to non-reciprocal phase shift of the fiber optic coils, which needs to be suppressed by temperature control or compensation algorithms (drift ≤ 0.1°/h in the whole temperature zone).

Polarization noise: polarization-preserving optical fiber and polarization filtering technology are adopted to reduce the impact of polarization fluctuation on zero bias.

2.Scale factor and nonlinear error

Key parameters

Scale factor: the ratio of output and input angular rate, reflecting the sensitivity, the nonlinear error of navigation grade products is ≤50ppm (full scale 300°/s).

Stability: affected by temperature and polarization state changes, linear fitting accuracy needs to be verified by dynamic angular velocity input.

Dynamic performance verification

High-speed response test: within the range of input angular velocity 0.1~1000°/s, the response time is ≤1ms, and the deviation of tracking accuracy is ≤±0.5%.

3．the random wandering coefficient and noise characteristics

Noise index classification

Angular Random Wander (ARW): reflecting angular velocity white noise, ≤0.0005°/√h for strategic grade products.

Rate noise density: noise power per unit bandwidth, and ARW there is a conversion relationship (typical value ≤ 0.001°/sec/√Hz).

Noise source

Photon spontaneous radiation, detector circuit noise, mechanical vibration, etc., need to combine digital filtering and anti-vibration design to reduce the impact.

4.Dynamic range and sensitivity

Threshold and resolution

Threshold: minimum detectable angular velocity (strategic level ≤ 0.0001°/h).

Resolution: Measurement of incremental sensitivity, directly related to the noise level.

Maximum input angular velocity

Typical dynamic range ±1500°/s, supports high-speed vehicle maneuvers and instantaneous angular velocity capture.

5. Environmental Adaptability

Temperature domain and vibration resistance

Operating temperature: -40°C to +85°C (military grade standard), zero bias change ≤ 0.1°/h after temperature drift compensation.

Vibration resistance: output fluctuation ≤0.03°/s under axial 3g RMS vibration (10Hz~2000Hz).

Electromagnetic compatibility

Shielded package and anti-jamming circuit design is adopted to maintain stable output under 100kV/m field strength.

6.Typical Performance Classification Comparison

Performance level Zero-bias stability (°/h) Random wandering coefficient (°/√h) Application scenario

Tactical grade ≤0.01 ≤0.01 UAV navigation

Navigation grade ≤0.001 ≤0.001 Submarine inertial guidance

Strategic level ≤0.0001 ≤0.0005 ICBM guidance

7.Error compensation technology

All-digital closed-loop control

Based on FPGA+ASIC architecture, real-time correction of optical path nonlinear error to improve zero-bias stability and dynamic response.

Multi-sensor fusion

Integration of temperature and vibration sensors, real-time compensation of environmental disturbances through Kalman filtering (integrated error ≤ 0.0015°/h).

Testing and verification standards

Allan ANOVA: Used to quantify the zero-bias stability and random wandering coefficient.

Dynamic calibration: Combined with the high-precision rotary table to simulate the actual working conditions, to verify the scale factor error and tracking accuracy.

Through the optimization and verification of the above core indexes, the fiber optic gyroscope has achieved technological breakthroughs in the fields of high-precision navigation, strategic weapons guidance, etc., and gradually replaced the traditional mechanical gyroscope.