An airborne intelligent sensor

Abstract

The application relates to the technical field of pressure sensing, and discloses an aviation airborne intelligent sensor, which comprises a pressure sensor probe and a pressure regulator, the pressure sensor probe comprises a pressure-sensitive chip and a temperature sensor, the pressure-sensitive chip is used for converting medium pressure into a pressure detection signal, the temperature sensor is used for collecting temperature information, the pressure sensor probe and the pressure regulator are arranged in a double-body type separation mode and are connected through a cable; a conditioning circuit board is arranged in the pressure regulator, the conditioning circuit board comprises a power supply circuit, an instrument amplification circuit, a conditioning circuit and an output circuit, wherein the instrument amplification circuit differentially amplifies the pressure detection signal, the conditioning circuit provides an excitation signal for the pressure-sensitive chip, and the excitation signal is combined with an amplified pressure signal and temperature information to perform temperature compensation, digital calibration and linear correction, so that a target pressure signal is obtained, and the output circuit outputs the target pressure signal as a standard voltage signal. Therefore, accurate pressure measurement is realized.

Description

Technical Field

[0001] This invention relates to the field of pressure sensing technology, and more specifically to an airborne intelligent sensor. Background Technology

[0002] Airborne pressure sensors are crucial measurement components in avionics systems, widely used in aircraft hydraulic systems, fuel systems, engine control systems, environmental control systems, and flight condition monitoring systems. They are used to detect medium pressure in real time and output corresponding electrical signals, providing fundamental data for flight control, fault diagnosis, and condition monitoring. Because aviation equipment operates under complex conditions such as alternating high and low temperatures, vibration, shock, and electromagnetic interference, high demands are placed on the measurement accuracy, stability, anti-interference capabilities, and long-term reliability of pressure sensors.

[0003] Currently, airborne pressure sensors typically consist of a pressure-sensitive element and a signal conditioning circuit. The pressure-sensitive element converts the medium pressure into a weak electrical signal, which is then amplified, compensated, and output by the circuit to form a standard voltage or current signal. Because the output signal amplitude of the pressure-sensitive element is small, it is easily affected by external electromagnetic interference, circuit noise, and device temperature drift. Therefore, amplification circuits, filtering circuits, and conditioning circuits are usually required to process the pressure signal to improve the stability of the output signal and the measurement accuracy.

[0004] However, existing airborne pressure sensors still have certain shortcomings. On the one hand, the weak differential signal output by the pressure-sensitive element is prone to common-mode noise and high-frequency interference during transmission and amplification, affecting the accuracy of subsequent signal processing. On the other hand, existing signal conditioning circuits lack sufficient coordination in the amplification, filtering, temperature compensation, digital calibration, and linear correction processes of pressure signals, making it difficult to balance anti-interference capability, measurement accuracy, and output stability in complex aviation environments. Furthermore, some pressure sensors lack compatibility with both voltage and current outputs, and their input terminals have limited protection against abnormal conditions such as overvoltage, surges, electrostatic discharge, and reverse connection, affecting the long-term stable operation and reliable application of airborne sensors. Summary of the Invention

[0005] The summary section of this invention provides a brief overview of the concepts, which will be described in detail in the detailed description section below. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0006] This invention proposes an airborne intelligent sensor to solve one or more of the technical problems mentioned in the background section above.

[0007] This invention provides an airborne intelligent sensor, comprising: a pressure sensor probe, the pressure sensor probe including a pressure-sensitive chip and a temperature sensor, the pressure-sensitive chip being used to convert medium pressure into a pressure detection signal, the temperature sensor being used to collect temperature information, and the pressure sensor probe and pressure regulator being separately configured as a dual-body unit and connected by a cable; The pressure regulator contains a conditioning circuit board, which includes a power supply circuit, an instrumentation amplifier circuit, a conditioning circuit, and an output circuit. The power supply circuit converts external power into the operating power required by the conditioning circuit, instrumentation amplifier circuit, and output circuit. The instrumentation amplifier circuit receives the pressure detection signal and differentially amplifies it to obtain an amplified pressure signal. The conditioning circuit provides an excitation signal to the pressure-sensitive chip, receives the amplified pressure signal and temperature information, and performs temperature compensation, digital calibration, and linear correction on the amplified pressure signal to obtain the target pressure signal. The output circuit receives the target pressure signal and outputs it as a standard voltage signal.

[0008] Optionally, the power supply circuit is also used to convert the target pressure signal into a standard current signal, which is then output by the output circuit.

[0009] Optionally, the conditioning circuit board may also include multiple filter circuits, which are respectively located at the input terminal of the instrument amplifier circuit, the output terminal of the instrument amplifier circuit, the input terminal of the conditioning circuit, and the output terminal of the conditioning circuit.

[0010] Optionally, the pressure-sensitive chip is fabricated using a metal thin-film process and has a Wheatstone bridge structure. The pressure-sensitive chip is encapsulated inside the pressure sensor probe through a laser-welded sealing structure.

[0011] Optionally, the conditioning circuit board may also include an input protection circuit, which protects against overvoltage, surge, electrostatic discharge, and reverse input from the external power supply.

[0012] Optionally, the conditioning circuit uses a voltage output programmable sensor regulator chip, which has a built-in EEPROM for storing calibration parameters.

[0013] Optionally, the filter circuit at the input of the conditioning circuit includes a common-mode filter component and a differential-mode filter component, wherein the cutoff frequency of the common-mode filter component is set to be more than ten times the cutoff frequency of the differential-mode filter component.

[0014] Optionally, the calibration parameters may include at least zero-point calibration parameters, range calibration parameters, zero-point drift compensation parameters, and range drift compensation parameters.

[0015] Optionally, the power supply circuit and the output circuit are integrated into the same precision current output converter chip.

