Multi-data fusion floating flat plate friction resistance measuring device and method

Abstract

The application discloses a floating plate friction resistance measuring device based on multi-data fusion, which comprises a floating plate (10), an angle code (20), a steel sheet (30), a horizontal plate (40), an oil box (50), a double-axis displacement platform (60), a metal base (70) and a metal hanging frame (80). The application also provides a floating plate friction resistance measuring method based on multi-data fusion. The application can solve the problems of the traditional force balance system, such as complexity, high cost and single measuring method. The sensor of the application has wide application range in the aspects of measuring efficiency, dynamic characteristics and anti-electromagnetic interference, and the range can be changed according to requirements.

Description

Technical Field

[0001] This invention relates to the field of wind tunnel testing technology, specifically to a floating flat plate friction resistance measurement device and method with multi-data fusion. Background Technology

[0002] In the aerospace and transportation fields, reducing turbulent frictional drag through flow control is crucial for improving the performance and efficiency of vehicles. Despite years of research in this area, the challenges of measuring turbulent frictional drag remain, given its relatively small magnitude. Therefore, there is an urgent need to develop a reliable frictional drag measurement technique with high precision and variable range, and to evaluate different drag reduction methods based on this. Existing frictional drag measurement methods can be broadly categorized into indirect and direct measurements. Typical indirect measurement methods utilize experimental equipment such as hot wire, laser Doppler (LDV), microscopic PIV, and oil film interferometry. These methods suffer from complex equipment, low measurement efficiency, and are mostly single-point local measurements, failing to quickly assess the effectiveness of large-area drag reduction control. Direct measurement devices mainly include strain gauge balances, MEMS sensors, and floating balances. While each technology has its advantages and disadvantages, they generally suffer from insufficient measurement accuracy (wind tunnel frictional drag is typically on the order of mN), weak anti-interference capabilities, and complex structures. Furthermore, although MEMS sensors are small and have a fast response, their manufacturing process is complex and extremely expensive, and they are prone to failure under high load conditions. Therefore, there is an urgent need to develop a new type of friction resistance measurement device and method that can achieve high-precision friction force measurement under high Reynolds number conditions, while also possessing good anti-interference ability and ease of operation. Summary of the Invention

[0003] To achieve the above objectives, this invention provides a floating plate friction resistance measuring device with multi-data fusion, hereinafter referred to as the "measuring device". The device includes a floating plate 10, angle brackets 20, steel plates 30, a horizontal plate 40, an oil box 50, a dual-axis displacement platform 60, a metal base 70, and a metal hanging frame 80.

[0004] The floating plate 10 includes a force measuring plate 101, a permanent magnet ring 102, a reflector 103, and a damping module 104. The floating plate 10 is roughly in the shape of an inverted triangle.

[0005] Establish a rectangular coordinate system with the x-axis pointing from the short side to the long side along the force plate 101, the y-axis pointing upwards perpendicular to the upper surface of the force plate, and the z-axis pointing from the long side to the short side along the force plate 101. Take the center of the upper surface of the force plate as the origin of the rectangular coordinate system.

[0006] The force measuring plate 101 is a rectangular thin plate; the cross-sectional area of ​​the force measuring plate 101, viewed from the side from top to bottom, has a draft angle; a mounting hole is left at the center of the force measuring plate 101; positioning holes or positioning grooves are left at the bottom of the force measuring plate 101 to facilitate the installation of the permanent magnet ring 102, the reflector 103, the damping module 104 and the corner bracket 20, and they are connected and fixed by fastening means;

[0007] Near the long side of the force measuring plate 101, two reflective plates 103 are arranged in a direction parallel to the z-axis, with a gap between the two reflective plates 103; one is used to attach and fix the permanent magnet ring 102, and the other is covered with reflective stickers to reflect infrared light; the specific position of the reflective plate 103 corresponds to the positioning groove reserved in the force measuring plate 101.

[0008] The damping module 104 is divided into three parts: upper, middle, and lower. The upper part consists of two hollow trusses suspended along the z-axis direction below the center of the force measuring plate 101. The two hollow trusses are symmetrical about the long side axis of the lower surface of the force measuring plate 101 and are fixedly connected to the force measuring plate 101. The middle part consists of a rectangular horizontal plate used to connect the two trusses and the damping block at the bottom of the horizontal plate. The projection center of the horizontal plate on the horizontal plane coincides with the projection center of the force measuring plate 101 on the horizontal plane. The lower part consists of multiple sets of rectangular blocks of the same thickness placed along the z-axis and with the same spacing in the x-axis direction. These rectangular blocks together form the damping block. The projection center of the damping block as a whole on the horizontal plane coincides with the projection center of the force measuring plate 101 on the horizontal plane. The projection of the damping block on the horizontal plane is smaller than the projection of the horizontal plate on the horizontal plane, and the projection centers of the two coincide.

[0009] The angle brackets 20 include two types, I-type and L-type, with different cross-sectional structural shapes, respectively suitable for the installation of steel plates 30 between the floating plate 10 and the horizontal plate 40; two pairs of I-type angle brackets are symmetrically distributed below the force measuring plate 101 along the z-axis direction, distributed on the outside of the damping module 104, and basically penetrate the length of the force measuring plate 101 along the z-axis direction, with only a certain degree of contraction at both ends to fit the edge contraction of the force measuring plate 101; the two pairs of I-type angle brackets are vertically fixed below the force measuring plate 101 by fastening means; each pair of I-type angle brackets needs to be used together to clamp the vertical steel plate 30 placed therein; at the corresponding position below the steel plate 30, two pairs of L-type angle brackets are arranged, and the two pairs of L-type angle brackets are vertically fixed to the upper surface of the horizontal plate 40 by fastening means. Similar to the aforementioned I-type angle brackets, the L-type angle brackets are used to clamp the vertical steel plate 30 placed therein; the upper pair of I-type angle brackets cooperates with the lower pair of L-type angle brackets at the corresponding position to clamp the steel plate 30 from both the upper and lower positions;

[0010] The steel sheet 30 is a vertical, thin cuboid shape, clamped between the upper and lower diagonal brackets; the length of the steel sheet 30 is consistent with that of the diagonal bracket 20, and the thickness of the steel sheet 30 is determined according to the magnitude of the force on the floating plate and the required range of variation.

[0011] The horizontal plate 40 includes an upper horizontal plate 401, a lower horizontal plate 402, precision adjusting screws 403, and tension springs 404. The height can be adjusted by the precision adjusting screws 403 installed at the four corners of the lower surface of the lower horizontal plate 402 according to actual needs. In addition, different lifting heights can also change the horizontal and pitch degrees of freedom of the upper horizontal plate 401 to ensure that the upper surface of the floating plate 10 is flush with the wind tunnel plate 100 to be installed.

[0012] The wind tunnel plate 100 has a slot in the middle for mounting the measuring device of the present invention; the upper surface of the floating plate 10 is flush with the wind tunnel plate 100 to be mounted; the floating plate and the wind tunnel plate 100 are not in contact, and the gap between them is as small as possible.

