An online alarm method for open-loop faults in the closed-loop of a fiber optic gyroscope

Abstract

The present invention relates to the technical field of fiber optic gyroscopes, and particularly to an online alarm method for open-loop faults in a closed-loop loop of a fiber optic gyroscope, which includes the following steps: S1, collect the operation data of the closed-loop loop of the fiber optic gyroscope; S2, perform signal feature analysis based on the operation data of the closed-loop loop. If the result of the signal feature analysis shows that there is only a DC component, it is determined that there is an open-loop fault in the closed-loop loop of the fiber optic gyroscope, and go to S3; otherwise, return to S1; S3, replace the rotational angular velocity information sent to the navigation system with the open-loop fault information of the closed-loop loop. The present invention can, when an open-loop fault occurs in the closed-loop loop of the fiber optic gyroscope, promptly inform the navigation system, enabling it to avoid giving incorrect attitude information, thereby preventing the command and control system from issuing incorrect commands, and can, to a certain extent, avoid economic losses and even casualties.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber optic gyroscopes, and particularly to an online alarm method for open circuit faults in the closed-loop loop of a fiber optic gyroscope. Background Art

[0002] The fiber optic gyroscope is a core device of an inertial navigation system, which uses the rotational angular velocity information provided by the fiber optic gyroscope to complete the attitude solution of the carrier. However, when a closed-loop fault occurs in the fiber optic gyroscope, it will still send abnormal data to the navigation system. Without knowing the closed-loop fault of the gyroscope, the navigation system will still perform attitude solution based on the abnormal data, resulting in the failure of the attitude north-seeking task. The incorrect attitude information provided by the navigation system may cause the command and control system to issue incorrect commands, thus causing huge economic losses and even casualties.

[0003] Therefore, it is very important to add a certain fault diagnosis function to the gyro device and provide the fault information to the navigation system. Based on this, the applicant of the present invention applied for a patent for invention with the publication number of CN 112683309 A, which discloses a method for alarming the closed-loop fault of a fiber optic gyroscope to the navigation system, and can realize the detection and alarm of the closed-loop fault of the fiber optic gyroscope. By detecting whether the dressing diagram is flat, it is possible to know whether there is a closed-loop fault. Specifically, when the dressing diagram is not flat, it can be judged that there is a closed-loop fault. In this way, the closed-loop fault can be detected quickly and accurately.

[0004] However, among the fiber optic gyroscope faults, in addition to the closed-loop fault, the open circuit fault of the closed-loop loop of the fiber optic gyroscope is also relatively common. Moreover, when an open circuit fault occurs in the fiber optic gyroscope, its dressing diagram will also be shown as a flat state. The above-mentioned patent cannot detect the open circuit fault. In addition, in the prior art, there is no self-diagnosis scheme designed for the open circuit fault.

[0005] If the open circuit fault of the closed-loop loop of the fiber optic gyroscope is informed to the navigation system in advance to avoid it from providing incorrect attitude information, further economic losses can be avoided. Therefore, how to let the navigation system know in time when an open circuit fault occurs in the fiber optic gyroscope has become an urgent problem to be solved at present. Summary of the Invention

[0006] Aiming at the above deficiencies of the prior art, the present invention provides an online alarm method for open circuit faults in the closed-loop loop of a fiber optic gyroscope, which can timely inform the navigation system when an open circuit fault occurs in the fiber optic gyroscope, so that it can avoid giving incorrect attitude information, thereby causing the command and control system to issue incorrect commands, and can avoid economic losses and even casualties to a certain extent.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] An online alarm method for open-loop faults in the closed-loop loop of a fiber optic gyroscope, comprising the following steps:

[0009] S1, collect the operation data of the closed-loop loop of the fiber optic gyroscope;

[0010] S2, perform signal feature analysis based on the operation data of the closed-loop loop. If the signal feature analysis result shows only a DC component, it is determined that there is an open-loop fault in the closed-loop loop of the fiber optic gyroscope, and proceed to S3; otherwise, return to S1;

[0011] S3, replace the rotational angular velocity information sent to the navigation system with the open-loop fault information of the closed-loop loop.

[0012] As a preferred solution, in S2, the signal feature analysis based on the operation data of the closed-loop loop includes: performing a difference comparison analysis on the operation data at the time of modulation state switching and the operation data within a preset duration before or after the switching. If the difference is less than a preset threshold, it is determined that the signal feature has only a DC component.

