Aircraft double-cabin door gap contact type measuring device and measuring method

Abstract

The application discloses a kind of aircraft double cabin door gap contact type measuring device and measuring method, including film pressure distribution sensor, modulator, USB collector, calibration equipment and host computer;Film pressure distribution sensor is arranged in the gap between two cabin doors, between the upper and lower ends of fuselage door frame and at least one cabin door;Several numbers of adhesive tape are evenly arranged on the outer surface of the aircraft double cabin door, and the adhesive tape is connected with adhesive tape-lever loading system;Load is applied by hydraulic actuator around the fuselage door frame;The resistance signal output by all film pressure distribution sensors is input into the input end of modulator;Calibration equipment calibrates the voltage signal output by modulator, determines the load coefficient and zero deviation value, and establishes the functional relationship between the pressure value and voltage value of the sensing layer unit of film pressure distribution sensor. The gap measurement of aircraft double cabin door under ground load test state is realized.

Description

Technical Field

[0001] This invention belongs to the field of gap testing technology, and specifically relates to a contact-type measuring device and method for measuring the gap of aircraft dual-door gap, used for measuring the gap under stress during ground testing of aircraft dual-door gap. Background Technology

[0002] Measuring aircraft door clearances is crucial for maintaining aircraft performance and combat effectiveness. From an airtightness perspective, aircraft experience drastic pressure changes during high-altitude, high-speed flight. Improper door clearance control can easily lead to seal failure, resulting in airflow infiltration or leakage. As a critical sealing component, the door's clearance directly affects the stability of the cabin's internal air pressure and the aircraft's control precision. From a stealth performance perspective, the door is a significant structural component affecting the aircraft's radar reflection characteristics. Assembly deviations or uneven clearances in the door not only create strong radar wave reflection points but also compromise overall smoothness, significantly increasing the radar cross-section and weakening stealth capabilities.

[0003] Currently, the main methods for measuring aircraft door clearance are laser ranging and eddy current sensing. Laser triangulation is more widely used. It uses a laser emitter to illuminate the two surfaces of the door. The reflected laser beam is received by an image sensor placed at a fixed angle. The clearance distance between the doors is calculated using triangulation formulas. This method is a non-contact optical measurement method, easily affected by background light, sensitive to changes in object position, and unstable. Eddy current sensors contain a coil energized with high-frequency alternating current, creating an alternating magnetic field near the coil. When the door approaches the magnetic field, eddy currents are induced inside the metal, forming a reverse magnetic field that affects the impedance of the sensor's original coil. By detecting the change in coil impedance, the distance between the doors is calculated. This method has an effective measurement range of approximately 0.2–10 mm and a narrow linear measurement area.

[0004] Chinese Patent Application No. 202411612820.6 discloses a gap sensor that uses the eddy current principle for gap measurement. The sensor includes a measuring body with probes at its ends, a measuring head consisting of an outer casing, and a transmitter. When the probes contact an object with a changing gap, the two probes move the eddy current probes on the internal body and the measured metallic conductor material as the gap changes. This changes the distance between the eddy current probes and the object, causing a linear change in the probe impedance. The distance is calculated by reading the voltage signal from the probes, thus achieving the purpose of measuring the distance between the probes and the object. This sensor measurement method uses the principle of magnetic field influence, which is ineffective for some non-conductive composite materials. If a two-probe cooperative method is used, problems such as probe deformation or asynchronous displacement can cause significant systematic errors. Furthermore, the presence of a coating on the surface of the object being measured will greatly reduce the measurement accuracy.

[0005] Therefore, there is a need to invent a novel contact-type aircraft dual-door gap measuring device and its measuring method, which is used to measure the actual contact gap between the two doors with high precision when the aircraft doors are closed. This device can reflect the gap changes under real working conditions such as structural fit and stress deformation, so as to meet the engineering requirements of flight safety, structural sealing and maintenance inspection, and provide a reliable basis for door assembly accuracy assessment, intelligent monitoring and assembly parameter adjustment. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a contact-type measurement device and method for the gap between aircraft dual doors. The device uses a built-in thin-film pressure distribution sensor to measure the pressure changes of the aircraft dual doors in real time during ground-load tests. A USB data acquisition unit processes and converts the acquired analog signals to obtain the gap change value of the aircraft dual doors under load. This solves the problem of the difficulty in measuring the three-dimensional dynamic micro-deformation mechanism between aircraft dual doors under ground-load conditions and provides a basis for future aircraft dual-door gap assessment, intelligent monitoring, and intelligent adjustment of control parameters. The measurement method solves the problem of the difficulty in measuring the three-dimensional dynamic micro-deformation mechanism between aircraft dual doors under ground-load test conditions, realizing the gap measurement of aircraft dual doors under ground-load test conditions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a contact-type measuring device for the gap between two aircraft doors, the device comprising a thin-film pressure distribution sensor, a modulator, a USB data acquisition device, a calibration device, and a host computer; the direction parallel to the gap between the two doors is defined as the X direction, the direction perpendicular to the X direction is defined as the Y direction, and the door thickness direction is defined as the Z direction;

[0009] P thin-film pressure distribution sensors are uniformly arrayed along the X direction in the gap between the two hatches to fully cover the inner side of the hatches and measure the micro-deformation of the gap along the X and Z directions; Q thin-film pressure distribution sensors are arrayed between the upper and lower ends of the fuselage door frame and at least one hatch to measure the micro-deformation of the door gap along the Y and Z directions.

