Fiber device with temperature, humidity, pressure, and multi-signal sensing

Abstract

The application belongs to the technical field of flexible electronics, and particularly provides a fiber device with temperature, humidity and pressure multi-signal sensing, which comprises a multi-modal sensing unit, a bipolar constant current excitation unit, an analog channel switching unit, a differential detection unit and a microcontroller; the multi-modal sensing unit comprises working sensing fibers and reference sensing fibers, which are coordinated with a switchable bipolar constant current excitation assembly, an analog channel switching assembly and a differential detection assembly, real-time acquisition of forward and reverse excitation voltages of the gated working sensing fibers, synchronous acquisition of actual excitation current of the loop, and solving of real-time resistances of the working sensing fibers and the reference sensing fibers, respectively; the reference sensing fibers only reflect the resistance change amount of the system common drift, and through the ways of stripping the common drift or correcting the detection baseline offset by using the common drift, the effective resistance change generated only by external pressure, temperature and humidity stimulation is acquired, and then the correction and compensation of the working sensing fiber detection output are completed.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronics technology, and in particular relates to a fiber device with multiple signals sensing of temperature, humidity and pressure. Background Technology

[0002] Silk-based polypyrrole conductive sensing fibers are flexible, weavable, and their resistance changes with external stimuli. They can be used as pressure, temperature, and humidity sensing elements. Existing solutions typically use voltage divider circuits or unidirectional constant current methods to read the fiber resistance and connect multiple sensing channels to analog-to-digital converters.

[0003] The above reading method is susceptible to the combined effects of operational amplifier input offset, wire thermoelectric potential, electrode contact potential, constant current source drift and power supply fluctuation during long-term operation. When the fiber resistance is in the range of hundreds to thousands of ohms, a small zero-point bias can be converted into a significant resistance calculation error. Unidirectional DC excitation may also produce interface polarization and ion accumulation in the humidity sensing layer with significant water content or ion migration, resulting in long recovery time, increased hysteresis and baseline drift in the humidity channel.

[0004] If the temperature sensing fiber is continuously energized, the Joule heat generated by the measuring current will cause the fiber's own temperature to rise, resulting in a deviation between the measured temperature and the ambient temperature. The pressure channel also requires a high update rate to capture rapid contact and pressing signals. Using the same excitation current and the same sampling frequency to read different channels makes it difficult to simultaneously meet the requirements of dynamic pressure response, low temperature self-heating, and low humidity polarization.

[0005] Furthermore, configuring an independent constant current source and independent acquisition circuit for each channel increases device area, power consumption, and wiring complexity; simply zeroing the baseline in software cannot effectively distinguish resistance changes caused by material aging, electrode contact changes, and external stimuli.

[0006] Therefore, it is necessary to provide a fiber device with multi-signal sensing capabilities for temperature, humidity, and pressure. Summary of the Invention

[0007] The purpose of this invention is to provide a fiber optic device with multi-signal sensing capabilities for temperature, humidity, and pressure. This solution establishes a common drift compensation mechanism by adding a reference sensing fiber, which can compensate for the output of the selected sensing fiber by calculating the resistance change, thereby achieving stable and accurate acquisition of multi-signal outputs under limited hardware resources.

[0008] This solution provides a fiber optic device with multi-signal sensing capabilities for temperature, humidity, and pressure, including: a multimodal sensing unit, a bipolar constant current excitation unit, an analog channel switching unit, a differential detection unit, and a microcontroller;

[0009] The multimodal sensing unit comprises working sensing fibers and reference sensing fibers with the same base fiber matrix and base conductive layer. The working sensing fibers include pressure sensing fibers, temperature sensing fibers, and humidity sensing fibers. The bipolar constant current excitation unit is coupled to both ends of the selected working sensing fiber and provides constant current in both directions to the selected working sensing fiber based on a time-division polarity switching sampling mechanism. The analog channel switching unit is used to select the working sensing fiber and connect any selected working sensing fiber and the reference sensing fiber to the differential detection unit to realize time-division multiplexing of multiple sensing fibers. The differential detection unit is connected to the microcontroller through an analog-to-digital conversion unit to perform differential noise reduction and fidelity conditioning on the output bidirectional excitation analog voltage signal and the actual excitation current signal. The microcontroller calculates the sensing fiber resistance based on the difference between the forward and reverse excitation voltages and the actual excitation current, and compensates and calibrates the output of the selected working sensing fiber based on the resistance change of the reference sensing fiber.