[0013] As a preferred solution, in S2, the preset duration is less than half of the modulation period.

[0014] As a preferred solution, in S3, the data structure of the rotational angular velocity information sent to the navigation system is: frame header + data + data check value, where the highest bit in the data is bound to a fixed number; when it is determined that the fiber optic gyroscope has a closed-loop fault, the frame header data is changed, and the rotational angular velocity information is replaced with the open-loop fault information of the closed-loop loop.

[0015] As a preferred solution, in the data structure, the first byte is the frame header 7FH, the second to the nth bytes are the gyro data, the (n + 1)th byte is the exclusive OR check value of the second to the nth bytes, and the highest bit of the second to the nth bytes is bound to 1; when it is determined that there is an open-loop fault in the closed-loop loop, the frame header is replaced with an alarm code data less than 7FH.

[0016] As a preferred solution, in S1, the collected operation data is A / D data.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. At present, there is no technology in the fiber optic gyroscope industry to send a closed-loop loop open circuit fault alarm to the navigation system. The closed-loop loop open circuit fault alarm method designed by the present invention can, when a closed-loop loop open circuit fault occurs in the fiber optic gyroscope, promptly inform the navigation system, enabling it to avoid giving incorrect attitude information, thereby preventing the command and control system from issuing incorrect instructions, and to a certain extent, avoiding economic losses and even casualties. Specifically, this application collects the A / D data during the modulation state switch and compares the difference with that before or after the switch. Because under normal circumstances, a pulse spike of a dressing wave will be generated during the modulation state switch, that is, the value of this difference will not be too small. If the actually obtained difference is less than the preset threshold, it can be determined that the detector signal is a constant DC signal without the pulse spike of the dressing wave, and thus it can be determined that a closed-loop loop open circuit fault has occurred. Therefore, an open circuit fault message is sent to the navigation system. Through such a clever design, this application provides a pioneering open circuit self-diagnosis method, which can inform the navigation system in advance of the closed-loop loop open circuit fault of the fiber optic gyroscope to avoid it from providing incorrect attitude information and further avoid economic losses.

[0019] 2. When it is determined that a closed-loop loop open circuit fault has occurred, this method will directly replace the rotational angular velocity information sent to the navigation system with the closed-loop loop open circuit fault information, which can prevent the incorrect rotational angular velocity information from still being sent to the navigation system, resulting in the navigation system issuing incorrect instructions based on the incorrect rotational angular velocity analysis, and further ensuring safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the objectives, technical solutions, and advantages of the invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings, where:

[0021] Figure 1 It is the detector signal waveform diagram under closed-loop in the embodiment;

[0022] Figure 2 It is an example diagram of the detector waveform under optical device failure in the embodiment;

[0023] Figure 3 It is the timing relationship diagram of the dressing wave pulse spike and the modulation state switch under normal circumstances in the embodiment;

[0024] Figure 4 It is the flowchart of the online alarm method for the closed-loop loop open circuit fault of the fiber optic gyroscope in the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following will be further described in detail through specific embodiments:

[0026] Embodiment

[0027] To facilitate the understanding of the principle of this application, the closed-loop principle of the fiber optic gyroscope will be described first. Taking square wave modulation as an example (the four-state modulation or other modulation methods are similar), the optical power reaching the detector under square wave modulation can be expressed by the following formula:

[0028]

[0029] In the formula: P0 is the optical power reaching the detector when the fiber optic gyroscope is absolutely stationary (when Φ S = 0); Φ S is the phase difference caused by rotation. In the formula: Φ m is:

[0030]

[0031] In the formula: Φ0 is the square wave modulation amplitude, and τ is the transit time of the fiber optic loop (i.e., the time for the light wave to travel one round in the fiber optic loop).