[0010] The measuring point density of the thin-film pressure distribution sensor is 10-15 measuring points / cm². 2 ;

[0011] A number of adhesive tapes are evenly distributed on the outer surface of the aircraft's two cabin doors to ensure that the doors are evenly loaded. The adhesive tapes are connected to an adhesive tape-lever loading system.

[0012] A load is applied around the fuselage door frame using hydraulic actuators;

[0013] The resistance signals output by all thin-film pressure distribution sensors are input to the input terminal of the modulator; the modulator processes the input resistance signals and converts them into voltage signals, which are then output to the USB data acquisition unit and the calibration device, respectively.

[0014] The calibration device calibrates the voltage signal output by the modulator, determines the load coefficient and zero-point deviation value, and establishes a functional relationship between the pressure value and voltage value of the sensing layer unit on the thin-film pressure distribution sensor.

[0015] The USB data acquisition unit collects the voltage signal output by the modulator and outputs it to the host computer, realizing digital reading, real-time display and storage of data;

[0016] The host computer acquires the function relationship of the calibration device and performs visual analysis on the voltage signal output by the USB acquisition device and extracts the three-dimensional micro-deformation feature information of the door gap.

[0017] Furthermore, the measuring device is used to measure the three-dimensional dynamic micro-deformation of the gap between the two aircraft doors in real time under different ground load test conditions, realizing the monitoring of minute deformation at the 10µm level.

[0018] Furthermore, the thin-film pressure distribution sensor is made of high-temperature and corrosion-resistant material, with a measuring point density of 13.3 measuring points / cm². 2 The range is 0.1mm to 0.15mm, and the thickness is 1mm to 1.5mm; preferably, it is a 6300 type thin film pressure distribution sensor with a size of 200mm×15mm.

[0019] Furthermore, the adhesive tape-lever loading system includes a thin steel wire and a lever. An even number of adhesive tapes are evenly and equidistantly arranged on the surface of the double-door. Every two adhesive tapes are connected to the levers through the thin steel wires. The adhesive tapes are connected to the levers in multiple layers through the thin steel wires, and the lever principle is used to amplify or change the direction and magnitude of the force.

[0020] Secondly, the present invention provides a contact-type measurement method for the gap between two aircraft cabin doors, wherein the measurement method uses the aforementioned measuring device, and the specific steps are as follows:

[0021] 1) Connect the various parts of the measuring device according to the above connection method. The thin film pressure distribution sensor is equidistantly arranged along the X direction of the inner side of the hatch to achieve full coverage measurement along the X direction of the hatch. At the same time, thin film pressure distribution sensors are equidistantly arranged at both ends of the hatch along the Y direction to achieve full coverage measurement along the Y direction of the hatch. Adjust the relative position of the thin film pressure distribution sensor and the hatch so that the thin film pressure distribution sensor fits better into the deformation area of ​​the hatch and ensures that the thin film pressure distribution sensor is within the effective range. Start all components in the measuring device to put them into normal working condition.

[0022] 2) Operate the tape-lever loading system and hydraulic actuator to apply load to the aircraft's dual-door level according to test requirements;

[0023] 3) Calibrate the thin-film pressure distribution sensor: All thin-film pressure distribution sensors used are of the same model. Under no-load conditions, read and record the voltage signal output by the modulator as the zero-point baseline data; apply a uniform known load condition to the area where the thin-film pressure distribution sensor is arranged, maintain the load stable for several seconds, and after the modulator output signal stabilizes, subtract the voltage signal at this time from the zero-point baseline data to obtain the corresponding voltage signal value under the current load condition.

[0024] Unload and change the load conditions, and test the pressure values ​​and corresponding voltage signal values ​​of each sensing layer unit of the thin-film pressure distribution sensor under different load conditions. Use the pressure values ​​and corresponding voltage signal values ​​of different sensing layer units as sample data points. Combine a large number of sample data points with a linear regression model and the least squares formula to fit and obtain the load coefficient k of the current thin-film pressure distribution sensor. f Based on the zero-point deviation value b, establish the functional relationship between the pressure value and voltage value of the sensing layer unit on the thin-film pressure distribution sensor;

