A tension measuring device and method for an amphibious unmanned aerial vehicle (UAV)

Abstract

This invention discloses a tension measurement device and method for an amphibious unmanned aerial vehicle (UAV). The device comprises a metal frame, a motor, a gear and rack transmission mechanism, a rotor blade interference device, a tension measurement platform, strain gauges, and a base with a thrust rod, among other simple components, to simulate the force exerted on the aircraft under different attitudes. The aircraft is fixed to the test platform, and the movement of the gear and rack is controlled to raise or lower the platform, thereby obtaining strain data under different attitudes. The test platform uses four strain gauges to express the torques in the roll, yaw, and pitch directions of the aircraft through strain. A thrust rod under the base adjusts the height of the platform. This platform can be placed in water to measure the tension of the amphibious UAV at the water boundary layer. Furthermore, the rotor blade interference device sprays different water streams onto the blades to measure the aerodynamic forces of the blades when the aircraft enters or exits the water at different angles.

Description

Technical Field

[0001] This invention relates to the field of amphibious unmanned aerial vehicle (UAV) technology, specifically to the implementation of a simple and accurate tensile force measurement technology for amphibious UAVs. Background Technology

[0002] Amphibious unmanned aerial vehicles (UAVs) are drones capable of both air and water flight, organically combining the advantages of aircraft and submarines. In UAV research, amphibious UAVs are an important research direction, offering greater possibilities for applications such as maritime rescue and reconnaissance. The key technology for amphibious UAVs lies in their ability to operate normally in both air and water, while maintaining stable switching between these modes. Currently, existing amphibious UAVs lack effective research on water entry and exit schemes, and lack solutions that can balance air and underwater performance. Due to the physical differences between the two working media, the rotor thrust and the torque of the entire aircraft in three directions will be completely different, especially in the liquid-gas boundary layer. Because it is impossible to accurately measure the forces acting on the entire UAV underwater and in the boundary layer, attitude control after exiting the water becomes a major challenge for the stable operation of amphibious aircraft. Summary of the Invention

[0003] In view of the complexity of existing amphibious unmanned aerial vehicles (UAVs), the purpose of this invention is to provide an efficient and accurate thrust measurement technology for amphibious UAVs. This technology can measure the rotor thrust, pitch, yaw, and roll torque of the UAV while it is underwater and about to emerge from the water, thereby achieving stable control of the UAV from underwater to air and improving the operability of amphibious UAVs.

[0004] This application achieves the above effects through the following technical solutions:

[0005] A tension measuring device for an amphibious unmanned aerial vehicle (UAV) includes a motor, two pairs of gear and rack meshing mechanisms controlling rotation in different directions, a test bench with strain gauges and a base with an attached thrust rod, a metal frame, and a rotor blade interference device. The rotor blade interference device is mounted on the metal frame, the middle of the metal frame is the rotor test bench, the rotor blade interference device is aligned with the rotor test bench, and the gear and rack meshing mechanisms are mounted on the test bench.

[0006] Furthermore, the output shaft of the external motor is connected to two gears via bearings and is positioned on the outside of the frame by fastening screws.

[0007] Furthermore, the gear and rack meshing transmission device includes a gear, a rack, a rectangular frame that fixes the two racks, and a device that allows the frame to move up and down.

[0008] Two racks are fixed on opposite sides of the test stand. The racks are long and narrow, with their ends tightly meshed with two gears. The racks are moved by the rotation of the gears.

[0009] The rack is fixed to both sides of the rectangular frame by bolts, which drives the rectangular frame to rotate in two different directions. The rectangular frame is tilted by the rack in two different horizontal and vertical directions, thereby adjusting the test platform to different positions.

[0010] The device for vertical movement consists of a fastening screw, a connecting nut, and a slender connecting rod. The height of the rectangular frame can be adjusted vertically by loosening the screw.

