Unmanned aerial vehicle propeller power and acoustic performance test system

Abstract

The invention provides an unmanned aerial vehicle propeller power and acoustic performance test system, and the system comprises a vertical column, the bottom of which is fixed on the ground through a supporting structure; the first cover closing type switching disc is arranged at the top end of the stand column; the six-axis torque sensor is arranged at the top end of the first cover closing type transfer disc; the second closed cover type adapter disc is arranged at the top end of the six-axis torque sensor, and an accommodating cavity is formed in the second closed cover type adapter disc; the magnetic encoder is fixedly mounted in the accommodating cavity; the motor is arranged at the top end of the second cover closing type transfer disc; the propeller is arranged on the motor shaft in a sleeving manner; the fairing is arranged outside the stand column in a covering mode; the electronic speed regulator is used for controlling the motor to rotate when the starting instruction is received; and the analysis module is used for acquiring force data and torque data output by the six-axis torque sensor and sound pressure data detected by the microphone, and obtaining a time domain graph, a frequency domain graph, a data table and a curve. The beneficial effects of the invention are that the device can more accurately measure and analyze the force, the torque and the radiated sound pressure of the propeller.

Description

Technical Field

[0001] The present invention relates to the technical field of aerodynamic propeller testing, and in particular to a propeller power and acoustic performance testing system for an unmanned aerial vehicle. Background Art

[0002] With the rapid development of the low-altitude economy around the world, developing UAVs with high power performance and low noise radiation is an important direction for countries to seek technological breakthroughs in this field. Propellers, as an important part of the UAV aerodynamic system, are key structures that affect the overall performance and noise radiation level of UAVs. Improving the propeller lift-to-drag ratio and reducing the noise of propellers and wingtips are the main goals of UAV research and development and manufacturing. To achieve this goal, we first need a suitable test platform to conduct a large number of propeller power performance and acoustic performance tests.

[0003] In the experimental research on the acoustic performance of the aerodynamic system of UAV, it is necessary to have a test bench with airflow conditions without velocity gradient and the ability to easily adjust the propeller speed to measure the propeller performance parameters. The propeller test bench should be able to change the speed of the brushless DC motor to make the propeller rotate at different fixed speeds to measure and quantitatively evaluate the lift and other performance parameters of the propeller under test. In this process, the thrust and torque of the propeller at different speeds are measured by a six-axis torque sensor to evaluate the propeller force efficiency performance. By arranging microphones in a fully anechoic environment, the acoustic response radiated by the propeller under test at different speeds is measured to analyze the propeller's acoustic radiation level.

[0004] Currently, most UAV propeller power test systems do not measure the acoustic radiation generated by the propeller, which significantly creates a gap in the comprehensive optimization design of the propeller and reduces the efficiency of the overall performance verification of the UAV power system.

[0005] Chinese patent publication number CN113734465A discloses a test bench for measuring the aerodynamic performance of a variable pitch propeller using multiple sensors respectively arranged on tension and torque beams. This design satisfies the simultaneous measurement of force, torque and sound, but lacks a mechanism for measuring propeller speed, and thus cannot examine the effect of propeller speed on lift and sound radiation changes. In addition, the design of this invention is not suitable for propeller acoustic performance testing because the high table top will block the smooth flow of downwash airflow and generate additional interference noise. Summary of the invention

[0006] The technical problem to be solved by the present invention is to more accurately measure and analyze the force, torque and radiated sound pressure of the propeller. In order to overcome the defects of the above-mentioned prior art (or related technology), the present invention provides a UAV propeller power and acoustic performance test system.

[0007] The present invention provides a UAV propeller power and acoustic performance testing system, comprising:

[0008] A column, the bottom of which is fixed to the ground through a supporting structure;

[0009] A first cover-type adapter plate is disposed at the top of the column, and the bottom end of the first cover-type adapter plate is fixedly connected to the top of the column;

[0010] a six-axis torque sensor, disposed on the top of the first cover-type adapter plate and fixedly connected to the top of the first cover-type adapter plate;

[0011] a second cover-type adapter plate, disposed at the top of the six-axis torque sensor, wherein the bottom of the second cover-type adapter plate is fixedly connected to the six-axis torque sensor, and an accommodating cavity is provided inside the second cover-type adapter plate;

[0012] A magnetic encoder, fixedly installed in the accommodating cavity;

[0013] a motor, disposed at the top of the second cover-type adapter plate and fixedly connected to the top of the second cover-type adapter plate, and a motor shaft of the motor is located at an end facing away from the column;

[0014] A propeller, sleeved on the motor shaft and fixedly connected to the motor shaft;

