Direct-current frequency stabilization control method for laser gyroscope

Abstract

The invention discloses a direct-current frequency stabilization control method for a laser gyroscope. The method comprises the following steps: realizing high-precision phase extraction and closed-loop control through a 80kHz and 5kHz interruption collaborative sampling mechanism; after the frequency stabilization instruction is triggered, the system collects an alternating current light intensity signal in real time and calculates a product accumulated value to extract phase information; when a direct current modulation period is met and 80kHz interruption reaches 16 times, assigning an accumulated value as a direct current modulation phase, performing zero clearing, and then dynamically assigning a modulation parameter through 5kHz interruption counting; after the phase is subjected to normalization processing, phase deviation is corrected by combining a PID (Proportion Integration Differentiation) controller, a regulating variable is generated and superposed with a direct-current modulation value to form a final frequency-stabilized driving voltage, and the final frequency-stabilized driving voltage is output to a hardware circuit through digital-to-analog conversion; the voltage is fed back to direct-current light intensity and enters sampling circulation again after being processed by a circuit, so that continuous closed-loop control is formed; according to the scheme, the frequency stabilization precision and the dynamic response speed are effectively improved, the anti-interference capability is enhanced, stable and reliable output of the laser gyroscope is ensured, and the method is suitable for high-precision frequency stabilization scenes.

Description

Technical Field

[0001] This invention relates to the field of laser inertial navigation technology, and in particular to a method for DC frequency stabilization control of a laser gyroscope. Background Technology

[0002] As a core component of inertial navigation systems, laser gyroscopes have become an indispensable key technology in aviation, aerospace, and maritime fields due to their advantages such as high precision, fast startup, wide dynamic range, excellent scaling factor linearity, and insensitivity to acceleration. Their working principle is based on the Sagnac effect in a ring-shaped optical path, where the phase difference between two clockwise and counterclockwise propagating beams in a closed optical path is linearly related to the rotational speed of the system relative to inertial space. In practical applications, the laser gyroscope generates an optical signal through a gas laser, a photodiode converts the optical power into a current signal, which is then processed by a transimpedance amplifier circuit into a negative voltage signal (DC light intensity). Finally, through DC blocking amplification and bandpass filtering, an AC light intensity signal is generated that can be acquired by a microcontroller. Traditional frequency stabilization control methods mainly rely on AC modulation technology, using hardware circuits (such as multiple operational amplifiers and modems) to achieve phase extraction and feedback control. However, these solutions suffer from problems such as circuit complexity, a large number of components, high cost, and high power consumption, limiting their widespread adoption in miniaturized and low-cost applications.

[0003] As inertial navigation systems increasingly demand miniaturization, low power consumption, and high reliability, the limitations of existing AC modulation frequency stabilization technologies are becoming more apparent. For example, the hardware circuitry typically requires more than 12 operational amplifier channels, resulting in a large circuit board area, high power consumption, and difficulty in adapting to harsh environments such as high temperatures and vibrations. Furthermore, the fixed AC modulation frequency (e.g., 2.5kHz) lacks flexibility and may introduce phase noise or response delay, affecting frequency stabilization accuracy. Summary of the Invention

[0004] This application provides a DC frequency stabilization control method for laser gyroscopes, achieving universal, low-power, and low-cost DC modulation digital frequency stabilization closed-loop control for various types of laser gyroscopes.

[0005] This application provides a DC frequency stabilization control method for a laser gyroscope, including:

[0006] S1, after the frequency stabilization start command is triggered, the control process starts immediately; when the 80kHz interrupt occurs, the microcontroller acquires the AC light intensity signal of the laser gyroscope; and calculates the multiplicative summation value of the current AC light intensity and the current modulation information value to extract the phase information;

[0007] S2, after completing the multiplication and accumulation calculation, the control flow executes to determine whether the DC modulation period is valid; if the condition is valid, it further determines whether the 80kHz interrupt has occurred 16 times; if the condition is not valid, the control flow returns to S1 and continues to execute the 80kHz interrupt sampling.

[0008] S3, when the condition that the 80kHz interrupt has occurred 16 times is met, the control flow executes to assign the multiply-accumulate value to the DC modulation phase and clear the multiply-accumulate value to zero; at the same time, the control flow waits for the 5kHz interrupt to occur, and when the 5kHz interrupt is triggered, it counts the number of 5kHz interrupts.

[0009] S4: Based on the count of 5kHz interrupts, the control flow executes the DC modulation value assignment, dynamically assigning the DC modulation parameters; the control flow then checks whether the DC modulation period is valid. If the condition is valid, the DC modulation phase data assigned in S3 is normalized; if the condition is invalid, the control flow returns to S3 and continues to execute the 5kHz interrupt count.

[0010] S5. After phase normalization is completed, the control flow performs PID control on the normalized phase, calculates the adjustment amount based on the phase deviation, and outputs a control signal to correct the frequency-stabilized drive voltage.

