Drop hammer device for impact performance test of unmanned aerial vehicle body structure and test method

Abstract

The invention discloses a drop hammer device for an impact performance test of an unmanned aerial vehicle body structure and a test method.The device comprises an impact force measurement test platform, an impact loading test platform and a multi-stage electric hydraulic telescopic rod, and the impact force measurement test platform is located above the impact loading test platform; the multi-stage electric hydraulic telescopic rod is mounted between the impact force measurement test platform and the impact loading test platform; the method comprises the following steps: S1, installing a drop hammer device and adjusting an impact loading test platform; s2, mounting and testing a tested object of the unmanned aerial vehicle; and S3, test recording. According to the drop hammer device for the impact performance test of the unmanned aerial vehicle body structure and the test method disclosed by the invention, the device can adjust the test positions of unmanned aerial vehicle tested objects with different shapes and specifications at high precision, solves the problem that centers of the three objects are coaxial, and can meet different drop hammer test conditions; the method is used for evaluating the collision safety of the civil light and small unmanned aerial vehicle with the maximum takeoff weight of about 0.25 kg-25 kg.

Description

Technical Field

[0001] The present invention belongs to the technical field of collision safety testing of unmanned aerial vehicles, and particularly relates to a drop hammer device and a test method for the impact performance test of the drone airframe structure. Background Art

[0002] In clause 6.1, the collision safety of the drone airframe structure in the national standard GB / T 44715-2024 "Collision Safety Requirements for Civil Light and Small Unmanned Aerial Vehicles", clear requirements are made for the structure of the drone: the drone airframe structure should have good collision energy absorption characteristics. When a collision occurs, the drone airframe structure can absorb or conduct the energy generated by the collision by undergoing a certain amount of plastic deformation or even structural damage. The test method is the impact performance test of the drone airframe structure in Appendix A3, and a drop hammer test device can be selected.

[0003] In the drop hammer test steps, it is strictly required that the drone under test be placed on the surface of the force measuring platform and its position be adjusted to ensure that the centers of the drone under test, the impact hammer head, and the force measuring platform are on the same axis. In addition, the impact hammer head can vertically impact the drone under test. Currently, the types of drop hammer test devices on the market are complex and diverse, but few can meet the above requirements.

[0004] Therefore, in view of the above problems, further improvements are made. Summary of the Invention

[0005] The main purpose of the present invention is to provide a drop hammer device and a test method for the impact performance test of the drone airframe structure. The device can accurately adjust the test position of drone under test with different shapes and specifications, solve the problem of the coaxiality of the centers of the three, and can meet different drop hammer test conditions (height, mass, impact energy, impact surface geometry, etc.), and is used for the assessment of the collision safety of civil light and small unmanned aerial vehicles with a maximum takeoff weight of about 0.25 kg to 25 kg.

[0006] To achieve the above objectives, the present invention provides a drop hammer device for the impact performance test of the drone airframe structure, including an impact force measuring test platform, an impact loading test platform, and a multi-stage electro-hydraulic telescopic rod. The impact force measuring test platform is located above the impact loading test platform, and the multi-stage electro-hydraulic telescopic rod is installed between the impact force measuring test platform and the impact loading test platform, where:

[0007] The impact force measurement test platform is provided with an X-axis slide rail groove and a Y-axis slide rail groove. The X-axis slide rail groove and the Y-axis slide rail groove vertically intersect at the geometric center of the impact force measurement test platform. A piezoelectric force sensor is fixedly installed in the space at the intersection. The force-receiving surface of the piezoelectric force sensor is flush with the impact force measurement test platform and the force center coincides with the geometric center. The X-axis slide rail groove is internally provided with an upper ball screw and a lower ball screw, which are respectively controlled to move by an upper AC servo motor and a lower AC servo motor outside in cooperation with corresponding couplings; the Y-axis slide rail groove is internally provided with a left ball screw and a right ball screw, which are respectively controlled to move by a left AC servo motor and a right AC servo motor outside the platform in cooperation with corresponding couplings; the upper ball screw, the lower ball screw, the left ball screw and the right ball screw are all vertically installed with folding push plates.

