Temperature compensation type optical fiber speckle displacement sensor

Abstract

The invention discloses a temperature compensation type optical fiber speckle displacement sensor, relates to the technical field of optical measurement, and solves the technical problem that the application of the optical fiber speckle displacement sensor in a high-temperature-difference environment is limited due to the fact that speckle changes caused by displacement and temperature are often difficult to effectively distinguish in the prior art. The method comprises the steps of obtaining a plurality of speckle data at a standard environment temperature T; generating speckle variation according to the environment temperature of the reference channel and the speckle data; generating measurement speckle data of the measurement channel according to the speckle variation and the speckle data of the measurement channel; generating displacement according to the measured speckle data; the alarm signal is generated according to the speckle data, the reference channel is designed to monitor the change of the ambient temperature to the speckle pattern, and the speckle pattern of the sensor is updated through the change of the speckle pattern of the reference channel, so that the measurement accuracy of the sensor is prevented from being reduced due to the change of the ambient temperature, and meanwhile, the application range of the optical fiber speckle displacement sensor is wider.

Description

Technical Field

[0001] The present application belongs to the field of optical measurement technology, and specifically is a temperature compensated optical fiber speckle displacement sensor. Background Art

[0002] A sensor is a device that converts non-electrical parameters into measurable electrical signals. It converts specific measured signals into usable signals according to certain rules through sensitive elements and conversion elements, and outputs them to meet the requirements of information transmission, processing, recording, display and control. Sensors can sense physical quantities such as force, temperature, light, sound, chemical composition, etc., and can convert these physical quantities into electrical quantities such as voltage and current or into the on-off state of a circuit according to certain rules. Fiber optic speckle displacement sensor is a displacement measurement device based on the laser speckle effect, which can be applied to industrial automation, structural health monitoring and precision manufacturing.

[0003] However, changes in ambient temperature can lead to slight changes in the optical path length inside the optical fiber, which in turn causes the speckle pattern to drift or deform, seriously affecting the accuracy and stability of the measurement results. Existing technologies often have difficulty effectively distinguishing between speckle changes caused by displacement and speckle changes caused by temperature changes, which limits the application of fiber optic speckle displacement sensors in high temperature difference environments. Therefore, further improvements are still needed for fiber optic speckle displacement sensors. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems existing in the prior art; to this end, the present application proposes a temperature-compensated optical fiber speckle displacement sensor to solve the technical problem that the prior art often finds it difficult to effectively distinguish between speckle changes caused by displacement and temperature, which limits the application of optical fiber speckle displacement sensors in high temperature difference environments.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a temperature-compensated optical fiber speckle displacement sensor, comprising: a data acquisition device, a data analysis device, an early warning device and a data storage device;

[0006] The data acquisition device: acquires the ambient temperature, displacement data and speckle data through the data acquisition device;

[0007] The data analysis device: acquires a number of speckle data under a standard ambient temperature T; generates a speckle variation according to the ambient temperature and speckle data of a reference channel; generates measured speckle data of a measuring channel according to the speckle variation and the speckle data of a measuring channel; generates a displacement according to the measured speckle data; and generates an alarm signal according to the speckle data;

[0008] The early warning device: gives a prompt according to the alarm signal and contacts the management personnel.

[0009] Through the above steps, the present application introduces a reference channel to obtain the speckle pattern changes caused by temperature, obtains the final speckle pattern of the sensor according to the speckle pattern at the current temperature of the sensor and the speckle pattern changes, realizes temperature compensation of the optical fiber speckle displacement sensor, and makes the application range of the optical fiber speckle displacement sensor wider.

[0010] Furthermore, generating the speckle variation according to the ambient temperature and speckle data of the reference channel includes:

[0011] Real-time acquisition of the ambient temperature T of the reference channel and the intensity distribution I of the speckle pattern in the corresponding speckle data CKT (x, y) and standard ambient temperature BT and the intensity distribution of the speckle pattern in the corresponding speckle data I CKBT (x, y);

[0012] By the formula ΔI=I CKT (x, y)-I CKBT (x, y) Calculate the speckle variation ΔI in the reference channel.

[0013] Further, generating the measured speckle data of the measurement channel according to the speckle variation and the speckle data of the measurement channel includes:

[0014] Obtain the speckle variation ΔI of the reference channel and the light intensity distribution I of the speckle pattern in the speckle data of the measurement channel at ambient temperature T CLT (x, y);

[0015] By formula I CLBT (x, y) = I CLT (x, y)-ΔI calculates the light intensity distribution I of the speckle pattern in the measurement channel at standard ambient temperature CLBT (x, y).