[0010] As the preferred embodiment of this application:

[0011] The bipolar constant current excitation unit integrates a precision reference source, a constant current sampling resistor, and a polarity switching H-bridge. The precision reference source provides a stable reference for the constant current output, and the polarity switching H-bridge is used to switch the direction of the excitation current. It also works with the constant current sampling resistor to collect the actual excitation current of the circuit in real time. In addition, combined with the analog channel switching component, multiple sensing fibers can share the same constant current detection link in a time-division manner.

[0012] As the preferred embodiment of this application:

[0013] The bipolar constant current excitation unit set adopts a time-division polarity switching sampling mechanism.

[0014] As the preferred embodiment of this application:

[0015] The actual excitation current The value is determined by calculation based on the voltage across the constant current sampling resistor and the resistance value of the constant current sampling resistor.

[0016] As the preferred embodiment of this application:

[0017] The analog-to-digital conversion unit is an ADS8688 analog-to-digital conversion module, which is configured with eight independent acquisition channels, corresponding to multi-modal fiber signal acquisition, excitation current sampling, power supply status monitoring, heating condition monitoring, and redundant backup monitoring, to achieve synchronous acquisition of multiple parameters.

[0018] As a preferred embodiment of this application: each sensing fiber is configured with a differentiated, dedicated excitation sampling strategy: the pressure sensing fiber adopts a first excitation mode, wherein the excitation current of the first excitation mode is 0.1–1 mA, the sampling frequency is 50–200 Hz, and the duration of a single positive or negative excitation is 1–5 ms; the temperature sensing fiber adopts a second excitation mode, wherein the excitation current of the second excitation mode is 20–200 μA, the sampling frequency is 2–20 Hz, and the excitation duty cycle is not higher than 10%; the humidity sensing fiber adopts a third excitation mode, wherein the excitation current of the third excitation mode is 10–100 μA, the sampling frequency is 0.5–5 Hz, and positive and negative polarity are alternately excited.

[0019] As a preferred embodiment of this application: the microcontroller calculates the sensing fiber resistance based on a bidirectional differential algorithm, and uses the actual excitation current obtained by real-time sampling to replace the theoretical current, thereby realizing dynamic calibration of the detection current drift;

[0020] The algorithm for the microcontroller to calculate the sensing fiber resistance R is as follows:

[0021]

[0022] in, This represents the fiber end voltage under positive constant current excitation. This refers to the fiber end voltage under reverse constant current excitation. Actual excitation current.

[0023] As a preferred embodiment of this application: the reference sensing fiber is encapsulated in a sealed reference area, does not directly bear external pressure or directly contact environmental water vapor, and is in the same working environment as the pressure, temperature and humidity sensing fibers.

[0024] As a preferred embodiment of this application: the humidity sensing fibers are arranged adjacent to each other with flexible heating branches; when the humidity sensing fibers fail to recover to the baseline allowable range within a preset time after the detection ends, the microcontroller stops humidity sampling and starts the flexible heating branches for pulse heating. The temperature sensing fibers are used to monitor the temperature during the heating process, and heating stops when the temperature reaches the preset upper limit or the humidity sensing fibers recover to the baseline allowable range.

[0025] As a preferred embodiment of this application, it further includes a wireless transmission unit for transmitting the output of the working sensing fiber to a terminal device, the wireless transmission unit being a short-range wireless communication module.

[0026] Compared with existing technologies, the advantages of this solution include:

[0027] (1) The multimodal sensing unit of this scheme includes a working sensing fiber and a sealed reference sensing fiber of the same source and process. It works in conjunction with a switchable bipolar constant current excitation component, an analog channel switching component and a differential detection component to collect the forward and reverse excitation voltages of the selected working sensing fiber in real time, and simultaneously obtain the actual excitation current of the circuit. The real-time resistances of the working sensing fiber and the reference sensing fiber are calculated respectively. Based on the fact that the reference sensing fiber only reflects the resistance change of the system common drift, the common errors introduced by material aging, circuit temperature drift and electrode contact offset are removed, or the detection baseline offset is corrected by the common drift. The effective resistance change caused only by external pressure, temperature and humidity stimulation is extracted to complete the correction and compensation of the detection output of the working sensing fiber. In addition, this design does not require separate independent reference elements for each working channel. It relies on the hardware structure of the same source reference fiber and the microcontroller compensation algorithm to realize the hardware and software collaborative drift correction, which greatly improves the stability and measurement accuracy of long-term multi-channel temperature, humidity and pressure detection.