[0025] 4) During the operation of the tape-lever loading system and the hydraulic actuator, the user sets the load magnitude and direction according to the simulation requirements, and simultaneously sets the sampling time, acquisition frequency, number of channels, maximum voltage value, and minimum voltage value. After setting the above parameters, the user starts the acquisition. The calibration equipment, based on the known load and the functional relationship determined in step 3), determines the corresponding actual pressure value after obtaining the voltage signal of the sensing layer unit of each membrane pressure distribution sensor under load, and thus obtains the two-dimensional pressure matrix F of each membrane pressure distribution sensor. i ;

[0026] 5) Based on the actual arrangement positions of each thin-film pressure distribution sensor, including the arrangement sequence in the X and Y directions and its initial installation coordinates (X... i ,Y i Establish spatial coordinate mapping relationships; through the correspondence between sensor numbers and their physical placement positions, construct the two-dimensional pressure matrix F of each thin-film pressure distribution sensor. i The images are pieced together to form a complete two-dimensional pressure distribution map of the hatch contact surface.

[0027] 6) Based on the starting coordinates (X) of each thin-film pressure distribution sensor. i Y i ), and by combining formula (5), the spatial coordinates (X, X) of each pixel in the two-dimensional pressure matrix in the three-dimensional coordinate system of the overall hatch are obtained. i,jk ,Y i,jk Z i,jk ), to obtain a three-dimensional micro-deformation map;

[0028]

[0029] Among them, X i Let X be the starting coordinate for the installation of the i-th sensor in the X direction, and Y be the starting coordinate for the installation of the i Z represents the starting coordinates for the installation of the i-th sensor in the Y direction, k is the column index of the sensor pixel, j is the row index of the sensor pixel, Δx is the X-axis spacing of the sensor pixels, and Δy is the Y-axis spacing of the sensor pixels; i,jk Let Z be the deformation displacement of the pixel in the j-th row and k-th column of the i-th sensor.

[0030] Furthermore, the method can be used for door assembly accuracy assessment, intelligent monitoring, and assembly parameter adjustment.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] This invention employs a high-sensitivity, high-resolution thin-film pressure distribution sensor, capable of sensing minute pressure changes in the door contact area in real time. Combined with a pre-calibrated functional relationship, the electrical signal is precisely converted into actual contact pressure data. Compared to traditional optical measurement techniques that rely on surface texture and viewing angle to obtain displacement field information, and are limited by environmental conditions such as illumination, reflectivity, and obstruction, this invention achieves highly stable and high-precision three-dimensional gap measurement under complex working conditions through contact-based multi-point array pressure acquisition and deformation field inversion technology. This method overcomes the bottleneck of optical measurement technology's limited application in low-light environments, enclosed areas, and non-transparent surfaces, and its measurement accuracy is significantly superior to optical measurement methods.

[0033] The arrangement of the thin-film pressure distribution sensors in this invention involves: seven thin-film pressure distribution sensors arrayed along the X-axis of the hatch to achieve full coverage measurement of the deformation values ​​in the X and Z directions of the hatch; and two thin-film pressure distribution sensors arrayed along the Y-axis at the upper and lower ends of the hatch to achieve full coverage measurement of the deformation values ​​in the Y and Z directions of the hatch. This scheme utilizes the flexible bonding characteristics of the thin-film pressure distribution sensors to accurately capture the minute deformations of the two hatches in the X, Y, and Z directions when they are closed, enabling three-dimensional reconstruction of the hatch gap space.

[0034] The thin-film pressure distribution sensor of this invention consists of an array of several sensing layer units. This array configuration enables multi-channel measurement. When deployed in the critical contact area of ​​the dual doors of an aircraft bomb bay, it can achieve high-resolution data acquisition of multiple points, synchronously, and continuously in the gap area. Each channel independently acquires the pressure signal at its corresponding position, improving the spatial resolution and measurement accuracy of the sensor system and effectively capturing the subtle deformations generated during the door closing process.

[0035] The thin-film pressure distribution sensor used in this embodiment of the invention is ultra-thin, highly flexible, and highly sensitive. It can adapt to deformation measurement under different curvature environments, and is simple, reliable, and easy to use.

[0036] The measuring device and method of this invention are used to measure the three-dimensional dynamic micro-deformation of the gap between two aircraft cabin doors in real time under ground load test conditions. The thin-film pressure distribution sensor used can achieve full coverage of both aircraft cabin doors and measure the gap deformation value through multiple channels. Compared with traditional optical measurement technology, this measurement method can achieve micro-deformation accuracy at the 10µm level. The measuring device can simulate airtight loads from above and below through the adhesive tape-lever loading system, and can simulate the squeezing force of the fuselage during flight through the hydraulic actuation cylinders set around the perimeter. Thus, the measuring device can set simulated load conditions according to actual working conditions to achieve high-precision monitoring under different working conditions. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the connection structure of an embodiment of the contact-type measuring device for the gap between two aircraft doors according to the present invention;

[0038] Figure 2 This is a schematic diagram of the adhesive tape-lever loading system structure of one embodiment of the contact measurement device for aircraft dual-door gaps of the present invention;

[0039] Figure 3 This is a schematic diagram of a scaled-down model of an aircraft with two cabin doors used in this invention.

