Compensation method for half-wave voltage temperature error of fiber-optic gyroscope

Abstract

The invention relates to the technical field of fiber-optic gyroscopes, in particular to a fiber-optic gyroscope half-wave voltage temperature error compensation method which comprises the following steps: measuring half-wave voltages of an integrated optical chip at different temperatures within a working temperature range, and establishing a first relation model representing a relation between the half-wave voltages of the integrated optical chip and an ambient temperature, establishing a second relation model representing the relation between the feedback gain coefficient and the environment temperature based on the first relation model and the digital closed-loop working principle of the fiber-optic gyroscope; determining a half-wave voltage temperature error compensation model according to the second relation model; a temperature sensor is used for measuring the environment temperature of the integrated optical chip in real time, and the average temperature in a preset compensation period is obtained; on the basis of the half-wave voltage temperature error compensation model, a compensated feedback gain is obtained according to the average temperature to adjust the fiber-optic gyroscope; according to the invention, the measurement precision of the fiber-optic gyroscope can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber optic gyroscopes, and particularly to a compensation method for the temperature error of the half-wave voltage of a fiber optic gyroscope. Background Art

[0002] A fiber optic gyroscope is an inertial sensor based on the principle of fiber optic interference and is widely used in fields such as aerospace, aviation, navigation, and precision navigation. Its working principle is to utilize the Sagnac effect to extract the phase difference between the counter-propagating light beams in the sensitive loop to measure the angular velocity along the axis of the loop space. Currently, the main factor affecting the measurement performance of fiber optic gyroscopes is still the fluctuating temperature. During the step-wave reset of a closed-loop fiber optic gyroscope, temperature fluctuations will cause fluctuations in the half-wave voltage, resulting in reset errors, thereby introducing drift errors, reset noise, and scale factor errors.

[0003] Generally, fiber optic gyroscopes utilize a digital closed-loop detection scheme to expand the measurement range and enhance the linearity of the scale factor. The closed-loop negative feedback modulation phase is generated by an integrated optical chip (IOC), which is driven by a digital step signal. Since the step signal cannot be increased or decreased infinitely, a reset will occur when the modulation phase reaches the threshold. The gain of the feedback channel is sensitive to fluctuations in the ambient temperature, which may lead to deviations in the reset phase and thus introduce errors into the detection system. The second closed-loop feedback system can effectively compensate for the influence of environmental interference on the reset error of the modulation signal. It adjusts the driving voltage of the IOC by comparing the demodulation values of two modulation half-cycles before and after the reset occurs, ensuring that the actual modulation phase is closely aligned with the ideal phase. However, this method is prone to failure in two cases. The first is that under high dynamic conditions, the modulation signal will reset frequently, which may introduce significant inaccuracies in the extraction process of the reset error itself. The second case occurs at low rotational speed inputs, where a long reset interval may lead to a decline or even failure in the tracking efficiency of the second closed-loop reset error. Due to the alternating operation of each axis, time-division multiplexing (TDM) fiber optic gyroscopes also face the problem of a long reset interval. Summary of the Invention

[0004] In view of the above problems, the present invention provides a compensation method for the temperature error of the half-wave voltage of a fiber optic gyroscope, which solves the technical problem of limited measurement accuracy of fiber optic gyroscopes in the prior art.

[0005] The present invention provides a compensation method for the temperature error of the half-wave voltage of a fiber optic gyroscope, including the following steps:

[0006] Step S1, measure the half-wave voltage of the integrated optical chip built in the fiber optic gyroscope at different temperatures within the working temperature range, and establish a first relationship model representing the relationship between the half-wave voltage of the integrated optical chip and the ambient temperature, specifically including:

[0007] Step S1-1: Apply different ambient temperatures to the optical chip based on the operating temperature range, and then use a temperature sensor to measure the half-wave voltage values of the integrated optical chip at different ambient temperatures;

[0008] Step S1-2: Take the ambient temperature as the independent variable and the half-wave voltage as the dependent variable, and obtain the functional relationship between the ambient temperature and the half-wave voltage as the first relationship model. The expression of the first relationship model is:

