Deep sea flexible inductive pressure sensor and automatic calibration method thereof

Abstract

The invention relates to a deep-sea flexible inductive pressure sensor and an automatic calibration method thereof. The deep-sea flexible inductive pressure sensor is mainly applied to pressure measurement when a deep-sea flexible gripper grabs an object. The sensor adopts a flexible printed circuit board and an inductance type pressure sensing technology, and comprises the flexible printed circuit board, a coil inductor drawn on the flexible printed circuit board, an ultra-soft silica gel layer uniformly coated on the flexible printed circuit board, a copper foil layer covered on the ultra-soft silica gel layer and a sealing film covered on the copper foil layer. When the pressure acts, the deformation of the copper foil causes the change of the inductance value of the coil, and the pressure detection is realized by detecting the inductance change. The sensor provided by the invention can provide high-sensitivity and high-reliability pressure measurement in an environment with high hydrostatic pressure and dynamic grasping pressure, can maintain high adaptability and reliability in a deep sea environment, and provides reliable technical support for deep sea exploration and engineering application.

Description

Technical Field

[0001] The invention belongs to the technical field of pressure sensors, and in particular relates to a deep-sea flexible inductive pressure sensor and an automatic calibration method thereof. Background Art

[0002] With the continuous development of deep-sea exploration and marine engineering, deep-sea flexible grippers are a key technology in modern marine engineering. They can perform complex operational tasks in extreme environments, such as collecting samples, operating equipment, and performing repairs. Compared with traditional rigid grippers, flexible grippers have higher adaptability and flexibility, and can better cope with the uncertainty and complexity of deep-sea environments. This puts a severe test on the performance and stability of sensors, and reliable pressure sensors are essential.

[0003] It is well known that traditional pressure sensors are prone to failure in deep sea environments. The main reasons are as follows:

[0004] 1) Challenges of high hydrostatic pressure to range and sensitivity: The hydrostatic pressure in deep-sea environments is very high, and traditional pressure sensors need to have extremely high ranges to accurately measure this pressure. However, high ranges usually cause the sensitivity of the sensor to drop significantly, making pressure perception in deep-sea environments more difficult. This means that in high hydrostatic pressure environments, the pressure perception ability of the sensor will be significantly weakened, affecting the accuracy and reliability of the measurement.

[0005] 2) Changes in bias and sensitivity caused by environmental conditions: Under different pressure conditions, the bias and sensitivity of the sensor will change. This change will cause inconsistent measurement results of the sensor under different pressure environments, increasing the uncertainty of the measurement. The deep-sea environment is complex and changeable, and factors such as temperature and salinity will affect the performance of the sensor, resulting in nonlinear changes in its output signal. Therefore, the performance of traditional pressure sensors in deep-sea environments is often not stable enough.

[0006] 3) Calibration requirements in practical applications: In order to ensure the accuracy of measurement, the sensor needs to be calibrated according to specific environmental conditions in practical applications. The calibration process of traditional pressure sensors is complicated and time-consuming, which increases the difficulty of use.

[0007] In addition, the material selection of traditional pressure sensors also has significant shortcomings: First, traditional pressure sensors usually use rigid materials, which cannot adapt to the bending and deformation of flexible grippers, and easily cause the sensors to break or fail. At the same time, rigid materials will also affect the perception ability of flexible grippers, reduce their sensitivity and adaptability, and affect the gripper's grip on objects. Secondly, in the deep-sea high-pressure environment, rigid materials are prone to fatigue and breakage, causing sensor failure. This not only affects the accuracy of the measurement, but also increases the cost of maintenance and replacement.

[0008] In summary, the application of traditional pressure sensors in deep-sea environments faces many challenges. Summary of the invention

[0009] In order to solve the various challenges faced by pressure sensors in deep-sea environments, the present invention proposes a deep-sea flexible inductive pressure sensor and an automatic calibration method thereof. The sensor can provide high-sensitivity and high-reliability pressure measurement under high hydrostatic pressure and dynamic gripping pressure environments, and the automatic calibration method can realize the calibration of the sensor to ensure that the sensor can maintain accurate and stable measurement performance under different pressure conditions.