[0008] The impact loading test platform includes a lifting top plate and a load-carrying flat plate. A strong electromagnetic suction plate is internally provided on the lower plane of the lifting top plate. When the coil in the strong electromagnetic suction plate is energized, it generates a strong magnetic force to adsorb the movable load-carrying flat plate, and positioning mounting holes for installing multi-stage electric hydraulic telescopic rods are provided at the four top corners of the lower plane; a through square hole is provided at the center of the lifting top plate for configuring the load-carrying device of the load-carrying flat plate. The load-carrying device includes a locking nut, a standard counterweight block and a drop hammer impact head.

[0009] As a further preferred technical solution of the above technical solution, a pouring hole for fixing the left slide bar is provided on the left side of the left AC servo motor, and a pouring hole for fixing the right slide bar is provided on the right side of the right AC servo motor.

[0010] As a further preferred technical solution of the above technical solution, the size of the lifting top plate is the same as that of the impact force measurement test platform, and the geometric centers are on the same axis;

[0011] The multi-stage electric hydraulic telescopic rod is provided with a driving motor for controlling the synchronous lifting of the multi-stage electric hydraulic telescopic rod; X-axis bubble levels and Y-axis bubble levels are installed on both the upper and lower planes of the lifting top plate. By observing the position of the bubbles, the telescopic amounts of each electric hydraulic telescopic rod are finely adjusted to ensure that the lifting top plate is in a horizontal state;

[0012] A screw rod is vertically welded at the geometric center of the load-carrying flat plate for positioning and assembling the standard counterweight block. The single body of the standard counterweight block is divided into four grades. The stacked standard counterweight blocks are fastened to the load-carrying flat plate through locking nuts. According to different drop hammer impact contact surfaces, the drop hammer impact heads are divided into three categories: First, a curved impact contact surface, a hemispherical hammer head; Second, a circular contact surface, a cylindrical hammer head; Third, a polygonal contact surface, a frustum-shaped hammer head; The handle of the drop hammer impact head is tapped with threads and matches with the screw hole at the bottom center of the load-carrying flat plate.

[0013] The left and right slide bars are symmetrically cast and fixed on the corresponding casting holes of the impact force test platform. The lifting top plate and the load plate are welded with left and right symmetrical sliding wing plates. The left and right sliding wing plates are respectively provided with coaxial sliding holes for installing the left and right slide bars.

[0014] To achieve the above objectives, the present invention further provides a method for testing the impact performance of a UAV body structure, comprising the following steps:

[0015] Step S1: installing the drop hammer device and adjusting the impact loading test platform;

[0016] Step S2: Installation and testing of the UAV test product;

[0017] Step S3: Test record.

[0018] As a further preferred technical solution of the above technical solution, for step S1:

[0019] The drop hammer device is installed and fixed as required, and then the impact loading test platform is adjusted according to the requirements of the unmanned aircraft drop hammer test. The hammer impact head is selected according to the geometric requirements of the impact surface. According to the range of the drop hammer mass requirements, the load-bearing device is equipped with standard counterweights, in the order of heavy weights first and light weights later. After installation, the locking nuts are tightened. The strong electromagnetic suction plate of the lifting top plate is energized to attract the load plate equipped with the load-bearing device. The drive motor is controlled by the PLC program to control the synchronous movement of the multi-stage electric hydraulic telescopic rod to raise the lifting top plate with the load plate to the specified height.

[0020] Fine-tune each electric hydraulic telescopic rod to keep the lifting top plate level. The adjustment method is as follows: Divide the electric hydraulic telescopic rods into four groups: Group A, Group B, Group C, and Group D. The lifting amount of the electric hydraulic telescopic rods in each group is kept synchronous and consistent. Specifically:

[0021] Step S1.1: Linkage adjustment of Group A and Group B. When the bubble of the X-axis bubble level is at the middle scale, the X-axis direction is parallel to the ground.