[0028] (2) By using bipolar constant current measurement in both directions and calculating the working fiber resistance based on the difference between the two voltages, the influence of operational amplifier offset, wire thermoelectric potential and electrode contact potential on the results can be reduced.

[0029] (3) Different excitation currents, pulse widths, duty cycles and sampling frequencies are used for pressure, temperature and humidity channels to match the acquisition method with the dynamic characteristics of each channel, taking into account the rapid pressure response, low temperature self-heating and low humidity polarization. This solves the problem that when using the same excitation current and the same sampling frequency to read different channels, it is difficult to simultaneously take into account the requirements of dynamic pressure response, low temperature self-heating and low humidity polarization.

[0030] (4) The three working channels and the reference channel share the bipolar constant current excitation link and the ADC analog-to-digital conversion unit through the analog channel switching unit, which reduces the number of independent constant current sources, independent ADCs and external wiring, simplifies the system structure and reduces the system power consumption. Attached Figure Description

[0031] Figure 1 This is a system framework diagram of the fiber device with multi-signal sensing of temperature, humidity, and pressure according to the present invention.

[0032] Figure 2 The present invention provides a system schematic diagram of a fiber optic device with multi-signal sensing capabilities for temperature, humidity, and pressure.

[0033] Figure 3 This is a schematic diagram illustrating the application of the intelligent fiber device of the present invention in a human-computer interaction system. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0035] Example 1:

[0036] This embodiment provides a fiber optic device with multi-signal sensing capabilities for temperature, humidity, and pressure, including a multimodal sensing unit, a bipolar constant current excitation unit, an analog channel switching unit, a differential detection unit, and a microcontroller; such as Figure 1 The diagram shown is a system framework diagram of a fiber optic device.

[0037] The multimodal sensing unit includes working sensing fibers and reference sensing fibers with the same base fiber matrix and base conductive layer. The working sensing fibers include pressure sensing fibers, temperature sensing fibers, and humidity sensing fibers that can sense pressure, temperature, and humidity signals. In this embodiment, the four types of fibers use the same base silk matrix and base polypyrrole conductive layer to reduce batch differences. In addition, the reference sensing fiber is set in a sealed reference area, which restricts direct pressure loading and isolates ambient water vapor. At the same time, it is in the same circuit board environment and ambient temperature as the working sensing fiber, so that the reference sensing fiber mainly responds to material aging, changes in electrode contact, circuit drift, and changes in the common ambient temperature.

[0038] As a preferred embodiment, the specific preparation method of the silk-based polypyrrole conductive sensing fiber and the reference fiber includes:

[0039] Step S1: Select natural silk as the fiber matrix, degumm it with sodium carbonate aqueous solution, wash it with deionized water and dry it; perform surface activation treatment on the degummed silk and immerse it in pyrrole monomer aqueous solution, the concentration of pyrrole monomer is preferably 0.02-0.08 mol / L, the immersion temperature is 0-5 ℃, and the immersion time is 20-60 min.

[0040] Step S2: Prepare a ferric chloride oxidant solution separately, with a molar ratio of ferric chloride to pyrrole monomer of 1.5:1 to 2.5:1:. Slowly add the oxidant at 0 to 10 °C and react for 2 to 8 h to form a continuous conductive layer of polypyrrole in situ on the surface of the silk. After the reaction is completed, wash with deionized water and ethanol in sequence, and dry at 40 to 50 °C.

[0041] Step S3: Select fibers with similar initial resistance values ​​from the same batch of conductive fibers as pressure, temperature, humidity and reference sensing fibers respectively: the effective length of each fiber is preferably 20 to 60 mm, the initial resistance is preferably in the range of 200 Ω to 20 kΩ, the reference sensing fiber is encapsulated with a thin-walled sealed sleeve, and the electrode areas at both ends are sealed with epoxy or silicone to prevent it from being directly subjected to pressure and from directly absorbing ambient water vapor.

