A New Dynamic Test Method of Fiber Optic Gyroscope

Abstract

The sway motion of ships follows sine law. Therefore, it needs high dynamic performance of fiber optic gyroscope (FOG) to meet the serious working environment. A new test method was introduced to make reasonable assessment on the dynamic performance of FOG. The principle of this new test method was that the sine wave provided by the IP core in FPGA was superimposed on the digital ladder to simulate the input signal of sway motion. It could be proved that the serial of sine signal, which was generated by this method, was equivalent to the external input signal. Moreover, the dynamic error model of FOG was established to provide the theory of dynamic test. The results of dynamic test of FOG indicated that the dynamic error did not have divergent trends, the system parameters set was reasonable and the FOG system was stable. It also can be seen that dynamic error of FOG was increased with the increasing of sine wave amplitude, which was accord with the actual situation. The new dynamic test method of FOG was verified.

Frequency characteristic measurement of a fiber optic gyroscope using a correlation spectrum analysis method based on a pseudo-random sequence

“…So, the measurement result has a relatively large error. A method based on the equivalent input is developed which adds a sinusoidal signal to the feedback serrodyne wave through an integrated optical phase modulator (IOPM) to generate an equivalent Sagnac sinusoidal test signal [15][16][17][18][19]. This method has a higher test bandwidth and could get a phase characteristic by using lock-in technology.…”

“…But the equivalent test signal's amplitude is related to test frequency; the amplitude will be too small at low test frequencies, which will increase the test error. To solve this, the sinusoidal signal is replaced by a pseudo-random signal, and the frequency characteristic test is accomplished by using the correlation method [20][21][22]. However, the test result includes the dynamic characteristic of IOPM, which will cause a deviation from the real frequency characteristic of the FOG, and this method can only be used for a closed-loop FOG.…”