[0040] Figure 4This is a schematic diagram of the thin-film pressure distribution sensor in an embodiment of the contact measurement device for the gap between two aircraft doors of the present invention. The small area formed by the white horizontal and vertical lines in the sensing area is the measuring point area.

[0041] Figure 5 This is a schematic diagram of the arrangement of a thin-film pressure distribution sensor in one embodiment of the present invention;

[0042] Figure 6 This is a flowchart illustrating the analysis software used in the contact measurement of the gap between two aircraft doors according to the present invention.

[0043] In the diagram: 1. Adhesive tape, 2. Thin steel wire, 3. Lever, 4. Aircraft double cabin door, 5. Thin film pressure distribution sensor, 6. Signal connection line, 7. Modulator, 8. USB data acquisition device, 9. Host computer, 10. Calibration equipment, 11. Hydraulic actuator, 12. Fuselage door frame. Detailed Implementation

[0044] The present invention will be further described below with reference to examples and accompanying drawings, but this is not intended to limit the scope of protection of the claims of this application.

[0045] This invention relates to a contact-type measuring device for the gap between two aircraft cabin doors (hereinafter referred to as the device, see [link]). Figure 1-5 The system includes: 1. Adhesive tape; 2. Thin steel wire; 3. Lever; 4. Aircraft double cabin door; 5. Thin film pressure distribution sensor; 6. Signal connection cable; 7. Modulator; 8. USB data acquisition device; 9. Analysis software; 10. Calibration equipment; The adhesive tape-lever loading system, composed of adhesive tape 1, thin steel wire 2, and lever 3, is combined with... Figure 3 The scaled-down model of the aircraft's double cabin door shown has dimensions of 1400×300×15mm (height refers to the thickness of the cabin door). Eight 170×110mm adhesive tapes 1 are selected and one side is pasted on the outer surface of the aircraft's double cabin door 4. Four adhesive tapes are equidistantly pasted around the outer surfaces of the left and right cabin doors to ensure uniform force distribution on the cabin doors during loading. The other side of the adhesive tapes 1 is connected to levers 3 through thin steel wires 2 to achieve multi-level connections. The adhesive tape-lever loading system in this invention can be implemented based on existing technology.

[0046] A hydraulic actuator 11 with X-direction loading is installed at both ends of the gap between the left and right hatches, and a hydraulic actuator 11 with Y-direction loading is installed on the central axis of the left and right hatches.

[0047] The device in this embodiment is used to simulate ground tests. The hatch is located on the belly of the wind turbine and opens to the left and right. The pressure on the left and right hatches is symmetrically distributed. Therefore, in this embodiment, only the force on the upper and lower ends of the left hatch is considered. The right hatch can be symmetrically obtained. The uniformly distributed load force can be formed on the door frame by applying hydraulic actuators in the X and Y directions.

[0048] The thin-film pressure distribution sensor 5 is elongated. Seven thin-film pressure distribution sensors are arranged in an array along the X-axis of the hatch, and two thin-film pressure distribution sensors are arranged in an array along the Y-axis at the top and bottom of the left hatch, respectively. Each thin-film pressure distribution sensor is independently connected to the modulator 7 via signal connection line 6, forming 11 channels to output pressure change values. The modulator 7 has 16 channels and processes the resistance signal changes output by the 11 thin-film pressure distribution sensors, converting them into voltage signals, which are then output to the USB acquisition device 8 and the calibration device 10, respectively. The USB acquisition device 8 records and stores the acquired voltage signals and outputs them to the host computer 9. The host computer is loaded with analysis software, and the calibration device 10 calibrates the voltage signals output by the modulator, determining the load coefficient and zero-point deviation value, and establishing a functional relationship between the pressure value and voltage value of the sensing layer unit on the thin-film pressure distribution sensor. The USB acquisition device acquires the voltage signals output by the modulator and outputs them to the host computer, realizing digital reading, real-time display, and storage of data.

[0049] The host computer acquires the function relationship of the calibration device and performs visual analysis on the voltage signal output by the USB acquisition device and extracts the three-dimensional micro-deformation feature information of the door gap.

[0050] Figure 5 The upper middle section is the right hatch, and the lower section is the left hatch. The X direction is parallel to the gap between the left and right hatches, and the Y direction is perpendicular to the X direction.

[0051] The thin-film pressure distribution sensor 5 described in this invention is a 6300-type thin-film pressure distribution sensor with dimensions of 200mm × 15mm, a thickness of 10-15μm, a sensing array of 40×10, 400 measuring points, a measuring range of 0.1mm to 0.15mm, and a supported temperature range of -20℃ to 200℃, meeting the actual operating conditions of aircraft flight. It is made of high-temperature and corrosion-resistant materials. The measuring point density of the thin-film pressure distribution sensor 5 is 13.3 measuring points / cm². 2 .