[0011] S6, the control process adds the DC modulation value and the PID control result, assigns the value to the frequency-stabilized drive voltage, generates the final voltage value, and outputs it to the hardware circuit through digital-to-analog conversion;

[0012] S7, the frequency-stabilized drive voltage is fed back to the DC light intensity through the circuit. The DC light intensity is processed by circuits such as DC blocking amplification and bandpass filtering to obtain the AC light intensity. The control flow automatically returns to S1 and continues to execute 80kHz interrupt sampling, forming a continuous control loop.

[0013] Preferably, the extraction of phase information includes: immediately initializing the control flow when the frequency stabilization start command is triggered; continuously monitoring an 80kHz timer interrupt, wherein the 80kHz interrupt occurs 80,000 times / second, i.e., once every 12.5 microseconds; when the 80kHz interrupt occurs, acquiring the AC light intensity signal of the laser gyroscope in real time through the analog-to-digital converter of the microcontroller, which is obtained by photodiode detection of light power, and then processed by transimpedance amplification, DC blocking and bandpass filtering circuits, and is expressed as a voltage; and synchronously reading the current modulation information value. This value originates from the DC modulation process and is a dynamically updated reference signal. The product of the current AC light intensity value and the current modulation information value is calculated and accumulated into the multiplier-accumulator. The current AC light intensity is the instantaneous voltage value collected by the microcontroller during the 80kHz interruption, in volts, representing the AC component of the optical power. The current modulation information value comes from the DC modulation stage and is dimensionless. The multiplier-accumulator value is temporarily stored as an intermediate result in the microcontroller's memory to extract the phase information from the AC light intensity, thereby identifying whether the laser gyroscope is operating near the point of maximum optical power.

[0014] Preferably, the control flow execution to determine whether the DC modulation period is valid includes: after completing the multiplication and accumulation calculation, the control flow executes to determine whether the DC modulation period is valid, wherein the DC modulation period duration is 5 milliseconds, based on a 200Hz frequency; if the condition is valid, it further determines whether the 80kHz interrupt has occurred 16 times, wherein 16 80kHz interrupts correspond to a 0.2 millisecond time window, and the threshold is 16 times; if the condition is not valid, the control flow returns to execute 80kHz interrupt sampling; the phase processing is determined to be performed only within the effective range of DC modulation activity.

[0015] Preferably, the control flow further determines whether the DC modulation cycle is valid, specifically including: when the condition that the 80kHz interrupt has occurred 16 times is met, the control flow assigns the multiply-accumulate value temporarily stored in the microcontroller memory to the DC modulation phase variable, which is used to store the phase information in the current modulation cycle; the multiply-accumulate is reset to zero to prepare for the next modulation cycle; the control flow enters an idle state and continuously listens for the 5kHz timer interrupt; when the 5kHz interrupt is triggered, the number of interrupts is counted, and the accumulated value is used to track the modulation timing and provide a reference for the subsequent DC modulation value assignment.

[0016] Preferably, the step of calculating the adjustment amount based on the phase deviation and outputting a control signal to correct the frequency-stabilized drive voltage specifically includes: obtaining the cumulative number of 5kHz interrupts, which is implemented by a microcontroller counter and represents the frequency of interrupts since the start of the current DC modulation cycle; dynamically assigning DC modulation parameters, including modulation amplitude or bias, based on the number of interrupts, with the assignment operation completed by table lookup or calculation, so that the modulation signal adapts to the change of the laser gyroscope's operating point; verifying whether the DC modulation cycle is valid, wherein the DC modulation cycle is based on a 200Hz frequency and has a duration of 5ms, and the determination is made by checking the current frequency using a software flag or timer. The system checks whether the current time step is within the valid window. If the DC modulation period condition is met, the DC modulation phase data assigned in step S3 is normalized using the normalization formula: Normalized phase = (DC modulation phase - minimum phase) / (maximum phase - minimum phase), where the minimum and maximum phase values ​​are calibrated according to the characteristics of the laser gyroscope. After normalization, the data is scaled to the standard range of 0-1. If the condition is not met, the control flow returns to step S3 and continues to execute the 5kHz interrupt count. The normalized phase data is temporarily stored in the microcontroller's memory as the direct input for subsequent PID control.