[0015] A fairing, which is arranged outside the column and covers the first cover-type adapter plate, the six-axis torque sensor, the second cover-type adapter plate and the motor;

[0016] an electronic speed regulator, connected to the motor, and configured to control the motor to rotate according to the start command input from the outside to drive the propeller to rotate;

[0017] An analysis module is respectively connected to the six-axis torque sensor and an external microphone, and is used to obtain force data, torque data output by the six-axis torque sensor and sound pressure data detected by the microphone, and obtain time domain graphs and frequency domain graphs based on the force data and the torque data to assist in evaluating the dynamic performance of the propeller, and obtain numerical tables and curves based on the sound pressure data to assist in evaluating the acoustic performance of the propeller.

[0018] Compared with the prior art, the present application discloses a system for testing the propeller power and acoustic performance of a UAV, which has the following advantages: in the present application, from the perspective of mechanical structure, the design of the first cover-type adapter plate, the second cover-type adapter plate and the fairing is utilized to make the airflow smooth and reduce the motor noise, so that the radiated sound field of the propeller is less disturbed, facilitating more accurate measurement and analysis of the propeller force, torque and radiated sound pressure, and the magnetic encoder in the present application can realize closed-loop speed control, and the electronic speed regulator can control the propeller to operate at any speed condition, allowing the force / torque and radiated sound pressure level of different speed ranges to be measured on a propeller with controllable speed, thereby obtaining the overall power and acoustic performance of the propeller.

[0019] In a possible embodiment, the support structure includes a base plate and a plurality of triangular brackets, the bottom end of the column is fixed to the top end of the base plate, one right-angled side of each triangular bracket is fixedly connected to the top end of the base plate, and the other right-angled side of each triangular bracket is fixedly connected to the outer peripheral wall of the column.

[0020] Compared with the prior art, the above technical solution can utilize the stable supporting structure performance of the triangular bracket to ensure the stability of the column.

[0021] In a possible implementation manner, the number of the triangular brackets is 4 and they are arranged at 90 degree intervals along the outer peripheral wall of the column.

[0022] In a possible implementation, the first closing adapter plate includes a first upper cover and a first lower cover, the first upper cover and the first lower cover are detachably connected, the top end of the first upper cover is fixedly connected to the six-axis torque sensor, and the bottom end of the first lower cover is fixedly connected to the top end of the column.

[0023] In a possible embodiment, the second closing type adapter plate includes a second upper cover and a second lower cover, the second upper cover and the second lower cover are detachably connected, the second upper cover and the second lower cover are both hollow inside to form the accommodating cavity when they cooperate with each other, the top end of the second upper cover is fixedly connected to the motor, and the bottom end of the second lower cover is fixedly connected to the six-axis torque sensor.

[0024] In a possible implementation, a power supply module is further included, connected to the six-axis torque sensor, the magnetic encoder and the electronic speed regulator for power supply.

[0025] In a possible implementation, a control module is further included, which is respectively connected to the magnetic encoder, the power supply module and the electronic speed regulator, and is used to obtain the real-time speed of the motor detected by the magnetic encoder, and calculate the speed difference based on the real-time speed and the preset speed, and control the electronic speed regulator to adjust the real-time speed of the motor according to the speed difference based on the PID control algorithm.

[0026] In a possible implementation, a data processing module is further included, which is respectively connected to the six-axis torque sensor, the microphone and the analysis module, and is used to receive the digital signals output by the six-axis torque sensor and the microphone, and obtain the force data, the torque data and the sound pressure data after calibration conversion, data fusion and time synchronization, and output them to the analysis module. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a cross-sectional schematic diagram of the testing system of the present invention;

[0028] Figure 2 It is a partial cross-sectional schematic diagram of a propeller of the present invention;

[0029] Figure 3 It is a schematic diagram of module connection of the present invention;

[0030] Figure 4 It is a structural schematic diagram of a first cover-type adapter tray of the present invention;

[0031] Figure 5 It is a structural schematic diagram of a second cover-type adapter tray of the present invention;

[0032] Figure 6 It is a structural schematic diagram of a magnetic encoder and a magnetic encoder fixing member of the present invention;

[0033] Figure 7 A schematic diagram of signal transmission of a test system of the present invention;

[0034] Figure 8 is a data output flow chart of the test system of the present invention;

[0035] Fig. 9 It is a schematic diagram of the propeller speed control principle of the present invention;

[0036] Fig.10 It is a schematic diagram of the relative positions and layout of the microphone array and the propeller to be tested of the present invention;

