FOG IMU in Cutting-Edge Defense Technology Field is a Solution that MEMS Cannot Achieve

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Fiber optic gyroscope IMU (FOG IMU) and MEMS IMU have significant differences in accuracy, environmental adaptability, reliability, and other aspects due to differences in technical principles. The position of fiber optic gyroscope IMU is still irreplaceable in the fields of strategic weapons, deep space/deep-sea exploration, high dynamic military systems, and scientific instruments. Its core advantages lie in the physical limit level accuracy, full temperature stability, and extreme environmental resistance. Even if some high-end MEMS approach tactical level performance, they still cannot meet the strategic level requirements of cutting-edge defense technology.

Core applications in the field of cutting-edge defense technology

1.       Strategic level military equipment navigation and guidance

Intercontinental ballistic missiles and strategic nuclear submarines need to maintain ultra-high precision positioning (zero bias stability ≤ 0.05 °/h) in environments without satellite signals (such as deep sea or space), and resist strong impacts (>25g), extreme temperatures (-45℃~70℃), and electromagnetic interference. The zero bias stability (usually ≥ 0.1°/h) and shock resistance of MEMS IMU are insufficient, and error accumulation can lead to guidance deviation from the target.

In satellite attitude control, the space environment requires microradian level angular velocity measurement (random walk ≤ 0.005°/√ h) and long-term stability (MTBF>20000 hours). The thermal stability and radiation resistance of fiber optic gyroscopes are superior to MEMS, which performs better in vacuum and

Drift easily under radiation.

2.       Strong electromagnetic interference and high dynamic tactical systems

In the strong electromagnetic field of electronic warfare platforms (such as radar jammers), MEMS is prone to data jumps due to the susceptibility of semiconductor structures to interference, while fiber optic gyroscopes adopt an all-optical design and have non-magnetic material characteristics that can completely resist electromagnetic interference.

During the guidance process of hypersonic aircraft, severe vibrations and high temperatures are generated during ultra high speed flight (>5 Mach). The IMU composed of fiber optic gyroscope and quartz accelerometer can withstand 100g impact and 2000Hz vibration, while the MEMS structure is prone to resonance failure.

In the fire control system of military fighter jets, real-time attitude angle calculation (error<0.01 °) is required during high maneuverability flight (such as 9g overload). The dynamic response linearity of fiber optic gyroscope (scale factor nonlinearity ≤ 50ppm) is much better than MEMS (≥ 500ppm).

3.       Deep sea exploration and autonomous underwater navigation

In the application field of unmanned underwater vehicles (AUV/ROV) and underwater seismometers, pure inertial navigation is required for several months in deep sea environments without GPS, and the position error needs to be less than 1% of the navigation distance. The long-term zero bias stability of fiber optic gyroscope (≤ 0.1°/h) and the low noise of quartz accelerometer (≤ 100 μg) can support microgravity measurement, while MEMS temperature drift (≥ 500 μg) and noise accumulation lead to positioning drift. For example, in underwater pipeline inspection, if the cumulative error exceeds 10 meters, it may cause equipment damage.

4.       Scientific exploration and precision surveying

In gravity gradient measurement and polar scientific exploration, polar magnetic field interference is large and there is no geomagnetic reference. The non-magnetic characteristics of fiber optic gyroscopes can achieve autonomous north finding (heading accuracy ≤ 0.08 °), while MEMS relies on magnetometers and fails in polar regions.  

In the deep space orbit calibration of spacecraft, relying on the combination of starlight and inertia navigation, the angle random walk of fiber optic gyroscope (≤ 0.002°/√h) approaches the quantum limit, and the MEMS noise is one to two orders of magnitude higher (≥ 0.03 °/√ h)

Key performance comparison

The following table summarizes the irreplaceable core advantages of FOG IMU: 

Core performance indicators of fiber optic gyroscope IMU

The following table lists the core performance indicators of two three-axis FOG IMU

Conclusion

Although MEMS IMUs have advantages in cost, size, and power consumption (such as consumer electronics and car navigation), FOG IMU are still the only choice for high-precision, high reliability, and strong anti-interference scenarios. With the advancement of MEMS technology, it is gradually penetrating the low-end fiber optic gyroscope market, but in the strategic areas mentioned above, the physical limitations of fiber optic technology are still irreplaceable.

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  Relationship between frequency response range and resonant frequency of accelerometer chip