[0017] Preferably, the control process performs PID control on the normalized phase, including: S71, in the feedback loop of step S7, the control process adds a function to record the average optical power; after each AC optical intensity sampling, the DC optical intensity signal is extracted, the current moving average is calculated using the sliding window averaging method, and stored in non-volatile memory with a 24-hour cycle, while recording the cumulative running time of the gyroscope to construct an optical power-time decay curve; S72, historical decay data is read, the decay trend is fitted using an exponential fitting algorithm, the λ value is optimized using the least squares method, and the optical power decay trajectory for the next 30 days is predicted; S73, the predicted optical power decay value is converted into a target phase correction amount, and before executing step S5, the target reference value of the normalized phase is adjusted from a fixed value to a fixed value plus the target phase correction amount; wherein, the formula for calculating the target phase correction amount is: P pred P is the predicted value. nom S74 represents the rated optical power, and K represents the calibration coefficient. The control process switches to calibration mode, compares the light source with the built-in standard light source, and measures the actual attenuation error. S75 monitors the attenuation rate change in real time. If accelerated attenuation is detected, a warning signal is triggered to indicate that the optical components may need to be maintained or replaced.

[0018] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0019] By employing coordinated sampling with 80kHz and 5kHz interrupts, the phase of the AC light intensity from the laser gyroscope is dynamically extracted and normalized. Combined with PID control, precise adjustment of the frequency-stabilized drive voltage is achieved, forming a closed-loop control cycle. This scheme effectively improves frequency stabilization accuracy and dynamic response speed, enhances anti-interference capability, ensures stable and reliable laser gyroscope output, and achieves high-precision, high-stability phase locking and voltage control, making it suitable for demanding frequency stabilization scenarios.

[0020] By introducing an adaptive compensation mechanism for long-term optical power attenuation, the problem of frequency reference drift caused by aging during the lifespan of laser gyroscopes is effectively solved. This scheme significantly improves long-term frequency stabilization accuracy by dynamically adjusting the target phase through real-time monitoring and prediction models, and extends the gyroscope's lifespan with the help of early warning functions. At the same time, its adaptive design enhances the reliability of the system in long-term operation, supports unattended applications, and provides a low-cost, low-maintenance solution for high-precision navigation. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating a DC frequency stabilization control method for a laser gyroscope according to an embodiment of the present invention. Detailed Implementation

[0022] To facilitate understanding of the present invention, a more complete description of this application will be given below with reference to the accompanying drawings, which illustrate preferred embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough and complete understanding of the disclosure of the present invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] Example 1: Figure 1 This is a flowchart illustrating a DC frequency stabilization control method for a laser gyroscope according to an embodiment of the present invention.

[0025] like Figure 1 As shown, a DC frequency stabilization control method for a laser gyroscope includes the following steps:

[0026] S1, after the frequency stabilization start command is triggered, the control process starts immediately; when the 80kHz interrupt occurs, the microcontroller acquires the AC light intensity signal of the laser gyroscope; and calculates the multiplication accumulator value of the current AC light intensity and the current modulation information value to extract the phase information.

[0027] Among them, the AC light intensity signal is obtained by conversion by a photodiode and processing by a circuit.

[0028] Specifically, when the "frequency stabilization start" command is triggered, the control flow is immediately initialized. This marks the start of the DC frequency stabilization closed-loop control, and the microcontroller enters a ready state, waiting for interrupt events.

[0029] The control flow continuously monitors for an 80kHz timer interrupt (occurring 80,000 times per second, or once every 12.5 microseconds). When an interrupt occurs, the flow pauses the current task and prioritizes the sampling operation.

[0030] The AC light intensity signal of the laser gyroscope is acquired in real time by an analog-to-digital converter (ADC) of a microcontroller. This signal is obtained by detecting the optical power by a photodiode, and then processed by transimpedance amplification, DC blocking, and bandpass filtering circuits, and is expressed in voltage form (referred to as "AC light intensity" in the document).

[0031] The current modulation information value is read synchronously. This value comes from the DC modulation process (such as the modulation parameters of the frequency stabilization drive voltage) and is a dynamically updated reference signal used for phase extraction.

[0032] The product of the current AC optical intensity value and the current modulation information value is calculated and accumulated in the multiplier-accumulator. The formula is as follows: Multiplier-accumulator value = Accumulated sum (current AC optical intensity × current modulation information value), where the current AC optical intensity is the instantaneous voltage value collected by the microcontroller during the 80kHz interrupt, and the unit can be volts (V), representing the AC component of the optical power. The current modulation information value is a reference value from the DC modulation stage, which is dimensionless and used for modulation and demodulation. This operation is performed once in each 80kHz interrupt, and the multiplier-accumulator is updated with the number of interrupts, aiming to extract the phase information (i.e., the relative phase difference of the optical power modulation state) from the AC optical intensity.

[0033] The accumulated value is stored temporarily in the microcontroller's memory as an intermediate result, providing a data basis for subsequent steps (such as the period determination in step B). The purpose of phase extraction is to identify whether the laser gyroscope is operating near the point of maximum optical power.

[0034] S2, after completing the multiplication and accumulation calculation in step S1, the control flow executes to determine whether the DC modulation period is valid; if the condition is valid (currently within the DC modulation period), then it further determines whether the 80kHz interrupt has occurred 16 times; if the condition is not valid, the control flow returns to S1 and continues to execute the 80kHz interrupt sampling.