[0042] A bipolar constant current excitation unit is coupled to both ends of the selected working sensing fiber. Based on a time-division polarity switching sampling mechanism, it provides constant current in both directions to the selected working sensing fiber, eliminating the inherent unidirectional bias error of the circuit. In this embodiment, the bipolar constant current excitation unit integrates a precision reference source, a constant current sampling resistor, and a polarity switching H-bridge. The precision reference source provides a stable reference for the constant current output, and the polarity switching H-bridge is used to switch the direction of the excitation current. In conjunction with the constant current sampling resistor, it collects the actual excitation current of the circuit in real time and dynamically calibrates the constant current output drift. At the same time, combined with the analog channel switching component, multiple sensing fibers can share the same constant current detection link in a time-division manner, simplifying the wiring layout.

[0043] As a preferred embodiment, a 2.5 V precision reference source is used to provide a reference for the constant current output, which can output a bidirectional constant excitation current of equal value to provide an electrical signal excitation for the sensing fiber without polarization interference; the constant current sampling resistor is a resistor with 0.05% accuracy and a temperature coefficient of no more than 25ppm / ℃. By switching the resistance value of the constant current sampling resistor, for example, 100 Ω, 1 kΩ, and 10 kΩ, the corresponding excitation ranges of milliampere, microampere, and microampere levels will be obtained.

[0044] As a preferred embodiment, the polarity-switching H-bridge preferably uses an H-bridge composed of a low on-resistance analog switch. This polarity-switching H-bridge can change the direction of the current flowing through each sensing fiber, and sequentially connect the pressure sensing fiber, temperature sensing fiber, humidity sensing fiber, and reference sensing fiber to the same constant current detection link. Specifically, the polarity-switching H-bridge is controlled to alternately change the direction of the current flowing through the tested working fiber. For any tested working sensing fiber, a positive constant current is first applied and the voltage V is collected. + Then apply a reverse constant current and sample the voltage V. -， By calculating V + With V - The difference can suppress operational amplifier offset, wire thermoelectric potential, and electrode contact potential that are independent of the current direction.

[0045] In this embodiment, the bipolar constant current excitation unit set adopts a time-division polarity switching sampling mechanism. Specifically, the current is first made to flow through the sensing fiber under test in the first direction, and after a delay of 0.5 to 3 ms until the circuit reaches a steady state, the forward excitation voltage is collected. Then, the excitation is turned off and left to stand still for 0.2 to 1 ms to release parasitic charges. Then, the current polarity is switched through the H-bridge and the same steady-state time is delayed to collect the reverse excitation voltage.

[0046] In this embodiment, each sensing fiber is configured with a differentiated, dedicated excitation sampling strategy: the pressure sensing fiber adopts a first excitation mode, with an excitation current of 0.1–1 mA, a sampling frequency of 50–200 Hz, and a single positive or negative excitation duration of 1–5 ms; the temperature sensing fiber adopts a second excitation mode, with an excitation current of 20–200 μA, a sampling frequency of 2–20 Hz, and an excitation duty cycle not exceeding 10%; the humidity sensing fiber adopts a third excitation mode, with an excitation current of 10–100 μA, a sampling frequency of 0.5–5 Hz, and alternating positive and negative polarity excitation. This differentiated, dedicated excitation sampling strategy not only perfectly adapts to the sensing characteristics of each working sensing fiber but also achieves multi-parameter interference-free synchronous detection, taking into account the optimal operating conditions of each channel.

[0047] The analog channel switching unit is used to select the working sensing fiber and connect any selected working sensing fiber and the reference sensing fiber to the differential detection unit to realize time-division multiplexing of multiple sensing fibers. In this embodiment, the analog channel switching unit has at least four inputs, which are respectively connected to the pressure sensing fiber, temperature sensing fiber, humidity sensing fiber and reference sensing fiber. After the channel switch is switched, it first enters a brief off state and then connects the target channel to reduce the measurement error caused by the instantaneous parallel connection of two fiber channels. In this embodiment, for the high-resistivity humidity channel, a voltage follower buffer can be added to reduce the impact of dynamic load on the ADC input. In this embodiment, the channel switcher of the analog channel switching unit preferably adopts a multi-channel analog switch with low leakage current, low on-resistance and low charge injection. After each channel is switched, a stable waiting time is set to reduce the impact of switching transients, capacitor charging and discharging and fiber impedance changes on the sampling results.