[0013] Both the upper part 401 and the lower part 402 of the horizontal plate are cuboid plates, and their projections on the horizontal plane coincide. Multiple sets of tension springs 404 are arranged between the upper part 401 and the lower part 402 of the horizontal plate along the x-axis and z-axis. The multiple sets of tension springs 404 are distributed along the x-axis and z-axis, located at the reserved holes between the upper part 401 and the lower part 402 of the horizontal plate, and are fixed to both of them.

[0014] Two pairs of L-shaped corner brackets are fixed to the upper surface of the horizontal plate 401 by fastening technology. The space between the two pairs of L-shaped corner brackets and in the middle of a pair of steel plates 30 is reserved for placing the oil box 50. The upper part of the oil box 50 is open to allow the damping blocks of the damping module 104 to be submerged in it. The projection center of the oil box 50 on the horizontal plane coincides with the projection center of the force measuring plate 101 on the horizontal plane. After the floating plate 10 is assembled, the damping blocks of the damping module 104 are all submerged in the damping fluid and do not contact the inner wall of the oil box.

[0015] The dual-axis displacement platform 60 is fixed between the horizontal plate 40 and the metal base 70. The dual-axis displacement platform 60 is fixed to the upper surface of the metal base 70 by fastening technology, and the horizontal plate 40 is fixed to the upper surface of the dual-axis displacement platform 60 by fastening technology. The dual-axis displacement platform 60 provides fine adjustment for the upper floating plate 10 in both the x-axis and z-axis directions. That is, the horizontal plate 40, the steel plate 30, and the floating plate 10 all produce slight displacements on the horizontal plane as the dual-axis displacement platform 60 is finely adjusted. Therefore, there must be a certain distance between the horizontal plate 40, the steel plate 30, the floating plate 10 and the metal hanging frame 80.

[0016] The metal base 70 and the metal hanging frame 80 are connected by fastening technology to form an outer frame with a cuboid inner cavity;

[0017] Measurement modules 90 are configured both inside and outside the measuring device.

[0018] In one specific embodiment of the present invention, the force measuring plate 101, viewed from top to bottom, is 300mm long and 200mm wide, and the thickness of the force measuring plate 101 is not less than 5mm; the draft angle of the force measuring plate 101 is 45°.

[0019] In another specific embodiment of the present invention, the corner bracket 20 has a length of 280mm, a height of 20mm, and a width of 10-30mm; the corner bracket 20 and the steel plate 30 are provided with equally spaced round holes for bolts to pass through.

[0020] In another specific embodiment of the present invention, the height of the steel sheet 30 is 100mm, and the thickness of the steel sheet 30 ranges from 0.1 to 0.3mm.

[0021] In another specific embodiment of the present invention, the overall dimensions of the horizontal plate 40 are 300mm in length and 200mm in width, and the height varies within 30±2mm.

[0022] In one embodiment of the present invention,

[0023] The floating plate 10 is made of resin, nylon, plexiglass, or polyetheretherketone.

[0024] Permanent magnet ring 102 is a ring-shaped magnet made of AlNiCo permanent magnet material;

[0025] The lower part of the damping module 104 consists of five identical rectangular blocks with a thickness of 5mm and a 5mm interval in the x-axis direction, placed along the z-axis. The damping module 104 is a structurally integrated design with arrayed holes in the horizontal plate and damping blocks for lightweight design.

[0026] The floating plate and the wind tunnel plate 100 are not in contact, and the gap between them does not exceed 1mm;

[0027] Five sets of 404 tension springs are distributed as follows: two sets along the x-axis and three sets along the z-axis, with a spacing of 40mm between each set.

[0028] The oil box 50 is made of materials such as acrylic, ABS or resin, and is filled with olive oil or silicone oil damping fluid.

[0029] The metal base 70 is designed in the shape of an hourglass. The metal base 70 and the metal hanging frame 80 are made of steel, iron or aluminum. The horizontal plate 40, the metal base 70 and the metal hanging frame 80 are all appropriately hollowed out. The hollowed-out parts should not affect the reserved assembly holes.

[0030] In another embodiment of the present invention, the measurement module 90 includes: an electromagnet 901, a laser rangefinder 902, and a strain gauge 903;

[0031] Outside the measuring device, electromagnet 901 is directly opposite permanent magnet ring 102, that is, its installation position is at the same height as permanent magnet ring 102, ensuring that the force between electromagnet 901 and permanent magnet ring 102 is always in the horizontal direction; when permanent magnet ring 102 and electromagnet 901 face each other, they can generate mutual repulsion force.

[0032] The laser rangefinder 902 is installed outside the measuring device, facing the reflector 103, and its measuring center is at the same height as the center of the reflector 103. In addition, the distance between the laser rangefinder 902 and the reflector 103 is limited to the normal operating range of the laser.

[0033] Inside the measuring device, a strain gauge 903 is attached to the outer wall of the steel sheet 30. The strain gauge 903 can be a metal strain gauge or a semiconductor strain gauge.

[0034] In another specific embodiment of the invention, the strain gauge 903 is fixed near the neutral axis of the bent portion.

[0035] A method for measuring the frictional resistance of a floating plate using multi-data fusion is provided, based on the aforementioned floating plate frictional resistance measuring device, as detailed below:

[0036] The floating plate 10 is installed flush with the wind tunnel plate 100. In an ideal two-dimensional situation, the floating plate 10 is not subjected to any force in the direction perpendicular to the plane. Therefore, two steel plates 30 are sufficient to maintain the balance of the floating plate 10. When the incoming boundary layer on the surface of the wind tunnel plate 100 flows from right to left across the floating plate 10, due to viscous friction, the incoming boundary layer will generate a leftward frictional resistance f on the floating plate 10. Under the action of this frictional resistance, the floating plate 10 deviates from the neutral position and begins to tilt to the left. The distance D of this movement can be measured by a laser rangefinder.

[0037] Specifically, based on whether the three different measurement modules 90 are working or not, there are two measurement schemes:

[0038] Option 1: A laser rangefinder 902 and strain gauge 903 are used; the floating plate 10, angle bracket 20, two steel plates 30, and horizontal plate 40 together constitute a statically indeterminate structure, which can be further simplified into two sets of cantilever beam structures. The displacement caused by the frictional resistance f on the floating plate 10 is approximately converted into the deflection change of the cantilever beam, and described by the following formula:

[0039]

[0040] Where b, l, and h represent the length, width, and thickness of the steel sheet, respectively; E is the Young's modulus of the steel sheet; accordingly, the displacement D of the floating plate 10 has a linear relationship with the frictional resistance f; further simplification yields the following expression for the frictional resistance:

[0041] f = k·D(2)

[0042] Where k is the calibration coefficient;

[0043] During calibration, a lightweight, flexible thin thread is preferred to connect the floating plate 10 to the calibration weight 905. The vertical downward gravity G of the weight is converted into a horizontal pulling force applied to the floating plate 10 by a fixed pulley 904 set at the tail edge of the wind tunnel plate 100, which is approximately equivalent to the frictional resistance f of the floating plate 10. Furthermore, the above process is repeated with weights of different masses, and the displacement output by the laser rangefinder 902 is recorded at the same time. A set of force and displacement data points are obtained, and the force and displacement data points are fitted to calibrate the calibration coefficient k in formula (2). Thus, the real-time change of frictional resistance can be deduced by measuring the displacement of the floating plate 10.