[0032] After the above square wave modulation, the odd and even sampling values of the fiber optic gyroscope can be obtained by sampling respectively in the half cycles of positive and negative modulations:

[0033]

[0034] The subtraction of the odd and even sampling values gives:

[0035] ΔP = P - - P + = P0sinΦ0sinΦ S ………………………(4)

[0036] Once the square wave modulation amplitude is determined, it is a fixed value. Therefore, P0sinΦ0 is a constant term and can be represented by A. On the other hand, when ΦS is a small quantity, there is sinΦS = ΦS. Thus, the difference between the odd and even samplings is:

[0037] ΔP = AΦ S ………………………(5)

[0038] It can be seen from equation (5) that the difference between the odd and even samplings under square wave modulation is proportional to the phase difference caused by rotation and can be used as the output of the rotation angular rate. At the same time, the total phase difference is servo-controlled near zero through closed-loop control. The odd and even sampling values after closed-loop control are:

[0039]

[0040] In the formula: Φf is the closed-loop feedback phase, which satisfies:

[0041] Φ f = -Φ S ………………………(7)

[0042] Therefore, Equation (6) can also be expressed as:

[0043]

[0044] As can be seen from the above, the function of the closed-loop in the closed-loop fiber optic gyroscope is to servo-control the total phase difference near zero. That is, the detector signal is flat, as Figure 1 shown.

[0045] According to the closed-loop principle of the fiber optic gyroscope, the first closed-loop calculates the feedback phase based on the positive and negative sampling differences to cancel the phase difference caused by rotation, and the second closed-loop calculates the 2π voltage adjustment amount based on the sampling differences before and after reset. Both closed-loops obtain the feedback amount based on the signal difference, that is, there must be a signal difference first to have a closed-loop feedback. If a certain link in the closed-loop circuit is disconnected (open circuit) or the light source (including the coupler) fails (no light is injected into the Y waveguide, fiber optic loop), at this time all sampling values are equal (in practice, due to noise, there will be a small difference and it is at the same level as the difference under closed-loop, but there is a closed-loop fault), so the feedback amount is a small amount near zero. At this time, it can be considered that a closed-loop circuit open fault has occurred.

[0046] The applicant has found through research that the closed-loop circuit open fault is mainly due to the fact that the detector signal only has a flat DC component (the detector has no signal or the signal fails to reach the AD sampling) due to the fault, and thus the rotation phase difference information cannot be obtained, and the closed-loop cannot be formed. Therefore, the main signal feature of the closed-loop circuit open fault is that there is only a DC component and no comb wave. The waveform diagram of the detector under the failure of an optical device is as Figure 2 shown. In other words, when a closed-loop circuit open fault occurs, its signal feature is that the detector signal is a constant DC signal without the pulse spikes of the comb wave. Under normal circumstances, the pulse spikes of the comb wave are caused by the switching of the modulation state under square wave modulation (the modulation state cannot change suddenly but requires a certain amount of time, and the specific time is related to the device response time). Under normal circumstances, the timing relationship diagram between the pulse spikes of the comb wave and the modulation state switching is as Figure 3 shown.

[0047] Based on the above research, the applicant proposes an on-line alarm method for the closed-loop circuit open fault of the fiber optic gyroscope, as Figure 4 shown, including the following steps:

[0048] S1, collect the operation data of the closed-loop of the fiber optic gyroscope; in specific implementation, the operation data is A / D data, and the operation data can be directly collected through the detector.

[0049] S2, perform signal feature analysis based on the operation data of the closed-loop circuit. If the signal feature analysis result is that there is only a DC component, it is determined that the fiber optic gyroscope has a closed-loop circuit open fault, and go to S3; otherwise, return to S1.

[0050] Among them, the signal feature analysis based on the operation data of the closed-loop loop includes: comparing the difference between the operation data at the time of modulation state switching and the operation data of a preset duration before or after the switching. If the difference is less than a preset threshold, it is determined that the signal feature has only a DC component. Specifically, in implementation, the preset duration is less than half of a modulation period. It should be noted that in this embodiment, the difference between the modulation state switching and before and after the switching takes the same modulation period as an example. In other embodiments, using the operation data separated by several modulation periods for the difference comparison analysis can still achieve the same effect and the principle is the same.