[0048] The differential detection unit is connected to the microcontroller through the analog-to-digital converter unit to perform differential noise reduction and fidelity conditioning on the output bidirectional excitation analog voltage signal and the actual excitation current signal, providing a high-fidelity and high-stability original sensing signal for subsequent analog-to-digital conversion and subsequent drift compensation correction.

[0049] In this embodiment, the analog-to-digital conversion unit is an ADS8688 analog-to-digital conversion module, which is configured with eight independent acquisition channels (CH0-CH7). CH0-CH3 correspond to pressure sensing fiber, temperature sensing fiber, humidity sensing fiber, and reference sensing fiber, respectively. CH4 acquires the voltage of the constant current sampling resistor to obtain the actual excitation current. The other channels can be used for power supply status monitoring, heating condition monitoring, and redundancy monitoring, etc., to achieve synchronous acquisition of multiple parameters. The ADS8688 analog-to-digital conversion module can synchronously convert the bidirectional excitation analog voltage signal, the actual excitation current analog signal, and other operating condition analog signals output by the front-end circuit into analog-to-digital signals, and transmit the digital sampling signal to the microcontroller. In this embodiment, the ADS8688 analog-to-digital conversion module communicates with the microcontroller at high speed via the SPI bus.

[0050] The microcontroller calculates the resistance of the sensing fiber based on the difference between the forward and reverse excitation voltages and the actual excitation current replacing the theoretical current. It then compensates and calibrates the output of the selected sensing fiber based on the resistance change of the reference sensing fiber. In this embodiment, the actual excitation current is denoted as... It is determined based on the voltage V across the constant current sampling resistor and the resistance R of the constant current sampling resistor.

[0051] Specifically, the formula for the sensing fiber resistance R is:

[0052]

[0053] In the formula, This represents the fiber end voltage under positive constant current excitation. This refers to the fiber end voltage under reverse constant current excitation. Actual excitation current.

[0054] In other words, the measured resistance of any working sensing fiber can be obtained using the above formula. (X represents pressure, temperature, and humidity). Meanwhile, using the exact same bipolar sampling algorithm, the real-time resistance of the sealed reference sensing fiber, free from external stimuli, is calculated. The resistance of the reference sensing fiber is only affected by common drift factors such as material aging, circuit temperature drift, and electrode contact changes, and is not affected by external measured signals such as temperature, humidity, and pressure. Then, the resistance change rate corresponding to each working sensing fiber and the reference sensing fiber is calculated. and As can be understood, in this embodiment, after power-on initialization, the initial resistances of the pressure sensing fiber, temperature sensing fiber, humidity sensing fiber, and reference fiber are recorded. Therefore, the relative change in resistance of each sensing fiber is: The common drift relative phase transition of the reference sensing fiber The change in the effective signal after compensation is , The common drift coupling coefficient is obtained from the factory calibration for pre-calibration. This means that only the actual sensing signals from pressure, humidity, and temperature are retained, while the inherent errors of the sensing fiber system are subtracted. In addition, it should be noted that the above algorithm is only suitable for pressure and humidity sensing signal compensation. Since the function of the temperature sensing fiber is to measure temperature, the common drift change of the reference sensing fiber cannot be directly subtracted. Instead, it is used to correct the detection baseline offset, while retaining the resistance change caused by temperature itself. This achieves compatibility between drift correction and effective temperature measurement, and avoids the effective temperature sensing signal being differentially canceled.

[0055] As can be seen, in this embodiment, the microcontroller performs common drift compensation for the pressure sensing fiber and the humidity sensing fiber based on the relative resistance change of the reference sensing fiber, and uses the reference sensing fiber to correct the long-term aging of the temperature sensing fiber and circuit drift.

[0056] This embodiment also includes a fault determination mechanism: when the voltage of any channel approaches the upper or lower limit of the range, the forward and reverse voltage difference is less than the minimum effective threshold, the actual excitation current deviates from the set value by more than the preset ratio, the forward and reverse calculated resistance difference exceeds the allowable range, or the sampling remains unchanged for multiple consecutive times, the microcontroller will mark the corresponding channel as open circuit, short circuit, poor contact, or excitation abnormality.