[0016] Optionally, the instrumentation amplifier circuit adopts a differential input and differential output amplification structure using dual operational amplifiers. The input terminal of the instrumentation amplifier circuit is equipped with a first low-pass filter, the feedback loop of the instrumentation amplifier circuit is equipped with a feedback compensation network, and the output terminal of the instrumentation amplifier circuit is equipped with a second low-pass filter.

[0017] This invention offers the following advantages: By separating the pressure sensor probe and pressure regulator into a dual-body design, the pressure-sensitive unit can be installed near the measured medium, while the conditioning circuit board is housed within the pressure regulator. This reduces the impact of complex environments such as high temperatures and vibrations on the electronic conditioning circuit, improving the overall reliability of the sensor. By incorporating an instrument amplification circuit, the pressure detection signal output from the pressure-sensitive chip is differentially amplified, improving the signal-to-noise ratio of weak pressure signals and providing a stable input signal for subsequent signal conditioning. The conditioning circuit, combined with temperature information, performs temperature compensation, digital calibration, and linear correction on the amplified pressure signal, effectively reducing temperature drift, zero-point offset, and nonlinear errors, thus improving pressure measurement accuracy and output consistency. The output circuit can output a standard voltage signal and, in conjunction with the power supply circuit, can output a standard current signal, enhancing the sensor's adaptability to different interface devices. Simultaneously, the conditioning circuit board incorporates multiple filtering circuits and input protection circuits to filter out noise during signal transmission and protect against overvoltage, surges, electrostatic discharge, and reverse input, further improving the sensor's anti-interference capability and long-term operational stability. Attached Figure Description

[0018] The above and other features, advantages, and aspects of the various embodiments of the present invention will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and elements are not necessarily drawn to scale.

[0019] Figure 1 This is a schematic diagram of the principle of an airborne intelligent sensor according to the present invention; Figure 2 This is a circuit diagram of the power supply circuit and input protection circuit of the present invention; Figure 3 This is the circuit diagram of the instrument amplifier circuit of the present invention; Figure 4 This is a partial circuit diagram of the conditioning circuit of the present invention; Figure 5 This is a physical image of the pressure sensor probe of the present invention; Figure 6 This is a physical image of the pressure regulator of the present invention. Detailed Implementation

[0020] The invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the invention. It should be understood that the drawings and embodiments of the invention are for illustrative purposes only and are not intended to limit the scope of protection of the invention.

[0021] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0022] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0023] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0024] The names of messages or information exchanged between the various devices of this invention are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0025] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] like Figure 1 The diagram shows a principle block diagram of an airborne intelligent sensor according to the present invention, which specifically includes a pressure sensor probe and a pressure regulator.

[0027] Among them, the pressure sensor probe includes a pressure-sensitive chip and a temperature sensor. The pressure-sensitive chip is used to convert the medium pressure into a pressure detection signal, and the temperature sensor is used to collect temperature information. The pressure sensor probe and the pressure regulator are set up separately in a dual-body manner and are connected by a cable. The pressure-sensitive chip is made using a metal thin-film process and has a Wheatstone bridge structure. The pressure-sensitive chip is encapsulated inside the pressure sensor probe through a laser-welded sealing structure.

[0028] In some embodiments, the pressure sensor probe is used to directly contact the measured medium and acquire pressure and temperature information. The pressure sensor probe includes a probe housing, a pressure-sensitive chip, a temperature sensor, a lead assembly, and a sealing assembly. The pressure-sensitive chip and temperature sensor are both disposed inside the probe housing. The lead assembly electrically connects the pressure-sensitive chip and temperature sensor to a pressure regulator, respectively. The sealing assembly seals the probe housing. The probe housing is preferably made of titanium alloy. A pressure inlet is provided at the front end of the probe housing, allowing compressed air, hydraulic oil, water, or other fluid media to enter the probe and act on the pressure-sensitive chip. The probe housing is sealed using laser welding, ensuring the pressure-sensitive chip operates in a sealed environment and preventing external moisture, dust, and corrosive media from entering the probe. The pressure-sensitive chip is fabricated using a metal thin-film process and includes an elastic sensitive diaphragm and a resistive bridge network formed on the surface of the elastic sensitive diaphragm. The resistive bridge network consists of multiple varistors forming a Wheatstone bridge. When the measured medium acts on the elastic sensitive diaphragm through the pressure inlet, the diaphragm undergoes elastic deformation. The piezoresistors formed on the surface of the diaphragm simultaneously strain, and the resistance of each piezoresistor changes with the strain. The Wheatstone bridge outputs a differential voltage signal corresponding to the medium pressure; this differential voltage signal is the pressure detection signal. A temperature sensor is placed near the piezoresistant chip and installed inside the same probe housing, ensuring that the temperature sensor and the piezoresistant chip are in the same thermal environment. The temperature sensor can be any of a thermistor, a platinum resistance thermometer (PT100), a digital temperature sensor, or an integrated temperature detection chip. In this embodiment, a platinum resistance thermometer (PT100) is preferred. The temperature sensor continuously monitors the internal temperature of the probe and outputs the corresponding temperature information, which is used by the subsequent conditioning circuit to perform temperature compensation.

[0029] To minimize the impact of heat generation and mechanical vibration from electronic components on the measurement accuracy of the pressure-sensitive chip, the pressure sensor probe and pressure regulator are designed as separate, dual-body units. This means the pressure sensor probe and pressure regulator each form two independent housings. The pressure sensor probe is installed at the pressure being measured, while the pressure regulator is installed in a location away from the pressure being measured. There is no rigid, integrated structure between the two housings. The pressure sensor probe and pressure regulator are connected by a cable. The cable includes a power conductor, a pressure signal conductor, a temperature signal conductor, and a common reference conductor. The pressure detection signal is transmitted to the pressure regulator via the pressure signal conductor, and the temperature information is transmitted to the pressure regulator via the temperature signal conductor. The pressure regulator provides power to the pressure sensor probe and the chip via the power conductor, thus enabling bidirectional transmission of pressure detection signals and temperature information. To reduce external electromagnetic interference, shielded cables are preferred. The shielding layer is connected to the grounding terminal of the pressure regulator to reduce the influence of external electromagnetic fields on the pressure detection signal transmission process and improve the stability of the pressure detection signal transmission.