[0051] S3. Replace the rotational angular velocity information sent to the navigation system with the closed-loop loop open-circuit fault information. Among them, the data structure of the rotational angular velocity information sent to the navigation system is: frame header + data + data check value, where the highest bit in the data is bound to a fixed number; when it is determined that the fiber optic gyroscope has a closed-loop fault, the frame header data is changed, and the rotational angular velocity information is replaced with the closed-loop loop open-circuit fault information. Specifically, in implementation, in the data structure, the 1st byte is the frame header 7FH, the 2nd to the nth bytes are the gyro data, the (n + 1)th byte is the exclusive OR check value of the 2nd to the nth bytes, and the highest bit of the 2nd to the nth bytes is bound to 1; when it is determined that there is a closed-loop loop open-circuit fault, the frame header is replaced with an alarm code data less than 7FH. In this embodiment, the value of n is 6, and the data format is defined as shown in the following table:

[0052]

[0053] Schematic table of the data structure of the rotational angular velocity information

[0054] Specifically, in implementation, when it is diagnosed that the fiber optic gyroscope has a closed-loop loop open-circuit fault, the frame header 7FH can be replaced with any alarm code data less than 7FH, and this data can be negotiated with the navigation system in advance. For example, sending 55H, that is, as long as the navigation system receives the 55H data, it means that the gyro has a closed-loop loop open-circuit fault, and the gyro is stopped from being used for attitude solution.

[0055] The closed-loop loop open-circuit fault alarm method designed by the present invention can, when a closed-loop loop open-circuit fault occurs in an optical fiber gyroscope, promptly inform the navigation system, enabling it to avoid providing incorrect attitude information, thereby preventing the command and control system from issuing incorrect instructions, and to a certain extent, avoiding economic losses and even casualties. Specifically, this application collects the A / D data during the modulation state switch and compares the difference with that before or after the switch. Because under normal circumstances, pulse spikes of the dressing wave will be generated during the modulation state switch, that is, the value of this difference will not be too small. If the actually obtained difference is less than the preset threshold, it can be determined that the detector signal is a constant DC signal without pulse spikes of the dressing wave, and thus it can be determined that a closed-loop loop open-circuit fault has occurred. Therefore, an open-circuit fault message is sent to the navigation system. In this way, the technical gap in the optical fiber gyroscope industry of not sending closed-loop loop open-circuit fault alarms to the navigation system is filled. Through such a clever design, this application provides a pioneering open-circuit self-diagnosis method, which can inform the navigation system in advance of the closed-loop loop open-circuit fault of the optical fiber gyroscope to avoid it providing incorrect attitude information and further avoid economic losses.

[0056] In addition, when it is determined that a closed-loop loop open-circuit fault has occurred, this method will directly replace the rotational angular velocity information sent to the navigation system with the closed-loop loop open-circuit fault information, which can avoid continuing to send incorrect rotational angle information to the navigation system, resulting in the navigation system issuing incorrect instructions after analyzing based on the incorrect rotational angular velocity, further ensuring safety.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the purpose and scope of the present technical solution shall be covered by the scope of the claims of the present invention.

Claims

1. An online alarm method for open-loop faults in a closed-loop loop of an optical fiber gyroscope, characterized in that, Including the following steps: S1. Collect the operation data of the closed-loop loop of the fiber optic gyroscope; wherein, the collected operation data is A / D data; S2. Conduct signal feature analysis based on the operation data of the closed-loop loop. If the signal feature analysis result shows only a DC component, it is determined that there is an open-circuit fault in the closed-loop loop of the fiber optic gyroscope, and proceed to S3; otherwise, return to S1; Among them, the signal feature analysis based on the operation data of the closed-loop loop includes: performing a difference comparison analysis on the operation data at the time of modulation state switching and the operation data within a preset time period before or after the switching. If the difference is less than a preset threshold, it is determined that the signal feature has only a DC component; the preset time period is less than half of the modulation period; S3. Replace the rotational angular velocity information sent to the navigation system with the open-circuit fault information of the closed-loop loop.

2. The online alarm method for open-loop open-circuit faults in the closed-loop loop of an optical fiber gyroscope according to claim 1, characterized in that: In S3, the data structure of the rotational angular velocity information sent to the navigation system is: frame header + data + data check value, where the highest bit in the data is bound to a fixed number; when it is determined that a closed-loop fault occurs in the fiber optic gyroscope, the frame header data is changed, and the rotational angular velocity information is replaced with the open-circuit fault information of the closed-loop loop.

3. The online alarm method for the open-loop fault of the closed-loop loop of the fiber optic gyroscope according to claim 2, wherein: In the data structure, the 1st byte is the frame header 7FH, the 2nd to the nth bytes are the gyro data, the (n + 1)th byte is the exclusive OR check value of the 2nd to the nth bytes, and the highest bit of the 2nd to the nth bytes is bound to 1; when it is determined that there is an open-circuit fault in the closed-loop loop, the frame header is replaced with an alarm code data less than 7FH.

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