[0044] The current scheme also uses a strain gauge 903 attached to the bottom of the steel plate 30. Taking the fixed point 401 between the steel plate 30 and the upper part of the horizontal plate as the fulcrum, the torque on the steel plate 30 is expressed by the following formula:

[0045] M = f·l(3)

[0046] The bending moment obtained by the strain gauge can be used to deduce the corresponding frictional resistance. Depending on the actual needs, multiple strain gauges can be connected in series or in parallel at the bottom of the steel sheet 30 to average the final measured moment, thereby improving the accuracy of the data.

[0047] Option 2: The laser rangefinder 902 or strain gauge 903, together with the electromagnet 901, constitute a feedback system. The laser rangefinder 902 serves as a feedback device, acquiring the minute displacement D of the floating plate 10 and transmitting it to the control computer. Based on the change in displacement D, the control computer uses a PID algorithm to adjust the input voltage of the electromagnet 901, thereby changing its repulsive force F on the permanent magnet ring 102. During this process, the floating plate 10 will swing to the right and gradually return to the neutral position. Simultaneously, the laser rangefinder 902 acquires the displacement D in real time for further adjustment.

[0048] In this case, the frictional resistance f on the upper surface of the floating plate 10 is opposite in direction and equal in magnitude to the repulsive force F on the lower end. The repulsive force F = frictional resistance f. The magnitude of the repulsive force is determined by the input voltage of the electromagnet 901. Therefore, by recording the input voltage, the magnitude of the frictional resistance borne by the floating plate 10 can be deduced.

[0049] Furthermore, when the laser rangefinder 902 fails, the strain gauge 903 can be used as a substitute to transmit the collected torque as a feedback signal to the control computer. The control computer adjusts the input voltage of the electromagnet 901 according to the change of torque M, thereby changing its repulsive force F on the permanent magnet ring 102. According to formula (3), torque M can represent the change of frictional resistance f. If the input voltage of the electromagnet 901 is adjusted, its repulsive force F on the permanent magnet ring 102 can be changed. Therefore, when the collected torque M is 0 or approximately 0, the repulsive force F at this time is equal to the frictional resistance f.

[0050] In another embodiment of the present invention, in situations where there are high-frequency airflow fluctuations or significant electromagnetic interference, data with low reliability need to be discarded; the measurement results obtained by using the laser rangefinder 902 or the electromagnet 901 alone are selected as the final data; in other relatively stable environments, a weighted average method is used to fuse multiple measurement data, and the weight allocation is based on the results of previous data analysis and practical operating experience.

[0051] This invention overcomes the shortcomings of traditional force balance systems, such as complexity, high cost, and limited measurement methods. The invented sensor also offers advantages in measurement efficiency, dynamic characteristics, and electromagnetic interference resistance, has a wide range of applications, and its measuring range can be adjusted according to requirements.

[0052] The advantages of this invention are as follows:

[0053] 1) Adjustable measuring range. The measuring range of the device of this invention is determined by the size of the steel sheet. For low-speed flow, the measuring range and amplification ratio can be increased by reducing the thickness of the steel sheet, thereby improving the force resolution of the sensor. In higher-speed flow, the measuring range can be increased in the opposite way. The applicable speed range of the sensor is not limited.

[0054] 2) High measurement accuracy. The measuring device of this invention employs multiple measurement schemes to achieve multi-data / method fusion, and different measurement methods can mutually verify each other. By replacing the steel sheet with a thinner one, the measurement of frictional resistance is amplified, and the measurement accuracy can reach 10. -4 On the order of N.

[0055] 3) High frequency response. In Scheme 1, frictional resistance is primarily evaluated using a laser rangefinder 902, which has a frequency response of 5kHz or higher. In Scheme 2, frictional resistance is evaluated using an electromagnet 901, which can restore the floating plate 10 to its neutral position within milliseconds. In other words, the frequency response of this measuring device can easily reach over 100Hz, facilitating real-time measurement of dynamic frictional resistance under complex airflow conditions.

[0056] 4) Low cost. The main components of this sensor, such as electromagnet 901, laser rangefinder 902, strain gauge 903, and dual-axis displacement platform 60, are all mature products. Other components, such as floating plate 10, horizontal plate 40, and metal base 70, have low processing costs. Therefore, the overall cost of use is far lower than that of MEMS triboelectric resistance sensors.

[0057] 5) Simple measurement process. The measuring device has good linearity. After simple calibration, the frictional resistance can be directly calculated by collecting the output voltage of the laser rangefinder / strain gauge / electromagnet. Attached Figure Description

[0058] Figure 1 Showing a three-dimensional view of the force balance;

[0059] Figure 2 Showing a three-dimensional exploded view of the force balance;

[0060] Figure 3 An inverted oblique view of the floating plate is shown;

[0061] Figure 4 Specific implementation methods are shown, wherein Figure 4 (a) shows its top view. Figure 4 (b) Shows its bottom view;

[0062] Figure 5 This invention illustrates the force analysis and measurement principle of the measuring device.

[0063] Figure label:

[0064] 10-Floating Plate 101-Force Plate 102-Permanent Magnet Ring 103-Reflector Plate 104-Damping Module 20-Angle Code 30-Steel Sheet 40-Level Plate 401-Level Plate Upper 402-Level Plate Lower 403-Precision Adjustment Screw 404-Tension Spring 50-Oil Box 60-Dual-Axis Displacement Platform 70-Metal Base 80-Metal Hanging Frame 90-Measuring Module 901-Electromagnet 902-Laser Rangefinder 903-Strain Gauge 904-Fixed Pulley 905-Weight 100-Wind Tunnel Plate

[0065] It should be noted that when a component is "fixed to", "mounted to", or "connected" to another component, it can be directly glued to or threaded onto the other component, or an adapter can be used for auxiliary connection. Detailed Implementation

[0066] The present invention will now be described in detail with reference to the accompanying drawings.

[0067] This invention provides a multi-data fusion floating plate friction resistance measuring device (hereinafter referred to as the "measuring device"), such as... Figure 1-2As shown, the measuring device consists of a floating plate 10, a corner bracket 20, a steel plate 30, a horizontal plate 40, an oil box 50, a dual-axis displacement platform 60, a metal base 70, and a metal hanging frame 80.

[0068] Figure 3 The above is an inverted oblique view of the floating plate 10, which is the core component of the entire measuring device. It includes a force measuring plate 101, a permanent magnet ring 102, a reflector 103, and a damping module 104. The floating plate 10 is roughly triangular in shape and can be made of insulating materials such as resin, nylon, plexiglass, and polyetheretherketone. Nylon, which is low in cost and high in strength, is preferred.