[0011] Furthermore, the test platform with strain gauges and the base with the attached thrust rod are adjusted by the rectangular frame to change the attitude angle of the test platform. In addition to the support rod, there is a thrust rod connected to the test platform by fastening screws. The height of the platform can be adjusted by adjusting the height of the thrust rod in conjunction with the rectangular frame and the device that allows the frame to move up and down. The strain gauges are installed under the fixed platform, with four strain gauges arranged at the center of the four sides of the test platform and connected to the frame with the rack below. The experimental data obtained are expressed by the strain gauges arranged in the four directions under the test platform.

[0012] Furthermore, the metal frame is composed of rectangular bodies made of metal rods, with rods on both sides that allow the gear and rack mechanism to move up and down.

[0013] Furthermore, the rotor blade interference device is supported by brackets arranged on both sides of the frame, with three nozzles arranged on each side. The three nozzles are connected by a shaft, and the entire structure forms a compound hinge. Each nozzle can rotate on a hinge to adjust the angle of water spray. Each nozzle can be replaced with a different nozzle to simulate different water flow conditions.

[0014] This application also provides a method for measuring the tensile force of an amphibious unmanned aerial vehicle, the method comprising:

[0015] Step 1: Install the rotor and secure the entire drone to the test stand with fastening screws. Since this testing device can adjust the drone's attitude by adjusting the test stand's attitude, there is no need to install an automatic tilter. Simply place the rotor disk horizontally with the test stand and then install a variable collective pitch device to increase the rotor blade thrust.

[0016] Step 2: Load interference. By adjusting the rotation angle and height of the entire test stand, determine the environment in which the aircraft is located. Then, activate the rotor blade interference device and adjust different spray angles and spray patterns to simulate the impact of water flow disturbance on the aircraft's power under different environments.

[0017] Step 3: By reading the data transmitted by the strain gauges, the strain force is detected, thereby analyzing the dynamics of the body under different postures and environments.

[0018] Furthermore, step 2 includes the following modes:

[0019] Mode 1: Place the entire measuring platform on the ground, enclose the surrounding area with glass, and fill it with water until it covers the fixed platform. When testing the aerodynamic parameters of the drone on the water surface, the motor simultaneously adjusts the rotation of the gear and the corresponding gear in the other direction, thereby driving the racks in two different directions to rotate, and then adjusting the attitude angle of the entire testing platform to test the aerodynamic parameters of the drone in different attitudes on the water surface.

[0020] Furthermore, step 2 includes the following modes:

[0021] Mode 2, when testing the aerodynamic parameters of the aircraft in water or about to emerge from the water, controls the height of the entire test platform to meet the experimental requirements by adjusting the height of the thrust rod and the height of the adjusting nuts connecting the rectangular frames on the left and right sides of the frame.

[0022] Furthermore, step 2 includes the following modes:

[0023] Mode 3, Water Ingress / Exit Simulation: When the rotor blades are exposed on the water surface, the rotor blade interference device is activated to spray water onto the blades to simulate the aerodynamic impact of water splashes on the entire aircraft under different attitudes and altitudes.

[0024] Alternatively, the spray angle of the nozzles can be adjusted so that both pairs of rotor blade interference devices spray water evenly onto the blades in the same direction to simulate the impact of blades under stable laminar flow; or the water flow can be sprayed unevenly onto the rotor tips, blades, and hub to simulate the aerodynamic effects of unstable turbulence or vortices on the entire aircraft. When the drone is underwater, with both the blades and the fuselage submerged, the rotor blade interference devices can be activated to simulate the dynamic analysis of underwater submersion modes under still water conditions, considering factors such as laminar flow, vortices, and bubbles. Activating only one rotor blade interference device can simulate the impact of incoming flow on the entire aircraft when the drone is submerged at a constant speed underwater. Alternatively, activating both rotor blade interference devices can create waves and vortices to simulate the impact of harsh underwater environments or waves from passing large ships on the underwater drone. Different nozzles can also be replaced to simulate the impact on the overall diving efficiency of the aircraft when underwater bubbles adhere to the propeller blades or the fuselage.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The present invention provides a simple and efficient tension measurement technology for an amphibious unmanned aerial vehicle (UAV). It adopts a new measurement mode in which strain gauges are placed directly under a fixed platform. The attitude of the fixed platform can be controlled by the gear and rack meshing mechanism on both sides and the thrust rod under the fixed platform, thereby measuring the torque and propeller thrust experienced by the aircraft when it pitches, rolls, and yaws at different altitudes, i.e., underwater positions.