[0052] The analysis software of this invention has an interface including an image acquisition section, a parameter setting section, an image display section, a storage control section, an image analysis section, a color level adjustment section, an image playback section, and a calibration section. The image acquisition section receives the voltage signal modulated by the modulator 7 output from the USB acquisition unit 8 and saves the acquired data. The parameter setting section allows setting parameters such as sampling frequency, acquisition channels, number of sampling points, maximum voltage value, and minimum voltage value. The image display section processes the voltage signal acquired by the USB acquisition unit 8 and displays the loaded image in 2D or 3D format. The storage control section stores the processed image data, supporting formats such as [format missing]. The system supports Excel files (*.xls), text files (*.txt), and image files (*.tdms). The image analysis section allows for operations such as zeroing, scatter analysis, and data fitting of the acquired image data. The color level adjustment section allows for highlighting critical load-bearing areas of the aircraft's dual doors (the area between the upper and lower ends of the doors and the fuselage) and areas with large three-dimensional micro-deformation. The image playback section, specifically View-2DReplay, can simultaneously display parameters such as total pressure and deformation when using the analysis-playback function. The calibration section calibrates the thin-film pressure distribution sensor 5 under various load conditions, significantly reducing output data errors.

[0053] The software flow of the analysis software described in this invention (see...) Figure 6 )yes:

[0054] (1) Initially, check whether the tape-lever loading system is working properly by checking whether the tape is too loose and whether the lever rotates normally. If it is normal, start the loading system; if it is abnormal, diagnose and handle it, and continue to check whether the tape-lever loading system is working properly.

[0055] (2) Start the modulator, USB acquisition device, analysis software and calibration device, and test whether the modulator, USB acquisition device, analysis software and calibration device are in normal working condition. If they are in normal working condition, proceed to step (3). If they are not in normal working condition, make adjustments and corrections, and continue to determine whether they are in normal working condition.

[0056] (3) The adhesive tape-lever loading system and hydraulic actuator cylinder are used for layered loading. The voltage signals under each working condition are output on the calibration interface of the analysis software. The actual pressure value F-voltage V signal curve is plotted. According to formula (1), the least squares method is used to fit the functional relationship between the two to determine the load factor k. f And the value of zero-point deviation b;

[0057] F = k f V+b (1)

[0058] (4) Open the parameter settings section of the analysis software and set the parameters such as sampling frequency, number of channels and filtering threshold. Select the sampling method as real-time acquisition and the image display method as 2D or 3D.

[0059] (5) Click the “Start Acquisition” button. The analysis software will start to receive the voltage signal data transmitted by the USB acquisition device in real time and sample the data of each channel synchronously. At the same time, it will automatically filter noise and remove invalid signals according to the preset filtering threshold to ensure data quality. During the data acquisition process, the analysis software will display the actual pressure-voltage signal curve. Users can dynamically adjust the display parameters as needed to realize local magnification, profile analysis and other operations for specific areas.

[0060] (6) After the data acquisition is completed, the voltage signal is converted into a pressure value according to the functional relationship calibrated in step (3), and a pressure distribution map is output. The three-dimensional micro-deformation displacement value of the gap between the two cabins is further calculated by pressure distribution inversion.

[0061] (7) Determine if the save button is pressed? If the save button is pressed, save the collected data as a *.xls, *.txt or *.tdms file for subsequent offline processing; then determine if the playback button is pressed? If the playback button is pressed, call the stored data file and proceed to step (8); if the playback button is not pressed, continue to determine if the playback button is pressed; if the save button is not pressed, proceed to step (8);

[0062] (8) Entering the data analysis stage, the analysis software loads the corresponding historical data files according to the user's selection, and replays the voltage signal curve, pressure distribution map and three-dimensional micro-deformation image in the original sampling time sequence; the user can perform operations such as pause, fast forward, slow playback, and jump on the playback interface, and can perform magnified display, profile analysis and comparative analysis on local areas at any time, and output the maximum deformation area and deformation value.

[0063] (9) Determine whether to change the acquisition parameters and continue the test? If the acquisition parameters are changed and the test continues, return to step (4); if the acquisition parameters do not need to be changed, turn off the tape-lever loading system, hydraulic actuator and measuring device in sequence to end the measurement.

[0064] This invention discloses a contact-type measurement method for the gap between two aircraft cabin doors (hereinafter referred to as the method). The method uses the aforementioned measuring device, and the specific steps are as follows:

[0065] 1) Connect the various parts of the device according to the above connection method. Seven thin-film pressure distribution sensors 5 are arranged in a horizontal array along the X direction of the hatch. Two thin-film pressure distribution sensors are arranged horizontally along the Y direction of the hatch at the upper and lower ends of the hatch, respectively. The thin-film pressure distribution sensor 5 includes a sensing area, a wiring area, and a wire outlet. The sensing area has several sensing layer units in an array. The sensing area is attached to the cross-sectional surface of the hatch. Adjust the relative position of the thin-film pressure distribution sensor and the cross-section of the hatch so that the sensing layer units of the thin-film pressure distribution sensor are aligned with the side of the hatch and ensure that the thin-film pressure distribution sensor is within the effective range. Start all components of the measuring device to put them into normal working condition.

