A test system for flapping-wing aircraft power system and a test method thereof

Abstract

This invention discloses a testing system and method for the power system of flapping-wing aircraft, belonging to the field of flapping-wing aircraft testing. In this system, a wind tunnel experimental platform is used to install the power system under test and provide test conditions; a signal measurement module is used to synchronously acquire electrical power, motor current and voltage, motor speed, rocker arm angle, rocker arm torque, lift, and net thrust; a motor characteristic testing platform is independently set up to establish the correspondence between motor output torque and line current and line voltage offline; a data acquisition and analysis module receives the above signals and correspondences, calculates the actual output torque of the motor, and thus obtains the efficiency of the electronic speed controller, motor, flapping-wing mechanism, as well as the overall efficiency and force efficiency of the power system. This invention can comprehensively reveal the energy flow and loss of each component within the power system of a flapping-wing aircraft, providing a quantitative basis for power system design verification and optimization, and is applicable to various types of motor-driven pure flapping-wing mechanisms.

Description

Technical Field

[0001] This invention belongs to the field of flapping-wing aircraft testing technology, specifically relating to a testing system and method for the power system of flapping-wing aircraft, and more specifically to a testing system and method for measuring the efficiency of components in the power system of flapping-wing aircraft. Background Technology

[0002] Ornithopter aircraft are aircraft that mimic the flight of living organisms by flapping their wings. In recent years, thanks to the rapid development of computer science, materials science, and manufacturing technology, research on ornithopter aircraft has yielded significant results. Furthermore, due to their low noise and good stealth capabilities, ornithopter aircraft have considerable application value and potential in fields such as environmental monitoring and reconnaissance exploration.

[0003] At present, the power system of a practical flapping-wing aircraft typically consists of a battery, electronic speed controller, brushless DC motor, gear reducer, and flapping wing mechanism (including flapping wing). This power system generates thrust and lift, which have a significant impact on the aircraft's flight performance. Regarding the testing of flapping-wing aircraft, Chinese invention patent CN120135475A proposes a multi-dimensional performance testing method for flapping-wing aircraft, which can measure the lift, thrust, and wind field energy conversion efficiency of flapping-wing aircraft under different operating conditions; Chinese invention patent CN120232609A proposes a method for measuring the lift of flexible flapping wings, which obtains the lift of internal components of the aircraft by combining experimental results of no wind, wind without flexible flapping wings, and wind with flexible flapping wings; Chinese invention patent CN119796522A provides an aerodynamic measurement device for flapping-wing aircraft, which can compare the aerodynamic forces of the aircraft under different flapping frequencies, different angles of attack, and different flapping wings.

[0004] Based on the aforementioned patents, it is clear that existing tests on flapping-wing aircraft primarily focus on the overall lift and thrust of the aircraft, without addressing the power flow and efficiency analysis of individual components within the propulsion system (such as motors, reducers, and flapping-wing mechanisms) under actual operating conditions. Therefore, there are currently no comprehensive testing methods for flapping-wing aircraft propulsion systems, making it difficult to quantitatively assess the actual operating conditions and energy losses of each component, thus hindering the provision of accurate verification criteria for the optimized design of the propulsion system. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that existing testing technologies for flapping-wing aircraft cannot obtain the working status and efficiency of various components inside the power system. It proposes a testing system and method that can simultaneously measure multiple parameters such as voltage, current, speed, angle, torque, lift, and thrust, and establish the correspondence between motor output torque and line current and line voltage through motor characteristic testing, thereby accurately calculating the power and efficiency of various components such as motor, electronic speed controller, and flapping-wing mechanism.

[0006] To achieve the above objectives, the technical solution provided by this invention is:

[0007] On the one hand, a test system for the power system of flapping-wing aircraft is provided, including a wind tunnel test platform, a signal measurement module, a motor characteristic test platform, and a data acquisition and analysis module;

[0008] The wind tunnel test platform has an installation interface for installing the power system of the flapping-wing aircraft under test, and is used to provide test conditions for the power system of the flapping-wing aircraft under test.