[0027] 2. The test stand described in this invention is surrounded by a metal frame, which can be used to place the device on the ground to test the dynamic parameters of a conventional rotorcraft under various motion modes, or to cover the surrounding area with glass to simulate the blade thrust problem in a still water environment. It can also be used in conjunction with the aforementioned gear and rack meshing mechanism and thrust rod to measure the aerodynamic forces of the aircraft in different media and boundary layers.

[0028] 3. The test stand described in this invention, when not covered by glass, can be placed directly in a natural aquatic environment or an artificial still water environment. Due to the rotor blade interference devices on both sides of the test stand frame, it can simulate various complex underwater environments such as bubbles, vortices, turbulence, and unstable laminar flow. This allows for a more in-depth study of aircraft attitude control experiments under multiple environments. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of this test bench;

[0030] In the diagram: 1. External main frame, 2. Glass platform, 3. Rotor test stand, 4. Rotor blade interference device;

[0031] Figure 2 This is a schematic diagram of the main structure of the test bench;

[0032] In the figure: 5. Adjusting nut, 6. Motor-driven gear, 7. Fixed platform, 8. Rectangular frame, 9. Rack and pinion mechanism, 10. Strain gauge, 11. Cross-shaped support base, 12. Thrust rod, 13. Support rod;

[0033] Figure 3 This is a schematic diagram of a rotor blade interference device.

[0034] In the figure, 14 is the rotating shaft fixing hole, 15 is the flow valve, and 16 is the nozzle. Detailed Implementation

[0035] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings in the embodiments of the present invention.

[0036] Example 1

[0037] As attached Figure 1As shown, a tension and torque measuring device for an amphibious rotary-wing unmanned aerial vehicle (UAV) is provided. The measuring device comprises a drive motor, a main metal frame, a gear and rack meshing transmission device, a cross-shaped support rod and an auxiliary thrust rod, two pairs of rotor blade interference devices, a main test station and four auxiliary strain gauges for measuring tension.

[0038] Furthermore, the two drive motors are connected via bearings, and nuts are fixed to the gears of the two drive gear rack mechanisms in two different directions of rotation, thereby driving the rack to rotate;

[0039] Furthermore, the rotation of the rack drives the rectangular frame, with two racks welded to its left and right ends in different directions, to rotate, thereby causing the fixed platform to rotate and changing the attitude position of the platform, i.e., the aircraft's attitude. Two pairs of fixed-position surfaces are perpendicular to each other using racks. One pair adjusts the tilt mode of the lateral horizontal plane, causing the aircraft to tilt left and right, the purpose of which is to test the aircraft's attitude dynamics at different roll angles; the other pair adjusts the tilt mode of the longitudinal horizontal plane, causing the aircraft to tilt forward and backward, the purpose of which is to test the aircraft's attitude dynamics at different pitch angles. The two pairs of rack and pinion mechanisms work together to simulate different aircraft attitudes.

[0040] Furthermore, the outermost part of the main test stand is welded from twelve metal rods. Inside the frames on both sides, there is a slender rod that allows the aforementioned gear and rack meshing mechanism to move up and down. To use, the platform is moved to the desired horizontal position, and the fastening screws are tightened to secure it. Adjustments are made by loosening the screws. Glass can be added around the frame to create a closed structure, which can simulate rotor dynamics in static water and facilitate observation of the aircraft's attitude. Alternatively, the entire frame can be placed in a water environment to study the impact of water flow, bubbles, and vortices on the blades in a realistic water environment, thereby investigating the problems arising from the coupling of blade aerodynamics and the water medium in complex water conditions.

[0041] Furthermore, the main test stand has four strain gauges distributed around its four sides. Information from these strain gauge sensors allows for the measurement of strain in each direction at different attitudes of the aircraft. This information is then used to calculate the forces acting in each direction, enabling the measurement of propeller thrust, pitch, roll, and yaw moments at various attitudes. Additionally, a thrust rod is connected to the main test stand. Adjusting the height of the thrust rod allows for the adjustment of the fixed platform's height, enabling the aircraft's entry and exit attitudes to be tailored to different water environments.