[0010] In order to achieve the above object, the technical solution specifically adopted by the present invention is as follows:

[0011] A deep-sea flexible inductive pressure sensor includes: a flexible printed circuit board (FPC); a coil inductor drawn on the flexible printed circuit board (FPC); an ultra-soft silicone layer uniformly coated on the flexible printed circuit board (FPC) and located above the coil inductor; a copper foil layer covering the ultra-soft silicone layer; and a sealing film covering the copper foil layer; wherein the ultra-soft silicone layer can ensure that the sensor has good flexibility and deformation characteristics; the copper foil will deform under pressure, and the relative displacement with the inductor coil on the flexible printed circuit board (FPC) will change, and the existence of the eddy current effect will cause the coil inductance to change, and the pressure can be detected by detecting the change in the coil inductance. The sealing film is set to protect the internal structure from seawater corrosion and maintain the overall sealing of the sensor.

[0012] The present invention also provides an automatic calibration method for the above-mentioned deep-sea flexible inductive pressure sensor, comprising the following steps:

[0013] S1. Calibrate the pressure sensor data in a laboratory environment to obtain the sensitivity and bias corresponding to different pressures and store them in a non-volatile memory;

[0014] S2. After the robot has finished diving, the water pressure reading is obtained through the water pressure gauge, and the sensitivity and bias corresponding to the current pressure are obtained by comparing the data stored in the non-volatile memory;

[0015] S3. When the soft robot grasps an object, pressure data is obtained according to the corresponding sensitivity and bias.

[0016] Furthermore, the step S1 comprises the following steps:

[0017] S11, prepare a pressure tank and an additional pressure generating device to simulate the high hydrostatic pressure environment of the deep sea; the additional pressure generating device includes multiple electromagnetic coils and multiple sets of weights, which are attracted by the electromagnetic effect, and then the power is turned off to sequentially place weights of different weights on the sensor to achieve the application of additional pressure to the sensor;

[0018] S12. Apply additional pressure and read sensor data under different static pressure conditions; specifically, increase the static pressure in the pressure tank to simulate the seawater pressure at different depths, and control the electromagnetic coil to lower weights of different weights to gradually increase the additional pressure P. y , read the water pressure gauge reading O x and sensor data V z ; That is, at each static pressure O x Under the conditions, read different additional pressures P y The corresponding sensor inductance value V z Change data.

[0019] S13, linear fitting is performed on the collected data to obtain sensitivity and bias, and the sensitivity and bias are stored in a non-volatile memory. Specifically, the collected data are first organized into a table, and then the additional pressure P is plotted in the coordinate system. y and the sensor output signal V z The data points are used to obtain the sensitivity k and bias b using linear fitting, and the fitting equation V is obtained. z =kP y +b.

[0020] Furthermore, in step S13, the least square method is used for linear fitting, including the following steps: 1) using the formula: and Calculate the additional pressure average and sensor data average Among them, P i is the pressure recording data, V i Record data for sensor data; 2) through the formula: Calculate the slope k, that is, the sensitivity of the sensor; 3) According to the formula: Calculate the bias b and get the fitting equation V z =kP y +b.

[0021] Furthermore, step S3 includes the following steps: in a deep-sea environment, reading the water pressure gauge reading in real time under non-grasping conditions, comparing the calibrated static pressure stored in the non-volatile memory, and obtaining the corresponding sensitivity and bias; after grasping is completed, reading the output signal of the flexible pressure sensor, and calculating the pressure data of the grasped object based on the sensitivity and bias.

[0022] Furthermore, the step S3 also includes the step of storing the calculated data in a data recording chip, wherein the calculated data includes the ambient water pressure, the sensor output signal, the calculated gripping pressure, etc.