[0037] Fig.11 It is a schematic diagram of the force and torque frequency domain diagram of the six-channel output of the present invention;

[0038] Fig.12It is a schematic diagram of the frequency domain diagram of the sound pressure and the frequency domain diagram of the sound pressure level of the motor of the present invention when the motor rotates at 6600 revolutions;

[0039] Explanation of the reference numerals in the accompanying drawings: 1. column; 2. first closing type adapter plate; 21. first upper cover; 22. first lower cover; 3. six-axis torque sensor; 4. second closing type adapter plate; 41. second upper cover; 42. second lower cover; 5. magnetic encoder; 6. motor; 7. propeller; 8. fairing; 9. electronic speed regulator; 10. analysis module; 11. microphone; 12. bottom plate; 13. triangular bracket; 14. power supply module; 15. control module; 16. data processing module; 17. magnetic encoder fixing part; 18. test system; 19. full anechoic chamber; 20. center sinking platform design ground; 21. microphone array. DETAILED DESCRIPTION

[0040] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0041] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] See also Figure 1 and Figure 2 The embodiment of the present application discloses a UAV propeller power and acoustic performance test system. The support structure includes a column 1 fixedly connected to the bottom plate 12 on the Z axis by screws. Four triangular brackets 13 use two triangular edges to support the column 1 and the bottom plate 12 so that the XY axis direction does not move, ensuring the stability of the entire structure in the three-axis direction. The propeller power system has a compact structure and a minimum overall design diameter, including a first cover-type adapter plate 2, see Figure 4 The first cover-type adapter plate 2 includes a first lower cover 22 for connecting the column 1 and a first upper cover 21 for connecting the six-axis torque sensor 3, and a second cover-type adapter plate 4, see Figure 5 The second cover-type adapter plate 4 includes a second lower cover 42 for connecting the six-axis torque sensor 3 and a second upper cover 41 for connecting the magnetic encoder fixing member 17 and the motor 6, wherein the magnetic encoder fixing member 17 is embedded under the second upper cover 41, and the magnetic encoder 5 is installed under the magnetic encoder fixing member 17. Figure 6 The motor 6 is installed above the second upper cover 41, the propeller 7 is fixed on the motor shaft, and the fairing 8 adopts a truncated airfoil design to wrap the above-mentioned devices to ensure that there is no noise interference from the gradient flow of the downwash airflow and reduce the motor noise.

[0043] See also Figure 3 , the electronic control part of the propeller power and acoustic performance test system can be found in Figure 7 The working principle is as follows: the power supply module 14 receives the voltage of the regulated DC power supply and divides the voltage to supply power to the control module 15, the electronic speed regulator 9, the six-axis torque sensor 3 and the magnetic encoder 5. The control module 15 is connected to the electronic speed regulator 9 for communication. After receiving the start command (Dshot digital protocol) from the control module 15, the electronic speed regulator 9 controls the motor 6 to rotate; the magnetic encoder 5 monitors the rotation angle of the motor 6 and transmits the angle information to the control module 15 through the IIC protocol. The control module 15 calculates the actual speed of the motor 6 as a reference according to the algorithm. According to the signal value of the actual speed and the input speed signal value of the control module 15, that is, the speed difference of the preset speed, the PID control algorithm is used to adjust the output of the electronic speed regulator 9. The low-pass filtering algorithm is used to reduce the fluctuation error caused by the magnetic encoder 5 to slow down the jitter problem caused by adjusting the motor speed too quickly. This cycle is repeated until the accuracy requirements are met to achieve a closed-loop control effect.

[0044] See also Figure 8 After the propeller starts to rotate, the six-axis torque sensor and microphone convert the mechanical and acoustic analog signals into digital signals. After being processed by the data processing module 16 (calibration conversion, data fusion algorithm and time synchronization, etc.), the force, torque and sound pressure data are saved locally in the host. The analysis module 10 performs the following two analysis methods on the data:

[0045] 1. When analyzing the six-channel data of force and torque, the time domain diagram and frequency domain diagram can be obtained through numerical processing and fast Fourier transform (FFT). The horizontal axis in the time domain diagram is time, and the vertical axis is the physical quantity of force or torque given by the sensor. The physical quantity value of force or torque in the diagram is filtered and used to finally calculate the average value of force and torque, which is used to evaluate the force efficiency performance of the propeller. The horizontal axis in the frequency domain diagram is frequency, and the vertical axis is the amplitude of force and torque, so as to further perform vibration analysis and evaluate the vibration characteristics of the propeller such as vibration source and amplitude;

[0046] 2. When analyzing the sound pressure signal of the microphone 11, the sound pressure of the sound field radiated by the propeller rotation at a specified speed can be represented by the sound pressure level (SPL), and the time domain and frequency domain data of the sound pressure can be output in the form of a table and a curve;

[0047] By comparing the forces, torques and sound pressures generated by different propellers 7, the advantages and disadvantages of the propeller 7 in terms of power performance can be evaluated. Combined with computational fluid dynamics and simulation, the design of the propeller 7 can be further optimized, and iterative improvements can be achieved to improve the thrust efficiency of the UAV propeller and reduce the noise level of the propeller 7.