[0030] The pressure regulator contains a conditioning circuit board, which includes a power supply circuit, an instrumentation amplifier circuit, a conditioning circuit, and an output circuit. The power supply circuit converts external power into the operating power required by the conditioning circuit, instrumentation amplifier circuit, and output circuit. The instrumentation amplifier circuit receives the pressure detection signal and differentially amplifies it to obtain an amplified pressure signal. The conditioning circuit provides an excitation signal to the pressure-sensitive chip, receives the amplified pressure signal and temperature information, and performs temperature compensation, digital calibration, and linear correction on the amplified pressure signal to obtain the target pressure signal. The output circuit receives the target pressure signal and outputs it as a standard voltage signal.

[0031] The conditioning circuit board also includes multiple filter circuits, which are respectively located at the input terminal of the instrument amplifier circuit, the output terminal of the instrument amplifier circuit, the input terminal of the conditioning circuit, and the output terminal of the conditioning circuit.

[0032] The conditioning circuit board also includes an input protection circuit, which protects against overvoltage, surge, electrostatic discharge, and reverse input from the external power supply.

[0033] The instrumentation amplifier circuit uses dual operational amplifiers to form a differential input and differential output amplification structure. The input terminal of the instrumentation amplifier circuit is equipped with a first low-pass filter, the feedback loop of the instrumentation amplifier circuit is equipped with a feedback compensation network, and the output terminal of the instrumentation amplifier circuit is equipped with a second low-pass filter.

[0034] In some embodiments, the pressure regulator is an electronic adjustment module used for powering, conditioning, digitally calibrating, and processing the pressure detection signal output by the pressure sensor probe. It has an internal metal mounting cavity, inside which a conditioning circuit board is fixedly mounted, and external power interface, probe connection interface, and signal output interface are provided. The pressure regulator is made with a sealed housing structure, which can be formed from aluminum alloy, stainless steel, or aerospace-grade titanium alloy. The conditioning circuit board is fixedly mounted inside the housing. The pressure sensor probe is connected to the conditioning circuit board via a cable. An external power supply is connected to the input terminal of the conditioning circuit board. The conditioned target pressure signal is output to an external control device through the output interface. The conditioning circuit board is a printed circuit board installed inside the pressure regulator, used to carry the power supply circuit, instrumentation amplification circuit, conditioning circuit, and output circuit, and to establish the electrical connections between these circuits. The conditioning circuit board is made of multi-layer PCB. The circuits are arranged in sequence according to the signal flow. The pressure detection signal output by the pressure sensor probe first enters the instrument amplification circuit, then enters the conditioning circuit to complete digital processing, and finally enters the output circuit for output. The external power supply first enters the power supply circuit, and then provides working power to the instrument amplification circuit, conditioning circuit and output circuit respectively.

[0035] The power supply circuit is a power management circuit that provides stable operating power to the various functional circuits of the conditioning circuit board. The power supply circuit includes a power input terminal, a power regulator module, a power filter module, and a power distribution module. After an external power source is connected, the power regulator module converts the input voltage into the stable operating voltage required by each functional circuit. The power filter module filters out ripple and high-frequency noise from the supply voltage. The power distribution module supplies power to the instrumentation amplifier circuit, conditioning circuit, and output circuit respectively, ensuring that each circuit maintains a stable operating state. The power supply circuit is integrated into a precision current output converter chip.

[0036] The input protection circuit is located at the external power supply input terminal of the conditioning circuit board, between the external power supply and the power supply circuit. It limits abnormal voltage on the power supply line before the external power supply enters the power supply circuit, preventing abnormal voltage from entering subsequent circuits. The external power supply is for the airborne intelligent sensor and can be provided by the aircraft's airborne power supply system, a dedicated power supply module for the programmable controller, or an independent DC power supply. The power supply circuit includes a positive power input terminal LOOP+, a negative power input terminal LOOP-, and system ground EGND. Overvoltage refers to a situation where the supply voltage exceeds the allowable operating voltage of the conditioning circuit board, such as a voltage overshoot during power-on. Surge refers to a short-duration, high-amplitude transient voltage or current, such as transient pulses generated by lightning strikes, motor start-up / stop, or cable switching. Electrostatic discharge (ESD) refers to a high-voltage pulse generated by the instantaneous release of static electricity accumulated in the human body or equipment through the power supply line. Reverse input refers to reverse power supply caused by reversing the positive and negative terminals of the external power supply.