[0023] The present invention adopts flexible design and automatic calibration method, so that the sensor has excellent adaptability and reliability in deep sea environment, and significantly simplifies the calibration operation, and has the following characteristics and beneficial effects:

[0024] 1) Improve calibration accuracy: By reading and analyzing water pressure and sensor data in real time, the sensitivity of the sensor can be accurately calculated to ensure the accuracy of measurements in deep-sea environments.

[0025] 2) Enhanced adaptability and reliability: The use of flexible printed circuit boards (FPC) and inductive pressure sensing technology enables the sensor to have a high range and high sensitivity, and can maintain accurate pressure measurement even in deep-sea high pressure, high salinity and low temperature environments, showing excellent adaptability and long-term reliability.

[0026] 3) Simplified operation: The automatic calibration method reduces manual intervention, simplifies the calibration operation, and makes sensor application more convenient.

[0027] 4) Real-time monitoring and control: Through real-time data recording and analysis, the working status of the sensor and environmental changes can be reflected instantly, which facilitates real-time monitoring and adjustment of the operation of the soft robot.

[0028] 5) Multi-purpose application: The method of the present invention is not only applicable to the calibration and use of deep-sea pressure sensors, but can also be extended to other pressure detection fields under high-pressure environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0030] Figure 1 It is a schematic diagram of the structure of a deep-sea flexible inductive pressure sensor;

[0031] In the figure: 1-flexible printed circuit board; 2-coil inductor; 3-ultra-soft silicone layer; 4-copper foil layer; 5-sealing film.

[0032] Figure 2 Block diagram of the calibration system for deep-sea flexible inductive pressure sensors.

[0033] Figure 3 Schematic diagram of the experimental setup for calibration of deep-sea flexible inductive pressure sensors.

[0034] Figure 4Calibration flow chart for deep-sea flexible inductive pressure sensor.

[0035] Figure 5 This is the working flow chart of deep-sea flexible inductive pressure sensor. DETAILED DESCRIPTION

[0036] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0037] Aiming at the many drawbacks of traditional pressure sensors in deep sea environment, the present invention proposes a deep sea flexible inductive pressure sensor, which adopts flexible printed circuit board (FPC) and inductive pressure sensing technology. Figure 1 As shown, it includes a flexible printed circuit board (FPC) 1, a coil inductor 2, an ultra-soft silicone layer 3, a copper foil layer 4 and a sealing film 5; when making it, first draw the coil inductor 2 on the flexible printed circuit board (FPC) 1, and then evenly apply a layer of ultra-soft silicone 3 on the coil inductor 2 on the printed circuit board (FPC) 1 to ensure that it has good flexibility and deformation characteristics. Then, a layer of copper foil 4 is covered on the ultra-soft silicone 3. When pressure acts on the pressure sensor, the copper foil will deform under the pressure, and the relative displacement with the inductor coil on the FPC will change. The existence of the eddy current effect will cause the coil inductance to change. The pressure is detected by detecting the change in the coil inductance. Then a layer of sealing material film 5 is covered on the copper foil 4 to protect the internal structure from seawater corrosion and maintain the overall sealing of the sensor. The pressure sensor of this structure has high sensitivity and good linearity.

[0038] In addition, based on the sensor, the present invention proposes an automatic calibration method, which first calibrates the pressure sensor data in a laboratory environment, obtains the sensitivity and bias corresponding to different pressures, and stores them in a non-volatile memory. Then, after the robot has finished diving, the water pressure reading is obtained through a water pressure gauge, and the sensitivity and bias corresponding to the current pressure are obtained by comparing the data stored in the non-volatile memory. Finally, when the soft robot grasps an object, the pressure data is obtained according to the corresponding sensitivity and bias. Figure 4 As shown, the specific steps include:

[0039] S1. Preparation of experimental equipment: prepare a pressure tank to simulate the high hydrostatic pressure environment of the deep sea, place the reading system and sensor in the pressure tank, and ensure that all connections are stable and reliable; then prepare an additional pressure generating device, which consists of multiple electromagnetic coils and multiple sets of weights. The weights are attracted by the electromagnetic effect, and then the power is turned off to lower weights of different weights onto the sensor in turn to apply additional pressure to the sensor.