[0035] Specifically, after calculating the multiply-accumulator value (used for phase extraction) in step S1, the control flow immediately proceeds to step S2. At this time, the multiply-accumulator value is temporarily stored in the microcontroller's memory as the data basis for the S2 decision.

[0036] The control flow checks the condition "whether the DC modulation period is valid". Condition definition: The DC modulation period is a predefined timing window representing the effective range of the laser gyroscope's DC modulation activity. According to Section 4 of the document, the DC modulation frequency is 200Hz, therefore the duration of each modulation period is 5 milliseconds (period = 1 / 200Hz). The judgment logic, based on a time counter or software flag, checks whether the current moment is within this 5-millisecond period. Threshold reference: The threshold is indirectly defined by time, i.e., a period length of 5 milliseconds. In actual implementation, the periodic signal can be generated through the microcontroller's timer module, or indirectly derived through interrupt counting (such as an 80kHz interrupt). This judgment aims to ensure that phase processing only occurs within a meaningful time window, avoiding invalid calculations.

[0037] When the condition is met, a sub-judgment verifies the number of 80kHz interrupts. If the DC modulation cycle condition is met (currently within a 5ms modulation window), the control flow further determines whether "16 80kHz interrupts have occurred." An 80kHz interrupt occurs once every 12.5 microseconds, and 16 interrupts correspond to a time span of 16 × 12.5 microseconds = 0.2 milliseconds. This judgment is implemented using a counter to check whether the cumulative number of 80kHz interrupts since the start of the current modulation cycle has reached 16. The threshold is 16, a fixed value based on the descriptions in steps B and C of Section 6 of the document (16 80kHz interrupts represent a complete DC modulation data acquisition sub-cycle). The formula is as follows: Interrupt Count Threshold = 16, where the interrupt count threshold is dimensionless and represents the cumulative number of 80kHz interrupts, used to define the integrity of data acquisition. This verification ensures that the phase data has sufficient sample points (16 samples), improving the accuracy of subsequent processing.

[0038] If the condition is not met, the process returns. If the DC modulation period condition is not met (currently outside the modulation period), the control flow does not perform further judgment and directly returns to step S1 to continue 80kHz interrupt sampling. This avoids unnecessary operations during inactive periods and saves computational resources.

[0039] If the DC modulation period condition is met and 16 80kHz interrupts have occurred, the control flow proceeds to step S3 (multiplying the accumulated value, assigning the value, and clearing it). If only the period condition is met but the number of interrupts has not reached 16, the flow may wait for subsequent interrupts (this is not explicitly stated in the documentation, but logically it should return to sampling or wait). The overall branch logic ensures that the phase assignment step can only proceed when the modulation period is valid and the data acquisition is complete.

[0040] The DC modulation cycle frequency is 200Hz with a period of 5 milliseconds, and the judgment is based on time or software flags. The threshold for the number of interrupts at 80kHz is 16, corresponding to a 0.2 millisecond time window, used for data integrity verification.

[0041] S3, when the condition in S2 that the 80kHz interrupt has occurred 16 times is met (representing the completion of a complete DC modulation cycle data acquisition), the control flow executes to assign the multiply-accumulate value to the DC modulation phase and clear the multiply-accumulate value to zero; at the same time, the control flow waits for the 5kHz interrupt to occur, and when the 5kHz interrupt is triggered, it counts the number of 5kHz interrupts.

[0042] Specifically, the control flow awaits the result of step S2. When the condition "16 interrupts occurred at 80kHz" in S2 is met (representing the completion of a full DC modulation cycle data acquisition, i.e., 16 samples were acquired within 0.2 milliseconds), the flow immediately proceeds to operation S3. This condition is based on a fixed threshold: the number of interrupts must precisely reach 16 to ensure data integrity.

[0043] The multiply-accumulate value (from the accumulation result in step S1) temporarily stored in the microcontroller's memory is assigned to the "DC modulation phase" variable. This variable is a software-defined storage unit used to store the phase information within the current modulation cycle, serving as direct input for subsequent normalization processing (step S4). The assignment operation ensures that the phase data is transferred from the temporary accumulator to the persistent variable.

[0044] Immediately after the assignment is complete, the multiply-accumulator is reset to zero. This zeroing operation prepares for the next DC modulation cycle, preventing old data from interfering with the accumulation of the new cycle and ensuring the real-time performance and accuracy of phase extraction.

[0045] The control flow enters an idle state, continuously listening for a 5kHz timer interrupt (frequency 5,000 times / second, i.e., once every 0.2 milliseconds). The 5kHz interrupt works in conjunction with the 80kHz interrupt, but at a lower frequency, for macroscopic coordination of modulation timing.