[0009] The signal measurement module is used to connect to multiple measurement points of the power system of the flapping-wing aircraft under test, so as to collect the electrical and mechanical signals generated by the power system of the flapping-wing aircraft under test during operation, and convert the electrical and mechanical signals into voltage signals;

[0010] The motor characteristic testing platform is set up independently of the wind tunnel test platform and is used to conduct offline testing of the motor in the power system of the flapping-wing aircraft under test. The motor characteristic testing platform has a motor mounting position for fixing the motor under test, a loading device for applying an adjustable load to the motor under test, and a measuring device for measuring the output torque, speed, line current and line voltage of the motor under test. The motor characteristic testing platform is used to output the correspondence between the output torque of the motor under test and the line current and line voltage.

[0011] The data acquisition and analysis module is connected to the output of the signal measurement module and the output of the motor characteristic test platform, respectively. It is used to acquire voltage signals and receive corresponding relationships to calculate the output torque of the motor under test, and then analyze the component efficiency, overall efficiency and force efficiency of the power system of the flapping-wing aircraft under test.

[0012] Furthermore, the signal measurement module includes:

[0013] The electric power measurement unit is used to measure the battery output power and electronic speed controller output power of the power system of the flapping-wing aircraft under test.

[0014] The motor current and voltage measurement unit is used to measure the line current and line voltage of the motor of the power system of the flapping-wing aircraft under test when it is running under wind tunnel test conditions.

[0015] The motor speed measurement unit is used to measure the motor speed of the power system of the flapping-wing aircraft under test when it is running under wind tunnel test conditions.

[0016] The rocker arm rotation angle measurement unit is used to measure the rotation angle of the rocker arm of the flapping wing mechanism in the power system of the flapping wing aircraft under test.

[0017] The rocker arm torque measurement unit is used to measure the torque of the rocker arm of the flapping wing mechanism;

[0018] The lift and net thrust measurement unit is used to measure the lift and net thrust generated by the flapping wing mechanism.

[0019] Furthermore, the rocker arm torque measurement unit includes strain gauges attached to the rocker arm and a double-arm half-bridge measurement circuit connected to the strain gauges.

[0020] Furthermore, the data acquisition and analysis module includes data acquisition hardware, host computer software, and data post-processing program. The data acquisition hardware includes a data acquisition card, the host computer software is used to display and save the acquired signals, and the data post-processing program is used to analyze and calculate the signals saved by the host computer software to obtain various characteristics of the power system of the flapping-wing aircraft under test.

[0021] On the other hand, a method for testing the power system of an flapping-wing aircraft based on the above-mentioned test system is provided, including the following steps:

[0022] Step 1: Install the power system of the flapping-wing aircraft under test onto the installation interface of the wind tunnel test platform;

[0023] Step 2: Use the motor characteristic testing platform to obtain the correspondence between the output torque of the motor under test and the line current and line voltage;

[0024] Step 3: Synchronously collect the electrical power, motor current, motor voltage, motor speed, rocker arm angle, rocker arm torque, lift and net thrust of the power system of the flapping-wing aircraft under test during operation through the signal measurement module;

[0025] Step 4: Calculate the motor output torque based on the corresponding relationship and the collected motor current and motor voltage.

[0026] Step 5: Based on the collected electrical power, motor speed, rocker arm angle, rocker arm torque, and calculated motor output torque, calculate the efficiency of each component, the overall efficiency, and the force efficiency of the power system of the flapping-wing aircraft under test.

[0027] Furthermore, step 2 specifically includes:

[0028] Fix the motor under test in the motor mounting position;

[0029] Multiple different load torques are applied to the motor under test using a loading device;

[0030] The output torque, speed, line current, and line voltage under each load torque are recorded using a measuring device.

[0031] The relationship between output torque and line current and line voltage was obtained by fitting the recorded data.

[0032] Furthermore, before acquiring the rocker arm torque in step 3, a calibration step for the rocker arm torque measurement unit is also included, specifically including:

[0033] Adjust the rocker arm to a horizontal position and restrict its rotation;

[0034] A weight is suspended on the rocker arm for loading, and the output voltage of the rocker arm torque measurement unit is recorded at different loading positions.