[0022] Step S1.2: Linkingly adjust Groups C and D until the bubble of the Y-axis bubble level 5 is at the middle scale and the Y-axis is parallel to the ground;

[0023] Step S1.3: Observe whether the bubble position in the X-axis direction is offset and repeat steps S1.1 to S1.3;

[0024] Step S1.4: When the bubbles on the X-axis bubble level and the Y-axis bubble level are both at the middle scale, the level adjustment of the lifting top plate is completed, and the ball head connection device of the positioning mounting hole is locked.

[0025] As a further preferred technical solution of the above technical solution, for step S2:

[0026] If the center of gravity of the UAV under test is not marked, use the UAV center of gravity weighing device to measure and project it onto the casing marking of the UAV. Place the UAV at the center of the impact force measuring test platform. Each folding push plate is paired with the aircraft tail wing, left wing, aircraft head, and right wing respectively. Expand the folding push plates up, down, left, and right appropriately according to the dimensions of the wing, tail wing, and aircraft height to ensure good contact between each push plate and the UAV. Adjust the center position of the UAV, convert the rotary motion of the AC servo motor into the linear motion of the folding push plate on the lead screw nut seat through the ball screw until the laser source hits the center of gravity projection point marked on the UAV casing. The centers of the UAV, impact hammer head, and impact force measuring test platform are on the same axis. At this time, remove the laser light source, install the required drop hammer impact head, adjust the optoelectronic displacement sensor to be flush with the height of the UAV, and record the force value measured by the piezoelectric force sensor as the weight of the UAV.

[0027] Start the test. The powerful electromagnetic suction plate on the lifting top plate is powered off, and the load flat plate with the drop hammer loading device freely falls to vertically impact the UAV. To prevent the load flat plate from colliding and rebounding, during the test, when the piezoelectric force sensor detects the force value in real time, when the maximum peak value appears and starts to decrease significantly, it is judged that the drop hammer device will produce a collision and rebound. Predict the inflection point of the real-time force value curve through the computer program. At the inflection point of the curve decline, apply a large current to the powerful electromagnetic suction plate on the lifting top plate to instantly suck the load flat plate and slowly lift it to avoid the influence of secondary impact.

[0028] As a further preferred technical solution of the above technical solution, for step S3:

[0029] Use a high-speed camera to record the failure mode of the UAV during the process of the hammer head impacting the UAV, and calculate the speed and acceleration at the drop hammer impact point through the optoelectronic displacement sensor, the load value of the loading device, the maximum impact force value measured by the piezoelectric force sensor, and the parameters of the deformation of the UAV.

[0030] The beneficial effects of the present invention are:

[0031] 1. Through the structural design of the drop hammer device and the operation method of the drop hammer test, it can achieve high-precision coaxiality of the centers of the UAV under test, impact hammer head, and force measuring platform. In addition, freely adjust the test position of the UAV under test on the impact force measuring test platform, which is simple and reliable.

[0032] 2. Drop hammer tests of the UAV under different conditions (height, mass, impact energy, impact surface geometry, etc.) can be carried out.

[0033] 3. During the drop hammer test, there is a function to prevent secondary impact, ensuring the stability and reliability of the test. Description of the Drawings

[0034] Figure 1 It is the overall structure diagram of the device of the present invention.

[0035] Figure 2 It is the structural diagram of the impact force measurement test platform of the device of the present invention.

[0036] Figure 3 It is the top view (from top to bottom) of the impact loading test platform of the device of the present invention.

[0037] Figure 4 It is the top view (from bottom to top) of the impact loading test platform of the device of the present invention;

[0038] Figure 5 is Figure 3 and Figure 4 the sectional view in the A direction in. Specific embodiments

[0039] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments in the following description are only examples, and other obvious variations can be thought of by those skilled in the art. The basic principles defined in the following description of the present invention can be applied to other implementation schemes, deformation schemes, improvement schemes, equivalent schemes and other technical schemes that do not deviate from the spirit and scope of the present invention.

[0040] In the preferred embodiment of the present invention, those skilled in the art should note that the UAV test samples and the like involved in the present invention can be regarded as the prior art.

[0041] Preferred embodiment.