[0009] V 2π (T) = f(T)

[0010]

[0011] where T represents the ambient temperature, V 2π (T) represents the half-wave voltage when the ambient temperature is T, and f(T) represents the functional relationship fitted by experimental data. represents the average ambient temperature, and β0, β1,..., β n are the regression parameters obtained by experimental fitting;

[0012] Step S2: Based on the first relationship model and the digital closed-loop working principle of the fiber optic gyroscope, establish a second relationship model representing the relationship between the feedback gain coefficient and the ambient temperature; determine the half-wave voltage temperature error compensation model according to the second relationship model;

[0013] Step S3: Use a temperature sensor to measure the ambient temperature of the integrated optical chip in real time, and obtain the average temperature within a preset compensation period;

[0014] Step S4: Based on the half-wave voltage temperature error compensation model, obtain the compensated feedback gain according to the average temperature within the preset compensation period, and adjust the fiber optic gyroscope based on the compensated feedback gain to complete the compensation of the half-wave voltage temperature error.

[0015] Preferably, in step S1-1, the operating temperature range is the operating temperature range of the fiber optic gyroscope, specifically -40°C to +60°C; use a thermostat to change the temperature at a preset step within the operating temperature range and apply different ambient temperatures to the optical chip.

[0016] Preferably, step S2 specifically includes:

[0017] Step S2-1: Based on the relationship between the half-wave voltage and the ambient temperature in the first relationship model and the relationship between the half-wave voltage and the feedback gain coefficient, determine the second relationship model representing the relationship between the feedback gain coefficient and the ambient temperature;

[0018] Step S2-2: Based on the second relationship model, compensate the uncompensated digital closed-loop feedback gain term to obtain the half-wave voltage temperature error compensation model.

[0019] Preferably, step S2-1 specifically includes:

[0020] Step S2-1-1: Determine the functional expression C(·) between the half-wave voltage and the feedback gain coefficient according to the functional relationship V2π(T) between the half-wave voltage and the ambient temperature and the digital closed-loop working principle of the fiber optic gyroscope;

[0021] Step S2-1-2: Determine the functional expression between the feedback gain coefficient and the ambient temperature from the functional expression between the half-wave voltage and the feedback gain coefficient:

[0022] C(T) = c0 + c1·V 2π (T)

[0023] where C(T) represents the feedback gain compensation coefficient, and c0, c1 represent the linear relationship coefficients between the feedback gain compensation coefficient and the half-wave voltage.

[0024] Preferably, step S2-2 specifically includes:

[0025] Compensate the digital closed-loop feedback gain term based on the relationship between the feedback gain coefficient and the ambient temperature, and establish the half-wave voltage temperature error compensation model. The expression is:

[0026]

[0027] where A represents the digital closed-loop feedback gain after compensation and correction, represents the temperature compensation coefficient at temperature T at time j j case, ε represents the half-wave voltage temperature error, A' represents the closed-loop feedback gain with half-wave voltage temperature error, K pm is the phase modulation gain of the integrated optical chip, K sd is the gain of the driving amplifier, K da is the voltage conversion gain of the DAC.

[0028] Preferably, step S3 specifically includes:

[0029] Step S3-1: Set a temperature sensor in the working area of the integrated optical chip to collect the ambient temperature regularly;

[0030] Step S3-2: Obtain the temperature values of all sampling points within the preset compensation period, sum up the temperature values of all sampling points, and divide by the number of sampling points to obtain the average temperature within the preset compensation period.

[0031] Preferably, the step S4 specifically includes:

[0032] Step S4-1: Process the average temperature within the preset compensation period through the half-wave voltage temperature error compensation model to obtain the compensated feedback gain;

[0033] Step S4-2: Apply the compensated feedback gain to the digital-to-analog converter and the integrated optical chip drive circuit to generate a compensated drive signal, and apply the compensated drive signal to the fiber optic gyroscope.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] (1) By establishing an accurate relationship model between the half-wave voltage and temperature and applying it to the feedback gain compensation of the fiber optic gyroscope, the present invention realizes the accurate compensation of the reset error caused by temperature fluctuations. Dynamically adjusting the circuit gain effectively overcomes the drift of the half-wave voltage of the optical chip caused by temperature changes, thereby stabilizing the performance of the fiber optic gyroscope and improving the measurement accuracy of the gyroscope.