[0046] When a 5kHz interrupt occurs, the process counts the number of interrupts. The counting operation is implemented through the microcontroller's counter module, and the accumulated value is used to track the modulation timing, providing a reference for the "DC modulation value assignment" in step S4 (such as dynamically adjusting the modulation parameters based on the count value).

[0047] S4: Based on the count of 5kHz interrupts in S3, the control flow executes the DC modulation value assignment, dynamically assigning DC modulation parameters (such as modulation amplitude or bias); the control flow again judges whether the DC modulation period is valid. If the condition is valid, the DC modulation phase data assigned in S3 is normalized (converted to a standard range, such as 0-1); if the condition is not valid, the control flow returns to S3 and continues to execute the 5kHz interrupt count.

[0048] Specifically, the control flow obtains the cumulative number of 5kHz interrupts in step S3. This number is implemented through a microcontroller counter, representing the frequency of interrupt occurrences since the start of the current DC modulation cycle, and is used for assigning modulation parameters.

[0049] Based on the 5kHz interrupt counting results, DC modulation parameters, such as modulation amplitude or bias, are dynamically assigned. This assignment is done through table lookup or calculation; for example, the counting results are mapped to predefined parameter curves to ensure that the modulation characteristics of the frequency-stabilized drive voltage match the operating point of the laser gyroscope. This step allows the modulation signal to adapt to changes, improving control flexibility.

[0050] The control flow verifies whether the DC modulation period is valid. The condition is based on a time window: the DC modulation frequency is 200Hz (Section 4 of the document), and each cycle lasts 5ms. The decision is made by checking, via a software flag or timer, whether the current moment falls within this 5ms valid window. The 5ms cycle length is a fixed threshold; it can be indirectly derived from an 80kHz interrupt (e.g., 400 80kHz interrupts correspond to 5ms), but the document explicitly uses the DC modulation period as the condition benchmark. This decision aims to avoid invalid operations during inactive periods, ensuring that normalization is only performed when the data is valid.

[0051] If the DC modulation cycle condition is met, the control flow normalizes the "DC modulation phase" data assigned in step S3. Normalization converts the original phase value into a standard range (e.g., 0-1), eliminating the influence of dimensions and facilitating stable operation of the PID algorithm. The formula is as follows: Normalized phase = (DC modulation phase - minimum phase value) / (maximum phase value - minimum phase value), where the DC modulation phase is the phase variable from step S3, representing the phase information of the current modulation cycle, and the unit can be a dimensionless relative value. The minimum phase value is the expected lower limit of the phase data, which needs to be calibrated according to the characteristics of the laser gyroscope, for example, determined through historical data statistics. The maximum phase value is the expected upper limit of the phase data, also based on the calibration data. After normalization, the data is scaled to the [0,1] interval, improving the versatility of subsequent control.

[0052] If the condition is not met, the process returns. If the DC modulation period condition is not met, the control flow does not perform normalization and directly returns to step S3 to continue executing the 5kHz interrupt counting. This ensures efficient resource utilization and avoids unnecessary calculations.

[0053] The normalized phase data is temporarily stored in the microcontroller's memory and serves as the direct input to step S5 (PID control). The entire process ensures that the phase information is standardized before entering the control algorithm.

[0054] S5. After phase normalization in S4 is completed, the control flow performs PID control (proportional-integral-derivative algorithm) on the normalized phase, calculates the adjustment amount based on the phase deviation, and outputs a control signal to correct the frequency-stabilized drive voltage.

[0055] Specifically, the control flow obtains normalized phase data from step S4. This data has been converted to a standard range (e.g., 0-1), eliminating dimensional effects and providing a stable input for PID control.

[0056] Determine the deviation between the normalized phase and the ideal operating point. The ideal operating point corresponds to the state of maximum optical power (referred to as the longitudinal mode point in the document), and the deviation value represents the difference between the current phase and the target, used to quantify control requirements.

[0057] Proportional-integral-derivative (PID) control is applied to address phase deviation. The PID algorithm outputs a control signal to dynamically correct the frequency-stabilized drive voltage. The formula can be simplified as: Control signal = Kp × Error + Ki × Error integral + Kd × Error derivative. Here, the error is the deviation of the normalized phase from the ideal value and is dimensionless. The ideal value is typically set to 0.5 (representing the midpoint of the standard range), but needs to be calibrated according to the characteristics of the laser gyroscope. Kp (proportional gain) adjusts the response speed; a larger value results in a faster response but may cause oscillations. The reference range needs to be adjusted experimentally, usually starting from 0.1. Ki (integral gain) eliminates steady-state error, calculated by accumulating historical errors. An excessively large value may lead to overshoot; the reference range is relatively small, such as 0.001-0.1. Kd (derivative gain) suppresses oscillations, calculated by the error change rate. An excessively large value may amplify noise; the reference range needs to balance stability, such as 0.01-0.5. The gain parameters Kp, Ki, and Kd need to be optimized for the dynamic characteristics of the laser gyroscope in practical applications.