[0016] Furthermore, generating the displacement according to the measured speckle data includes:

[0017] Obtaining the light intensity distribution of the speckle pattern in the measured speckle data;

[0018] The light intensity distribution is input into a displacement calibration model to obtain a displacement; the displacement calibration model is constructed through an artificial intelligence model.

[0019] Furthermore, the displacement calibration model is constructed by an artificial intelligence model, including:

[0020] Obtaining several historical light intensity distributions and their corresponding displacements;

[0021] Dividing a number of historical light intensity distributions and their corresponding displacements into training data, verification data, and test data; performing data preprocessing on the training data, verification data, and test data to obtain a training set, a verification set, and a test set;

[0022] Select an AI model as the base model;

[0023] Train the basic model with the training set, and adjust the learning rate and hyperparameters on the validation set to obtain the pre-trained model;

[0024] By verifying the pre-trained model on the test set, we finally obtain a displacement calibration model whose input is light intensity distribution and output is displacement.

[0025] Further, generating an alarm signal according to the speckle data includes:

[0026] The ambient temperature T of the reference channel and the intensity distribution I of the speckle pattern in the corresponding speckle data are obtained several times within the time period SJ. CK (x, y);

[0027] By formula ΔI CKs =I CKs (x, y)-I CK(s-1) (x, y) calculates the change ΔI of the light intensity distribution of the reference channel in the time period SJ CK ;

[0028] By the formula ΔT s =T s -T s-1 Calculate the change ΔT of the ambient temperature of the reference channel in the time period SJ s ; Wherein, s = 1, 2, ..., S; S represents the total number of times data is collected in SJ;

[0029] Determine whether the absolute value of the light intensity distribution change is greater than the light intensity change threshold;

[0030] Yes, when the absolute value of the ambient temperature change is greater than the temperature change threshold, no operation is performed; otherwise, a reference channel fault alarm signal is generated;

[0031] No, do nothing.

[0032] Compared with the prior art, the present application has the following beneficial effects: by acquiring a number of speckle data under a standard ambient temperature T; generating a speckle variation according to the ambient temperature and speckle data of a reference channel; generating measured speckle data of a measurement channel according to the speckle variation and the speckle data of the measurement channel; generating a displacement according to the measured speckle data; generating an alarm signal according to the speckle data, designing a reference channel to monitor the change of the speckle pattern due to the ambient temperature, updating the speckle pattern of the sensor according to the change of the reference channel speckle pattern, thereby avoiding the reduction of the measurement accuracy of the sensor due to the change of the ambient temperature, and making the application range of the optical fiber speckle displacement sensor wider. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 This is a schematic diagram of the principle of a temperature-compensated optical fiber speckle displacement sensor of the present application;

[0035] Figure 2 This is a flow chart of a temperature-compensated optical fiber speckle displacement sensor method of the present application. DETAILED DESCRIPTION

[0036] The technical solution of the present application will be described clearly and completely in conjunction with the embodiments below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0037] See also Figure 1-Figure 2 , the first aspect of the present application provides a temperature-compensated optical fiber speckle displacement sensor, including: a data acquisition device, a data analysis device, an early warning device and a data storage device;

[0038] Data acquisition device: obtain ambient temperature, displacement data and speckle data through data acquisition equipment; the data acquisition equipment includes cameras and temperature sensors, etc.;

[0039] Data analysis device: obtains a number of speckle data under a standard ambient temperature T; generates a speckle variation according to the ambient temperature and speckle data of a reference channel, the speckle variation refers to the variation of the light intensity distribution of a speckle pattern; generates measured speckle data of a measurement channel according to the speckle variation and the speckle data of a measurement channel, the measured speckle data refers to the speckle data after temperature compensation of the sensor; generates a displacement according to the measured speckle data, the displacement refers to the displacement value of the sensor; generates an alarm signal according to the speckle data; the value of the standard ambient temperature T is set according to experience, and in this embodiment, T is set to 25°C;

[0040] Early warning device: Prompts are given based on alarm signals and management personnel are contacted; alarm signals include reference channel failure alarm signals, etc.

[0041] In this embodiment, when collecting speckle data, two cameras are used to collect data from different channels respectively; in another embodiment, the same camera is used to monitor the speckle patterns of two channels, reducing the number of cameras used and increasing the compactness of the system.

[0042] In this embodiment, generating the speckle variation according to the ambient temperature and speckle data of the reference channel includes:

[0043] Real-time acquisition of the ambient temperature T of the reference channel and the intensity distribution I of the speckle pattern in the corresponding speckle data CKT (x, y) and standard ambient temperature BT and the intensity distribution of the speckle pattern in the corresponding speckle data I CKBT (x, y);

[0044] By the formula ΔI=I CKT (x, y)-I CKBT (x, y) calculates the speckle variation ΔI in the reference channel; the greater the difference in light intensity distribution between the ambient temperature T and the standard ambient temperature BT in the reference channel, the greater the absolute value of the speckle variation in the reference channel.