[0042] Furthermore, two rows of rotor blade interference devices are located on both sides of the main test stand. The arrangement consists of three evenly spaced nozzles on each of the left and right sides in the direction of flight. These three nozzles are connected to the same plane via a common shaft. Each nozzle controls the water output through a valve, or the spray angle can be controlled via a hinged shaft. The purpose of this rotor blade interference device is to simulate the aerodynamic problems of rotors caused by different types of water flow impacting the blades in a natural aquatic environment. The three nozzles on one side can be adjusted to uniformly impact the blades with water flow, simulating rotor thrust in underwater laminar flow conditions. Alternatively, they can be adjusted to simultaneously impact the fuselage and blades with three different nozzle angles, simulating the coupling mode of the blades and fuselage when the aircraft is impacted by turbulence at the water-air boundary layer during entry and exit from water. When all six nozzles simultaneously spray water at the same horizontal height, the impact of underwater vortices on the blades can be simulated. Different nozzles can also be replaced to simulate bubble-like, unstable laminar flow environments.

[0043] A tension and torque measuring device for an amphibious rotary-wing unmanned aerial vehicle (UAV) includes a drive motor, a main metal frame, a gear and rack meshing transmission device, a cross-shaped support rod and an auxiliary thrust rod, two pairs of rotor blade interference devices, a main test station, and four auxiliary strain gauges for measuring tension.

[0044] Place the entire measuring platform on the ground, enclose it with glass, and fill it with water until it covers the fixed platform surface. When testing the aerodynamic parameters of the drone on the water surface, the rotation of gear 6 and its corresponding gear in the other direction can be adjusted simultaneously by the motor, thereby driving the two racks in different directions to rotate, and thus adjusting the attitude angle of the entire testing platform. This allows for the testing of the aerodynamic parameters of the drone in different attitudes on the water surface.

[0045] Furthermore, when testing the aerodynamic parameters of the aircraft in water or about to emerge from the water, the height of the entire test stand can be controlled by adjusting the height of the thrust rod and the height of the adjusting nuts connecting the rectangular frames on the left and right sides of the frame, thereby meeting the experimental requirements.

[0046] Furthermore, when the drone is on or in water, with the rotor blades exposed to the water surface, the rotor blade interference device can be activated to spray water onto the blades. This simulates the aerodynamic impact of water splashes on the drone's entire body at different attitudes and altitudes. Simultaneously, the spray angle can be adjusted. The two pairs of rotor blade interference devices can either spray water evenly onto the blades in one direction to mimic the blade impact problem under stable laminar flow, or spray water unevenly onto the rotor tip, blades, and hub to simulate the aerodynamic impact of water splashes caused by unstable turbulence or water surface eddies on the entire drone.

[0047] When a drone is underwater or in the water-air boundary layer, with both the propellers and the fuselage submerged, a rotor blade interference device can be activated to simulate the dynamics of underwater submersion under still water conditions, considering factors such as laminar flow, vortices, and bubbles. Activating only one rotor blade interference device can simulate the impact of incoming flow on the entire drone during uniform underwater submersion. Alternatively, activating both rotor blade interference devices can create waves and vortices to simulate the impact of harsh underwater environments or waves generated by passing large ships on the underwater drone. Different nozzles can also be used to simulate the impact of underwater bubbles adhering to the propellers or fuselage on the overall submersion efficiency.

[0048] Example 2

[0049] This application also provides a method for measuring the tensile force of an amphibious unmanned aerial vehicle, the method comprising:

[0050] Step 1: Install the rotor and secure the entire drone to the test stand with fastening screws. Since this testing device can adjust the drone's attitude by adjusting the test stand's attitude, there is no need to install an automatic tilter. Simply place the rotor disk horizontally with the test stand and then install a variable collective pitch device to increase the rotor blade thrust.