[0036] (2) Using the real-time measured ambient temperature, the present invention dynamically adjusts the feedback gain through a preset compensation model, effectively offsetting the adverse effects of temperature fluctuations on the performance of the fiber optic gyroscope. Therefore, compared with the traditional fixed compensation method, the method provided by the present invention has strong adaptability to the environment and can maintain the measurement accuracy of the system under both large angular velocity and small angular velocity input conditions.

[0037] (3) The present invention has strong adaptability and can therefore be widely applied to high-precision inertial navigation systems, such as aerospace and satellite navigation fields, providing an effective solution for scenarios requiring high-precision angular velocity measurement. This technology is of great significance for improving the overall performance of the navigation system and enhancing its reliability in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings are only for the purpose of illustrating specific embodiments and are not considered to be a limitation of the present invention.

[0039] Figure 1 It is a flowchart of the compensation method for the half-wave voltage temperature error of the fiber optic gyroscope provided by the present invention.

[0040] Figure 2 It is a relationship diagram between the half-wave voltage and the ambient temperature provided by the present invention.

[0041] Figure 3 It is an approximate diagram of the dynamic model of the feedback gain of the fiber optic gyroscope provided by the present invention.

[0042] Figure 4 It is a schematic diagram of adjusting the circuit gain by temperature fluctuations provided by the present invention. Detailed implementation manners

[0043] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0044] The present invention provides a method for compensating the temperature error of the half-wave voltage of a fiber optic gyroscope. This method makes full use of the relationship between temperature and modulation phase voltage, dynamically adjusts the system gain efficiently, effectively compensates for the reset error caused by temperature fluctuations, and thus significantly improves the measurement accuracy of the fiber optic gyroscope. This method can effectively overcome the problem that the second closed-loop is prone to failure under high-speed and low-speed input conditions.

[0045] In order to illustrate the effectiveness of the method proposed by the present invention, the above-mentioned technical solutions of the present invention will be described in detail below through a specific embodiment. A specific embodiment of the present invention is as Figure 1 shown, and discloses a method for compensating the temperature error of the half-wave voltage of a fiber optic gyroscope. The specific implementation steps are as follows:

[0046] Step S1: Measure the half-wave voltage of the integrated optical chip at different temperatures within the working temperature range, and establish a first relationship model representing the relationship between the half-wave voltage of the integrated optical chip and the ambient temperature.

[0047] The present invention uses an experimental method. Taking the working temperature range as the temperature range, different ambient temperatures are applied to the environment of the optical chip, and then a temperature sensor is used to measure the half-wave voltage values of the integrated optical chip at different ambient temperatures.

[0048] In some embodiments, the working temperature range is selected as the working temperature range of the fiber optic gyroscope, and can be set to -40°C to +60°C.

[0049] In some embodiments, temperature control devices such as an incubator or a temperature control platform can be used to change the temperature at a preset step within the preset working temperature range. There are already various measurement methods for the half-wave voltage of integrated optical chips in the prior art. These methods are simple, efficient and easy to apply in batches. The present invention does not limit the measurement method of the half-wave voltage of the integrated optical chip.

[0050] Using temperature as the independent variable and half-wave voltage as the dependent variable, a functional relationship between temperature and half-wave voltage is obtained as the first relationship model to accurately quantify the influence of temperature change on the modulation phase voltage. The specific expression is:

[0051] V2π (T) = f(T)

[0052] Wherein, T represents the ambient temperature, V2π(T) represents the half-wave voltage when the ambient temperature is T, and f(T) represents the functional relationship fitted by the experimental data.