[0037] like Figure 2The diagram shows the circuit schematic of the power supply circuit and input protection circuit of this invention. In specific implementation, a bidirectional transient voltage suppressor diode D3 (model XNT6(C)A30SK) is connected between LOOP+ and LOOP-. When the input voltage exceeds its breakdown voltage, D3 quickly enters the conducting state, rapidly discharging the abnormal current and limiting the voltage between LOOP+ and LOOP- to a safe range. A ceramic capacitor C12 (10nF) is connected in parallel across D3 to absorb high-frequency transient energy and reduce high-frequency peak voltage. To achieve reverse input protection, a Schottky diode D2 (model XNB5819WSP, belonging to the B5819W series) is connected in series in the power supply input circuit. When the external power supply polarity is correctly connected, D2 conducts in the forward direction (forward voltage drop of approximately 600mV); when the positive and negative terminals of the external power supply are reversed, D2 is cut off, preventing reverse current from flowing into the conditioning circuit board, thereby avoiding damage to subsequent circuits due to reverse power supply. To enhance lightning surge protection, a bidirectional transient voltage suppressor diode D1 (model SMBJ24CA) is installed at the power input terminal, forming a lightning surge protection network together with D4. When the power supply line is subjected to lightning strikes or surge pulse impacts, D1 and D4 simultaneously enter the conducting state, dissipating surge energy to system ground EGND, reducing the surge voltage entering subsequent circuits to a safe range. Ferrite beads FB1 and FB2 (600Ω) are also connected in series at the power input terminal to filter out high-frequency electromagnetic interference in the power supply line, preventing external high-frequency noise from being conducted along the power line into the conditioning circuit board. The power supply voltage, processed by the input protection circuit, is then input to the power supply circuit, which performs the power conversion and provides a stable operating power to the instrumentation amplifier circuit, conditioning circuit, and output circuit. The power supply circuit and the 4-20mA current output circuit are integrated into the precision current output converter chip LC115. This chip has a positive power input terminal V+ and a negative power input terminal V-. After being processed by the input protection circuit, the external power supply powers the chip through the V+ and V- pins. The chip's VREG pin outputs a 5V linear regulated power supply, providing operating power to the instrumentation amplifier circuit, conditioning circuit, and other downstream circuits on the conditioning circuit board. This 5V power supply network is labeled VREG_1. A 100nF filter capacitor C10 is located at the VREG output. The chip's VREF pin outputs a 2.5V bandgap reference voltage, labeled VREF_1. This reference voltage, after being divided by an external resistor R10 (191kΩ), flows into the chip's IIN pin to generate a constant offset current IREF, used to set the zero-point offset of the output current. A 100nF filter capacitor C9 is located at the VREF output. The current flowing into the IIN pin is amplified by a precision resistor network with a fixed gain of 100 inside the chip, and the corresponding current signal is output from the IO pin.The IRET pin is the current return terminal for the input circuit. The current from the external input circuit (including the path where R10 is located and the target pressure signal path output by the conditioning circuit) must flow back to the chip through the IRET pin to form a complete input current loop. The power input terminal is equipped with a 2.2μF / 25V decoupling capacitor C13 to smooth the input voltage ripple.

[0038] The output circuit receives the target pressure signal (voltage signal) output from the conditioning circuit and converts it into a standard current signal for output. Since the input control terminal of the precision current output converter chip LC115 is a current-type input (i.e., the IIN pin), the target pressure signal voltage output from the conditioning circuit needs to be converted into a current signal. The output circuit includes a series resistor topology connected between the output terminal of the conditioning circuit and the IN pin of the LC115 chip. This series resistor topology includes a first resistor and a second resistor connected in series. The target pressure signal voltage output from the conditioning circuit is applied across this series resistor topology, generating a corresponding input current IIN, which flows into the IIN pin of the LC115 chip. Simultaneously, the offset current IREF generated by the 2.5V reference voltage output from the VREF pin of the LC115 chip via resistor R10 merges and superimposes with the aforementioned input current IIN at the IRET pin, forming the total input current flowing into the IN pin. The LC115 chip amplifies this total input current by a fixed gain of 100 and outputs the amplified current from the IO pin. To enhance the output current carrying capacity, the B / BASE pin of the LC115 chip drives the base of an external NPN transistor Q1 (model XNS9014SQ). The current at the emitter of Q1 is detected through the E / EMITTER pin, forming a closed-loop feedback regulation. This allows the current output from the IO pin to be amplified by Q1 and then output as a standard 4mA to 20mA current signal from the loop output terminal (between LOOP+ and LOOP-).

[0039] In some embodiments, the instrument amplifier circuit receives the pressure detection signal output by the pressure sensor probe and performs pre-stage differential amplification on the pressure detection signal to increase its amplitude while suppressing external interference signals, thus providing a stable amplified pressure signal for subsequent conditioning circuits. For example... Figure 3The diagram shows the circuit schematic of the instrument amplifier circuit of the present invention. The pressure detection signal is a differential analog voltage signal output from the bridge sensitive resistor of the pressure-sensitive chip. The pressure detection signal includes a first differential voltage signal VIN1 and a second differential voltage signal VIN2. The two signals are connected to the two differential input terminals of the instrument amplifier circuit through cables. The first differential voltage signal VIN1 is connected to the first input terminal of the dual operational amplifier U7A, and the second differential voltage signal VIN2 is connected to the second input terminal of the dual operational amplifier U7B, so that the dual operational amplifiers U7A and U7B simultaneously acquire the two pressure detection signals and establish a differential input relationship between the two pressure detection signals. The instrument amplifier circuit uses a dual operational amplifier ZGW2333NR to form a differential input differential output amplification structure, where U7A and U7B are two operational amplifier units of the dual operational amplifier ZGW2333NR. The dual operational amplifiers are externally connected to a high-precision resistor network, including resistors R35, R36, and R37, which are used to set the gain. Each resistor has a 0.1% precision to ensure consistent resistance values ​​in the two amplification channels, maintaining the same amplification factor for both pressure detection signals and improving the common-mode rejection capability of the instrumentation amplifier circuit. Dual operational amplifiers U7A and U7B synchronously amplify the two pressure detection signals and calculate the voltage difference between them. This voltage difference is amplified proportionally according to a preset differential gain GAIN=2, while ensuring that the common-mode voltage present in both signals is not significantly amplified, resulting in a differentially amplified pressure detection signal output by the instrumentation amplifier circuit. The formula for calculating the differential gain GAIN is as follows: .

[0040] Common-mode noise is the interference voltage in the same direction simultaneously superimposed on two pressure detection signals. The differential-mode signal is the voltage difference between the two pressure detection signals, corresponding to the actual pressure change information detected by the pressure-sensitive chip. The instrument amplifier circuit primarily amplifies the differential-mode signal while maintaining unity gain for the common-mode noise, thereby improving the signal-to-noise ratio of the pressure detection signal.

