A combined contact sensor model and its measurement method

Abstract

The present invention relates to the technical field of aerospace equipment, and specifically relates to a combined contact sensor model and its measurement method. A motor platform is respectively arranged at the front and rear of the bottom of the vehicle frame. Wheels are arranged on both sides of the motor platform. A stepping reduction motor is arranged on the front-end motor platform, and a transmission gear is provided. The terminal platform is supported by four support columns. A three-channel displacement sensor terminal is installed on the terminal platform. A three-channel ranging sensor passes through the terminal platform below the three-channel displacement sensor terminal. The bottom of the three-channel ranging sensor is installed on the vehicle frame. The bottom of the three-channel ranging sensor is provided with three-channel ranging sensor probes and passes through the vehicle frame. The combination of three displacement sensors is used to solve the surface curvature. The cooperation between the wheels and the stepping motor with a fixed speed is used to obtain the traveling distance of the trolley, so as to solve the defect position. The surface curvature is calculated by using multiple points of the displacement sensor, and the advantages of the multi-point sensor are flexibly utilized and the surface curvature is restored by using the limit idea.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace equipment, and specifically relates to a combined contact sensor model and a measurement method thereof. Background Art

[0002] Large-sized curved surfaces have important requirements in aerospace equipment. Since the outer surface of aerospace equipment operates at high speed and high pressure, micron-level tiny defects on the curved surface may cause changes in the state of air flow on the aircraft surface or huge changes in the curved surface stress, leading to unpredictable risks.

[0003] When machining large-sized curved surfaces, due to the large size, the tool cannot complete the machining in one go, so there is a situation of changing tools. Tool changing may cause the machining trajectory connection line to be not smooth and continuous, resulting in defects. Based on requirements such as confidentiality of key technologies, means such as laser ultrasonic and other overall part scanning detections cannot be used.

[0004] Currently, contact detection for detecting surface defects of workpieces generally uses a coordinate measuring machine. Although the coordinate measuring machine has accurate measurement data and meets the requirements for detecting micron-level defects. However, in terms of measuring large curved surfaces, coordinate measuring machines over 5 meters are already relatively rare, which limits the size of the workpiece curved surface that can be detected, and large coordinate measuring machines are very expensive.

[0005] There is a laser non-destructive detection-based solution in the prior art, such as the patent: CN201711281706.X, a laser non-destructive detection device based on a 90° optical mixer. This detection solution scans the surface of the curved surface as a whole through a laser interferometer, obtains the distance information between the curved surface and the interferometer, and models and compares the data with a standard part. This solution theoretically also has a very large detection size range, but at the same time, it is necessary to build a corresponding stable and customized optical path scanning track, which is not only extremely costly, but also the overall scanning may leak the overall model of the workpiece, with poor confidentiality.

[0006] Therefore, in order to solve the above problems, the present application proposes a combined contact sensor model and a measurement method thereof. The combined sensor device used is not only portable, low-cost, but also has a very large detection size range, can meet the requirements for detecting large-sized curved surfaces at the aerospace level, and can also reach the micron level in terms of accuracy. Summary of the Invention

[0007] The purpose of the present invention is to fill the gaps in the prior art, and provides a combined contact sensor model and a measurement method thereof. The combined sensor device used is not only portable, low-cost, but also has a very large detection size range, can meet the requirements for detecting large-sized curved surfaces at the aerospace level, and can also reach the micron level in terms of accuracy.

[0008] To achieve the above object, the present invention provides a combined contact sensor model, which includes three displacement sensor terminals, three ranging sensors, three ranging sensor probes, a stepper reduction motor, a transmission gear, a wheel, a ruby foot, a vehicle frame, a support column. There is a motor platform respectively at the front and rear of the bottom of the vehicle frame. There are wheels on both sides of the motor platform. The stepper reduction motor is arranged on the rear motor platform, and the transmission gear is arranged on the stepper reduction motor. The terminal platform is supported by four support columns on the vehicle frame. Three displacement sensor terminals are installed on the terminal platform. Three equidistant ranging sensors are arranged below the three displacement sensor terminals. The bottoms of the three ranging sensors are installed on the vehicle frame, and three ranging sensor probes are arranged at the bottoms of the three ranging sensors and pass through the vehicle frame.

[0009] Three ruby feet are arranged at the bottom of the vehicle frame.

[0010] The bottom of the ruby foot is fitted to the measured curved surface.