[0035] The flapping wing mechanism was reversed, and weights were suspended on the rocker arm again for loading. The output voltage of the rocker arm torque measurement unit was recorded at different loading positions.

[0036] Based on the calibration data, the relationship between the actual torque and the output voltage when the rocker arm is horizontally upward and downward is fitted respectively.

[0037] Furthermore, step 3, which involves collecting lift and net thrust, specifically includes:

[0038] Set the angle of attack for the wind tunnel test platform;

[0039] Record the forces in the x and z directions of the mechanism's axis system under conditions where no wings are installed and the wind speed is zero;

[0040] Under the condition of installing the wing and zero wind speed, record the forces in the x and z directions of the mechanism's axis system;

[0041] Record the forces in the x and z directions of the mechanism's axis system under the condition that the wings are not installed and the wind speed is set;

[0042] Under the conditions of installing the wings, setting the wind speed, and setting the flapping frequency, record the forces in the x and z directions of the mechanism's axis system;

[0043] Based on the data recorded in the four instances above, the force generated by the flapping wing was calculated.

[0044] Based on the set angle of attack, the force generated by the flapping wing is converted into lift and net thrust.

[0045] Furthermore, the efficiency of each component in step 5 is calculated using the following formula:

[0046]

[0047] In the formula, Indicates the component number. For the first The efficiency of each component For flapping wing motion period; for electronic speed controller, For battery output power, This refers to the input power to the motor; for a motor, For the output power of the electronic speed controller, This is the product of the motor's output torque and its speed; for flapping wing mechanisms, It is the product of the motor output torque and the motor speed. It is twice the product of the rocker arm torque and the rocker arm speed.

[0048] Furthermore, the formula for calculating the force effect in step 5 is as follows:

[0049]

[0050]

[0051] In the formula, and These are lift efficiency and net thrust efficiency, respectively. For the flapping wing motion period, and These are instantaneous lift and instantaneous net thrust, respectively. This refers to the instantaneous output power of the battery.

[0052] The advantages of this invention are:

[0053] 1. This invention organically combines a wind tunnel testing platform, a signal measurement module, a motor characteristic testing platform, and a data acquisition and analysis module. It enables simultaneous multi-parameter measurement of the flapping-wing aircraft's propulsion system, allowing real-time acquisition of key data such as battery output power, electronic speed controller output power, motor current and voltage, motor speed, rocker arm angle, rocker arm torque, lift, and net thrust. Based on the offline established correspondence between motor output torque and line current and voltage on the motor characteristic testing platform, combined with online measured current and voltage values, the output torque of the motor during actual operation can be accurately calculated. Furthermore, the average input power, average output power, and efficiency of each component, including the electronic speed controller, motor, and flapping wing mechanism, during a complete flapping cycle can be calculated, along with the overall efficiency, lift efficiency, and net thrust efficiency of the entire propulsion system. This invention not only reveals the energy flow and losses within each component of the flapping-wing aircraft's propulsion system and clarifies the working status of each component, but also provides precise and quantitative data for the design verification and performance improvement of the propulsion system.

[0054] 2. This invention is applicable to various types of motor-driven pure flapping wing mechanisms, and has good versatility and expandability. Attached Figure Description

[0055] The above and / or other features and advantages of the present invention will become more readily understood from the following description with reference to the accompanying drawings, which are not drawn to scale and some features are enlarged or reduced to show details of specific parts.

[0056] Figure 1This is a schematic diagram of the basic framework of the test system for the power system of an flapping-wing aircraft according to an embodiment of the present invention;

[0057] Figure 2 This is a first view of the experimental fixture structure for the flapping wing mechanism according to an embodiment of the present invention;

[0058] Figure 3 This is a second view of the experimental fixture structure for the flapping wing mechanism according to an embodiment of the present invention;

[0059] Figure 4 This is a schematic diagram of the rocker arm rotation angle measurement method in an embodiment of the present invention;

[0060] Figure 5 This is a signal conditioning circuit diagram for rocker arm torque measurement in an embodiment of the present invention;

[0061] Figure 6 This is a schematic diagram of the wiring method for measuring electrical power in an embodiment of the present invention;

[0062] Figure 7 This is a schematic diagram of the host computer software interface in an embodiment of the present invention;

[0063] Figure 8 This is a basic flowchart of the test method for the power system of an flapping-wing aircraft according to an embodiment of the present invention;

[0064] Figure 9 This is a graph showing the fitting results of the motor characteristic test in an embodiment of the present invention;

[0065] Figure 10 This is a schematic diagram of the strain gauge calibration method in an embodiment of the present invention;

[0066] Figure 11 This is a diagram showing the strain gauge calibration results in an embodiment of the present invention;

[0067] Figure 12 This is a graph showing the measured lift and net thrust values ​​in an embodiment of the present invention.