[0069] Establish a rectangular coordinate system with the x-axis pointing from the short side to the long side of the force plate 101, the y-axis pointing upwards perpendicular to the upper surface of the force plate, and the z-axis pointing from the long side to the short side (to the left in the figure) of the force plate 101. The center of the upper surface of the force plate can be used as the origin of the rectangular coordinate system.

[0070] The force plate 101 is roughly a thin rectangular plate, 300mm long and 200mm wide when viewed from top to bottom. From a structural strength perspective, the thickness of the force plate 101 is no less than 5mm. The cross-sectional area of ​​the force plate 101, viewed from the side, exhibits a certain degree of contraction (i.e., draft angle), with a preferred draft angle of 45°. This design helps reduce the pressure difference between the upper and lower surfaces of the force plate in the wind tunnel, making the horizontal force measured by the measuring device closer to the actual frictional resistance. A mounting hole is provided at the center of the force plate 101 for easy calibration or installation of other models to be measured. Positioning holes or slots are provided at the bottom of the force plate 101 for the installation of the permanent magnet ring 102, reflector 103, damping module 104, and angle bracket 20, which are then connected and fixed using screws or adhesive.

[0071] Figure 2 An exploded view of the entire force measuring device is shown. Figure 3 An inverted oblique view of the floating plate 10 is shown. Near the long side of the force-measuring plate 101, two reflective plates 103, roughly cuboid in shape, are arranged parallel to the z-axis, with a distance maintained between them. One reflective plate is used to attach and fix the permanent magnet ring 102, while the other has a reflective sticker on its surface to reflect infrared light. The present invention does not limit the specific fixing position of the reflective plates 103, as long as they correspond to the positioning grooves pre-drilled in the force-measuring plate 101 and meet the operating distance requirements of the measuring sensor. The permanent magnet ring 102 is a common circular magnet, preferably made of AlNiCo permanent magnet material.

[0072] The damping module 104 is divided into three parts: upper, middle, and lower. The upper part consists of two hollow trusses suspended along the z-axis direction below the center of the force measuring plate 101. The two hollow trusses are symmetrical about the long side axis of the lower surface of the force measuring plate 101 and are fixedly connected to the force measuring plate 101, serving to connect the force measuring plate 101 and the damping module 104. The shape of the hollow trusses is determined according to the needs. The hollow truss shown in the figure is a common rectangular truss, with the inner triangle being the basic unit of the truss. The middle part is a rectangular horizontal plate used to connect the two trusses and the damping block at the bottom of the horizontal plate. The projection of the horizontal plate on the horizontal plane... The projection center of the damping module 104 coincides with the projection center of the force plate 101 on the horizontal plane. The lower part consists of multiple sets (e.g., five sets) of rectangular blocks placed along the z-axis, with identical thicknesses (e.g., 5 mm) and equal spacing (e.g., 5 mm) in the x-axis direction. These rectangular blocks together form a damping block, similar in shape to heat sink fins commonly found in electronic engineering design, to increase the contact area between the damping module 104 and the damping fluid. In a specific embodiment of the invention, the projection center of the damping block as a whole on the horizontal plane coincides with the projection center of the force plate 101 on the horizontal plane. The projection of the damping block on the horizontal plane is smaller than the projection of the horizontal plate, and their projection centers coincide. The damping module 104 is a structurally integrated design, with arrayed holes drilled in the horizontal plate and damping block for lightweight design.

[0073] like Figure 1 , 2 As shown in Figure 5, the corner bracket 20 is designed with two different cross-sectional shapes, I-shaped and L-shaped, depending on the installation position, respectively suitable for the installation of the steel sheet 30 between the floating plate 10 and the horizontal plate 40. In a specific embodiment of the present invention, the corner bracket 20 has a length of 280 mm, a height of 20 mm, and a width of 10-30 mm. Two pairs of I-shaped corner brackets are symmetrically distributed below the force measuring plate 101 along the z-axis direction, located outside the damping module 104. They basically penetrate the length of the force measuring plate 101 along the z-axis direction, with only a certain degree of contraction at both ends to fit the edge contraction of the force measuring plate 101. The two pairs of I-shaped corner brackets are vertically fixed below the force measuring plate 101 by screws in a manner well known to those skilled in the art. Each pair of I-shaped corner brackets must be used together to clamp the vertical steel sheet 30 placed therein. Two pairs of L-shaped brackets are arranged at the corresponding positions below the steel sheet 30. These L-shaped brackets are vertically fixed to the upper surface of the horizontal plate 40 using screws. Similar to the aforementioned I-shaped brackets, the L-shaped brackets are used to clamp the vertical steel sheet 30 placed within it. The upper pair of I-shaped brackets cooperates with the lower pair of L-shaped brackets at their corresponding positions to clamp the steel sheet 30 from both above and below. Equally spaced circular holes are provided at the connection points of the brackets 20 and the steel sheet 30 for bolts to pass through, serving to clamp, fix, and align the components.

[0074] The steel sheet 30 is a vertical, thin cuboid shape, clamped between the upper and lower diagonal brackets. The length of the steel sheet 30 is consistent with that of the diagonal brackets 20, and the height can be selected as 100mm. The thickness of the steel sheet 30 depends on the magnitude of the force on the floating plate and the required range of variation, and can be selected from 0.1 to 0.3mm, preferably 0.2mm.

[0075] The horizontal plate 40 serves as a base, supporting the floating plate 10 and inducing minor bending (displacement). The horizontal plate 40 mainly consists of an upper horizontal plate 401, a lower horizontal plate 402, precision adjusting screws 403, and a tension spring 404 (the precision adjusting screws 403 and tension springs 404 are mechanical components commonly used by those skilled in the art). In one specific embodiment of the invention, the overall dimensions of the horizontal plate 40 are 300mm in length and 200mm in width (i.e., the length and width of the upper horizontal plate 401 and the lower horizontal plate 402), and its height can vary within 30±2mm. The height is adjusted according to actual needs by the precision adjusting screws 403 installed at the four corners of the lower surface of the lower horizontal plate 402. Furthermore, different lifting heights can also change the horizontal and pitch degrees of freedom of the horizontal plate 401 to ensure that the upper surface of the floating plate 10 is flush with the wind tunnel plate 100 to be installed.

[0076] The wind tunnel plate 100 is a common plate model used in wind tunnel plate experiments (such as...). Figure 4 As shown in the figure, in this invention, a slot is cut in the middle of the wind tunnel plate 100 to measure the frictional resistance of the surface of the wind tunnel plate 100, so as to install the measuring device of this invention. In order to make the frictional resistance measured by the measuring device approximately equal to the frictional resistance of the wind tunnel plate, the following two points need to be achieved: 1. The upper surface of the floating plate 10 is flush with the wind tunnel plate 100 to be installed; 2. The floating plate and the wind tunnel plate 100 are not in contact, and the gap between them is as small as possible, preferably not exceeding 1 mm. Figure 5 This reflects these two requirements.