[0048] Continue to see Figure 1Compared with patent CN113734465A, from the perspective of mechanical structure, the UAV propeller power and acoustic performance test system of the present invention uses the design of the adapter plate and the fairing 8 to make the airflow smooth and reduce the motor noise, so that the radiated sound field of the propeller 7 is less disturbed, which is convenient for more accurate measurement and analysis of the force, torque and radiated sound pressure of the propeller 7. In addition, the adapter plate in the present invention can facilitate the integration of different test function devices, which are added to the test bench one by one like a "sugar gourd". For example, the duct kit is used to study the force efficiency of the ducted propeller and the airspeed meter is used to supplement the experimental data of the air flow speed. The test system adjusts the test function devices according to the different purposes of the propeller test to obtain the required test data; from the control perspective, the magnetic encoder 5 can realize the speed closed-loop control, and the system can control the propeller to work at any speed condition, allowing the propeller 7 with controllable speed to measure the force / torque and radiated sound pressure level of different speed sections, so as to obtain the overall power and acoustic performance of the propeller 7.

[0049] Embodiment 1

[0050] Provide a procedure for implementing a propeller dynamic and acoustic performance test system;

[0051] Step 1: If Figure 1 , the first machined cover-type adapter plate 2, the six-channel output strain gauge six-axis torque sensor 3, the second machined cover-type adapter plate 4, the magnetic encoder with a speed monitoring range of 0-12000 rpm 5, the 3D printed magnetic encoder fixing 17, the 880KV motor 6, the self-designed propeller with a size of 9*5, and the 3D printed fairing 8 are sequentially placed, as shown in FIG. Figure 2 As shown, it is installed on the iron machined column 1 to complete the mechanical installation; Fig.10 , the test system 18 is placed on the central sinking platform design floor 20 in the full anechoic chamber 19, and the anechoic wedge is filled into the sinking platform. This design enhances the vibration resistance and stability of the test system 18 and minimizes noise interference. An appropriate number of microphone arrays 21 are installed in the space around the propeller 7 as required. Fig.10 Place quantity and manner for reference;

[0052] Step 2: Connect the power supply to the power supply module 14, the motor controller and the electronic speed regulator 9 are connected in parallel to the power supply module 14, the IIC communication line of the magnetic encoder 5 is connected to the IIC interface of the motor controller, the three-phase line of the motor 6 is connected to the three-phase line of the electronic speed regulator 9, and the signal line of the electronic speed regulator 9 is connected to the UAV flight controller to complete the overall circuit connection;

[0053] Step 3: Write the input parameters such as motor speed required by the system according to the control principle. Fig. 9 ;

[0054] Step 4: Power on each device and open the control and analysis software, and enter the programmed input parameters. At this time, enter the required speed in the self-written host computer software and wait for the motor to adjust the speed to the set value. When the motor speed is stable within the set value error range, the six-axis torque sensor 3 continues to collect data and records it in txt file format after software processing. The microphone 7 collects and records the sound pressure signal during this process and displays it on the host computer platform;

[0055] Step 5: Change the speed of the propeller 7 and repeat step 4. In this embodiment, the speed is selected from 3600-7200 rpm. The digital signals obtained from the six-axis torque sensor 3 and the microphone 7 are stored locally on the host. The propeller force and torque signals are obtained through the fast Fourier transform algorithm and low-pass filter algorithm in the software. The speed of the case is 6600 rpm. The results are shown in Fig.11 The microphone array 21 collects the sound pressure of the sound field radiated by the propeller 7, calculates the sound pressure level through the software, and gives the propeller sound pressure and sound pressure level analysis results. A microphone in the microphone array 21 is selected as a case for analysis (the height is 132CM, the relative height to the test system is 20CM and the distance to the test system is 70CM). Fig.12 ;

[0056] Through this process, the force, torque and radiated sound pressure distribution of propeller 7 in a set speed range can be obtained, and the performance information of propeller 7 can be obtained by comparing the lift and sound pressure level. By replacing different propellers 7 and repeating steps 1 to 5, a propeller 7 with the best performance can be obtained.