[0045] In this embodiment, a reference channel is designed. The structure of the reference channel and the sensor are completely consistent. The optical fiber of the reference channel is in a straightened state without obvious bending. Therefore, the speckle pattern of the reference channel will be affected by temperature. The influence is compensated in the sensor, thereby improving the application temperature range of the optical fiber speckle displacement sensor.

[0046] In this embodiment, generating the measured speckle data of the measurement channel according to the speckle variation and the speckle data of the measurement channel includes:

[0047] Obtain the speckle variation ΔI of the reference channel and the light intensity distribution I of the speckle pattern in the speckle data of the measurement channel at ambient temperature T CLT (x, y); the measurement channel is the location of the multimode optical fiber in the sensor, and the speckle pattern obtained by the measurement channel is the speckle pattern obtained by the sensor;

[0048] By formula I CLBT (x, y) = I CLT (x, y)-ΔI calculates the light intensity distribution I of the speckle pattern in the measurement channel at standard ambient temperature CLBT (x, y); when ΔI is determined, I CLBT (x, y) with I CLT increases with the increase of (x, y).

[0049] In this embodiment, generating the displacement according to the measured speckle data includes:

[0050] Obtaining the light intensity distribution of the speckle pattern in the measured speckle data;

[0051] The light intensity distribution is input into the displacement calibration model to obtain the displacement; the displacement calibration model is constructed through an artificial intelligence model.

[0052] The displacement calibration model in this embodiment is constructed by an artificial intelligence model, including:

[0053] Obtaining several historical light intensity distributions and their corresponding displacements;

[0054] Dividing a number of historical light intensity distributions and their corresponding displacements into training data, verification data, and test data; performing data preprocessing on the training data, verification data, and test data to obtain a training set, a verification set, and a test set;

[0055] Select an artificial intelligence model as the basic model; the artificial intelligence model includes a convolutional neural network model, etc.; the ratio between the training set, test set, and validation set is 7:2:1;

[0056] Train the basic model with the training set, and adjust the learning rate and hyperparameters on the validation set to obtain the pre-trained model;

[0057] By verifying the pre-trained model on the test set, we finally obtain a displacement calibration model whose input is light intensity distribution and output is displacement.

[0058] In this embodiment, generating an alarm signal according to the speckle data includes:

[0059] The ambient temperature T of the reference channel and the intensity distribution I of the speckle pattern in the corresponding speckle data are obtained several times within the time period SJ. CK (x, y); the time period SJ is set according to experience;

[0060] By formula ΔI CKs =I CKs (x, y)-I CK(s-1) (x, y) calculates the change ΔI of the light intensity distribution of the reference channel in the time period SJ CK ;

[0061] By the formula ΔT s =T s -T s-1 Calculate the change ΔT of the ambient temperature of the reference channel in the time period SJ s ; Wherein, s = 1, 2, ..., S; S represents the total number of times data is collected in SJ;

[0062] Determine whether the absolute value of the light intensity distribution change is greater than the light intensity change threshold; the light intensity change threshold is set based on experience;

[0063] Yes, when the absolute value of the ambient temperature change is greater than the temperature change threshold, no operation is performed; otherwise, a reference channel fault alarm signal is generated; the temperature change threshold is set based on experience;

[0064] No, do nothing.

[0065] This embodiment determines the change of the speckle pattern in the reference channel and compares it with the ambient temperature. When the ambient temperature changes slightly but the speckle pattern changes significantly, a fiber optic failure may occur in the reference channel. An early warning operation is performed to ensure the normal operation and measurement accuracy of the fiber optic speckle displacement sensor.

[0066] In this embodiment, a wide-bandwidth fiber laser is used for laser generation; in another embodiment, a narrow-bandwidth fiber laser and a visible light semiconductor laser may be used to replace the wide-bandwidth fiber laser to further increase the sensing sensitivity.

[0067] Part of the data in the above formula is calculated by removing the dimension and taking its numerical value. The formula is a formula closest to the actual situation obtained by software simulation of a large amount of collected data; the preset parameters and preset thresholds in the formula are set by technical personnel in this field according to actual conditions or obtained through simulation of a large amount of data.