[0011] A touchable liquid crystal display screen, a mobile power supply and a serial port transceiver communication module are arranged inside the three displacement sensor terminals.

[0012] The three displacement sensor terminals are electrically connected to the stepper reduction motor, the speed measurement sensor, the mobile power supply and the upper computer.

[0013] A measurement method of a combined contact sensor model is characterized by including the following steps:

[0014] S1. Place the assembled model on a plane with good flatness, appropriately adjust the height of the wheels to ensure that the ruby feet of the trolley are fitted to the plane, record the initial length of the three ranging sensors at this time, and use this initial length as the zero point.

[0015] S2. Place the model on the target curved surface, and drive it straight along the curved surface profile direction after starting the detection. The distances returned by the probes of the three ranging sensors at each moment are respectively defined as C 1 , C 2 , C 3 ;

[0016] S3. The distances between the three ranging sensors are the same as L1. Calculate the curvature R of the curved surface at this moment. The formula is as follows:

[0017]

[0018] S4. When the curved surface is not a standard circle, the curved surface is regarded as a surface composed of smooth tangential combinations of circles with infinitesimal different curvature radii. When the sampling frequency of the sensor is high enough, the length of the curved surface calculated within each time interval can be approximately regarded as infinitesimal compared with the large-sized curved surface.

[0019] S5. Calculate the length of each approximately circular curved surface in combination with the speed of the trolley movement, and reconstruct the overall curvature change model of the target curved surface;

[0020] S6. When the probe of the displacement sensor passes through a defect, a large jump will occur. At this time, using the original formula will introduce incorrect curvature. Therefore, different algorithms need to be adopted for correction when different probes pass through the defect. The specific method is as follows:

[0021] S6-1. Denote the distance between probe 2 and the support leg of the combined sensor as L 2 , when probes 1 and 3 pass through the defect, a formula can be constructed based on the three points of probe 2 and the two sensor support legs: R 2 = L 2 2 + [R - C 3 2

[0022] S6-2. When probe 2 passes through the defect, a formula can be constructed based on the four points of probes 1 and 3 and the two sensor support legs:

[0023] S7. Replicate the curved surface through step S6, calculate the advancing distance according to the vehicle speed, find the position from the starting point to the defect, so as to locate the defect.

[0024] Compared with the prior art, the present invention uses the combination of three displacement sensors to solve the curved surface curvature, uses the cooperation of the wheel and the stepping motor with a fixed rotation speed to obtain the traveling distance of the trolley so as to solve the defect position, uses the displacement sensor to calculate the curved surface curvature at multiple points, flexibly utilizes the advantages of the multi-point sensor and uses the limit idea to restore the curved surface curvature. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of the model of the present invention.

[0026] Figure 2 It is a curvature jump retrieval diagram of an embodiment of the present invention.

[0027] Figure 3 It is a curved surface simulation diagram of an embodiment of the present invention.

[0028] Description of the Reference Numerals

[0029] 1 is the terminal of the three-way displacement sensor, 2 is the three-way distance measuring sensor, 3 is the probe of the three-way distance measuring sensor, 4 is the stepping reduction motor, 5 is the transmission gear, 6 is the wheel, 7 is the ruby column foot, 8 is the vehicle frame, and 9 is the support column. Detailed Embodiment

[0030] The present invention will be further described in conjunction with the accompanying drawings.​

[0031] Please refer to Figures 1 to 3 a combined contact sensor model, which includes a three-way displacement sensor terminal 1, three-way ranging sensors 2, three-way ranging sensor probes 3, a stepper reduction motor 4, a transmission gear 5, wheels 6, ruby pedestals 7, a vehicle frame 8, support columns 9. A motor platform is respectively arranged at the front and rear of the bottom of the vehicle frame 8. Wheels 6 are arranged on both sides of the motor platform. The stepper reduction motor 4 is arranged on the front-end motor platform. The transmission gear 5 is arranged on the stepper reduction motor 4. The vehicle frame 8 supports a terminal platform through four support columns 9. The three-way displacement sensor terminal 1 is installed on the terminal platform. Three-way ranging sensors 2 with the same spacing are arranged below the three-way displacement sensor terminal 1. The bottoms of the three-way ranging sensors 2 are installed on the vehicle frame 8. Three-way ranging sensor probes 3 are arranged at the bottoms of the three-way ranging sensors 2 and pass through the vehicle frame 8.