[0057] Preferably, in this embodiment, the microcontroller presets standardized cycle scanning logic to complete a single full parameter detection cycle with a fixed process of system zero-point calibration, reference channel benchmark acquisition, multi-working channel time-division detection, operating condition parameter acquisition, and data compensation correction.

[0058] As a preferred embodiment,

[0059] The humidity sensing fibers are arranged adjacent to each other with flexible heating branches. When the humidity sensing fibers fail to recover to the baseline allowable range within a preset time after the detection ends, the microcontroller stops humidity sampling and starts the flexible heating branches for pulse heating. The temperature sensing fibers are used to monitor the temperature during the heating process. Heating stops when the temperature reaches the preset upper limit or the humidity sensing fibers recover to the baseline allowable range.

[0060] Specifically, a serpentine flexible heating electrode is placed next to the humidity sensing fiber. The heating electrode is controlled by a microcontroller (preferably an STM32 chip) via a MOS transistor. The CH6 channel of the ADS8688 is used to monitor the voltage of the heating branch, and a constant current sampling resistor can be connected in series on the power supply side to monitor the heating current. When the humidity stimulus is removed, if the humidity channel does not recover to the range of ±2% to ±10% of the initial baseline within 30 to 180 seconds, the STM32 stops humidity measurement and starts pulse heating with a duty cycle of 10% to 50%. During heating, the temperature channel monitors the local temperature at a higher update frequency. When the local temperature reaches 40 to 60 ℃, the cumulative heating time reaches the upper limit, or the humidity channel recovers to the allowable range, heating is stopped. After stopping heating, wait 5 to 60 seconds before resuming normal humidity sampling.

[0061] This process avoids performing low-current humidity measurements while the device is heated, reducing crosstalk from the heating current to the measurement link; the temperature channel participates in limiting the heating temperature, enabling the humidity recovery function to work in synergy with the multi-channel acquisition system.

[0062] As a preferred embodiment, it further includes a wireless transmission unit for transmitting the output of the working sensing fiber to a terminal device. This wireless transmission unit is a short-range wireless communication module including a Bluetooth transmission module, a wireless local area network module, etc. Figure 2 As shown.

[0063] Specifically, the microcontroller encapsulates the device number, timestamp, pressure resistor, temperature resistor, humidity resistor, reference resistor, actual excitation current, compensation result, power supply status, heating status, and channel fault flag into a data frame, and sends it to the mobile terminal or computer via a Bluetooth Low Energy module.

[0064] like Figure 3 The image shows the application of the fiber device provided in this embodiment in a robot hand:

[0065] Pressure, temperature, and humidity sensing fibers are attached to the fingertips or palm of the robot's dexterous hand, while reference sensing fibers are placed in a sealed area near the back of the hand or control circuitry. The pressure channel acquires contact and gripping changes at a high sampling frequency; the temperature channel samples the object's surface temperature at a low duty cycle; and the humidity channel determines the humidity of the object's surface or surrounding environment using a low-frequency alternating polarity method.

[0066] After receiving wireless data, the robot controller can display the gripping status based on pressure results, provide a high-temperature warning based on temperature results, and determine the surface moisture status based on humidity results. Reference channel data, actual excitation current, and fault flags are simultaneously uploaded to distinguish between sensor changes and data acquisition link anomalies.

[0067] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics in the solutions is not described in detail here. It should be noted that those skilled in the art can make several improvements without departing from the present invention, and these should also be considered within the scope of protection of the present invention. These improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of the claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A fiber optic device with multi-signal sensing capabilities for temperature, humidity, and pressure, characterized in that: include: Multimodal sensing unit, bipolar constant current excitation unit, analog channel switching unit, differential detection unit and microcontroller; The multimodal sensing unit comprises working sensing fibers and reference sensing fibers with the same base fiber matrix and base conductive layer. The working sensing fibers include pressure sensing fibers, temperature sensing fibers, and humidity sensing fibers. The bipolar constant current excitation unit is coupled to both ends of the selected working sensing fiber and provides constant current in both directions to the selected working sensing fiber based on a time-division polarity switching sampling mechanism. The analog channel switching unit is used to select the working sensing fiber and connect any selected working sensing fiber and the reference sensing fiber to the differential detection unit to realize time-division multiplexing of multiple sensing fibers. The differential detection unit is connected to the microcontroller through an analog-to-digital conversion unit to perform differential noise reduction and fidelity conditioning on the output bidirectional excitation analog voltage signal and the actual excitation current signal. The microcontroller calculates the resistance of the sensing fiber based on the difference between the forward and reverse excitation voltages and the actual excitation current, and compensates and calibrates the output of the selected sensing fiber based on the resistance change of the reference sensing fiber.