[0053] In some embodiments, the present invention uses n-order linear regression to fit the above expression. The measurement results of the half-wave voltage and ambient temperature of a fiber optic gyroscope optical modulator are as follows: Figure 2 As shown, the data can be fitted using the n-order linear regression method to obtain the following functional relationship:

[0054]

[0055] in, represents the average ambient temperature, β0,β1,...,β n are the regression parameters obtained from experimental fitting.

[0056] In some embodiments, a second-order linear regression may be employed to fit the above expression.

[0057] By the above method, the present invention fits the experimental data of the half-wave voltage of the integrated optical chip at different temperatures, and obtains a first relationship model representing the relationship between the half-wave voltage of the integrated optical chip and the ambient temperature.

[0058] Step S2: establishing a second relationship model representing the relationship between the feedback gain coefficient and the ambient temperature based on the first relationship model and the digital closed-loop working principle of the fiber optic gyroscope; and determining a half-wave voltage temperature error compensation model according to the second relationship model.

[0059] The digital closed-loop system of the fiber optic gyroscope is based on the Sagnac effect and measures the angular velocity by detecting the phase change of the interference signal. The system maintains the phase zero point through the feedback mechanism to achieve high precision. The feedback gain model of the digital closed-loop system of the fiber optic gyroscope is as follows: Figure 3 As shown in the figure, the fiber optic gyroscope converts the input rotation rate Ω into a Sagnac phase difference, which is modulated by a square wave bias, converted to photoelectricity I0, and then the forward path circuit gain G and the digital integrator. The output of the measured angular rate Ω0 is obtained, and the output of the digital integrator is fed back to the input of the interferometer after digital-to-analog conversion, driving amplifier and phase modulation. The simplified calculation expression of the digital closed-loop feedback gain is: K pm K sd K da .

[0060] Among them, K pm is the phase modulation gain of the integrated optical chip, K sd is the gain of the driver amplifier, Kda is the voltage conversion gain of the DAC.

[0061] Based on the digital closed-loop working principle of the above fiber optic gyroscope, a compensation coefficient C(T) is multiplied by the closed-loop feedback gain, and it changes with the ambient temperature. The relational expression between the digital closed-loop feedback gain compensation coefficient and the half-wave voltage is:

[0062] C(T) = c0 + c1·V 2π (T)

[0063] Wherein, C(T) represents the feedback gain compensation coefficient, and c0 and c1 are used to form the linear relationship between the feedback gain compensation coefficient and the half-wave voltage.

[0064] Based on the relationship between the digital closed-loop feedback gain coefficient and the ambient temperature, the present invention compensates the closed-loop feedback channel, and establishes the half-wave voltage temperature error compensation model. The expression is:

[0065]

[0066] Wherein, ε represents the half-wave voltage temperature error, A' represents the closed-loop feedback gain with the half-wave voltage temperature error, that is: A' = A(1 + ε), A represents the closed-loop feedback gain after compensation and correction. represents the temperature compensation coefficient at the temperature of T j in the case of the j-th moment.

[0067] Through the above steps, the present invention establishes the relationship model between the feedback gain coefficient and the ambient temperature based on the relationship between the feedback gain coefficient and the half-wave voltage, and further establishes the half-wave voltage temperature error compensation model. This model can reduce the influence of temperature on the feedback gain, enhance the adaptability of the system to temperature changes, and reduce the measurement error caused thereby.

[0068] Step S3: Use a temperature sensor to measure the ambient temperature of the integrated optical chip in real time, and obtain the average temperature within a preset compensation period.

[0069] In this step, a temperature sensor is installed in the working area of the integrated optical chip to ensure that the sensor can accurately capture the change of the ambient temperature; the ambient temperature is monitored in real time by the temperature sensor, and the average ambient temperature of a certain compensation period is calculated.

[0070] In some embodiments, in order to measure the ambient temperature of the integrated optical chip, it is necessary to install a temperature sensor in the working area of the chip to monitor the ambient temperature in real time. Specifically, devices such as thermistors can be used as temperature sensors, and the thermistors are set on the substrate of the integrated optical chip.