[0066] 2) Operate the tape-lever loading system and hydraulic actuator to apply load to the aircraft's dual-door level according to test requirements;

[0067] 3) Calibration of the thin-film pressure distribution sensor: All thin-film pressure distribution sensors used in this application are of the same model. During the calibration phase, pressure elements are set at the sensing layer unit positions of the thin-film pressure distribution sensor to obtain the pressure value at the current position. After calibration, the pressure elements can be omitted in actual measurements. Under no-load conditions, the voltage signal output by the modulator is read and recorded as the zero-point baseline data; a uniform known load condition is applied to the area where the thin-film pressure distribution sensor is arranged, and the load is kept stable for several seconds. After the modulator output signal stabilizes, the voltage signal at this time is subtracted from the zero-point baseline data to obtain the corresponding voltage signal value under the current load.

[0068] Unload and change the load conditions, and test the pressure value and corresponding voltage signal value of each sensing layer unit of the thin film pressure distribution sensor under different load conditions. The pressure value of each sensing layer unit can be obtained through a miniature pressure sensor during the calibration stage. The pressure value and corresponding voltage signal value of different sensing layer units are used as a sample data point. A large number of sample data points are combined with the linear regression model and the least squares formula (1) to fit and obtain the load coefficient k of the current thin film pressure distribution sensor. f Using the zero-point deviation value b, a functional relationship between the pressure value and voltage value of the sensing layer unit on the thin-film pressure distribution sensor is established and transmitted to the analysis software for storage.

[0069]

[0070] Where N is the number of sample data points, V l Let F be the voltage value of the l-th sample data point. l Let ∑V be the pressure value corresponding to the l-th sample data point. l The sum of all voltage values, ∑F l The sum of all pressure values, ∑V l F l The sum of the products of each voltage and its corresponding pressure. It is the sum of the squares of all voltage values;

[0071] 4) After calibration, arrange the set number of membrane pressure distribution sensors according to the installation space requirements in the gaps and the gaps between the upper and lower ends of at least one hatch and the fuselage door frame 12. During the operation of the tape-lever loading system and the hydraulic actuator, the user sets the load magnitude and direction according to the simulation requirements, and simultaneously sets the sampling time, acquisition frequency, number of channels, maximum voltage value, and minimum voltage value. After setting the above parameters, start the acquisition button; zero the membrane pressure distribution sensors, i.e., subtract the zero-point baseline data, start the tape-lever loading system and the hydraulic actuator, and conduct a ground loading test on the hatch according to the predetermined working conditions; each membrane pressure distribution sensor acquires the resistance signal under load and outputs it to the modulator, which converts it into a voltage signal. The USB acquisition device acquires the voltage signal value converted by the modulator, forming a two-dimensional matrix V of the voltage signal of each membrane pressure distribution sensor. i ;

[0072]

[0073] Among them, V i,jk This represents the voltage output of the i-th sensor in the j-th row and k-th column, where m×n is the pixel dimension of each thin-film pressure distribution sensor (the sensor used in this embodiment is 40×10).

[0074] The load factor k is obtained by calibration in step (2). f The linear fitting model of formula (3) is obtained by combining the zero-point deviation value b, and the two-dimensional matrix V of the voltage signal of each thin-film pressure distribution sensor is obtained. i Then, the voltage value V of each sensing layer unit can be obtained according to formula (3). i,jk The corresponding pressure value is then used to obtain the two-dimensional pressure matrix F for each thin-film pressure distribution sensor. i ;

[0075] F i,jk =k f ·V i,jk +b (3)

[0076] Where F i,jk The pressure value in the j-th row and k-th column of the i-th sensor;

[0077] 5) Based on the actual arrangement position of each thin-film pressure distribution sensor (including the arrangement sequence in the X and Y directions and its initial installation coordinates (X... i ,Y iDuring the arrangement, each thin-film pressure distribution sensor can be numbered sequentially in a clockwise or counterclockwise direction, and a spatial coordinate mapping relationship can be established with the lower left point of the thin-film pressure distribution sensor as the installation starting point. Through the correspondence between the sensor number and its physical placement, the two-dimensional pressure matrix F of each thin-film pressure distribution sensor can be generated. i A complete two-dimensional pressure distribution map of the hatch contact surface is assembled.