2. The fiber device with multi-signal sensing of temperature, humidity, and pressure according to claim 1, characterized in that: The bipolar constant current excitation unit integrates a precision reference source, a constant current sampling resistor, and a polarity switching H-bridge. The precision reference source provides a stable reference for the constant current output, and the polarity switching H-bridge is used to switch the direction of the excitation current. It also works with the constant current sampling resistor to collect the actual excitation current of the circuit in real time. In addition, combined with the analog channel switching component, multiple sensing fibers can share the same constant current detection link in a time-division manner.

3. The fiber device with multi-signal sensing of temperature, humidity, and pressure according to claim 1, characterized in that: The bipolar constant current excitation unit set adopts a time-division polarity switching sampling mechanism.

4. The fiber device with multi-signal sensing of temperature, humidity, and pressure according to claim 1, characterized in that: The actual excitation current The value is determined by calculation based on the voltage across the constant current sampling resistor and the resistance value of the constant current sampling resistor.

5. The fiber device with multi-signal sensing of temperature, humidity, and pressure according to claim 1, characterized in that: The analog-to-digital conversion unit is an ADS8688 analog-to-digital conversion module, which is configured with eight independent acquisition channels, corresponding to multi-modal fiber signal acquisition, excitation current sampling, power supply status monitoring, heating condition monitoring, and redundant backup monitoring, to achieve synchronous acquisition of multiple parameters.

6. The fiber device with multi-signal sensing of temperature, humidity, and pressure according to claim 1, characterized in that: Each sensing fiber is configured with a differentiated, dedicated excitation sampling strategy: the pressure sensing fiber adopts a first excitation mode, with an excitation current of 0.1–1 mA, a sampling frequency of 50–200 Hz, and a single positive or negative excitation duration of 1–5 ms; the temperature sensing fiber adopts a second excitation mode, with an excitation current of 20–200 μA, a sampling frequency of 2–20 Hz, and an excitation duty cycle not exceeding 10%; the humidity sensing fiber adopts a third excitation mode, with an excitation current of 10–100 μA, a sampling frequency of 0.5–5 Hz, and uses alternating positive and negative polarity excitation.

7. The fiber device with multi-signal sensing of temperature, humidity, and pressure according to claim 1, characterized in that: The microcontroller calculates the resistance of the sensing fiber based on a bidirectional differential algorithm and uses the actual excitation current obtained by real-time sampling to replace the theoretical current, thereby achieving dynamic calibration of the detection current drift. The algorithm for the microcontroller to calculate the sensing fiber resistance R is as follows: in, This represents the fiber end voltage under positive constant current excitation. This refers to the fiber end voltage under reverse constant current excitation. Actual excitation current.

8. The fiber device with multi-signal sensing of temperature, humidity, and pressure according to claim 1, characterized in that: The reference sensing fiber is encapsulated in a sealed reference area, does not directly bear external pressure or come into direct contact with ambient water vapor, and is in the same working environment as the pressure, temperature, and humidity sensing fibers.

9. The fiber device with multi-signal sensing of temperature, humidity, and pressure according to claim 1, characterized in that: The humidity sensing fibers are arranged adjacent to each other with flexible heating branches. When the humidity sensing fibers fail to recover to the baseline allowable range within a preset time after the detection ends, the microcontroller stops humidity sampling and starts the flexible heating branches for pulse heating. The temperature sensing fibers are used to monitor the temperature during the heating process. Heating stops when the temperature reaches the preset upper limit or the humidity sensing fibers recover to the baseline allowable range.

10. The fiber device with multi-signal sensing of temperature, humidity, and pressure according to claim 1, characterized in that: It also includes a wireless transmission unit, which transmits the output of the working sensing fiber to the terminal device. This wireless transmission unit is a short-range wireless communication module.

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