[0032] Three ruby pedestals 7 are arranged at the bottom of the vehicle frame 8.

[0033] The bottom of the ruby pedestal 7 is in contact with the measured curved surface.

[0034] A touchable liquid crystal display screen, a mobile power supply and a serial port transceiver communication module are arranged inside the three-way displacement sensor terminal 1.

[0035] The three-way displacement sensor terminal 1 is electrically connected to the stepper reduction motor 4, a speed measurement sensor, a mobile power supply and a host computer.

[0036] A measurement method of a combined contact sensor model is characterized by including the following steps:

[0037] S1. Place the assembled model on a plane with good flatness, appropriately adjust the height of the wheels to ensure that the ruby pedestals of the trolley are in contact with the plane, record the initial length of the three-way ranging sensors 2 at this time, and use this initial length as the zero point;

[0038] S2. Place the model on the target curved surface, and drive it straight along the curved surface profile direction after starting the detection. The distances returned by the probes of the three-way ranging sensors 2 at each moment are respectively defined as C 1 , C 2 , C 3 ;

[0039] S3. The spacing of the three-way ranging sensors 2 is the same as L 1 , and calculate the curvature R of the curved surface at this moment. The formula is as follows:

[0040]

[0041] S4. When the surface is not a standard circle, the surface is regarded as a surface composed of smooth tangential combinations of circles with infinitesimal different radii of curvature. When the sampling frequency of the sensor is high enough, the surface length calculated within each time interval can be approximated as infinitesimal compared to the large-sized surface.

[0042] S5. Calculate the length of each approximate circular surface in combination with the speed of the trolley movement, and reconstruct the overall curvature change model of the target surface.

[0043] S6. When the probe of the displacement sensor passes through a defect, a large jump will occur. At this time, using the original formula will introduce incorrect curvature. Therefore, different algorithms need to be adopted for correction when different probes pass through the defect. The specific method is as follows:

[0044] S6-1. Denote the distance between probe 2 and the support feet of the combined sensor as L 2 . When probes 1 and 3 pass through the defect, a formula can be constructed based on the three points of probe 2 and the two sensor support feet: R 2 = L 2 2 + [R - C 3 2

[0045] S6-2. When probe 2 passes through the defect, a formula can be constructed based on the four points of probes 1 and 3 and the two sensor support feet:

[0046] S7. Replicate the surface through step S6, calculate the advancing distance based on the vehicle speed, find the position from the starting point to the defect, so as to locate the defect.

[0047] Embodiment:

[0048] Place the combined contact sensor model on the surface to be measured, drive it forward uniformly with a uniform speed stepping and decelerating motor 4, and make the wheels around the vehicle carrier fit the surface to be measured. Use the mobile power supply carried on the model to supply power to the speed measurement sensor, the sensor terminal, and the uniform speed stepping and decelerating motor 4, and use the serial port to connect to the upper computer to obtain the sampling data of the sensor. This model requires auxiliary means to ensure its straight forward movement.

[0049] After the data of the three-way ranging sensors of the displacement sensor are recorded, they are processed uniformly.

[0050] First, preprocess the data obtained by the three-way ranging sensors, such as Figure 2The figure shows the processing flowchart of one of the distance measurement sensors. The "sensor value" curve represents the length value of the probe contraction of the sensor in this channel. The mutation points are the defect points. It is incorrect to calculate the surface curvature using the values at these points. Therefore, curve fitting and difference calculation are performed on these values. The parts with higher differences after screening indicate the parts where the sensor probe passes through the defects. Record their indices in the data set for subsequent elimination and replacement with the correct curvature. When this step is completed, we will obtain the index values of the numerical jumps caused by the defects in each of the three distance measurement sensors. Substitute the data of the three distance measurement sensors into the formula to calculate the approximate curvature change. Use the index part of the curvature calculation results where data jumps occur in the first and third distance measurement sensors and recalculate and replace the curvature using the formula ; Use the index part of the curvature calculation results where data jumps occur in the second distance measurement sensor and recalculate and replace the curvature using the formula R 2 = L 2 2 + [R - C 3 2 Read the recorded value of the vehicle speed sensor. According to the return value of this sensor, the duration of different curvatures can be calculated. Based on the smooth change of the curvature, the model of the measured surface can be calculated and restored by the tangency of the surface and the length of the surface. The width of the defect can be obtained from the mutation width of the C2 value, and the height of the defect can be obtained by subtracting the normal value from the maximum point of the mutation value. The defect position can be obtained from the established measured surface model and the traveling distance, as shown in Figure 2 . The elliptical part is the defect position.