[0041] To further reduce the impact of high-frequency noise on differential amplification, a first low-pass filter is installed at the input of the instrumentation amplifier circuit. The first low-pass filter consists of... Figure 3The circuit consists of resistors R31 (1kΩ / 0.1%) and R32 (1kΩ / 0.1%), and capacitor C35 (1nF). Before the pressure detection signals VIN1 and VIN2 enter the dual operational amplifiers U7A and U7B, they first pass through a first low-pass filter. This filter removes common-mode and differential-mode high-frequency noise from the pressure detection signals and limits signals above the preset cutoff frequency to entering the dual operational amplifiers. To ensure stable operation of the dual operational amplifiers U7A and U7B, feedback compensation networks are set in the feedback loops of the dual operational amplifiers. Each feedback compensation network consists of feedback resistors (including the feedback branches containing resistors R35 and R36) and capacitors C16 (100pF) and C36 (100pF) connected in parallel across the feedback resistors. The feedback compensation network limits the operating bandwidth of the instrumentation amplifier circuit by reducing the high-frequency closed-loop gain, preventing high-frequency self-oscillation in the dual operational amplifiers U7A and U7B and improving the stability of the amplification process. To further filter out high-frequency noise generated during amplification, a second low-pass filter is installed at the output of the instrumentation amplifier circuit. The second low-pass filter consists of... Figure 3 The circuit consists of resistors R33 (1kΩ / 0.1%) and R34 (1kΩ / 0.1%), and capacitor C37 (1nF). The differential amplified signal output from the dual operational amplifiers U7A and U7B passes through a second low-pass filter to further filter out residual high-frequency noise, resulting in the amplified pressure signal. Decoupling capacitors C32+ and C34 (100nF) are respectively installed at the power supply terminals of the dual operational amplifiers U7A and U7B to filter out high-frequency noise on the power lines, ensuring a stable operating power supply VREG for the operational amplifiers. The amplified pressure signal is a differential analog voltage signal after input filtering, differential amplification, feedback stabilization, and output filtering. This amplified pressure signal maintains the pressure change relationship corresponding to the original pressure detection signal, while having a higher signal amplitude and higher anti-interference capability. It is transmitted as the input signal to the conditioning circuit for subsequent temperature compensation, digital calibration, and linear correction. The formula for calculating the cutoff frequency of the first low-pass filter is as follows:

[0042] The formula for calculating the cutoff frequency of the second low-pass filter is as follows:

[0043] in, Indicates the cutoff frequency.

[0044] The conditioning circuit uses a voltage output programmable sensor regulator chip, which has a built-in EEPROM for storing calibration parameters.

[0045] The filter circuit at the input of the conditioning circuit includes a common-mode filter component and a differential-mode filter component. The cutoff frequency of the common-mode filter component is set to be more than ten times the cutoff frequency of the differential-mode filter component.

[0046] The calibration parameters include at least zero-point calibration parameters, range calibration parameters, zero-point drift compensation parameters, and range drift compensation parameters.

[0047] In some embodiments, such as Figure 4 The circuit diagram shown is a partial circuit diagram of the conditioning circuit of the present invention. Specifically, the conditioning circuit is implemented using a voltage output programmable sensor regulator chip (PGA chip). The PGA chip is mounted on the conditioning circuit board, and its signal input terminals are connected to the output terminals of the instrumentation amplifier circuit and the temperature sensor, respectively. Its excitation output terminal is connected to the varistor chip, and its output terminal is connected to the output circuit. The excitation signal is the bridge excitation voltage for the varistor chip, provided by the VEXC network. Specifically, the PGA chip integrates a constant voltage excitation source. After the sensor is activated, the PGA chip outputs a stable bridge excitation voltage to the excitation terminal of the varistor chip's Wheatstone bridge through the VEXC network, keeping the internal bridge of the varistor chip in a stable working state. When external pressure is applied to the varistor chip, the resistance of the bridge arms changes, thereby outputting a corresponding pressure detection signal.

[0048] The conditioning circuit features bridge excitation, initial span and offset voltage adjustment, span and offset voltage temperature adjustment, internal / external temperature measurement capability, output over-range and under-range limiting, fault detection, digital calibration, and input signal filtering. The PGA chip can acquire and condition differential voltage signals, and provides functions such as zero-point calibration, range setting, zero-point drift, range drift, and digital calibration of sensor linearization error, as well as applied stress (pressure, strain, etc.). The response speed is adjustable from 1kHz to 400kHz. Calibration is performed via a single-wire digital serial interface or a two-wire industry standard connection. The chip integrates 16-Kbit I / O. 2 The C-compatible serial EEPROM stores calibration parameters in its built-in EEPROM. Chip GNDA is analog ground, providing a reference ground for the chip's internal analog circuitry; VSA is analog power supply, powering the chip's internal analog circuitry. PGA chip VSJ is the test node, used for signal detection and functional verification during production testing; VFB is the feedback input, used to connect to an external feedback network to set gain or filter parameters.

[0049] The core of the conditioning circuit is a voltage output programmable sensor regulator chip. This chip integrates an input multiplexer, an automatic zeroing instrument PGA (Programmable Gain Amplifier), a multi-stage compensated DAC (Digital-to-Analog Converter), a linearization excitation circuit, an output operational amplifier, a precision voltage reference, an internal oscillator, an on-chip temperature measurement ADC (Analog-to-Digital Converter), temperature compensation lookup table logic, a one-wire / two-wire communication interface, sensor fault detection, range limiting, a complete power-on reset circuit, and an EEPROM. In this design, only an input signal needs to be provided to the chip, and the required signal can then be retrieved through the digital interface.