[0071] In some embodiments, a microcontroller (MCU) or a field-programmable gate array (FPGA) can be used to obtain the temperature value output by the temperature sensor at a set sampling frequency (e.g., 1 Hz or 10 Hz). To calculate the average ambient temperature of a compensation period, the temperature values of all sampling points within this period are recorded, and all the temperature values are summed. The resulting value is the average ambient temperature of this compensation period and is used for subsequent temperature compensation algorithms. For example, if a compensation period is 100 milliseconds and the sampling frequency is 250 Hz, then 25 temperature data are collected within this period, and the sum of these 25 temperature data is used to represent the average ambient temperature within this 100 - millisecond period.

[0072] Step S4: Based on the half - wave voltage temperature error compensation model, obtain the compensated feedback gain according to the average temperature within the preset compensation period, and adjust the fiber optic gyroscope based on the compensated feedback gain to complete the compensation for the half - wave voltage temperature error.

[0073] The schematic diagram of the temperature fluctuation adjustment circuit gain of the present invention is as Figure 4 shown.

[0074] The signal collected by the photodetector undergoes amplification and filtering, analog - to - digital conversion, data sampling, and demodulation to obtain the uncompensated feedback gain; after the temperature sensor obtains the average temperature within the preset compensation period, it is processed through the half - wave voltage temperature error compensation model to obtain the compensated feedback gain. The compensated feedback gain acts on the digital - to - analog converter and the integrated optical chip driving circuit to generate a compensated driving signal, which acts on the fiber optic gyroscope to adapt to the current ambient temperature, realizes the effective compensation of the modulation phase, and outputs a high - precision angular velocity quantity.

[0075] As Figure 2 shown, the data obtained from experiments show that the relationship between the half - wave voltage and temperature is a decreasing function. If the temperature fluctuation is low, the half - wave voltage will be high, that is, the actual half - wave modulation voltage is larger than the preset value, and a larger voltage is required to adjust to the 2π phase. Therefore, it is necessary to increase the closed - loop feedback gain coefficient.

[0076] The present invention realizes the efficient compensation of the half - wave voltage temperature error of the fiber optic gyroscope by measuring and modeling the influence of the ambient temperature on the fiber optic gyroscope error, combined with real - time temperature monitoring and dynamic feedback gain adjustment. This method can effectively improve the accuracy of the fiber optic gyroscope, especially in an environment with large temperature changes, and has a wide range of application prospects.

[0077] While the specific embodiments of the present invention depict the various actions or steps in a particular order, this should be understood as requiring such actions or steps to be performed in the particular order shown or in a sequential order, or requiring all of the illustrated actions or steps to be performed to achieve the desired result. In certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although a number of specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the present disclosure. Certain features described in the context of separate embodiments may also be implemented in combination in a single implementation. Conversely, the various features described in the context of a single implementation may also be implemented separately or in any suitable sub-combination in multiple implementations.

[0078] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A compensation method for the temperature error of the half-wave voltage of an optical fiber gyroscope, characterized in that It includes the following steps: Step S1: Measure the half-wave voltage of the integrated optical chip built in the fiber optic gyroscope at different temperatures within the working temperature range, and establish a first relationship model representing the relationship between the half-wave voltage of the integrated optical chip and the ambient temperature. Specifically, it includes: Step S1-1: Apply different ambient temperatures to the optical chip based on the working temperature range, and then use a temperature sensor to measure the half-wave voltage values of the integrated optical chip at different ambient temperatures; Step S1-2: Take the ambient temperature as the independent variable and the half-wave voltage as the dependent variable, and obtain the functional relationship between the ambient temperature and the half-wave voltage as the first relationship model. The expression of the first relationship model is: V 2π (T) = f(T) where T represents the ambient temperature, V 2π (T) represents the half-wave voltage at the ambient temperature of T, and f(T) represents the functional relation fitted by experimental data, represents the average ambient temperature, and β0, β1,..., β n are regression parameters obtained by experimental fitting; Step S2: Based on the first relationship model and the digital closed-loop working principle of the fiber optic gyroscope, establish a second relationship model representing the relationship between the feedback gain coefficient and the ambient temperature; determine the half-wave voltage temperature error compensation model according to the second relationship model; Step S3: Use a temperature sensor to measure the ambient temperature of the integrated optical chip in real time, and obtain the average temperature within the preset compensation period; Step S4: Based on the half-wave voltage temperature error compensation model, obtain the compensated feedback gain according to the average temperature within the preset compensation period, and adjust the fiber optic gyroscope based on the compensated feedback gain to complete the compensation of the half-wave voltage temperature error.

