[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.
[0026] The fiber optic gyroscope with on-line fault self-checking function in the embodiment of the present invention includes two parts, an optical path and a detection circuit, such as figure 1 shown. The optical circuit part includes a light source, a 2×2 coupler, a Y-waveguide, an optical fiber ring, a photodetector 1, and a photodetector 2. The photodetector 1 is used to detect the Sagnac interference light signal, and the photodetector 2 is used to detect the output light of the light source. Signal. The output pigtail of the light source is connected to the 1-port pigtail of the 2×2 coupler, the 2-port pigtail of the 2×2 coupler is connected to the 1-port pigtail of the photodetector, and the 3-port pigtail of the 2×2 coupler is connected to the Y-waveguide The input pigtail is connected, the 4-port pigtail of the 2×2 coupler is connected to the photodetector 2 pigtail, and the two output pigtails of the Y waveguide are respectively connected to the fiber ring pigtail. The dots in the figure represent the optical fiber fusion splices. Photodetectors 1 and 2 can be selected from various forms of photodetectors such as PINFET components, PIN tubes, and PD tubes. The Y-waveguide can also be replaced by other forms of phase modulators.
[0027] The detection circuit part includes a photodetector 1 signal amplification and ADC sampling circuit, a photodetector 2 signal amplification and ADC sampling circuit, a digital logic chip, a waveguide phase modulation circuit, and a data interface circuit. Among them, the photodetector 1 signal amplification and ADC sampling circuit performs power detection, voltage conversion and data sampling on the Sagnac interference optical signal, and can continuously obtain the Sagnac phase difference information by demodulating the photodetector 1 signal in real time. The photodetector 2 signal amplification and ADC sampling circuit performs power detection, voltage conversion and data sampling on the original optical signal of the light source. By monitoring the photodetector 2 signal in real time, the real-time value of the light source optical power and the information of the fluctuation amplitude can be continuously obtained. . Digital logic chips, waveguide phase modulation circuits, data interface circuits, etc. are all general configuration circuits for digital closed-loop fiber optic gyroscopes.
[0028] In the embodiment of the present invention, a program module for light source optical power detection is designed in the data processing logic program (or software) of the fiber optic gyroscope, and its function is to perform automatic online detection for abnormal failure modes of the light source optical power. This program module continuously reads the sampling data of the photodetector 2 signal in each sampling period, and sets a reasonable value range for it, such as [100~2000], and sets a value fluctuation limit, such as 30, as figure 2shown. Compare the current value of the sampled data in each sampling period with the value range to determine whether it is within the set range. If the current value continues to be less than the minimum limit of the set range, it can be judged that the optical power of the light source is too low. ; If the current value is continuously greater than the upper limit of the set interval, it can be judged that the light power of the light source is too large. Compare the difference between the maximum value and the minimum value of the sampled data in multiple consecutive sampling periods with the set numerical fluctuation limit to determine whether it does not exceed the limit. If it exceeds the limit, it can be determined that the light source optical power is unstable.
[0029] In the embodiment of the present invention, a program module for data detection of the photodetector 1 is also designed to perform automatic online detection for failure modes such as the optical power of the photodetector 1 exceeding the limit and the abnormality of the first closed loop and the second closed loop. This program module continuously reads the sampling data of the photodetector 1 on the premise that the FOG runs the first closed-loop and second closed-loop logic programs, and calculates the pulse amplitude, A closed-loop error and a second closed-loop error, such as image 3 shown. Set a reasonable value range for the pulse amplitude, such as [900~1800]; set an upper limit for the first closed-loop error, such as 50; set an upper limit for the second closed-loop error, such as 150. In each eigencycle, the calculated three indicators are compared with their set values. If the pulse amplitude is less than the lower limit of the value interval, it can be determined that the optical power received by the photodetector 1 is too low; if the pulse amplitude is greater than the upper limit of the value interval, it can be determined that the optical power received by the photodetector 1 is too large. If the first closed loop error exceeds the upper limit, it may be determined that the first closed loop fails or is unstable. If the second closed loop error exceeds the upper limit, it may be determined that the second closed loop fails or is unstable.
[0030] In the embodiment of the present invention, a program module for detecting the angular velocity output data is also designed to perform automatic online detection for the failure mode of abnormal output data of the angular velocity of the fiber optic gyroscope. This program function module reads the value of the FOG angular velocity output data register in real time, and subtracts the current value of the angular velocity output data from the previous value to obtain the data change at the current moment. According to the register bit width and the FOG maximum sensitive angular acceleration, Set a reasonable value range for the current data value and the data change amount, such as [-65536~ 65535]. If the current value of the data or the amount of data change exceeds the value range, it can be determined that the output data of the angular velocity of the fiber optic gyroscope overflows or exceeds the range.
[0031] Finally, when the fiber optic gyroscope performs external data communication, it is usually necessary to frame or package the angular velocity output data and other byte information such as frame header, identifier, check word, etc., and then send it to the inertial system or external device according to the agreed communication format. . In the embodiment of the present invention, a fault status word is added to the data frame or data packet of the fiber optic gyroscope to represent the alarm information in the above-mentioned various failure modes, and the inertial system or external device connected to the fiber optic gyroscope reads the status word information. , you can judge whether the fiber optic gyroscope is working fault, and can further read the cause of the fault. It is assumed that the fault status word is a byte, that is, 8-bit binary data. When the fiber optic gyroscope works normally, the 8 bits of the fault status word are all 1'b0, that is, the fault status word should be 8'b00000000; when the fiber optic gyroscope fails, the status bits of D6~D0 can be set to 1'b1 correspondingly , different status bits set 1'b1 to represent different failure modes. For example, if D1~D0 is set to 2'b01, it means that the optical power of the light source is too low. If D1~D0 is set to 2'b10, it means that the optical power of the light source is too high. If D1~D0 is set to 2'b11, it means that the optical power of the light source is unstable. D4~D2 bits set to 3'b001 represent the optical power received by the photodetector is too low, D4~D2 bits set to 3'b010 to represent the optical power received by the photodetector is too high, D4~D2 bits set to 3'b011 to represent the first closed loop Failure or instability, D4~D2 bits are set to 3'b100 to represent the second closed loop failure or instability. D5 bit set to 1'b1 represents the fiber optic gyroscope angular velocity output data overflow or out of range. The D7 bit is the total alarm bit of the fault status word. As long as one of the status bits of D6 to D0 is not 1'b0, it is set to 1'b1, which means that the fiber optic gyro has entered the working fault mode. By introducing the fault status word in the data frame (data packet), real-time online fault status alarm can be realized, so that the inertial system or external equipment can know the working status of the fiber optic gyroscope in time and reduce the fault loss.
[0032] It should be understood that, for those skilled in the art, improvements or changes can be made according to the above description, and all these improvements and changes should fall within the protection scope of the appended claims of the present invention.