[0050] The amplified pressure signal, after differential amplification by the instrumentation amplifier circuit, is input to the differential input terminals VIN1 and VIN2 of the PGA chip via a filter circuit. The filter circuit at the input of the conditioning circuit consists of resistors R11 (39.2kΩ), R12 (39.2kΩ), capacitors C6 (10nF), C7 (10nF), and C8 (100nF). R11 is connected in series in the positive differential input path VIN1+, R12 is connected in series in the negative differential input path VIN1-, and C8 is connected between the two differential input terminals VIN1+ and VIN1- to form a differential-mode filter branch. C6 is connected between the positive input terminal VIN1+ and reference ground GND_1, and C7 is connected between the negative input terminal VIN1- and reference ground GND_1 to form a common-mode filter branch. Together, they constitute the input low-pass filter network, attenuating high-frequency AC noise entering the PGA chip. This input filter simultaneously incorporates both common-mode and differential-mode filtering components. Since the sensor voltage signal is a DC signal, its cutoff frequency is set to a very low value to reduce any possible AC noise. The differential-mode filter requires a cutoff frequency of 20Hz to effectively reduce all differential-mode AC noise; the common-mode filter's cutoff frequency is set to approximately 100Hz, so that common-mode noise (such as 60Hz power frequency noise) is attenuated before reaching the differential input of the PGA chip. Combined with the inherent suppression of common-mode signals by the instrumentation amplifier circuit, this prevents common-mode noise from being amplified by the PGA chip. To set the required differential filter frequency, calculating R11 and C6 will automatically achieve this requirement. The cutoff frequency of the filter circuit at the conditioning circuit input is defined by the following formula:

[0051]

[0052]

[0053] in, The cutoff frequency required for the differential mode filter component. This represents the required cutoff frequency for the common-mode filter component. R11 and R12 are differential-mode filter resistors, C8 is a differential-mode filter capacitor, and C6 and C7 are common-mode filter capacitors. Based on conventional design experience, a commonly used value of 10nF is chosen for C6. The required values ​​of R11 and R12 are then calculated by rearranging the above formulas to achieve a differential-mode cutoff frequency of 20Hz. The required value of R11 is defined as follows:

[0054] The closest standard resistance value was selected after calculation: R11=R12=39.2kΩ. The conditioning circuit includes a decoupling capacitor C5 (100pF) to filter high-frequency noise from the power supply line. The conditioning circuit also includes a filter capacitor C11 (10nF) to suppress noise in various environments, protect the subsequent stages from DC drift, and prevent self-oscillation of the on-chip operational amplifier. When the sensor signal reaches the PGA chip, the chip's internal gain, offset, and linearization circuits perform the necessary conditioning functions, outputting the target pressure signal VOUT after conditioning. The target pressure signal VOUT output by the PGA chip is transmitted to the input front end of the precision current output converter chip via the VOUT network.

[0055] The temperature information refers to the real-time operating temperature of the probe, acquired by the temperature sensor. The temperature sensor is installed inside the pressure sensor probe and positioned close to the pressure-sensitive chip, ensuring that the acquired temperature reflects the current operating environment temperature of the pressure-sensitive chip. The temperature sensor transmits the measured temperature information to the PGA chip for subsequent temperature compensation calculations. Based on this, the PGA chip reads the current temperature information and calls the pre-stored zero-point drift compensation parameters and range drift compensation parameters corresponding to different temperatures in the EEPROM to perform compensation calculations on the amplified pressure signal. This eliminates zero-point drift and sensitivity drift caused by changes in ambient temperature, ensuring a consistent pressure signal output for the same pressure value at different operating temperatures. Furthermore, during the product calibration phase, a single-wire digital serial interface or I / O is used... 2 The C-type digital interface writes calibration parameters to the PGA chip and stores them in the PGA chip's built-in EEPROM. The calibration parameters include at least zero-point calibration parameters, range calibration parameters, zero-point drift compensation parameters, and range drift compensation parameters. During operation, the PGA chip reads the calibration parameters from the EEPROM and digitally corrects the current amplified pressure signal to ensure the output pressure value meets design accuracy requirements. Based on the pressure-sensitive chip linearization parameters stored in the EEPROM, the PGA chip compensates for the nonlinearity error between the pressure-sensitive chip's output curve and the ideal linear output curve, performs linearization calculations on the amplified pressure signal, reduces the impact of the pressure-sensitive chip's inherent nonlinearity error on the measurement results, and ensures a linear correspondence between the output signal and the actual pressure.

[0056] Furthermore, to obtain the calibration parameters required for digital calibration, the airborne intelligent sensor was calibrated after the sensor hardware assembly was completed. Specifically, the pressure sensor probe was installed on a pressure regulating platform and connected to a pressure regulator via a cable. The pressure regulator was then connected to the testing device, a high-precision benchtop digital multimeter, and PC-based calibration software. Depending on the output format of the product to be calibrated, the testing device was switched to voltage or current mode. The external power supply was turned on, and calibration began after confirming normal operation of the testing device via indicator lights. Before calibration, a pre-pressure test was performed, applying pressure three times consecutively within the range of the pressure sensor probe to check the seal between the probe and the regulator and to confirm the actual output range of the probe. Once the seal was normal and the output range met design requirements, the calibration pressure range and interval were determined. Subsequently, starting from the minimum pressure value of the calibration pressure range, the pressure was increased incrementally at preset intervals, completing data acquisition at five calibration pressure points. After reaching the maximum calibration pressure, the pressure was decreased incrementally at the same intervals, completing data acquisition at five calibration pressure points, thus forming a complete calibration process. The above calibration process is executed three times consecutively, recording the pressure detection signal, temperature information, and output results corresponding to each calibration pressure point. The PC-based calibration software calculates the zero-point offset, range offset, temperature compensation parameters, and linear correction parameters based on the three calibration data, and generates digital calibration parameters. When all three calibration results meet the preset accuracy requirements, the generated digital calibration parameters are written to the PGA chip's built-in EEPROM for storage. During subsequent normal sensor operation, the PGA chip calls the digital calibration parameters stored in the EEPROM to perform temperature compensation, digital calibration, and linear correction on the amplified pressure signal, outputting the target pressure signal.