[0042] As Figures 1-5 shown, the present invention discloses a drop hammer device for the impact performance test of the UAV airframe structure, including an impact force measurement test platform 1, an impact loading test platform and multi-stage electric hydraulic telescopic rods (212, 222, 232, 242). The impact force measurement test platform 1 is located above the impact loading test platform, and the multi-stage electric hydraulic telescopic rods (212, 222, 232, 242) are installed between the impact force measurement test platform 1 and the impact loading test platform, wherein:

[0043] The structural structure of the impact force measurement test platform 1 is: the upper impact collision surface and the lower support surface are thickened square alloy steel plates with a side length of 1 m, and the middle layer between the two is cast with reinforced concrete. Screw holes are provided at the four top corners of the thickened square alloy steel plate on the upper impact collision surface of the square platform for facilitating the installation of the multi-stage electric hydraulic telescopic rods (212, 222, 232, 242), and two rectangular slide rail grooves with a width of 0.02 m, a length of 0.9 m and a moderate depth are provided at the geometric center.

[0044] The impact force measurement test platform 1 is provided with an X-axis slide rail groove and a Y-axis slide rail groove. The X-axis slide rail groove and the Y-axis slide rail groove intersect perpendicularly at the geometric center of the impact force measurement test platform 1 (in a "cross" shape. The X-axis slide rail groove is perpendicular to the upper and lower sides of the platform 1, and the extension lines intersect at the midpoints of the upper and lower sides of the platform 1; the Y-axis slide rail groove is perpendicular to the left and right sides of the platform 1, and the extension lines intersect at the midpoints of the left and right sides of the platform 1). Inside the space (0.02m * 0.02m) at the intersection, a piezoelectric force sensor 13 (with high precision and high dynamic response) is fixedly installed. The force-receiving surface of the piezoelectric force sensor 13 is flush with the impact force measurement test platform 1 and the force center coincides with the geometric center. The X-axis slide rail groove is internally provided with an upper ball screw 113 and a lower ball screw 111, which are respectively controlled to move by an upper-side AC servo motor 103 and a lower-side AC servo motor 101 outside in cooperation with corresponding couplings; the Y-axis slide rail groove is internally provided with a left ball screw 112 and a right ball screw 114, which are respectively controlled to move by a left-side AC servo motor 102 and a right-side AC servo motor 104 outside the platform in cooperation with corresponding couplings; the ratio of the ball radius to the screw pitch of the ball screw should be less than or equal to 0.03, and the minimum displacement can be achieved within 0.1 mm. Foldable push plates (121, 122, 123, 124) are vertically installed on the nut seats of the upper ball screw 113, the lower ball screw 111, the left ball screw 112, and the right ball screw 114. According to parameters such as the height, length, wingspan, rotor position and quantity of the unmanned aerial vehicle, the foldable push plates are reasonably unfolded or folded to accurately adjust the position of the unmanned aerial vehicle test specimen on the impact force measurement test platform 1, which is consistent with the structural design of the impact force measurement test platform 1. The upper, lower, left, and right side AC servo motors are all installed in the vacant space in the middle layer, and the upper and lower steel plates are welded to the upper and lower steel plates of the square test platform).

[0045] The impact loading test platform includes a lifting top plate 6 and a load-carrying flat plate 8. The lower plane of the lifting top plate 6 is internally provided with a strong electromagnetic suction plate. When the coil inside the strong electromagnetic suction plate is energized, it generates a strong magnetic force to adsorb the movable load-carrying flat plate 8, and positioning installation holes (213, 223, 233, 243, preferably using a ball head connection method with a locking function) are provided at the four top corners of the lower plane; a through square hole 61 is provided at the center of the lifting top plate 6 for configuring the load device 7 of the load-carrying flat plate 8. The load device 7 includes a locking nut 71, a standard counterweight 72, and a drop hammer impact head 73.

[0046] Specifically, a pouring hole for fixing the left slide bar 31 is provided on the left side of the left-side AC servo motor 102, and a pouring hole for fixing the right slide bar 41 is provided on the right side of the right-side AC servo motor 104.