[0040] S2. Increase the static pressure in the pressure tank to simulate the seawater pressure at different depths and read the water pressure gauge. x At the same time, the electromagnetic coil is controlled to put down weights of different weights, gradually increasing the additional pressure P y , read sensor data V z For example, the collected data may be: static pressure O1: (P1, V1), (P2, V2), (P3, V3) ...; static pressure O2: (P1, V1), (P2, V2), (P3, V3) ...; static pressure O3: (P1, V1), (P2, V2), (P3, V3) ... That is, at each static pressure O x Under the conditions, read different additional pressures P y The inductance value of the sensor is V z Change data.

[0041] S3. Calculate the corresponding water pressure gauge reading O x The sensitivity and bias of the pressure sensor are plotted in the coordinate system, and a linear fit is used to obtain the fitting equation. Specifically:

[0042] First, the collected data pairs are organized into tables to ensure the time synchronization and accuracy of the data. Then the additional pressure P is plotted in the coordinate system. y The data points of the sensor output signal V are used to perform curve fitting using the least squares method to obtain the sensitivity k and bias b, and the fitting equation V is obtained. z =kP y +b. The specific calculation steps of the least squares method are: 1) Through the formula: and Calculate the additional pressure average and sensor data average Among them, P i is the pressure recording data, V i Record data for sensor data; 2) through the formula: Calculate the slope k, that is, the sensitivity of the sensor; 3) According to the formula: Calculate the bias b and get the fitting equation V z =kP y +b.

[0043] S4, repeat steps S2 and S3 to find the water pressure gauge reading O under different hydrostatic pressures. x The corresponding slope k and bias b, and the water pressure gauge reading O x The corresponding slope k and bias b are recorded. For example, the calculated and recorded data pairs may be: water pressure gauge reading O1: (k1, b1); water pressure gauge reading O2: (k2, b2); water pressure gauge reading O3: (k3, b3)... Store these data in the non-volatile memory chip. The calibration process is completed.

[0044] The automatic calibration method of the present invention relies on the automatic calibration system of the deep-sea flexible inductive pressure sensor, such as Figure 2 As shown, the system includes a deep-sea flexible inductive pressure sensor, a water pressure gauge reading circuit, an inductive sampling circuit, a central control unit, a power supply circuit, a non-volatile memory, etc. Among them:

[0045] The water pressure gauge reading circuit uses an integrated water pressure gauge to obtain the deep sea hydrostatic pressure in real time. During the dive, the hydrostatic pressure value is read in real time.

[0046] The inductance sampling circuit uses an inductance sampling chip (such as LDC1614) as the main chip to read the sensor (water pressure gauge) data, obtain the change of coil inductance in real time and convert it into pressure data, that is, convert the inductance value of the sensor into a digital value;

[0047] The central control unit uses the main control MCU, which is responsible for reading and processing the data of the inductance sampling chip and the water pressure gauge. It can communicate with the flexible pressure sensor reading module, read the flexible pressure sensor information to obtain the sensor digital quantity, and read the water pressure gauge to achieve real-time reading of water pressure to obtain static water pressure. During the calibration process, the algorithm is run to calculate the sensitivity and bias of the sensor; in actual use, the read inductance sampling chip data and the sensitivity obtained by calibration are analyzed and calculated to output the perceived pressure value.

[0048] The power circuit uses a power chip to power the entire system and ensure that the system can operate reliably in a deep-sea environment;

[0049] Non-volatile memory, using an integrated non-volatile memory chip, is used to store calibration data, including slope and bias under different hydrostatic pressures.

[0050] In deep-sea environments, the sensitivity parameters k and bias b obtained by calibration can be used to monitor and estimate the pressure of the soft robot's flexible gripper grasping an object in real time. Figure 5 As shown, the specific steps are as follows:

[0051] Step 1: Water pressure measurement in non-gripping state: In deep sea environment, read the water pressure gauge reading P in real time under non-gripping conditions. env , compare and calibrate the static pressure stored in the non-volatile memory O env , get O env The corresponding sensitivity k env and bias b env .