[0051] The above is only the preferred implementation manner of the present invention, which is only used to help understand the method and its core idea of the present application. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should also be regarded as the protection scope of the present invention.

[0052] As a whole, the present invention solves the problems in the prior art that coordinate measuring machines for measuring large curved surfaces are relatively rare, which limits the size of the workpiece curved surfaces that can be detected, and the need to build corresponding stable and customized optical path scanning tracks, which not only costs extremely high, but also the overall scanning may leak the overall model of the workpiece, resulting in poor confidentiality. The combined sensor device adopted is not only portable, low-cost, but also has a very large detection size range, which can meet the requirements of aerospace-grade large-size curved surface detection, and can also reach the micron level in terms of accuracy, having good market value.​

Claims

1. A combined contact sensor model, characterized in that, it includes three displacement sensor terminals (1), three ranging sensors (2), three ranging sensor probes (3), a stepper reduction motor (4), a transmission gear (5), a wheel (6), a ruby foot (7), a vehicle frame (8), and a support column (9). There is a motor platform respectively at the front and rear of the bottom of the vehicle frame (8). There are wheels (6) on both sides of the motor platform. The stepper reduction motor (4) is arranged on the front-end motor platform. The transmission gear (5) is arranged on the stepper reduction motor (4). The vehicle frame (8) supports a terminal platform through four support columns (9). The three displacement sensor terminals (1) are installed on the terminal platform. Below the three displacement sensor terminals (1), there are three ranging sensors (2) with the same spacing. The bottom of the three ranging sensors (2) is installed on the vehicle frame (8). The bottom of the three ranging sensors (2) is provided with three ranging sensor probes (3) which pass through the vehicle frame (8); The measurement method of the combined contact sensor model includes the following steps: S1. Place the assembled model on a plane with good flatness. Appropriately adjust the height of the wheels to ensure that the ruby feet of the trolley are in contact with the plane. Record the initial length of the three ranging sensors (2) at this time, and take this initial length as the zero point; S2. Place the model on the target surface and make it travel linearly along the surface profile direction after starting the detection. The distances returned by the probes of each of the three-way ranging sensors (2) at each moment are respectively defined as C 1 , C 2 , C 3 ; S3. The spacing of the three-way ranging sensors (2) is the same, which is L. 1 , and the curvature R of the curved surface at this moment is calculated. The formula is as follows: S4. When the curved surface is not a standard circle, consider the curved surface as a surface composed of infinitesimal circular smooth tangencies with different curvature radii. When the sensor sampling frequency is high enough, the curved surface length calculated within each time interval can be approximated as infinitesimal compared to the large-size curved surface; S5. Calculate the curved surface length of each approximate circle in combination with the speed of the trolley movement, and reconstruct the overall curvature change model of the target curved surface; S6. When the probe of the displacement sensor passes over a defect, a large jump will occur. At this time, using the original formula will introduce incorrect curvature. Therefore, different algorithms need to be adopted for correction when different probes pass over the defect. The specific method is as follows: S6-1. Denote the distance between probe 2 and the feet of the combined sensor as L 2 , when probes 1 and 3 pass over the defect, a formula can be constructed based on the three points of probe 2 and the two feet of the sensor: S6-2. When the probe 2 passes through a defect, a formula can be constructed based on the four points of the probes 1 and 3 and the two sensor feet; S7. Replicate the curved surface through the S6 step, calculate the forward distance based on the vehicle speed, and find the position from the starting point to the defect, so as to locate the defect.

2. A combined contact sensor model according to claim 1, characterized in that, there are three ruby feet (7) at the bottom of the vehicle frame (8).

3. A combined contact sensor model according to claim 1, characterized in that, the bottom of the ruby foot (7) is in contact with the measured curved surface.

4. A combined contact sensor model according to claim 1, characterized in that, the three displacement sensor terminals (1) are internally provided with a touchable liquid crystal display screen, a mobile power supply, and a serial port transceiver communication module.

5. A combined contact sensor model according to claim 1, characterized in that, the three displacement sensor terminals (1) are electrically connected to the stepper reduction motor (4), a speed measurement sensor, a mobile power supply, and an upper computer.

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