[0047] More specifically, the size of the lifting top plate 6 is the same as that of the impact force measurement test platform 1, and they are on the same axis of the geometric center;

[0048] The multi-stage electro-hydraulic telescopic rod (212, 222, 232, 242) is provided with drive motors (211, 221, 231, 241) for controlling the synchronous lifting of the multi-stage electro-hydraulic telescopic rod; X-axis bubble levels 51 and Y-axis bubble levels 52 are installed on the upper and lower planes of the lifting top plate 6. By observing the position of the bubbles, the telescopic amount of each electro-hydraulic telescopic rod is finely adjusted to ensure that the lifting top plate 6 is in a horizontal state (the multi-stage electro-hydraulic telescopic rod can extend and retract the rods of the required grade according to different test requirements);

[0049] (The load-carrying flat plate 8 is also of a square structure, with a size smaller than that of the lifting top plate 6 on the same axis and can be placed inside the positioning and installation holes of the lifting top plate 6.) A screw rod 81 is vertically welded to the geometric center of the load-carrying flat plate 8 for positioning and assembling the standard counterweight 72. The single unit of the standard counterweight 72 is divided into four grades (0.1 kg, 0.5 kg, 1 kg, 5 kg). The stacked standard counterweights 72 are fastened to the load-carrying flat plate 8 through lock nuts 71. According to different impact contact surfaces of the drop hammer, the drop hammer impact heads are divided into three categories: First, the curved impact contact surface, with a hemispherical hammer head; Second, the circular contact surface, with a cylindrical hammer head; Third, the polygonal contact surface, with a frustum-shaped hammer head; The handle of the drop hammer impact head 73 is tapped with threads and is matched with the screw hole 82 at the bottom center of the load-carrying flat plate 8;

[0050] The left sliding rod 31 and the right sliding rod 41 are symmetrically cast and fixed on the corresponding casting holes of the impact force measuring test platform 1. The lifting top plate 6 and the load-carrying flat plate 8 are both welded with left and right symmetric sliding wing plates. Coaxial sliding holes (33 and 43) for installing the left sliding rod and the right sliding rod are respectively provided on the left and right sliding wing plates. For the purpose of achieving a freely falling drop hammer, the sliding rods should be polished, and there should be a fitting clearance within the allowable tolerance range with the coaxial sliding holes. If necessary, lubricant is applied to the inner side of the coaxial sliding holes. To ensure the safety of the test, simple and effective height limiting devices (32 and 33) are installed on the left sliding rod 31 and the right sliding rod 41 of the drop hammer device. Preferably, a thick rubber sleeve is used in combination with a clamp to lock and stop at a height of 10 m on the sliding rod to limit the excessive rise of the multi-stage electro-hydraulic telescopic rod. The right sliding rod 41 is equipped with an optoelectronic displacement sensor 9 for calculating the impact speed and acceleration of the test.)

[0051] The present invention also discloses a method for the impact performance test of an unmanned aerial vehicle body structure, including the following steps:

[0052] Step S1: Installation of the drop hammer device and adjustment of the impact loading test platform;

[0053] Step S2: Installation and test of the unmanned aerial vehicle under test;

[0054] Step S3: Test recording.

[0055] Specifically, for Step S1:

[0056] The drop hammer device is installed and fixed as required, and then the impact loading test platform is adjusted according to the requirements of the unmanned aircraft drop hammer test. The hammer impact head is selected according to the geometric requirements of the impact surface. According to the range of the drop hammer mass, the load-bearing device 7 is equipped with a standard counterweight 72, in the order of heavy first and light later. After installation, the locking nut 71 is tightened; the strong electromagnetic suction plate of the lifting top plate 6 is energized to attract the load-bearing plate 8 equipped with the load-bearing device 7. The drive motor is controlled by the PLC program to control the synchronous movement of the (4) multi-stage electric hydraulic telescopic rods to raise the lifting top plate 6 with the load-bearing plate 8 to the specified height (if the drop hammer test requires a specified drop hammer impact energy, in order to ensure test safety, the preferred test method is to increase the drop hammer counterweight and reduce the drop hammer height. According to E=mgh, the load-bearing device 7 is configured to the maximum allowable weight, and the multi-stage electric hydraulic telescopic rod is adjusted to raise and lower the first-stage telescopic rod with the largest outer diameter);