[0068] Figure 13 This is a graph showing the effective values ​​of motor line current and line voltage measured in an embodiment of the present invention;

[0069] Figure 14 This is a diagram showing the rocker arm rotation angle and torque measured in an embodiment of the present invention;

[0070] Figure 15 This is a graph showing the measured motor torque and speed in an embodiment of the present invention;

[0071] Figure 16 These are the power diagrams of various parts measured in the embodiments of the present invention.

[0072] In the picture:

[0073] 1-Wind tunnel test platform; 11-Wind tunnel test platform support frame;

[0074] 2-Motor characteristic testing platform;

[0075] 3-Power system of the tested flapping-wing aircraft; 31-MN1804 brushless DC motor; 32-Reducer; 321-Large gear of the reducer; 33-Flapping wing mechanism; 331-Rocker arm; 332-Flapping wing;

[0076] 4-Signal measurement module; 411-AH3503 Hall sensor; 412-Magnet for rotational speed measurement; 413-Hall sensor mount; 421-GTF non-contact angle sensor; 422-Angle sensor bracket; 423-Magnet mount; 424-Magnet for angle measurement; 431-BE120-3AA-P300 strain gauge; 432-Calibration rod; 433-Weight; 441-MINI40 six-dimensional force sensor; 442-Six-dimensional force sensor connecting plate; 443-Main connecting plate; 45-Base plate; 46-Flapping wing fixing seat; 47-Flapping wing mechanism bracket;

[0077] 5. Data Acquisition and Analysis Module. Detailed Implementation

[0078] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments thereof. It should be noted that the following detailed description of the present invention is for illustrative purposes only and is not intended to limit the scope of the invention.

[0079] This invention provides a test system for the power system of flapping-wing aircraft and a test method for the power system of flapping-wing aircraft based on the test system. The aim is to accurately obtain the instantaneous power, periodic average power, efficiency of each component (electronic speed controller, motor, flapping mechanism, etc.) inside the power system of flapping-wing aircraft, as well as the total efficiency and force efficiency of the entire power system, through multi-parameter synchronous measurement and offline motor characteristic modeling, thereby providing quantitative basis for the design verification and performance optimization of the power system of flapping-wing aircraft.

[0080] This embodiment uses a certain type of flapping-wing aircraft as an example. Its power system consists of the following components: a battery pack composed of four Panasonic 18650 lithium batteries, with a nominal voltage of 7.4 V (2s) and a capacity of 6800 mAh; an electronic speed controller of EMAX (Silver Swallow) DSHOT BULLET type, with a maximum stable operating current of 30 A; a T-motor MN1804 brushless DC motor; a reducer of deployable two-stage cylindrical helical gear transmission; and a flapping wing mechanism of single crank and double rocker arm, with a flapping angle range of -30° to 30°, a cruise flapping wing frequency of 9 Hz, and a cruise angle of attack of 12°. The aircraft weighs approximately 230 g.

[0081] First refer to Figures 1 to 7 A test system for a flapping-wing aircraft power system, which is an exemplary embodiment of the present invention, will be described in detail.