[0057] After temperature compensation, digital calibration, and linear correction, the PGA chip outputs the corresponding target pressure signal. The target pressure signal is a standard voltage signal that has undergone temperature drift compensation, zero-point calibration, range calibration, and linear correction. This target pressure signal is output to the output circuit. When the airborne intelligent sensor uses a voltage output mode, the target pressure signal is directly output by the output circuit. When the airborne intelligent sensor uses a current output mode, the target pressure signal is first input to the voltage / current conversion module in the power supply circuit, converted into a standard current signal, and then output by the output circuit.

[0058] In some embodiments, the output circuit is mounted on a conditioning circuit board, with its input connected to the output of the conditioning circuit and its output connected to avionics equipment or an external control system, for outputting a conditioned pressure signal. The output circuit is also integrated into a precision current output converter chip. The input of the output circuit is electrically connected to the output of the PGA chip. After the PGA chip completes internal signal conditioning, it sends the output voltage signal to the output circuit, which then serves as the final output interface. The standard voltage signal is an analog voltage signal that meets the input requirements of external devices, and its voltage value corresponds to the medium pressure. External avionics equipment can obtain the corresponding pressure value based on the standard voltage signal. Specifically, the output of the PGA chip is directly connected to the output circuit. The output circuit no longer amplifies, compensates, or calibrates the target pressure signal; it only serves as a voltage output interface, directly outputting the target pressure signal to the external control system or avionics equipment, thereby completing the voltage output of the pressure signal. The power supply circuit also converts the target pressure signal into a standard current signal, which is then output by the output circuit.

[0059] In some embodiments, because it is also compatible with current-output type airborne smart sensors, in another embodiment, when a standard current signal needs to be output, the target pressure signal output by the PGA chip does not directly enter the output circuit, but is first input to a voltage / current conversion module located in the power supply circuit. The voltage / current conversion module is implemented using a precision current output chip, with its input connected to the output of the PGA chip and its output connected to the output circuit. Specifically, Figure 4 The target pressure signal output by the PGA chip The current is converted through series resistors R13 (11.3kΩ) and R14 (10kΩ). :

[0060] A constant offset current is generated by a fixed reference voltage VREF_1 in conjunction with resistor R10 (191kΩ). Resistor R16 (100Ω) is an auxiliary resistor used in conjunction with the VREF_1 network to provide an additional reference voltage shunt path to enhance the stability and load regulation capability of the VREF output network.

[0061]

[0062] and The total input current is generated after superposition. The current flows into the input terminal of the voltage / current conversion module:

[0063] The current gain of the voltage / current conversion module is fixed at 100. After amplification, the final current signal is output through a two-wire current loop. :

[0064] To achieve a linear output range of 4mA-20mA, The required output current is 40µA-200µA. To accommodate over-range and under-range faults, this design extends the output range as follows, with a minimum value... Set to 2.85mA, maximum value The current is set to 25mA. Correspondingly, this corresponds to the minimum output voltage range of the PGA chip. Set to 0.15V, maximum value Set to 4.85V.

[0065] R13 and R14 convert the output voltage of the PGA chip. To current value The total series resistance required for R13 and R14 is from the target. and The calculated range, considering a current gain of 100 for the voltage / current conversion module, is as follows:

[0066] Calculations show that the series connection of R13 and R14 is 21.2kΩ. After selecting R14 = 10kΩ, The standard value is taken as 11.3kΩ. Further calculation of the actual minimum output current revealed the need for additional current; therefore, IREF, generated by VREF_1 and R10, is introduced. The required current is calculated... :

[0067] Then calculate:

[0068] Calculated The standard value is 191kΩ. Before the signal enters the voltage / current conversion module, a first-order low-pass filter composed of R13 and C14 (10nF) attenuates high-frequency noise above 2kHz generated by the PGA chip. The cutoff frequency of this low-pass filter is defined by the following formula:

[0069] The PGA chip generates noise of 2kHz and above; therefore, the cutoff frequency of this low-pass filter is set to approximately 1.4kHz. Since the value of R13 is already determined, C14 is calculated using the cutoff frequency formula:

[0070] C14 was calculated to have a standard value of 10nF. Thus, based on the requirements of this design, all parameters in the hardware design were obtained through theoretical calculations, and all errors were corrected during the subsequent calibration process. The conditioning circuit also has a core excitation function, which can provide an excitation signal to the pressure core to obtain a corresponding output voltage signal. The excitation is performed via external leads.

[0071] In some embodiments, in order to verify the measurement performance of the airborne smart sensor of this application, a performance test is performed on the calibrated airborne smart sensor.

[0072] Specifically, a voltage output pressure sensor with a range of 0MPa to 1.5MPa and a voltage output range of 0.3V to 2.8V, and a current output pressure sensor with a range of 0MPa to 3MPa and a current output range of 4mA to 20mA were used as test objects. The voltage output pressure sensor was powered by a 12V±0.5V power supply, and the current output pressure sensor was powered by a 15V±0.5V power supply. The physical structure of the pressure sensor probe and pressure regulator is as follows: Figure 5 and Figure 6 As shown in the diagram. During testing, the pressure sensor probe was mounted on a precision gas piston-type pressure regulating platform and connected to a calibrated precision digital pressure gauge. The signal output of the pressure regulator was connected to a high-precision benchtop digital multimeter. Subsequently, different pressure values ​​were applied to the pressure sensor probe through the precision gas piston-type pressure regulating platform, and pressure tests were completed at room temperature, -55℃, and 125℃. Specifically, the voltage output type pressure sensor underwent pressure boosting and depressurization tests at pressure points of 0 kPa, 300 kPa, 600 kPa, 900 kPa, 1200 kPa, and 1500 kPa; the current output type pressure sensor underwent pressure boosting and depressurization tests at pressure points of 0 kPa, 500 kPa, 1000 kPa, 1500 kPa, 2000 kPa, 2500 kPa, and 3000 kPa. During the test, the corresponding output voltage or output current was recorded at each pressure point, and the measured results were compared with the corresponding rated output value and allowable output range. The measurement error and full-scale accuracy of each test point were calculated. The test results are shown in Tables 1 to 6.