[0077] Both the upper part 401 and the lower part 402 of the horizontal plate are cuboid plates. In one embodiment of the invention, the thickness of the lower part 402 is greater than the thickness of the upper part 401, and the thickness of the upper part 401 is greater than the thickness of the force measuring plate 101. The projections of the upper part 401 and the lower part 402 on the horizontal plane coincide. To ensure the integrity of the two horizontal plates and the stability of height adjustment, multiple sets (e.g., five sets) of tension springs 404 are provided between the upper part 401 and the lower part 402 along the x-axis and z-axis. In one embodiment of the invention, two sets of tension springs 404 are distributed along the x-axis and three sets are distributed along the z-axis, with a spacing of 40 mm. They are located at the reserved holes between the upper part 401 and the lower part 402 and are fixed to both by pins, providing preload force between the upper part 401 and the lower part 402.

[0078] Two pairs of L-shaped brackets are fixed to the upper surface of the horizontal plate 401 with bolts. A space for placing the oil box 50 is reserved between the two pairs of L-shaped brackets and in the middle of a pair of steel plates 30. The oil box 50 is typically cuboid in shape with an open top, used to submerge the damping blocks of the damping module 104. The projection center of the oil box 50 on the horizontal plane coincides with the projection center of the force measuring plate 101 on the horizontal plane. The oil box 50 can be made of materials such as acrylic, ABS, or resin, and can be filled with a high-viscosity damping fluid such as olive oil or silicone oil. In practice, after the floating plate 10 is assembled, the damping blocks of the damping module 104 are precisely submerged in the damping fluid without contacting the inner wall of the oil box, ensuring improved stability of the floating plate 10 during use.

[0079] A dual-axis displacement platform 60 is fixed between a horizontal plate 40 and a metal base 70. The dual-axis displacement platform 60 is bolted to the upper surface of the metal base 70, and the horizontal plate 40 is bolted to the upper surface of the dual-axis displacement platform 60. The dual-axis displacement platform 60 provides fine-tuning (1mm) of displacement in both the x-axis and z-axis directions for the upper floating plate 10. That is, the horizontal plate 40, steel plate 30, and floating plate 10 all undergo slight displacement on the horizontal plane as the dual-axis displacement platform 60 is adjusted. Therefore, a certain distance must exist between the horizontal plate 40, steel plate 30, floating plate 10, and the metal hanging frame 80. This invention does not limit the configuration of the dual-axis displacement platform 60; a commonly available cross-guide rail type displacement platform is used, and will not be described in detail further.

[0080] The metal base 70 is connected to the metal hanging frame 80 via bolts, forming an outer frame with a rectangular inner cavity, serving functions such as load-bearing, fixing, and installation. The shape of the metal base 70 is not strictly limited, as long as it can support the components placed on it. In one embodiment of the invention, to reduce weight, the metal base 70 is designed in a roughly hourglass shape, such as... Figure 2 As shown. Figure 5 In the design, all eight corners inside the rectangle are chamfered, but this is not mandatory; it is only for the convenience of staff. The metal base 70 and the metal hanging frame 80 can be made of common metals (such as steel, iron, and aluminum), with aluminum alloy, which has low density and high structural strength, being the preferred material.

[0081] The horizontal plate 40, metal base 70, and metal hanging frame 80 are all appropriately hollowed out to achieve a lightweight design for the entire measuring device. The hollowed-out sections also facilitate external adjustment of the measuring device. The hollowed-out sections must not affect the pre-reserved assembly holes; generally, hollowing out is done on areas that do not significantly impact structural strength or the model's function, or on large blank areas within the model.

[0082] Since the entire measuring device is suspended below the wind tunnel plate 100 (or the position to be measured), and it is necessary to ensure that the force measuring plate 101 is flush with the surface of the wind tunnel plate 100 (as described above), a portion of the upper part of the force measuring plate 101 needs to protrude outside the metal hanging frame 80.

[0083] To achieve multi-data fusion measurement, a measurement module 90 is configured both inside and outside the measurement device, comprising an electromagnet 901, a laser rangefinder 902, and a strain gauge 903. Outside the measurement device, the electromagnet 901 faces the permanent magnet ring 102, meaning its installation position is at the same height as the permanent magnet ring 102, ensuring that the force (repulsive force) between the electromagnet 901 and the permanent magnet ring 102 is always horizontal. In this invention, the magnetic material and polarity configuration of the permanent magnet ring 102 are not limited, as long as it can generate a repulsive force when facing the electromagnet 901. The laser rangefinder 902 is installed outside the measurement device, facing the reflector 103, with its ranging center at the same height as the center of the reflector 103. Furthermore, the distance between the laser rangefinder 902 and the reflector 103 is limited to the normal operating range of the laser, preferably 15-17 mm, ensuring that the laser rangefinder 902 achieves accurate measurements with a precision of 1 μm within a 2 mm range. Since the floating plate 10 causes the underlying steel sheet 30 to bend during use, a strain gauge 903 can be attached to an appropriate position on the outer wall of the steel sheet 30 inside the measuring device to record the strain caused by the bending deformation of the steel sheet 30. In one embodiment of the present invention, the strain gauge 903 is fixed near the neutral axis of the bent portion, because the strain is more pronounced in this area, which helps to accurately measure the material deformation. Depending on actual needs, the strain gauge 903 can be any type of strain gauge, such as a metal strain gauge or a semiconductor strain gauge, and is not limited in the present invention.

[0084] Based on the above-mentioned measuring device, the present invention also provides a method for measuring the frictional resistance of a floating plate by multi-data fusion, which is used to measure frictional resistance, as follows.

[0085] like Figure 4 As shown, in one embodiment, the long side of the measuring device is perpendicular to the direction of the incoming flow. The metal hanging frame 80 is fitted and installed at the central slot of the wind tunnel plate 100. The entire measuring device and the wind tunnel plate 100 are set together in the wind tunnel. By adjusting the four precision adjusting screws 403 in the level plate 40, it is ensured that the floating plate 10 is installed flush with the surface of the wind tunnel plate 100. The dual-axis displacement platform 60 is adjusted to ensure that the distance between the floating plate 10 and the edge of the central slot of the wind tunnel balance 100 is controlled within 1mm, which meets the movement distance of the floating plate 10 during use. Figure 4 As shown in (b), both the electromagnet 901 and the laser rangefinder 902 are installed side by side at the downstream end of the measuring device through threaded holes pre-drilled in the bottom 100 of the wind tunnel plate.

[0086] Taking two-dimensional flat plate boundary layer flow as an example, the working principle of the measuring device of the present invention is explained. Figure 4 This is a schematic diagram of the force analysis of the measuring device. The floating plate 10 is installed flush with the wind tunnel plate 100. In an ideal two-dimensional situation, the floating plate 10 is not subjected to any force in the direction perpendicular to the plane. Therefore, two steel plates 30 can be used to maintain the balance of the floating plate 10. When the boundary layer of the incoming flow on the surface of the wind tunnel plate 100 is from right to left (e.g., Figure 5 As shown) when flowing through the floating plate 10 (from Figure 4 (Viewed from bottom to top), due to viscous friction, the surface boundary layer generates a leftward frictional resistance f on the floating plate 10. Under the action of this frictional resistance, the floating plate 10 deviates from its neutral position and begins to tilt (translate) to the left. The distance D of this movement can be measured using a laser rangefinder.