[0057] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0058] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A UAV propeller power and acoustic performance test system, characterized in that: include: A column (1), the bottom of which is fixed to the ground via a supporting structure; A first cover-type adapter plate (2) is arranged at the top end of the column (1), and the bottom end of the first cover-type adapter plate (2) is fixedly connected to the top end of the column (1); a six-axis torque sensor (3), arranged at the top of the first cover-type adapter plate (2) and fixedly connected to the top of the first cover-type adapter plate (2); a second cover-type adapter plate (4), arranged at the top end of the six-axis torque sensor (3); the bottom end of the second cover-type adapter plate (4) is fixedly connected to the six-axis torque sensor (3); and a receiving cavity is provided inside the second cover-type adapter plate (4); A magnetic encoder (5) fixedly installed in the accommodating cavity; a motor (6) disposed at the top of the second cover-type adapter plate (4) and fixedly connected to the top of the second cover-type adapter plate (4), and a motor shaft of the motor (6) is located at an end facing away from the column (1); a propeller (7), sleeved on the motor shaft and fixedly connected to the motor shaft; a fairing (8), which is arranged outside the column (1) and covers the first cover-type adapter plate (2), the six-axis torque sensor (3), the second cover-type adapter plate (4) and the motor (6); an electronic speed regulator (9), connected to the motor (6), and used to control the motor (6) to rotate according to the start command input from the outside to drive the propeller (7) to rotate; An analysis module (10) is respectively connected to the six-axis torque sensor (3) and an external microphone (11), and is used to obtain force data and torque data output by the six-axis torque sensor (3) and sound pressure data detected by the microphone (11), and to obtain a time domain diagram and a frequency domain diagram based on the force data and the torque data to assist in evaluating the dynamic performance of the propeller (7), and to obtain a numerical table and a curve based on the sound pressure data to assist in evaluating the acoustic performance of the propeller (7).

2. The UAV propeller (7) power and acoustic performance testing system according to claim 1, characterized in that: The support structure comprises a base plate (12) and a plurality of triangular brackets (13); the bottom end of the column (1) is fixed to the top end of the base plate (12); one right-angled side of each triangular bracket (13) is fixedly connected to the top end of the base plate (12); and the other right-angled side of each triangular bracket (13) is fixedly connected to the outer peripheral wall of the column (1).

3. The UAV propeller power and acoustic performance testing system according to claim 2, characterized in that: The number of the triangular brackets (13) is four and they are arranged at 90-degree intervals along the outer peripheral wall of the column (1).

4. The UAV propeller power and acoustic performance testing system according to claim 1, characterized in that: The first cover-type adapter plate (2) comprises a first upper cover (21) and a first lower cover (22); the first upper cover (21) and the first lower cover (22) are detachably connected; the top end of the first upper cover (21) is fixedly connected to the six-axis torque sensor (3); and the bottom end of the first lower cover (22) is fixedly connected to the top end of the column (1).

5. The UAV propeller power and acoustic performance testing system according to claim 1, characterized in that: The second cover-type adapter plate (4) comprises a second upper cover (41) and a second lower cover (42); the second upper cover (41) and the second lower cover (42) are detachably connected; the second upper cover (41) and the second lower cover (42) are both hollow inside so as to form the accommodating cavity when they cooperate with each other; the top end of the second upper cover (41) is fixedly connected to the motor (6), and the bottom end of the second lower cover (42) is fixedly connected to the six-axis torque sensor (3).

6. The UAV propeller power and acoustic performance testing system according to claim 1, characterized in that: It also includes a power supply module (14) connected to the six-axis torque sensor (3), the magnetic encoder (5) and the electronic speed regulator (9) for power supply.

7. The UAV propeller power and acoustic performance test system according to claim 6, characterized in that: The invention also comprises a control module (15), which is respectively connected to the magnetic encoder (5), the power supply module (14) and the electronic speed regulator (9), and is used to obtain the real-time speed of the motor (6) detected by the magnetic encoder (5), calculate the speed difference according to the real-time speed and the preset speed, and control the electronic speed regulator (9) to adjust the real-time speed of the motor (6) according to the speed difference based on the PID control algorithm.

8. The UAV propeller power and acoustic performance testing system according to claim 1, characterized in that: The device also includes a data processing module (16), which is respectively connected to the six-axis torque sensor (3), the microphone (11) and the analysis module (10), and is used to receive the digital signals output by the six-axis torque sensor (3) and the microphone (11), and obtain the force data, the torque data and the sound pressure data after calibration conversion, data fusion and time synchronization, and output them to the analysis module (10).

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