[0057] Fine-tune each electric hydraulic telescopic rod to keep the lifting top plate 6 level. The adjustment method is as follows: Divide the electric hydraulic telescopic rods into four groups: Group A (212, 222), Group B (232, 242), Group C (212, 242), and Group D (222, 232). The lifting amount of the electric hydraulic telescopic rods in each group is kept synchronous and consistent. Specifically:

[0058] Step S1.1: Linkage adjustment of Group A and Group B, when the bubble of the X-axis bubble level 51 is at the middle scale, the X-axis direction is parallel to the ground;

[0059] Step S1.2: Linkage adjustment of Groups C and D, when the bubble of the Y-axis bubble level 52 is at the middle scale and the Y-axis direction is parallel to the ground;

[0060] Step S1.3: Observe whether the bubble position in the X-axis direction is offset and repeat steps S1.1 to S1.3;

[0061] Step S1.4: until the bubbles of the X-axis bubble level 51 and the Y-axis bubble level 52 are both at the middle scale, the horizontal adjustment of the lifting top plate 6 is completed, and the ball head connection devices of the positioning mounting holes (213, 223, 233, 243) are locked.

[0062] Furthermore, calibrate the coaxiality between the impact hammer head 73 and the center of the impact force test platform 1. A simple and efficient preferred solution is to vertically mount a small laser source at the aforementioned screw hole 82, aiming the light at the force measurement center of the piezoelectric force sensor 13, i.e., coaxially. Otherwise, fine-tune the piezoelectric force sensor 13 and secure it.

[0063] More specifically, for step S2:

[0064] If the center of gravity of the UAV test article is not marked, use the UAV center of gravity weighing device to measure and project it onto the housing marking of the UAV. Place the UAV in the center of the impact force measuring test platform 1. Each folding push plate is paired with the aircraft tail wing, left wing, aircraft head, and right wing respectively. The folding push plate 121 is paired with the aircraft tail wing, the folding push plate 122 is paired with the left wing, the folding push plate 123 is paired with the aircraft head, and the folding push plate 124 is paired with the right wing. Expand the folding push plates (121, 122, 123, 124) appropriately up, down, left, and right according to the dimensions of the wings, tail wing, and aircraft height to ensure effective contact between each push plate and the UAV. Adjust the center position of the UAV. Convert the rotary motion of the AC servo motors (101, 102, 103, 104) into the linear motion of the folding push plates (121, 122, 123, 124) on the lead screw nut seats through the ball screws (111, 112, 113, 114) until the laser source hits the center of gravity projection point marked on the UAV housing. The centers of the UAV, impact hammer head, and impact force measuring test platform are on the same axis. At this time, remove the laser light source, install the required drop hammer impact head 73, adjust the photoelectric displacement sensor 9 to be level with the height of the UAV, and record the force value measured by the piezoelectric force sensor 13, which is the weight of the UAV.

[0065] Start the test. Cut off the power supply of the strong electromagnetic suction plate on the lifting top plate 6. The load flat plate 8 with the drop hammer loading device 7 falls freely and vertically impacts the UAV. To prevent the load flat plate 8 from colliding and rebounding, during the test, when the piezoelectric force sensor 13 detects the force value in real time, when the maximum peak value appears and starts to decrease significantly, it is judged that the drop hammer device will produce a collision and rebound. Predict the inflection point of the real-time force value curve through the computer program. At the inflection point of the curve decline, apply a large current to the strong electromagnetic suction plate on the lifting top plate 6 to instantaneously suck the load flat plate 8 and slowly lift it to avoid the influence of secondary impact.

[0066] Furthermore, for step S3:

[0067] Use a high-speed camera to record the failure mode of the UAV during the process of the hammer head impacting the UAV. Calculate the speed and acceleration at the drop hammer impact point through the photoelectric displacement sensor 9, the load value of the loading device 7, the maximum impact force value measured by the piezoelectric force sensor 13, and the parameters of the deformation of the UAV.