[0087] Specifically, based on whether the three different measurement modules 90 are working or not, the present invention has two measurement schemes:

[0088] Option 1: Using a laser rangefinder 902 and strain gauge 903. The floating plate 10, angle bracket 20, two steel plates 30, and horizontal plate 40 together constitute a statically indeterminate structure, which can be further simplified to two sets of cantilever beam structures. The displacement caused by the frictional resistance f on the floating plate 10 is approximately converted into the deflection change of the cantilever beam, and described by the following formula:

[0089]

[0090] Where b, l, and h represent the length (280 mm), width (100 mm), and thickness (0.2 mm) of the steel sheet, respectively. E is the Young's modulus of the steel sheet (194020 MPa). Therefore, the displacement D of the floating plate 10 has a linear relationship with the frictional resistance f. Further simplification yields the following expression for the frictional resistance:

[0091] f = k·D(2)

[0092] Where k is the calibration coefficient. In the specific implementation process, it is not necessary to adjust the values ​​of b, l and h mentioned above. It is only necessary to use the calibration coefficient k in the linear relationship between f and D to directly calculate the corresponding frictional resistance using formula (2).

[0093] In the specific implementation plan, during calibration, lightweight, flexible fine wires are preferred. Figure 4 and Figure 5 The floating plate 10 (with the dashed line in the middle) is connected to the calibration weight 905 (the force generated by the mass of the calibration weight is greater than the range of variation of the friction force to be measured), and is connected by a fixed pulley 904 located at the trailing edge of the wind tunnel plate 100. Figure 4 and Figure 5 The downward vertical force G of the weights is converted into a horizontal pulling force (from right to left) applied to the floating plate 10, which is approximately equivalent to the frictional resistance f experienced by the floating plate 10. Furthermore, the above process is repeated with weights of different masses, while simultaneously recording the displacement output by the laser rangefinder 902. A set of force and displacement data points is obtained, and the calibration coefficient k in formula (2) is calibrated by fitting these data points. Therefore, by measuring the displacement of the floating plate 10, the real-time change in frictional resistance can be deduced.

[0094] The current scheme also uses a strain gauge 903 attached to the bottom of the steel plate 30. With the fixing point 401 of the steel plate 30 and the upper part of the horizontal plate as the fulcrum (the fulcrum is the point where the steel plate to which the strain gauge is attached is clamped and fixed by the L-shaped angle bracket below), the torque on the steel plate 30 is expressed by the following formula:

[0095] M = f·l(3)

[0096] The bending moment measured by the strain gauge can be used to deduce the corresponding frictional resistance. The use of strain gauge 903 is familiar to those skilled in the art, and its applications are varied and will not be detailed here. A preferred method is to construct a Wheatstone bridge and use it in conjunction with a known resistance. Depending on actual needs, multiple strain gauges can be connected in series or parallel at the bottom of the steel sheet 30 to average the final measured torque (the deduced frictional resistance), thereby improving data accuracy.

[0097] In this scheme, the laser rangefinder 902 uses optical measurement methods to monitor the displacement of the reflector 103 in the floating plate 10; the strain gauge 903 measures the steel sheet 30, and the bending deformation of the steel sheet 30 is mainly determined by the material's inherent properties. In the specific implementation of this combined measurement scheme, the influence of environmental factors such as temperature, humidity, and air pressure is minimal, and it is essentially not simultaneously affected by electromagnetic interference. This allows the two measurement data to be mutually verified, thereby significantly improving the accuracy of the measurement.

[0098] Option 2: In this option, the laser rangefinder 902 (or strain gauge 903) and the electromagnet 901 together form a feedback system, which differs from Option 1 where the laser rangefinder 902 is directly used for measurement results. The laser rangefinder 902 serves as a feedback device, acquiring the minute displacement D of the floating plate 10 and transmitting it to the control computer. Based on the change in displacement D, the control computer adjusts the input voltage of the electromagnet 901 using algorithms such as PID (a classic control algorithm well-known to those skilled in the art), thereby changing its repulsive force F on the permanent magnet ring 102. During this process, the floating plate 10 will swing to the right, gradually returning to its neutral position. Simultaneously, the laser rangefinder 902 acquires the displacement D in real time for further adjustment.

[0099] In this case, the frictional resistance f on the upper surface of the floating plate 10 is opposite in direction and equal in magnitude to the repulsive force F on the lower end, and the repulsive force F = frictional resistance f. The magnitude of the repulsive force is determined by the input voltage of the electromagnet 901. Therefore, by recording the input voltage, the magnitude of the frictional resistance experienced by the floating plate 10 can be deduced.

[0100] Furthermore, when the laser rangefinder 902 fails, the strain gauge 903 can be used as a substitute, transmitting the collected torque as a feedback signal to the control computer. The control computer adjusts the input voltage of the electromagnet 901 according to the change in torque M, thereby changing its repulsive force F on the permanent magnet ring 102. As can be seen from formula (3), torque M can represent the change in frictional resistance f. If the input voltage of the electromagnet 901 is adjusted, its repulsive force F on the permanent magnet ring 102 can be changed. Therefore, when the collected torque M is 0 or approximately 0, the repulsive force F = frictional resistance f. To achieve multi-data fusion, it is necessary to perform confidence analysis on the data measured by different schemes according to the actual application scenario to evaluate the reliability of each method in different scenarios. In practical applications, in some situations where there are high-frequency fluctuations in airflow or large electromagnetic interference, different degrees of noise and interference may be encountered. For example, when the measurement object is dielectric barrier discharge (DBD) plasma high-frequency excitation, the data displayed by the strain gauge 903 will inevitably have a large number of glitch, and the data reliability is extremely low, so it needs to be discarded. At this point, to ensure the accuracy of the results, the measurement results obtained from either the laser rangefinder 902 (Scheme 1) or the electromagnet 901 (Scheme 2) can be preferentially selected as the final data to avoid erroneous judgments caused by unreliable strain gauge 903 data. In other relatively stable environments, a weighted average method is used to fuse multiple measurement data, with the weight allocation based on the results of previous data analysis and practical operational experience. For example, if the laser rangefinder 902 and strain gauge 903 measurement results can be mutually verified under certain conditions and have a high signal-to-noise ratio, then a higher weight can be assigned to them during fusion. In this way, the fusion of multiple data not only improves measurement accuracy but also effectively suppresses potential errors, thereby achieving accurate monitoring and analysis of the frictional resistance experienced by the floating plate 10.