[0058] The PID control result is temporarily stored as an adjustment value in the microcontroller's memory, awaiting synthesis with the DC modulation value from S4 (step S6). This signal is directly related to the correction amount of the frequency-stabilized drive voltage.

[0059] S6, the control process adds the DC modulation value of S4 and the PID control result of S5, assigns it to the frequency-stabilized drive voltage, generates the final voltage value, and outputs it to the hardware circuit through digital-to-analog conversion.

[0060] Specifically, the control flow obtains the DC modulation value from step S4. This value is a dynamically assigned modulation parameter (such as modulation amplitude or bias) generated based on the 5kHz interrupt count result. Simultaneously, it obtains the PID control result from step S5. This result is the adjustment amount calculated based on the normalized phase, representing the compensation signal for the phase deviation. Both are temporarily stored in the microcontroller's memory as the basis for synthesis in step S6.

[0061] The DC modulation value and the PID control result are added together to generate a composite signal. The formula is as follows: Stable frequency drive voltage = DC modulation value + PID control result. The DC modulation value is the parameter assigned in step S4, representing the reference component of the modulation signal. Its unit can be volts (V) or dimensionless, depending on the hardware calibration, and it is used to maintain modulation characteristics. The PID control result is the control output from step S5, representing the adjustment calculated by the proportional-integral-derivative algorithm. Its unit is consistent with the DC modulation value to ensure computational compatibility, and it is used to dynamically compensate for phase deviation. The addition operation aims to integrate the modulation effect and intelligent adjustment, enabling the stable frequency drive voltage to adapt to changes in the laser gyroscope's operating point while eliminating errors in real time.

[0062] The calculated sum is assigned to the "Stable Frequency Drive Voltage" variable. This variable is a storage unit defined in the microcontroller used to temporarily store the final drive signal, ensuring that the data is correctly saved before output.

[0063] The control flow calls a digital-to-analog converter (DAC) to convert the digital value of the frequency-stabilized drive voltage into an analog voltage signal. The converted analog signal is output to the drive circuit (such as an amplifier) ​​of the laser gyroscope, directly affecting the gas laser and influencing its optical power state.

[0064] After the output is completed, the control flow automatically switches to step S7 (feedback and loop). The frequency-stabilized drive voltage is fed back to the DC light intensity through the circuit, which in turn affects the AC light intensity, forming a closed loop.

[0065] S7: The frequency-stabilized drive voltage is fed back to the DC light intensity (affecting the laser gyroscope's optical power) through the circuit. The DC light intensity is then processed by circuits such as DC blocking amplification and bandpass filtering to obtain the AC light intensity. The control flow automatically returns to S1 to continue executing 80kHz interrupt sampling, forming a continuous control loop.

[0066] Specifically, the control process outputs the frequency-stabilized drive voltage (analog signal) generated in step S6 to the drive circuit of the laser gyroscope. This voltage directly acts on the gas laser, affecting electron energy transitions and thus changing the optical power state. The feedback loop adjusts the DC light intensity (a negative voltage signal characterizing optical power) accordingly, ensuring that the operating point approaches the longitudinal mode point.

[0067] The DC light intensity signal is amplified by a DC blocking circuit to remove the DC component, and then a bandpass filter circuit is used to extract specific frequency components (such as the AC component related to modulation) to finally generate an AC light intensity signal. This signal is a voltage form that can be sampled by the microcontroller, providing input for the subsequent 80kHz interrupt sampling in step S1.

[0068] After the AC light intensity signal is generated, the control flow immediately jumps back to step S1 (frequency stabilization start-up and signal acquisition) and re-executes operations such as 80kHz interrupt sampling and multiplication-accumulation value calculation. This jump is instantaneous, forming an infinite loop to ensure that the frequency stabilization control responds in real time to the dynamic changes of the laser gyroscope.

[0069] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0070] By employing coordinated sampling with 80kHz and 5kHz interrupts, the phase of the AC light intensity from the laser gyroscope is dynamically extracted and normalized. Combined with PID control, precise adjustment of the frequency-stabilized drive voltage is achieved, forming a closed-loop control cycle. This scheme effectively improves frequency stabilization accuracy and dynamic response speed, enhances anti-interference capability, ensures stable and reliable laser gyroscope output, and achieves high-precision, high-stability phase locking and voltage control, making it suitable for demanding frequency stabilization scenarios.