[0078] 6) Based on the starting coordinates (X) of each thin-film pressure distribution sensor. i Y i ), and by combining formula (5), the spatial coordinates (X, X) of each pixel in the two-dimensional pressure matrix in the three-dimensional coordinate system of the overall hatch are obtained. i,jk ,Y i,jk Z i,jk ), to obtain a three-dimensional micro-deformation map;

[0079]

[0080] Where X i Let X be the starting coordinate for the installation of the i-th sensor in the X direction, and Y be the starting coordinate for the installation of the i Z represents the starting coordinates for the installation of the i-th sensor in the Y direction, k is the column index of the sensor pixel, j is the row index of the sensor pixel, Δx is the X-axis spacing of the sensor pixels, and Δy is the Y-axis spacing of the sensor pixels; i,jk Let Z be the deformation displacement of the pixel in the j-th row and k-th column of the i-th sensor.

[0081] The micro-deformation of the hatch under loading satisfies the elastic small deformation theory, and a local linear contact stiffness model is adopted:

[0082]

[0083] Where Δz i,jk Let F be the deformation displacement of the pixel in the j-th row and k-th column of the i-th sensor in the Z-direction (door thickness direction). i,jk k represents the corresponding pressure value. c The contact stiffness constant is related to the inherent properties of the thin-film pressure distribution sensor; the initial z is 0, and a three-dimensional micro-deformation map is obtained through the mapping relationship. The three-dimensional micro-deformation map can directly output which part has a large deformation and the magnitude of the deformation value.

[0084] In this invention, the thin-film pressure distribution sensor can be set to different sizes according to the actual dimensions of the hatch and the required fitting accuracy. The base film in the internal structure is made of flexible polymer materials such as polyimide and polyethylene, which has good flexibility, is suitable for curved surface measurement needs, and has strong adjustability. Seven thin-film pressure distribution sensors are arranged along the X-axis of the hatch, and two thin-film pressure distribution sensors are arranged along the Y-axis at both the top and bottom ends of the hatch. The seven thin-film pressure distribution sensors are connected in an independent working mode using identical pressure distribution sensors. The installation positions of the seven thin-film pressure distribution sensors on the side of the hatch are as follows: Figure 5 As shown, this allows for real-time structural health monitoring across the entire area without blind spots.

[0085] The working principle of this invention is as follows: During the loading process of the adhesive tape-lever loading system and the hydraulic actuator cylinder, the voltage signal during the loading process can be directly measured, and the deformation displacement value of the door gap can be obtained after signal processing and analysis. When the loading system (the load applied by the adhesive tape-lever loading system and the hydraulic actuator cylinder) is loaded, the flight environment is simulated according to the actual working conditions. The outer surface of the door will be subjected to the compressive force of the airtight load and the airtight door will be subjected to the compressive force of the fuselage around it. The compressive force is transmitted to the thin-film pressure distribution sensor. The door will undergo gap deformation under the airtight load. This deformation signal is picked up by the thin-film pressure distribution sensor installed on the side of the door. Then, the voltage signal converted by the modulator and the load coefficient and zero-point deviation obtained by the calibration equipment are transmitted to the USB acquisition device through the signal connection line, and then transmitted to the acquisition and control software. Finally, the deformation information of the door gap is obtained by analysis. This information is the actual stress and deformation of the door under ground test, and this information is more accurate and reliable.

[0086] Any aspects not covered in this invention are applicable to existing technologies, and all components involved are commercially available.

Claims

1. An aircraft dual door gap contact type measuring device, characterized by, The device comprises a thin film pressure distribution sensor, a modulator, a USB collector, a calibration device and a host computer; the direction parallel to the gap between the two cabin doors is defined as the X direction, the direction perpendicular to the X direction is the Y direction, and the thickness direction of the cabin door is the Z direction; P thin film pressure distribution sensors are evenly arranged in the gap between the two cabin doors along the X direction to fully cover the gap between the two cabin doors and measure the micro deformation of the gap along the X and Z directions; Q thin film pressure distribution sensors are arranged between the fuselage door frame and the upper and lower ends of at least one cabin door to measure the micro deformation of the cabin door gap along the Y and Z directions; The thin film pressure distribution sensor has a measuring point density of 10-15 measuring points / cm 2 ; A certain number of adhesive tapes are evenly arranged on the outer surfaces of the two cabin doors to make the cabin doors bear loads uniformly, and the adhesive tapes are connected with an adhesive tape-lever loading system; Hydraulic actuators are used to apply loads around the fuselage door frame; The resistance signals output by all the thin film pressure distribution sensors are input into the input end of the modulator; the modulator converts the input resistance signals into voltage signals and outputs the voltage signals to the USB collector and the calibration device respectively; The calibration device calibrates the voltage signals output by the modulator to determine the load coefficient and the zero point deviation value and establish the functional relationship between the pressure value and the voltage value of the sensing layer unit of the thin film pressure distribution sensor; The USB collector collects the voltage signals output by the modulator and outputs the voltage signals to the host computer to realize digital reading, real-time display and storage of data; The host computer obtains the functional relationship of the calibration device and performs visual analysis on the voltage signals output by the USB collector and extracts the three-dimensional micro deformation feature information of the cabin door gap.