[0068] The working principle of the present application is as follows: by acquiring ambient temperature, displacement data and speckle data; acquiring a number of speckle data under a standard ambient temperature T; generating a speckle variation according to the ambient temperature and speckle data of a reference channel; generating measured speckle data of a measurement channel according to the speckle variation and the speckle data of the measurement channel; generating a displacement according to the measured speckle data; generating an alarm signal according to the speckle data; making a prompt according to the alarm signal and contacting the management personnel, designing a reference channel to monitor the change of the speckle pattern due to the ambient temperature, updating the speckle pattern of the sensor according to the change of the reference channel speckle pattern, avoiding the reduction of the measurement accuracy of the sensor due to the change of the ambient temperature, and making the application range of the optical fiber speckle displacement sensor wider, avoiding the problem that the prior art is often difficult to effectively distinguish the speckle changes caused by displacement and temperature, which limits the application of the optical fiber speckle displacement sensor in high temperature difference environments.

[0069] The above embodiments are only used to illustrate the technical method of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical method of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present application.

Claims

1. A temperature-compensated optical fiber speckle displacement sensor, characterized in that: include: Data collection device, data analysis device, early warning device and data storage device; The data acquisition device: acquires the ambient temperature, displacement data and speckle data through the data acquisition device; The data analysis device: acquires a number of speckle data under a standard ambient temperature T; generates a speckle variation according to the ambient temperature and speckle data of a reference channel; generates measured speckle data of a measuring channel according to the speckle variation and the speckle data of a measuring channel; generates a displacement according to the measured speckle data; and generates an alarm signal according to the speckle data; The early warning device: gives a prompt according to the alarm signal and contacts the management personnel.

2. The temperature-compensated optical fiber speckle displacement sensor according to claim 1, characterized in that: The step of generating the speckle variation according to the ambient temperature and speckle data of the reference channel comprises: Real-time acquisition of the ambient temperature T of the reference channel and the intensity distribution I of the speckle pattern in the corresponding speckle data CKT (x, y) and standard ambient temperature BT and the intensity distribution of the speckle pattern in the corresponding speckle data I CKBT (x, y); By the formula ΔI=I CKT (x, y)-I CKBT (x, y) Calculate the speckle variation ΔI in the reference channel.

3. The temperature-compensated optical fiber speckle displacement sensor according to claim 1, characterized in that: The step of generating the measured speckle data of the measurement channel according to the speckle variation and the speckle data of the measurement channel comprises: Obtain the speckle variation ΔI of the reference channel and the light intensity distribution I of the speckle pattern in the speckle data of the measurement channel at ambient temperature T CLT (x, y); By formula I CLBT (x, y) = I CLT (x, y)-ΔI calculates the light intensity distribution I of the speckle pattern in the measurement channel at standard ambient temperature CLBT (x, y).

4. The temperature-compensated optical fiber speckle displacement sensor according to claim 1, characterized in that: Generating the displacement according to the measured speckle data comprises: Obtaining the light intensity distribution of the speckle pattern in the measured speckle data; The light intensity distribution is input into a displacement calibration model to obtain a displacement; the displacement calibration model is constructed through an artificial intelligence model.

5. The temperature-compensated optical fiber speckle displacement sensor according to claim 4, characterized in that: The displacement calibration model is constructed by an artificial intelligence model, including: Obtaining several historical light intensity distributions and their corresponding displacements; Dividing a number of historical light intensity distributions and their corresponding displacements into training data, verification data, and test data; performing data preprocessing on the training data, verification data, and test data to obtain a training set, a verification set, and a test set; Select an AI model as the base model; Train the basic model with the training set, and adjust the learning rate and hyperparameters on the validation set to obtain the pre-trained model; By verifying the pre-trained model on the test set, we finally obtain a displacement calibration model whose input is light intensity distribution and output is displacement.

6. The temperature-compensated optical fiber speckle displacement sensor according to claim 1, characterized in that: The generating of an alarm signal according to the speckle data comprises: The ambient temperature T of the reference channel and the intensity distribution I of the speckle pattern in the corresponding speckle data are obtained several times within the time period SJ. CK (x, y); By formula ΔI CKs =I CKs (x, y)-I CK(s-1) (x, y) calculates the change ΔI of the light intensity distribution of the reference channel in the time period SJ CK ; By the formula ΔT s =T s -T s-1 Calculate the change ΔT of the ambient temperature of the reference channel in the time period SJ s ; Wherein, s = 1, 2, ..., S; S represents the total number of times data is collected in SJ; Determine whether the absolute value of the light intensity distribution change is greater than the light intensity change threshold; Yes, when the absolute value of the ambient temperature change is greater than the temperature change threshold, no operation is performed; otherwise, a reference channel fault alarm signal is generated; No, do nothing.

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