[0071] Example 2: In Example 1, when the abnormal probability value sequence of the electricity meter does not completely meet the judgment condition of the first threshold, the corresponding metering error value is input into the metering fault identification model of the corresponding power line group (power lines of the same type) for detection and judgment. However, the proportion of abnormal probability values ​​less than the first threshold varies greatly under different circumstances. The abnormal proportion is the result of comparing the electricity meter with multiple other electricity meters (electricity meters whose normality is unknown). Faced with metering error values ​​of different proportions (the metering difference between the electricity meter and the electricity meter that has been detected as normal), using a unified model will inevitably result in training errors and weak generalization ability. Since there are differences in the abnormal probability value sequences between abnormal electricity meters and other electricity meters on the same power line in the past, the judgment requirements for metering error values ​​will inevitably differ. In order to further refine the training of metering error values ​​and obtain more accurate detection results, it is necessary to consider the abnormal proportion of the electricity meter to be tested and the metering error value at the same time, and carry out further optimization and improvement.

[0072] In some embodiments, the control flow performs PID control on the normalized phase, and step S7 further includes:

[0073] S71, in the feedback loop of step S7, the control process adds the function of recording the average optical power; after each AC optical intensity sampling is completed, the DC optical intensity signal (negative voltage) is extracted, the current moving average is calculated using the sliding window averaging method (window size is 1000 sampling points), and stored in non-volatile memory with a period of 24 hours. At the same time, the cumulative running time of the gyroscope is recorded to construct the optical power-time decay curve.

[0074] S72 reads historical attenuation data, uses an exponential fitting algorithm to fit the attenuation trend, optimizes the λ value using the least squares method, and predicts the optical power attenuation trajectory for the next 30 days.

[0075] The formula for fitting the decay trend is P(t)=P0·e -(λt) P(t) is the predicted optical power at time t, P0 is the initial optical power, and λ is the attenuation coefficient.

[0076] S73, convert the predicted optical power attenuation value into a target phase correction amount. Before executing step S5, adjust the target reference value of the normalized phase from a fixed value to a fixed value plus the target phase correction amount.

[0077] The formula for calculating the target phase correction is as follows: P pred P is the predicted value. nom Where is the rated optical power, and K is the calibration coefficient.

[0078] S74, the control process switches to calibration mode, compares with the built-in standard light source, and measures the actual attenuation error.

[0079] The S75 monitors the attenuation rate in real time. If accelerated attenuation is detected, it triggers a warning signal indicating that the optical components may need to be maintained or replaced.

[0080] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0081] By introducing an adaptive compensation mechanism for long-term optical power attenuation, the problem of frequency reference drift caused by aging during the lifespan of laser gyroscopes is effectively solved. This scheme significantly improves long-term frequency stabilization accuracy by dynamically adjusting the target phase through real-time monitoring and prediction models, and extends the gyroscope's lifespan with the help of early warning functions. At the same time, its adaptive design enhances the reliability of the system in long-term operation, supports unattended applications, and provides a low-cost, low-maintenance solution for high-precision navigation.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for DC frequency stabilization control of a laser gyroscope, characterized in that, include: S1, after the frequency stabilization start command is triggered, the control process starts immediately; when the 80kHz interrupt occurs, the microcontroller collects the AC light intensity signal of the laser gyroscope; It also calculates the accumulator value of the current AC light intensity and the current modulation information value to extract phase information; S2, after completing the multiplication and accumulation calculation, the control flow executes to determine whether the DC modulation period is valid; if the condition is valid, it further determines whether the 80kHz interrupt has occurred 16 times; if the condition is not valid, the control flow returns to S1 and continues to execute the 80kHz interrupt sampling. S3, when the condition that the 80kHz interrupt has occurred 16 times is met, the control flow executes to assign the multiply-accumulate value to the DC modulation phase and clear the multiply-accumulate value to zero; at the same time, the control flow waits for the 5kHz interrupt to occur, and when the 5kHz interrupt is triggered, it counts the number of 5kHz interrupts. S4, based on the count of 5kHz interrupts, the control flow executes the DC modulation value assignment, dynamically assigning DC modulation parameters; the control flow again judges whether the DC modulation period is valid, and if the condition is valid, the DC modulation phase data assigned in S3 is normalized. If the condition is not met, the control flow returns to S3 and continues to execute the 5kHz interrupt counter. S5. After phase normalization is completed, the control flow performs PID control on the normalized phase, calculates the adjustment amount based on the phase deviation, and outputs a control signal to correct the frequency-stabilized drive voltage. S6, the control process adds the DC modulation value and the PID control result, assigns the value to the frequency-stabilized drive voltage, generates the final voltage value, and outputs it to the hardware circuit through digital-to-analog conversion; S7, the frequency-stabilized drive voltage is fed back to the DC light intensity through the circuit. The DC light intensity is processed by circuits such as DC blocking amplification and bandpass filtering to obtain the AC light intensity. The control flow automatically returns to S1 and continues to execute 80kHz interrupt sampling, forming a continuous control loop.