[0068] It is worth mentioning that the technical features such as the UAV test article involved in this invention patent application should be regarded as the prior art. The specific structures, working principles, and possible control methods and spatial layout methods of these technical features can be selected conventionally in this field and should not be regarded as the invention points of this invention patent. This invention patent will not be further specifically elaborated.

[0069] For those skilled in the art, it is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A drop hammer device for the impact performance test of an unmanned aerial vehicle body structure, characterized in that It includes an impact force measurement test platform, an impact loading test platform and a multi-stage electro-hydraulic telescopic rod. The impact force measurement test platform is located above the impact loading test platform, and the multi-stage electro-hydraulic telescopic rod is installed between the impact force measurement test platform and the impact loading test platform, where: The impact force measurement test platform is provided with an X-axis slide rail groove and a Y-axis slide rail groove. The X-axis slide rail groove and the Y-axis slide rail groove are vertically intersected at the geometric center of the impact force measurement test platform. A piezoelectric force sensor is fixedly installed in the space at the intersection. The force-receiving surface of the piezoelectric force sensor is flush with the impact force measurement test platform and the force center coincides with the geometric center. The X-axis slide rail groove is internally provided with an upper ball screw and a lower ball screw, which are respectively controlled to move by an upper-side AC servo motor and a lower-side AC servo motor outside in cooperation with corresponding couplings; the Y-axis slide rail groove is internally provided with a left ball screw and a right ball screw, which are respectively controlled to move by a left-side AC servo motor and a right-side AC servo motor outside the platform in cooperation with corresponding couplings; the upper ball screw, the lower ball screw, the left ball screw and the right ball screw are all vertically installed with folding push plates; The impact loading test platform includes a lifting top plate and a load-carrying flat plate. A strong electromagnetic suction plate is built in the lower plane of the lifting top plate. When the coil in the strong electromagnetic suction plate is energized, it generates a strong magnetic force to adsorb the movable load-carrying flat plate, and positioning mounting holes for installing the multi-stage electro-hydraulic telescopic rod are provided at the four top corners of the lower plane; a through square hole is provided at the center of the lifting top plate for configuring the load-carrying device of the load-carrying flat plate. The load-carrying device includes a locking nut, a standard counterweight block and a drop hammer impact head.

2. The drop hammer device for the impact performance test of the UAV airframe structure according to claim 1, characterized in that, A pouring hole for fixing the left slide bar is provided on the left side of the left-side AC servo motor, and a pouring hole for fixing the right slide bar is provided on the right side of the right-side AC servo motor.

3. The drop hammer device for the impact performance test of the UAV airframe structure according to claim 2, wherein The size of the lifting top plate is the same as that of the impact force measurement test platform, and they are on the same axis of the geometric center; The multi-stage electro-hydraulic telescopic rod is provided with a driving motor for controlling the synchronous lifting of the multi-stage electro-hydraulic telescopic rod; X-axis bubble levels and Y-axis bubble levels are installed on both the upper and lower planes of the lifting top plate. By observing the position of the bubbles, the telescopic amount of each electro-hydraulic telescopic rod is finely adjusted to ensure that the lifting top plate is in a horizontal state; A screw rod is vertically welded at the geometric center of the load-carrying flat plate for positioning and assembling the standard counterweight block. The single body of the standard counterweight block is divided into four grades. The stacked standard counterweight blocks are fastened to the load-carrying flat plate through locking nuts. According to different drop hammer impact contact surfaces, the drop hammer impact heads are divided into three categories: First, a curved impact contact surface, a hemispherical hammer head; Second, a circular contact surface, a cylindrical hammer head; Third, a polygonal contact surface, a frustum-shaped hammer head; The handle of the drop hammer impact head is tapped with threads and is matched with the screw hole at the bottom center of the load-carrying flat plate; The left slide bar and the right slide bar are symmetrically cast and fixed on the corresponding pouring holes of the impact force measurement test platform. The lifting top plate and the load-carrying flat plate are both welded with left and right symmetric sliding wing plates, and coaxial sliding holes for installing the left slide bar and the right slide bar are respectively provided on the left and right sliding wing plates.