[0073] Table 1. Room temperature test data of 0MPa~1.5MPa pressure sensors

[0074] Table 2 Test data of 0MPa~1.5MPa pressure sensors at -55℃

[0075] Table 3 Test data of 0MPa~1.5MPa pressure sensors at 125℃

[0076] Table 4. Room temperature test data of 0MPa~3MPa pressure sensors

[0077] Table 5. Test data of 0MPa~3MPa pressure sensors at -55℃

[0078] Table 6 Test data of 0MPa~3MPa pressure sensors at 125℃

[0079] As shown in Tables 1 to 6, the voltage output pressure sensor's output values ​​at each pressure point fall within the designed output range under normal temperature, -55℃, and 125℃ conditions, with a measurement accuracy of less than ±0.25%FSR. Similarly, the current output pressure sensor's output current at each pressure point meets the designed output range under the same conditions, with a measurement accuracy of less than ±0.25%FSR. Both types of airborne intelligent sensors meet the design requirement of a precision of less than or equal to ±0.5%FSR, demonstrating that the dual-body structure, instrument amplification circuit, conditioning circuit, and digital calibration scheme adopted in this application can ensure that the airborne intelligent sensor maintains high measurement accuracy and output stability over a wide temperature range.

[0080] In these embodiments, by adopting a dual-body separate arrangement of the pressure sensor probe and pressure regulator, the pressure-sensitive unit can be installed near the measured medium, while the conditioning circuit board is located inside the pressure regulator. This reduces the impact of complex environments such as high temperature and vibration on the electronic conditioning circuit, improving the overall reliability of the sensor. By incorporating an instrumentation amplification circuit, the pressure detection signal output from the pressure-sensitive chip is differentially amplified, improving the signal-to-noise ratio of weak pressure signals and providing a stable input signal for subsequent signal conditioning. The conditioning circuit, combined with temperature information, performs temperature compensation, digital calibration, and linear correction on the amplified pressure signal, effectively reducing temperature drift, zero-point offset, and nonlinear errors, improving pressure measurement accuracy and output consistency. The output circuit can output a standard voltage signal and, in conjunction with the power supply circuit, can achieve a standard current signal output, improving the sensor's adaptability to different interface devices. Simultaneously, the conditioning circuit board incorporates multiple filtering circuits and input protection circuits to filter out noise during signal transmission and protect against overvoltage, surges, electrostatic discharge, and reverse input, further enhancing the sensor's anti-interference capability and long-term operational stability.

[0081] The above description is merely a selection of preferred embodiments of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention is not limited to specific combinations of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. An airborne intelligent sensor, characterized in that, include: A pressure sensor probe, comprising a pressure-sensitive chip and a temperature sensor, wherein the pressure-sensitive chip is used to convert the medium pressure into a pressure detection signal, and the temperature sensor is used to collect temperature information; the pressure sensor probe and the pressure regulator are separately configured as a dual-body unit and connected by a cable. A pressure regulator is provided, which internally includes a conditioning circuit board. The conditioning circuit board comprises a power supply circuit, an instrumentation amplification circuit, a conditioning circuit, and an output circuit. The power supply circuit converts external power into the operating power required by the conditioning circuit, the instrumentation amplification circuit, and the output circuit. The instrumentation amplification circuit receives the pressure detection signal and differentially amplifies it to obtain an amplified pressure signal. The conditioning circuit provides an excitation signal to the pressure-sensitive chip, receives the amplified pressure signal and the temperature information, and performs temperature compensation, digital calibration, and linear correction on the amplified pressure signal to obtain a target pressure signal. The output circuit receives the target pressure signal and outputs it as a standard voltage signal.

2. The airborne intelligent sensor according to claim 1, characterized in that, The power supply circuit is also used to convert the target pressure signal into a standard current signal, which is then output by the output circuit.

3. The airborne intelligent sensor according to claim 1, characterized in that, The conditioning circuit board also includes multiple filter circuits, which are respectively located at the input terminal of the instrument amplifier circuit, the output terminal of the instrument amplifier circuit, the input terminal of the conditioning circuit, and the output terminal of the conditioning circuit.

4. The airborne intelligent sensor according to claim 1, characterized in that, The pressure-sensitive chip is fabricated using a metal thin-film process and has a Wheatstone bridge structure. The pressure-sensitive chip is encapsulated inside the pressure sensor probe by a laser-welded sealing structure.

5. An airborne intelligent sensor according to claim 1, characterized in that, The conditioning circuit board also includes an input protection circuit, which is used to protect against overvoltage, surge, electrostatic discharge and reverse input generated by the external power supply.

6. An airborne intelligent sensor according to claim 1, characterized in that, The conditioning circuit uses a voltage output programmable sensor regulator chip, which has a built-in EEPROM for storing calibration parameters.

7. An airborne intelligent sensor according to claim 3, characterized in that, The filter circuit at the input of the conditioning circuit includes a common-mode filter component and a differential-mode filter component, and the cutoff frequency of the common-mode filter component is set to be more than ten times the cutoff frequency of the differential-mode filter component.

8. An airborne intelligent sensor according to claim 6, characterized in that, The calibration parameters include at least zero-point calibration parameters, range calibration parameters, zero-point drift compensation parameters, and range drift compensation parameters.

9. An airborne intelligent sensor according to claim 1, characterized in that, The power supply circuit and the output circuit are integrated into the same precision current output converter chip.

10. An airborne intelligent sensor according to claim 1, characterized in that, The instrumentation amplifier circuit uses dual operational amplifiers to form a differential input and differential output amplification structure. The input terminal of the instrumentation amplifier circuit is equipped with a first low-pass filter, the feedback loop of the instrumentation amplifier circuit is equipped with a feedback compensation network, and the output terminal of the instrumentation amplifier circuit is equipped with a second low-pass filter.

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