1 zero deviation and zero drift
Zero offset is the output of the gyroscope when the input angular velocity is zero (that is, the gyroscope is at rest). It is expressed by the equivalent input angular velocity corresponding to the average value of the output measured in the specified time, and ideally is the component of the angular velocity of the earth's rotation.Zero drift is zero offset stability, which represents the degree of dispersion of gyroscope output around its zero offset mean value when the input angular rate is zero, and is represented by the equivalent input angular rate corresponding to the standard deviation of the output in the specified time.Zero drift is the most important and basic index to measure the accuracy of FOG(fiber optic gyro).The main cause of zero drift is the non-reciprocal phase shift error introduced in the fiber coil by the change of ambient temperature distribution along the fiber.Usually in order to stabilize zero drift, often need to IFOG temperature control or temperature compensation.In addition, polarization will also have a certain impact on zero drift. Polarization filtering and polarization-maintaining optical fiber are often used to eliminate the influence of polarization on zero drift in IFOG.
2 scale factor
Scaling factor is the ratio of gyroscope output to input angular rate, which can be expressed by the slope of a specific line on the coordinate axis. It is an index reflecting gyroscope sensitivity, and its stability and accuracy are an important index of gyroscope, which comprehensively reflect the testing and fitting accuracy of FOG.The stability of a scaling factor is dimensionless and is usually expressed in parts per million (PPM).The error of the scaling factor mainly comes from the temperature change and the instability of the polarization state of the fiber.
3. Random walk coefficient
A technical index representing the white noise of the angular velocity output in a fiber optic gyroscope. It reflects the uncertainty accumulated over time in the angular velocity integral of the output of a fiber optic gyroscope. Therefore, it can also be called the angular random walk.The random walk coefficient reflects the development level of gyroscope and also reflects the minimum detectable angular velocity of gyroscope.The error mainly comes from random spontaneous emission of photons, noise introduced by photodetector and digital circuit and mechanical jitter.
4 Thresholds and resolutions
The threshold represents the minimum input rate that the FOG can sense.Resolution represents the minimum input rate increment that a gyroscope can sense at a given input angular rate.Both threshold and resolution represent the sensitivity of the fiber optic gyroscope.
Maximum input angular velocity
Represents the maximum input rate of gyro in the positive and negative directions, and represents the dynamic range of gyro, that is, the sensing rate range of fiber optic gyro.