2. The laser gyroscope DC frequency stabilization control method as described in claim 1, characterized in that, The extraction of phase information includes: immediately initializing the control flow when the frequency stabilization start command is triggered; continuously monitoring the 80kHz timer interrupt, where the 80kHz interrupt occurs 80,000 times / second, i.e., once every 12.5 microseconds; when the 80kHz interrupt occurs, the analog-to-digital converter of the microcontroller acquires the AC light intensity signal of the laser gyroscope in real time. This signal is obtained by the photodiode detecting the light power, and then processed by the transimpedance amplification, DC blocking, and bandpass filtering circuits, and is expressed as a voltage; synchronously reading the current modulation information value, which comes from the DC modulation process and is a dynamically updated reference signal; calculating the product of the current AC light intensity value and the current modulation information value, and accumulating the result into the multiplier accumulator, where the current AC light intensity is the instantaneous voltage value acquired by the microcontroller during the 80kHz interrupt, in volts, representing the AC component of the light power, and the current modulation information value comes from the DC modulation stage and is dimensionless; and temporarily storing the multiplier accumulator value as an intermediate result in the microcontroller's memory to extract the phase information in the AC light intensity to identify whether the laser gyroscope is operating near the point of maximum light power.

3. The laser gyroscope DC frequency stabilization control method as described in claim 1, characterized in that, The control flow execution determines whether the DC modulation period is valid, including: after completing the multiplication and accumulation calculation, the control flow executes to determine whether the DC modulation period is valid, wherein the DC modulation period duration is 5 milliseconds, based on a 200Hz frequency; if the condition is valid, it further determines whether the 80kHz interrupt has occurred 16 times, wherein 16 80kHz interrupts correspond to a 0.2 millisecond time window, and the threshold is 16 times; if the condition is not valid, the control flow returns to execute 80kHz interrupt sampling; the phase processing is determined to be performed only within the effective range of DC modulation activity.

4. The laser gyroscope DC frequency stabilization control method as described in claim 1, characterized in that, The control process then determines whether the DC modulation cycle is valid. Specifically, when the condition that the 80kHz interrupt has occurred 16 times is met, the control process assigns the multiply-accumulate value temporarily stored in the microcontroller's memory to the DC modulation phase variable, which is used to store the phase information within the current modulation cycle; the multiply-accumulate is reset to zero to prepare for the next modulation cycle; the control process enters an idle state and continuously listens for the 5kHz timer interrupt; when the 5kHz interrupt is triggered, the number of interrupts is counted, and the accumulated value is used to track the modulation timing and provide a reference for subsequent DC modulation value assignment.

5. The laser gyroscope DC frequency stabilization control method as described in claim 4, characterized in that, The step of calculating the adjustment amount based on the phase deviation and outputting a control signal to correct the frequency-stabilized drive voltage specifically includes: acquiring the cumulative number of 5kHz interrupts, which is implemented by a microcontroller counter and represents the frequency of interrupts since the start of the current DC modulation cycle; dynamically assigning DC modulation parameters, including modulation amplitude or bias, based on the number of interrupts, with the assignment operation completed by table lookup or calculation, so that the modulation signal adapts to the change of the laser gyroscope's operating point; and verifying whether the DC modulation cycle is valid, wherein the DC modulation cycle is based on a 200Hz frequency and has a duration of 5ms, and the determination is made by checking the current time using a software flag or timer. The system checks whether the current phase is within the valid window. If the DC modulation period condition is met, the DC modulation phase data assigned in step S3 is normalized using the normalization formula: Normalized phase = (DC modulation phase - minimum phase) / (maximum phase - minimum phase), where the minimum and maximum phase values ​​are calibrated according to the characteristics of the laser gyroscope. After normalization, the data is scaled to the standard range of 0-1. If the condition is not met, the control flow returns to step S3 and continues to execute the 5kHz interrupt count. The normalized phase data is temporarily stored in the microcontroller's memory as the direct input for subsequent PID control.

6. The laser gyroscope DC frequency stabilization control method as described in claim 1, characterized in that, The control process performs PID control on the normalized phase, including: S71, adding an average optical power recording function in the feedback loop of step S7; after each AC optical intensity sampling, extracting the DC optical intensity signal, calculating the current moving average using the sliding window averaging method, and storing it in non-volatile memory with a 24-hour cycle, while recording the cumulative running time of the gyroscope to construct an optical power-time decay curve; S72, reading historical decay data, using an exponential fitting algorithm to fit the decay trend, optimizing the λ value using the least squares method, and predicting the optical power decay trajectory for the next 30 days; S73, converting the predicted optical power decay value into a target phase correction amount, adjusting the target reference value of the normalized phase from a fixed value to a fixed value plus the target phase correction amount before executing step S5; wherein, the formula for calculating the target phase correction amount is: P pred P is the predicted value. nom S74 represents the rated optical power, and K represents the calibration coefficient. The control process switches to calibration mode, compares the light source with the built-in standard light source, and measures the actual attenuation error. S75 monitors the attenuation rate change in real time. If accelerated attenuation is detected, a warning signal is triggered to indicate that the optical components may need to be maintained or replaced.

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