Claims

1. A multi-data fusion floating plate friction resistance measuring device, characterized in that, The device includes a floating plate (10), corner brackets (20), steel plates (30), a horizontal plate (40), an oil box (50), a dual-axis displacement platform (60), a metal base (70), and a metal hanging frame (80), among which... The floating plate (10) includes a force measuring plate (101), a permanent magnet ring (102), a reflector (103) and a damping module (104). The floating plate (10) is roughly in the shape of an inverted triangle. Establish a rectangular coordinate system with the x-axis pointing from the short side to the long side along the force plate (101), the y-axis pointing upward perpendicular to the upper surface of the force plate, and the z-axis pointing from the long side to the short side along the force plate (101). Take the center of the upper surface of the force plate as the origin of the rectangular coordinate system. The force measuring plate (101) is a rectangular thin plate; the cross-sectional area of ​​the force measuring plate (101) has a draft angle when viewed from the side from top to bottom; there is a mounting hole at the center of the force measuring plate (101); there are positioning holes or positioning grooves at the bottom of the force measuring plate (101) to facilitate the installation of the permanent magnet ring (102), the reflector (103), the damping module (104) and the corner bracket (20), and they are connected and fixed by fastening means; Two reflectors (103) are arranged along the direction parallel to the z-axis near the long side of the force measuring plate (101), with a distance between the two reflectors (103); one is used to attach and fix the permanent magnet ring (102), and the other is covered with reflective stickers to reflect infrared light; the specific position of the reflector (103) corresponds to the positioning groove reserved in the force measuring plate (101); The damping module (104) is divided into three parts: upper, middle, and lower. The upper part consists of two hollow trusses suspended along the z-axis direction at the center below the force plate (101). The two hollow trusses are symmetrical about the long side axis of the lower surface of the force plate (101) and are fixedly connected to the force plate (101). The middle part consists of a rectangular horizontal plate used to connect the two trusses and the damping block at the bottom of the horizontal plate. The projection center of the horizontal plate on the horizontal plane coincides with the projection center of the force plate (101) on the horizontal plane. The lower part consists of multiple sets of rectangular blocks of the same thickness placed along the z-axis and with the same spacing in the x-axis direction. These rectangular blocks together form the damping block. The projection center of the damping block as a whole on the horizontal plane coincides with the projection center of the force plate (101) on the horizontal plane. The projection of the damping block on the horizontal plane is smaller than the projection of the horizontal plate on the horizontal plane, and the projection centers of the two coincide. The corner brackets (20) include two types, I-type and L-type, with different cross-sectional structural shapes, which are respectively suitable for the installation of steel plates (30) between the floating plate (10) and the horizontal plate (40); two pairs of I-type corner brackets are symmetrically distributed below the force measuring plate (101) along the z-axis direction, distributed on the outside of the damping module (104), and basically penetrate the length of the force measuring plate (101) along the z-axis direction, with only a certain amount of contraction at both ends to fit the edge contraction of the force measuring plate (101); the two pairs of I-type corner brackets are vertically fastened by fastening means. The vertical steel sheet (30) is fixed below the force measuring plate (101); each pair of I-type angle brackets must be used together to clamp the vertical steel sheet (30) placed therein; at the corresponding position below the steel sheet (30), two pairs of L-type angle brackets are arranged, and the two pairs of L-type angle brackets are vertically fixed to the upper surface of the horizontal plate (40) by fastening means. Similar to the aforementioned I-type angle brackets, the L-type angle brackets are used to clamp the vertical steel sheet (30) placed therein; the upper pair of I-type angle brackets and the lower pair of L-type angle brackets cooperate to clamp the steel sheet (30) from the upper and lower positions together; The steel sheet (30) is a vertical, thin cuboid shape, clamped between the upper and lower diagonal brackets; the length of the steel sheet (30) is consistent with that of the diagonal bracket (20), and the thickness of the steel sheet (30) is determined according to the magnitude of the force on the floating plate and the required range of change. The horizontal plate (40) includes an upper part (401), a lower part (402), precision adjusting screws (403), and a tension spring (404). The height can be adjusted by the precision adjusting screws (403) installed at the four corners of the lower surface of the lower part (402) of the horizontal plate according to actual needs. In addition, different lifting heights can also change the horizontal and pitch degrees of freedom of the upper part (401) of the horizontal plate to ensure that the upper surface of the floating plate (10) is flush with the wind tunnel plate (100) to be installed. A slot is cut in the middle of the wind tunnel plate (100) to install a measuring device; the upper surface of the floating plate (10) is flush with the wind tunnel plate (100) to be installed; the floating plate and the wind tunnel plate (100) are not in contact, and the gap between them is as small as possible. The upper part (401) and the lower part (402) of the horizontal plate are both cuboid plates, and their projections on the horizontal plane coincide. Multiple sets of tension springs (404) are provided between the upper part (401) and the lower part (402) of the horizontal plate along the x-axis and z-axis. The multiple sets of tension springs (404) are distributed along the x-axis and z-axis, located at the reserved holes between the upper part (401) and the lower part (402) of the horizontal plate and are fixed to both of them. Two pairs of L-shaped corner brackets are fixed to the upper surface of the horizontal plate (401) by fastening technology. The oil box (50) is reserved between the two pairs of L-shaped corner brackets and in the middle of a pair of steel plates (30). The upper part of the oil box (50) is open to allow the damping block of the damping module (104) to be sunk into it. The projection center of the oil box (50) on the horizontal plane coincides with the projection center of the force measuring plate (101) on the horizontal plane; after the floating plate (10) is assembled, the damping blocks of the damping module (104) can be immersed in the damping fluid and do not contact the inner wall of the oil box. The dual-axis displacement platform (60) is fixed between the horizontal plate (40) and the metal base (70). The dual-axis displacement platform (60) is fixed to the upper surface of the metal base (70) by fastening technology, and the horizontal plate (40) is fixed to the upper surface of the dual-axis displacement platform (60) by fastening technology. The dual-axis displacement platform (60) provides fine adjustment of displacement in the x-axis and z-axis directions for the upper floating plate (10). That is, the horizontal plate (40), the steel plate (30), and the floating plate (10) all produce small displacements on the horizontal plane with the fine adjustment of the dual-axis displacement platform (60). Therefore, there must be a certain distance between the horizontal plate (40), the steel plate (30), the floating plate (10) and the metal hanging frame (80). The metal base (70) and the metal hanging frame (80) are connected by fastening technology to form an outer frame with a cuboid inner cavity; Measurement modules (90) are configured inside and outside the measuring device.

2. The floating plate friction resistance measuring device with multi-data fusion as described in claim 1, characterized in that, The force measuring plate (101) is 300 mm long and 200 mm wide when viewed from top to bottom, and the thickness of the force measuring plate (101) is not less than 5 mm; the draft angle of the force measuring plate (101) is 45°.

3. The floating plate friction resistance measuring device with multi-data fusion as described in claim 1, characterized in that, The corner bracket (20) is 280 mm long, 20 mm high, and 10-30 mm wide; the corner bracket (20) and the steel plate (30) are connected with equally spaced round holes for bolts to pass through.

4. The floating plate friction resistance measuring device with multi-data fusion as described in claim 1, characterized in that, The height of the steel sheet (30) is 100 mm, and the thickness of the steel sheet (30) ranges from 0.1 to 0.3 mm.

5. The floating plate friction resistance measuring device with multi-data fusion as described in claim 1, characterized in that, The overall dimensions of the horizontal plate (40) are 300 mm in length and 200 mm in width, and the height varies within 30 ± 2 mm.