[0051] Step 2: Load interference. By adjusting the rotation angle and height of the entire test stand, determine the environment in which the aircraft is located. Then, activate the rotor blade interference device and adjust different spray angles and spray patterns to simulate the impact of water flow disturbance on the aircraft's power under different environments.

[0052] Step 3: By reading the data transmitted by the strain gauges, the strain force is detected, thereby analyzing the dynamics of the body under different postures and environments.

[0053] Furthermore, step 2 includes the following modes:

[0054] Mode 1: Place the entire measuring platform on the ground, enclose the surrounding area with glass, and fill it with water until it covers the fixed platform. When testing the aerodynamic parameters of the drone on the water surface, the motor simultaneously adjusts the rotation of the gear and the corresponding gear in the other direction, thereby driving the racks in two different directions to rotate, and then adjusting the attitude angle of the entire testing platform to test the aerodynamic parameters of the drone in different attitudes on the water surface.

[0055] Furthermore, step 2 includes the following modes:

[0056] Mode 2, when testing the aerodynamic parameters of the aircraft in water or about to emerge from the water, controls the height of the entire test platform to meet the experimental requirements by adjusting the height of the thrust rod and the height of the adjusting nuts connecting the rectangular frames on the left and right sides of the frame.

[0057] Furthermore, step 2 includes the following modes:

[0058] Mode 3, Water Ingress / Exit Simulation: When the rotor blades are exposed on the water surface, the rotor blade interference device is activated to spray water onto the blades to simulate the aerodynamic impact of water splashes on the entire aircraft under different attitudes and altitudes.

[0059] Alternatively, the spray angle of the nozzles can be adjusted so that both pairs of rotor blade interference devices spray water evenly onto the blades in the same direction to simulate the impact of blades under stable laminar flow; or the water flow can be sprayed unevenly onto the rotor tips, blades, and hub to simulate the aerodynamic effects of unstable turbulence or vortices on the entire aircraft. When the drone is underwater, with both the blades and the fuselage submerged, the rotor blade interference devices can be activated to simulate the dynamic analysis of underwater submersion modes under still water conditions, considering factors such as laminar flow, vortices, and bubbles. Activating only one rotor blade interference device can simulate the impact of incoming flow on the entire aircraft when the drone is submerged at a constant speed underwater. Alternatively, activating both rotor blade interference devices can create waves and vortices to simulate the impact of harsh underwater environments or waves from passing large ships on the underwater drone. Different nozzles can also be replaced to simulate the impact on the overall diving efficiency of the aircraft when underwater bubbles adhere to the propeller blades or the fuselage.

Claims

1. A tensile force measuring device for an amphibious unmanned aerial vehicle, characterized in that: The measuring device includes a motor, two pairs of gear rack meshing mechanisms that control rotation in different directions, a test bench with strain gauges and a base with an attached thrust rod, a metal frame, and a rotor blade interference device; wherein, the rotor blade interference device is mounted on the metal frame, the middle of the metal frame is the rotor test bench, the rotor blade interference device is aligned with the rotor test bench, and the gear rack meshing mechanism is mounted on the test bench. The output shaft of the motor is connected to two gears via bearings and is positioned on the outside of the frame by fastening screws. The gear and rack meshing transmission device includes a gear, a rack, a rectangular frame that fixes the two racks, and a device that allows the frame to move up and down. Two racks are fixed on opposite sides of the test stand. The racks are long and narrow, with their ends tightly meshed with two gears. The racks are moved by the rotation of the gears. The rack is fixed to both sides of the rectangular frame by bolts, which drives the rectangular frame to rotate in two different directions. The rectangular frame is tilted by the rack in two different horizontal and vertical directions, thereby adjusting the test platform to different positions. The device for vertical movement comprises a fastening screw, a connecting nut, and a slender connecting rod. The height of the rectangular frame can be adjusted vertically by loosening the screw. The rotor blade interference device is supported by brackets arranged on both sides of the frame, with three nozzles arranged on each side. The three nozzles are connected by a shaft, and the entire structure forms a compound hinge. Each nozzle rotates on a hinge to adjust the angle of water spray. Each nozzle can be replaced with a different nozzle to simulate different water flow conditions.