[0082] like Figure 1 As shown, the testing system includes a wind tunnel experimental platform 1, a motor characteristic testing platform 2, a signal measurement module 4, and a data acquisition and analysis module 5. The test flapping-wing aircraft power system 3 is mounted on the wind tunnel experimental platform 1, which has its installation interface, and operates under different angles of attack, airspeeds, and other conditions provided by the wind tunnel experimental platform 1. The signal measurement module 4 is connected to multiple measurement points of the test flapping-wing aircraft power system 3, collecting the electrical and mechanical signals generated during operation and converting the collected electrical and mechanical signals into voltage signals. The motor characteristic testing platform 2 is set up independently of the wind tunnel experimental platform 1 and is used for offline testing of the motor to obtain the correspondence between the motor output torque and line current and line voltage, i.e., the motor model. The data acquisition and analysis module 5 is connected to the output terminals of the signal measurement module 4 and the motor characteristic testing platform 2, respectively, collecting voltage signals and receiving the above correspondence, calculating the output torque of the motor in actual operation, and then analyzing and obtaining the efficiency of each component and the overall efficiency.

[0083] The motor characteristic testing platform 2 includes a motor mounting position for fixing the motor under test, a loading device for applying an adjustable load to the motor under test, and a measuring device for measuring the output torque, speed, line current, and line voltage of the motor under test. In this embodiment, the motor characteristic testing platform 2 uses a Shanghai Songbao WD1KB / W eddy current dynamometer and a matching motor measurement and control system. The motor mounting position is an adjustable three-axis platform used to fix the motor and ensure alignment between the motor shaft and the dynamometer shaft. The loading device is an eddy current dynamometer capable of applying a continuously adjustable load torque to the motor. The measuring device includes a torque-speed sensor and a voltage-current measurement unit integrated into the dynamometer, used to measure the motor's output torque, speed, and the effective values ​​of line current and line voltage, respectively. By measuring these parameters under different loads, a correspondence between the motor's output torque and line current and line voltage (i.e., a motor model) can be fitted. This correspondence is received by the data acquisition and analysis module 5 and used to subsequently calculate the motor's output torque during actual operation based on the online measured current and voltage values.

[0084] The signal measurement module 4 is one of the core components of the test system of the present invention. In this embodiment, the signal measurement module 4 includes six units: an electric power measurement unit, a motor current and voltage measurement unit, a motor speed measurement unit, a rocker arm rotation angle measurement unit, a rocker arm torque measurement unit, and a lift and net thrust measurement unit.

[0085] The power measurement unit is used to measure the battery output power and electronic speed controller output power in the power system 3 of the flapping-wing aircraft under test. In this embodiment, a HIOKI PW8001 power analyzer is selected, paired with a CT6872 current sensor.

[0086] The motor current and voltage measurement unit also uses the aforementioned power analyzer to measure the effective values ​​of the motor's line current and line voltage, which are then substituted into the motor model to calculate the motor's output torque.

[0087] The motor speed measurement unit consists of magnets axially distributed at the north and south poles and a linear Hall sensor. The magnets are mounted on the end face of the large gear in the first stage of the reducer. The gear speed is measured by detecting the pulse frequency of the magnets passing through the Hall sensor, and the motor speed is then calculated based on the reducer's transmission ratio. In this embodiment, a small magnet with a diameter of 2 mm and a thickness of 1.5 mm and an AH3503 type linear Hall sensor are used.

[0088] The rocker arm rotation angle measurement unit consists of radially distributed magnets at the north and south poles and a non-contact angle sensor. The magnets are fixed to the rocker arm and rotate with it. The angle sensor detects changes in the direction of the magnetic field and outputs a voltage signal proportional to the rotation angle. In this embodiment, a GTF-type non-contact angular displacement sensor from Taizhou Quantum Electronics Technology Co., Ltd. is used, along with radially distributed magnets at the north and south poles with a diameter of 8 mm and a thickness of 3.5 mm.

[0089] The rocker arm torque measurement unit consists of strain gauges symmetrically attached to the upper and lower surfaces of the rocker arm and a connected double-arm half-bridge measurement circuit, which converts the torque borne by the rocker arm into a voltage signal output. In this embodiment, the BE120-3AA-P300 resistance strain gauge from AVIC Electromechanical Measurement is selected, and the double-arm half-bridge measurement circuit is designed independently.