2. The compensation method for the temperature error of the half-wave voltage of the fiber optic gyro according to claim 1, wherein, In step S1-1, the working temperature range is the working temperature range of the fiber optic gyroscope, specifically -40°C to +60°C; use a thermostatic chamber to change the temperature at a preset step within the working temperature range to apply different ambient temperatures to the optical chip.

3. The compensation method for the temperature error of the half-wave voltage of the fiber optic gyro according to claim 2, characterized in that The specific content of step S2 includes: Step S2-1: Based on the relationship between the half-wave voltage and the ambient temperature in the first relationship model and the relationship between the half-wave voltage and the feedback gain coefficient, determine a second relationship model representing the relationship between the feedback gain coefficient and the ambient temperature; Step S2-2: Based on the second relationship model, compensate the uncompensated digital closed-loop feedback gain term to obtain the half-wave voltage temperature error compensation model.

4. The compensation method for the temperature error of the half-wave voltage of the fiber optic gyro according to claim 3, characterized in that, The specific content of step S2-1 includes: Step S2-1-1. Determine the functional expression C(·) between the half-wave voltage and the feedback gain coefficient according to the functional relationship V 2π (T) between the half-wave voltage and the ambient temperature and the digital closed-loop working principle of the fiber optic gyroscope; Step S2-1-2: Determine the functional expression between the feedback gain coefficient and the ambient temperature from the functional expression between the half-wave voltage and the feedback gain coefficient: C(T) = c0 + c1·V 2π (T) Where, C(T) represents the feedback gain compensation coefficient, and c0, c1 represent the linear relationship coefficients between the feedback gain compensation coefficient and the half-wave voltage.

5. The compensation method for the temperature error of the half-wave voltage of the fiber optic gyro according to claim 4, wherein, The specific content of step S2-2 includes: Based on the relationship between the feedback gain coefficient and the ambient temperature, compensate the digital closed-loop feedback gain term, and establish the half-wave voltage temperature error compensation model, the expression of which is: Wherein, A represents the digital closed-loop feedback gain after compensation and correction, represents the temperature compensation coefficient at temperature T at the j-th moment, ε represents the half-wave voltage temperature error, A' represents the closed-loop feedback gain with half-wave voltage temperature error, K j is the phase modulation gain of the integrated optical chip, K pm is the gain of the drive amplifier, K sd is the voltage conversion gain of the DAC. da ​ 6. The compensation method for the temperature error of the half-wave voltage of the fiber optic gyro according to claim 5, characterized in that The specific content of step S3 includes: Step S3-1: Set a temperature sensor within the working area of the integrated optical chip to collect the ambient temperature regularly; Step S3-2: Obtain the temperature values of all sampling points within the preset compensation period, sum up the temperature values of all sampling points, and divide by the number of sampling points to obtain the average temperature within the preset compensation period.

7. The compensation method for the temperature error of the half-wave voltage of the fiber optic gyro according to claim 6, wherein The specific content of step S4 includes: Step S4-1: Process the average temperature within the preset compensation period through the half-wave voltage temperature error compensation model to obtain the compensated feedback gain; Step S4-2: Apply the compensated feedback gain to the digital-to-analog converter and the integrated optical chip drive circuit to generate a compensated drive signal, and apply the compensated drive signal to the fiber optic gyroscope.

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