4. A method for the impact performance test of an unmanned aerial vehicle airframe structure, which is applied to the drop hammer device for the impact performance test of an unmanned aerial vehicle airframe structure described in any one of claims 1-3, characterized in that, It includes the following steps: Step S1: Installation of the drop hammer device and adjustment of the impact loading test platform; Step S2: Installation and test of the UAV test article; Step S3: Test record.

5. A method for the impact performance test of an unmanned aerial vehicle airframe structure according to claim 4, characterized in that, For step S1: The drop hammer device is installed and fixed as required, and then the impact loading test platform is adjusted according to the requirements of the UAV drop hammer test. The hammer impact head is selected according to the geometric requirements of the impact surface. According to the range requirements of the drop hammer mass, the load-bearing device is equipped with standard counterweights in the order of heavy weights first and light weights later. After installation, tighten the lock nut; The powerful electromagnetic suction plate of the lifting top plate is energized to attract the load-bearing plate equipped with the load-bearing device. The drive motor is controlled by the PLC program to control the synchronous movement of the multi-stage electric hydraulic telescopic rod to raise the lifting top plate with the load-bearing plate to the specified height. Fine-tune each electric hydraulic telescopic rod to keep the lifting top plate level. The adjustment method is as follows: Divide the electric hydraulic telescopic rods into four groups: Group A, Group B, Group C, and Group D. The lifting amount of the electric hydraulic telescopic rods in each group is kept synchronous and consistent. Specifically: Step S1.1: Linkage adjustment of Group A and Group B. When the bubble of the X-axis bubble level is at the middle scale, the X-axis direction is parallel to the ground. Step S1.2: Linkingly adjust Groups C and D until the bubble of the Y-axis bubble level 5 is at the middle scale and the Y-axis is parallel to the ground; Step S1.3: Observe whether the bubble position in the X-axis direction is offset and repeat steps S1.1 to S1.3; Step S1.4: When the bubbles on the X-axis bubble level and the Y-axis bubble level are both at the middle scale, the level adjustment of the lifting top plate is completed, and the ball head connection device of the positioning mounting hole is locked.

6. A method for the impact performance test of an unmanned aerial vehicle airframe structure according to claim 5, characterized in that, For step S2: If the drone test piece does not have a marked center of gravity, use the drone center of gravity weighing device to measure it and project it onto the casing mark. Place the drone in the center of the impact force test platform. Pair the folding push plates with the tail, left wing, head, and right wing of the aircraft respectively. Expand the folding push plates up and down and left and right according to the size of the wings, tail, and aircraft height to ensure that each push plate is in effective contact with the drone. Adjust the center position of the drone and convert the rotary motion of the AC servo motor into the linear motion of the folding push plate on the screw nut seat through the ball screw until the laser source hits the center of gravity projection point marked on the drone casing. The centers of the drone, impact hammer head, and impact force test platform are on the same axis. At this time, remove the laser light source, install the required drop hammer impact head, adjust the photoelectric displacement sensor to be flush with the drone height, and record the force value measured by the piezoelectric force sensor as the weight of the drone. At the beginning of the test, the powerful electromagnetic suction plate of the lifting top plate is powered off, and the load-bearing plate with a drop hammer load-bearing device falls freely, vertically impacting the drone. To prevent the load-bearing plate from colliding and rebounding, during the test, the piezoelectric force sensor detects the force value in real time. When the maximum peak value appears and begins to decrease significantly, it is judged that the drop hammer device will produce a collision rebound. The inflection point of the real-time force value curve is predicted by a computer program. At the inflection point of the descending curve, a large current is passed through the powerful electromagnetic suction plate of the lifting top plate, which instantly absorbs the load-bearing plate and slowly recovers it to avoid secondary impact.

7. A method for the impact performance test of an unmanned aerial vehicle body structure according to claim 6, characterized in that, For step S3: A high-speed camera was used to record the failure mode of the drone during the hammer impact process. The velocity and acceleration at the impact point of the falling hammer were measured by a photoelectric displacement sensor. The load value of the load-bearing device and the piezoelectric force sensor were used to measure the maximum impact force and the deformation parameters of the drone.

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