[0052] Step 2: Read the output signal of the gripping state sensor: After the gripping is completed, read the output signal V of the flexible pressure sensor. grip , according to the formula The pressure data of the grasped object can be obtained, where k env and b env are the sensitivity and bias obtained after calibration respectively.

[0053] Step 3: Store the calculated data in a data recording chip (EEPROM or FLASH), including the ambient water pressure, the sensor output signal, the calculated gripping pressure, etc.

[0054] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A deep-sea flexible inductive pressure sensor, characterized in that: include: Flexible printed circuit boards; a coil inductance drawn on the flexible printed circuit board; An ultra-soft silicone layer coated on the flexible printed circuit board and located above the coil inductor; A copper foil layer covering the ultra-soft silicone layer; as well as A sealing film covering the copper foil layer; When pressure acts on the pressure sensor, the deformation of the copper foil causes the coil inductance value to change. The pressure is detected by detecting the change in the coil inductance.

2. The automatic calibration method for a deep-sea flexible inductive pressure sensor according to claim 1, characterized in that: The following steps are involved: S1. Calibrate the pressure sensor data in a laboratory environment to obtain the sensitivity and bias corresponding to different pressures and store them in a non-volatile memory; S2. After the robot has finished diving, the water pressure reading is obtained through the water pressure gauge, and the sensitivity and bias corresponding to the current pressure are obtained by comparing the data stored in the non-volatile memory; S3. When the soft robot grasps an object, pressure data is obtained according to the corresponding sensitivity and bias.

3. The automatic calibration method of the deep-sea flexible inductive pressure sensor according to claim 2, characterized in that: The step S1 comprises the following steps: S11. Prepare pressure tanks and additional pressure generating devices to simulate the high hydrostatic pressure environment of the deep sea; S12, applying additional pressure and reading sensor data under different static pressure conditions; S13. Perform linear fitting on the collected data to obtain sensitivity and bias, and store them in a non-volatile memory.

4. The automatic calibration method for a deep-sea flexible inductive pressure sensor according to claim 3, characterized in that: The additional pressure generating device includes a plurality of electromagnetic coils and a plurality of groups of weights. The weights are attracted by the electromagnetic effect. Then, the power is turned off and the weights of different weights are placed on the sensor in sequence, so as to apply additional pressure to the sensor.

5. The automatic calibration method for a deep-sea flexible inductive pressure sensor according to claim 3, characterized in that: In step S13, the collected data pairs are first organized into a table, and then the additional pressure P is plotted in the coordinate system. y and the sensor output signal V z The data points are used to obtain the sensitivity k and bias b using linear fitting, and the fitting equation V is obtained. z =kP y +b, where V z Represents the sensor output signal, P y For extra pressure.

6. The automatic calibration method for a deep-sea flexible inductive pressure sensor according to claim 5, characterized in that: The least square method is used for linear fitting, including the following steps: 1) by formula: and Calculate the additional pressure average and sensor data average Among them, P i is the pressure recording data, V i Record data for sensor data; 2) through the formula: Calculate the slope k, that is, the sensitivity of the sensor; 3) According to the formula: Calculate the bias b and get the fitting equation V z =kP y +b.

7. The automatic calibration method for a deep-sea flexible inductive pressure sensor according to claim 2, characterized in that: The step S3 comprises the following steps: in a deep sea environment, reading the water pressure gauge reading in real time under non-grasping conditions, comparing the calibrated static pressure stored in the non-volatile memory, and obtaining the corresponding sensitivity and bias; after grasping is completed, reading the output signal of the flexible pressure sensor, and calculating the pressure data of the grasped object based on the sensitivity and bias.

8. The automatic calibration method for a deep-sea flexible inductive pressure sensor according to claim 7, characterized in that: The step of storing the calculated data in a data recording chip is also included, wherein the calculated data includes the ambient water pressure, the sensor output signal, and the calculated gripping pressure.

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