2. The measuring device of claim 1, wherein, The measurement device is used to measure the three-dimensional dynamic micro deformation of the cabin door gap under different ground load test conditions in real time and realize micro deformation monitoring at the level of 10 um.

3. The measuring device of claim 1, wherein, The thin film pressure distribution sensor is made of high-temperature-resistant and corrosion-resistant material, has a measuring point density of 13.3 measuring points / cm 2 , a measuring range of 0.1mm~0.15mm, and a thickness of 1mm~1.5mm.

4. The measuring device of claim 1, wherein, The thin film pressure distribution sensor is a 6300 type thin film pressure distribution sensor with a size of 200 mm x 15 mm.

5. The measuring device of claim 1, wherein, The adhesive tape-lever loading system comprises a thin steel wire and a lever. An even number of adhesive tapes are evenly and equidistantly arranged on the surfaces of the two cabin doors. Each two adhesive tapes are connected with the lever through the thin steel wire. The adhesive tapes are connected with the lever through the thin steel wire in multiple levels. The lever principle is used to change the direction and size of the force.

6. A method for measuring the clearance between the two doors of an aircraft by contact, characterized in that, The measurement method uses the measurement device of any one of claims 1-5, and the specific steps are as follows: 1) Connect each part of the measurement device according to the above connection method. The thin film pressure distribution sensors are equidistantly arranged along the X direction of the cabin door to realize full coverage measurement along the X direction of the cabin door. Meanwhile, the thin film pressure distribution sensors are equidistantly arranged along the Y direction of the cabin door at the upper and lower ends of the cabin door to realize full coverage measurement along the Y direction of the cabin door. Adjust the relative position of the thin film pressure distribution sensor and the cabin door to make the thin film pressure distribution sensor better fit in the deformation area of the cabin door and ensure that the thin film pressure distribution sensor is within the effective range. Start all components of the measurement device to make them in normal working state; 2) Run the adhesive tape-lever loading system and the hydraulic actuator to apply loads to the two cabin doors in multiple levels according to the test requirements. 3) Calibration of the film pressure distribution sensor: the film pressure distribution sensors used are of the same type. In the no-load state, the voltage signal output by the modulator is read and recorded as the zero baseline data. A uniform known load is applied to the area where the film pressure distribution sensor is arranged. The load is kept stable for several seconds. After the output signal of the modulator stabilizes, the voltage signal at this time is subtracted from the zero baseline data to obtain the corresponding voltage signal value under the current load condition; Unloading and changing load conditions, test the pressure value and corresponding voltage signal value of each sensing layer unit of the thin film pressure distribution sensor under different load conditions, take the pressure value and corresponding voltage signal value of different sensing layer units as a sample data point, and a large number of sample data points are combined with a linear regression model and a least square method formula to fit the load coefficient k of the current thin film pressure distribution sensor f And the zero point deviation value b, the function relationship between the pressure value and the voltage value of the sensing layer unit on the thin film pressure distribution sensor is established. 4) During the working process of the adhesive tape-lever loading system and the hydraulic actuator cylinder, the user sets the load application size and direction according to the simulation requirements, and sets the sampling time, collection frequency, channel number, maximum voltage value and minimum voltage value. After setting the above parameters, the collection button is started; The calibration device determines the actual pressure value corresponding to the voltage signal of the sensing layer unit of each thin-film pressure distribution sensor in the loaded state according to the function relationship determined in combination with step 3) under the known load, and then obtains the two-dimensional pressure matrix F of each thin-film pressure distribution sensor i ; 5) Based on the actual arrangement positions of each thin-film pressure distribution sensor, including the arrangement sequence in the X and Y directions and their initial installation coordinates ( , Establish spatial coordinate mapping relationships; through the correspondence between sensor numbers and their physical placement positions, construct the two-dimensional pressure matrix F of each thin-film pressure distribution sensor. i The images are pieced together to form a complete two-dimensional pressure distribution map of the hatch contact surface. 6) According to the arrangement starting coordinates of each thin film pressure distribution sensor ( , ), combined with formula (5), the spatial coordinates of each pixel point in the two-dimensional pressure matrix in the three-dimensional coordinate system of the whole cabin door are obtained ( ), and a three-dimensional micro-deformation map is obtained. (5) wherein, is the installation starting coordinate of the i-th sensor X direction, is the installation starting coordinate of the i-th sensor Y direction, k is the column index of the sensor pixel point, and j is the row index of the sensor pixel point, is the X direction spacing of the sensor pixel point, is the Y direction spacing of the sensor pixel point; is the deformation displacement of the i-th sensor j-th row k-th column pixel point in the Z direction; is the contact stiffness constant; is the pressure value of the i-th sensor j-th row k-th column pixel point.

7. The method of claim 6, wherein, The method can be used for cabin door assembly precision evaluation, intelligent monitoring and assembly parameter adjustment.

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