6. The floating plate friction resistance measuring device with multi-data fusion as described in claim 1, characterized in that, The floating plate (10) is made of nylon, plexiglass or polyetheretherketone; The permanent magnet ring (102) is a ring-shaped magnet made of AlNiCo permanent magnet material; The lower part of the damping module (104) consists of five identical rectangular blocks with a thickness of 5 mm and a 5 mm interval in the x-axis direction, placed along the z-axis. The damping module (104) is a structurally integrated design with arrayed holes in the horizontal plate and damping blocks for lightweight design. The floating plate and the wind tunnel plate (100) are not in contact, and the gap between them does not exceed 1 mm; Five sets of tension springs (404 stainless steel) are distributed along the x-axis (two sets) and the z-axis (three sets), with a spacing of 40 mm between each set. The oil box (50) is made of acrylic or ABS material and is filled with olive oil or silicone oil damping fluid. The metal base (70) is designed in the shape of an hourglass. The metal base (70) and the metal hanging frame (80) are made of steel, iron or aluminum. The horizontal plate (40), the metal base (70) and the metal hanging frame (80) are all properly hollowed out. The hollowed-out parts should not affect the reserved assembly holes.

7. The floating plate friction resistance measuring device with multi-data fusion as described in claim 1, characterized in that, The measurement module (90) includes: an electromagnet (901), a laser rangefinder (902), and a strain gauge (903); Outside the measuring device, the electromagnet (901) is directly opposite the permanent magnet ring (102), that is, its installation position is at the same height as the permanent magnet ring (102), ensuring that the force between the electromagnet (901) and the permanent magnet ring (102) is always in the horizontal direction; when the permanent magnet ring (102) and the electromagnet (901) are facing each other, they can generate a repulsive force; The laser rangefinder (902) is installed outside the measuring device, facing the reflector (103), and its ranging center is at the same height as the center of the reflector (103). In addition, the distance between the laser rangefinder (902) and the reflector (103) is limited to the normal working range of the laser. Inside the measuring device, a strain gauge (903) is attached to the outer wall of the steel sheet (30). The strain gauge (903) can be a metal strain gauge or a semiconductor strain gauge.

8. The floating plate friction resistance measuring device with multi-data fusion as described in claim 7, characterized in that, The strain gauge (903) is fixed near the neutral axis of the bent portion.

9. A method for measuring the frictional resistance of a floating plate using multi-data fusion, based on the floating plate frictional resistance measuring device as described in any one of claims 1 to 8, characterized in that, Specifically as follows: The floating plate (10) is installed flush with the wind tunnel plate (100). In an ideal two-dimensional situation, the floating plate (10) is not subjected to any force in the direction perpendicular to the plane. Therefore, the balance of the floating plate (10) can be maintained by using two steel plates (30). When the incoming boundary layer on the surface of the wind tunnel plate (100) flows from right to left across the floating plate (10), due to viscous friction, the incoming boundary layer will generate a leftward frictional resistance f on the floating plate (10). Under the action of this frictional resistance, the floating plate (10) deviates from the neutral position and begins to translate to the left. The displacement D of this translation can be measured by a laser rangefinder. Specifically, based on whether the three different measurement modules (90) are working or not, there are two measurement schemes: Option 1: A laser rangefinder (902) + strain gauge (903) is used; the floating plate (10), angle bracket (20), two steel plates (30) and horizontal plate (40) together constitute a statically indeterminate structure, which can be further simplified into two sets of cantilever beam structures. The displacement caused by the frictional resistance f of the floating plate (10) is approximately converted into the deflection change of the cantilever beam, and described by the following formula: （1） Where b, l, and h represent the length, width, and thickness of the steel sheet, respectively; E is the Young's modulus of the steel sheet; accordingly, the displacement D of the floating plate (10) has a linear relationship with the frictional resistance f it experiences; further simplification yields the following expression for the frictional resistance: （2） Where k is the calibration coefficient; During calibration, a lightweight, flexible thin thread is preferred to connect the floating plate (10) to the calibration weight (905). The vertical downward gravity G of the weight is converted into a horizontal pulling force applied to the floating plate (10) by a fixed pulley (904) set at the tail edge of the wind tunnel plate (100), which is approximately equivalent to the frictional resistance f of the floating plate (10). Furthermore, the above process is repeated with weights of different masses, and the displacement output by the laser rangefinder (902) is recorded at the same time. A set of force and displacement data points are obtained, and the force and displacement data points are fitted to calibrate the calibration coefficient k in formula (2). Thus, by measuring the displacement of the floating plate (10), the real-time change of frictional resistance can be deduced. The current scheme also uses strain gauges (903) attached to the bottom of the steel sheet (30), with the fixed point between the steel sheet (30) and the upper part (401) of the horizontal plate as the fulcrum. The torque on the steel sheet (30) is expressed by the following formula: （3） The bending moment obtained by the strain gauge can be used to deduce the corresponding frictional resistance. Depending on the actual needs, multiple strain gauges can be connected in series or in parallel at the bottom of the steel sheet (30) to average the final measured torque, thereby improving the accuracy of the data. Option 2: A laser rangefinder (902) or strain gauge (903) and electromagnet (901) together form a feedback system; the laser rangefinder (902) is used as a feedback device, which collects the small displacement D of the floating plate (10) and transmits it to the control computer; the control computer adjusts the input voltage of the electromagnet (901) according to the change of displacement D, thereby changing its repulsive force F on the permanent magnet ring (102); during this process, the floating plate (10) will swing to the right and gradually return to the neutral position; at the same time, the laser rangefinder (902) collects the displacement D in real time for further adjustment; In this case, the frictional resistance f on the upper surface of the floating plate (10) is opposite in direction and equal in magnitude to the repulsive force F on the lower end. The repulsive force F = frictional resistance f. The magnitude of the repulsive force is determined by the input voltage of the electromagnet (901). Therefore, by recording the input voltage, the magnitude of the frictional resistance borne by the floating plate (10) can be deduced. Furthermore, when the laser rangefinder (902) fails, the strain gauge (903) can be used as a substitute to transmit the collected torque as a feedback signal to the control computer. The control computer adjusts the input voltage of the electromagnet (901) according to the change of torque M, thereby changing its repulsive force F on the permanent magnet ring (102). According to formula (3), torque M can represent the change of frictional resistance f. If the input voltage of the electromagnet (901) is adjusted, its repulsive force F on the permanent magnet ring (102) can be changed. Therefore, when the collected torque M is 0 or approximately 0, the repulsive force F at this time is equal to the frictional resistance f.

10. The method for measuring the frictional resistance of a floating plate using multi-data fusion as described in claim 9, characterized in that, In situations where there are high-frequency airflow fluctuations or significant electromagnetic interference, data with low reliability need to be discarded; the measurement results obtained by using a laser rangefinder (902) or an electromagnet (901) alone are selected as the final data; in other relatively stable environments, a weighted average method is used to fuse multiple measurement data, and the weight allocation is based on the results of previous data analysis and practical operating experience.

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