2. The tensile force measuring device for an amphibious unmanned aerial vehicle according to claim 1, characterized in that: The test bench with strain gauges and the base of the attached thrust rod are adjusted by the rectangular frame to change the attitude angle of the test bench. In addition to the support rod, there is a thrust rod connected to the test bench by fastening screws. The height of the thrust rod is adjusted to adjust the height of the platform together with the rectangular frame and the device that allows the frame to move up and down. The strain gauges are installed under the fixed platform, with four strain gauges arranged at the center of the four sides of the test bench and connected to the frame with the rack below. The experimental data obtained are expressed by the strain gauges arranged in four positions under the test bench.

3. The tensile force measuring device for an amphibious unmanned aerial vehicle according to claim 1, characterized in that: The metal frame consists of a rectangular body made of metal rods, with rods on both sides that allow the gear and rack mechanism to move up and down.

4. A method for measuring the tensile force of an amphibious unmanned aerial vehicle (UAV), characterized in that: The method is implemented based on the measuring device as described in claim 1, and the method comprises: Step 1: Install the rotor. Secure the entire drone to the test stand with fastening screws. Place the rotor disk horizontally on the test stand and install a variable collective pitch device to increase the thrust of the rotor blades. Step 2: Load interference. By adjusting the rotation angle and height of the entire test stand, determine the environment in which the aircraft is located. Then, turn on the rotor blade interference device and adjust different spray angles and spray patterns to simulate the impact of water flow disturbance on the aircraft's power under different environments. Step 3: By reading the data transmitted by the strain gauges, the strain force is detected, thereby analyzing the dynamics of the body under different postures and environments.

5. The method for measuring the tensile force of an amphibious unmanned aerial vehicle according to claim 4, characterized in that: Step 2 includes the following modes: Mode 1: Place the entire measuring platform on the ground, enclose the surrounding area with glass, and fill it with water until it covers the fixed platform. When testing the aerodynamic parameters of the drone on the water surface, the motor simultaneously adjusts the rotation of the gear and the corresponding gear in the other direction, thereby driving the racks in two different directions to rotate, and then adjusting the attitude angle of the entire testing platform to test the aerodynamic parameters of the drone in different attitudes on the water surface.

6. The method for measuring the tensile force of an amphibious unmanned aerial vehicle according to claim 4, characterized in that: Step 2 includes the following modes: Mode 2, when testing the aerodynamic parameters of the aircraft in water or about to emerge from the water, controls the height of the entire test platform to meet the experimental requirements by adjusting the height of the thrust rod and the height of the adjusting nuts connecting the rectangular frames on the left and right sides of the frame.

7. The method for measuring the tensile force of an amphibious unmanned aerial vehicle according to claim 4, characterized in that: Step 2 includes the following modes: Mode 3, Water Ingress / Exit Simulation: When the rotor blades are exposed on the water surface, the rotor blade interference device is activated to spray water onto the blades to simulate the aerodynamic impact of water splashes on the entire aircraft under different attitudes and altitudes. Alternatively, the angle of the nozzles can be adjusted so that the two pairs of rotor blade interference devices spray water evenly onto the blades in the same direction to simulate the blade impact under stable laminar flow; or the water flow can be sprayed unevenly onto the rotor tip, blades and hub to simulate the aerodynamic effect of unstable turbulence or water vortex on the entire aircraft. When the drone is underwater, with both the propellers and the fuselage submerged, the rotor blade interference device is activated to simulate the dynamic analysis of underwater submersion modes under still water conditions, considering factors such as laminar flow, vortices, and bubbles. Activating only one side of the rotor blade interference device simulates the impact of incoming currents on the entire fuselage when the drone is submerged at a constant speed underwater. Alternatively, activating both sides of the rotor blade interference device can create waves and vortices to simulate the impact of harsh underwater environments or waves generated by large ships passing by on the underwater drone. Alternatively, different nozzles can be used to simulate the impact on the overall diving efficiency of the aircraft when underwater bubbles adhere to the propeller blades or the fuselage.

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