[0090] The lift and net thrust measurement unit employs a six-dimensional force sensor, mounted between the base plate and the wind tunnel experimental platform support. It can simultaneously measure forces and moments in the x, y, and z directions of the body axis (defined below). This test primarily uses the forces in the x and z directions. Subsequent data processing removes gravity interference from the mechanism and wing, as well as wind resistance interference from the mechanism, to obtain the lift and net thrust generated by the flapping wing. In this embodiment, the ATI MINI40 six-dimensional force sensor is selected.

[0091] The above six units work together to achieve synchronous measurement of electrical quantities (power, current, voltage) and mechanical quantities (speed, angle, torque, force) of the flapping-wing aircraft's power system, providing complete raw data for subsequent power and efficiency calculations.

[0092] like Figure 2 , Figure 3 and Figure 4As shown, the flapping wing mechanism 33 is fixedly mounted on the flapping wing mechanism bracket 47, which is bolted to the base plate 45. The leading edge of the flapping wing 332 is mounted in the mounting hole of the rocker arm 331, and the trailing edge is mounted through the flapping wing fixing seat 46, which is bolted to the base plate 45. Six speed measuring magnets 412 are evenly distributed on the end face of the large gear 321 of the first stage of the reducer 32, with their north and south poles axially distributed. The AH3503 Hall sensor 411 is fixed on the Hall sensor seat 413 at a suitable height to detect the magnets 412, forming a speed sensor. The speed and flapping frequency of the MN1804 brushless DC motor 31 can be calculated through the transmission ratio. The GTF non-contact angle sensor 421 is fixed on the angle sensor bracket 422, which is fixed to the base plate 45. Angle measuring magnet 424, with its north and south poles radially distributed, is fixed to a magnet base 423. The magnet base 423 is fixed to a rocker arm 331 and is used to measure the rocker arm's rotation angle. Specifically, the angle measuring magnet 424 rotates with the rocker arm 331, and the GTF non-contact angle sensor 421 outputs a voltage signal proportional to the rotation angle by detecting changes in the magnetic field. A MINI40 six-dimensional force sensor 441 is mounted under the base plate 45 via a six-dimensional force sensor connecting plate 442, and then fixed to the wind tunnel experimental platform support 11 via a main connecting plate 443, used to measure lift and net thrust. BE120-3AA-P300 strain gauges 431 are symmetrically attached to the upper and lower surfaces of the rocker arm 331, and the two strain gauges form a double-arm half-bridge circuit to measure the rocker arm torque.

[0093] like Figure 5 As shown, two BE120-3AA-P300 strain gauges (431) and a fixed resistor form a double-arm half-bridge circuit. The driving voltage is provided by a REF5030 voltage source and a voltage follower based on an OPA192 operational amplifier. The two signals output from the bridge are first filtered by a primary low-pass filter consisting of a 1kΩ@100MHz ferrite bead, a 120Ω resistor, and a 470nF capacitor to remove high-frequency noise. Then, they are input to an INA818 differential amplifier for subtraction, with the amplification factor configured to 1000 using a 50Ω resistor. The amplified signals are further filtered by a secondary low-pass filter consisting of a 6.8kΩ resistor, a 15kΩ resistor, a 22nF capacitor, and a 10nF capacitor before being finally output to the data acquisition card. This circuit can accurately extract the weak voltage signal corresponding to the strain gauge resistance change, enabling real-time measurement of the rocker arm torque.

[0094] like Figure 6 As shown, the HIOKI PW8001 power analyzer uses the 1P2W wiring method to measure the battery output power and the 3P3W3M wiring method to measure the three-phase output power of the electronic speed controller. The power analyzer directly outputs power data to the data acquisition and analysis module 5.

[0095] The data acquisition and analysis module 5 includes data acquisition hardware, host computer software, and a data post-processing program. The data acquisition hardware includes a data acquisition card, signal connection cables, and a computer. The host computer software runs on the computer and is used to display and save the acquired signals. The data post-processing program analyzes and calculates the signals saved by the host computer software, ultimately obtaining various characteristics of the tested flapping-wing aircraft's power system (such as the power, efficiency, overall efficiency, and force efficiency of each component). In this embodiment, the data acquisition hardware uses two NI 9220 acquisition cards and an NI cDAQ 9174 chassis, connected to the computer via a USB cable. The host computer software is developed based on the LabVIEW platform, such as... Figure 7 As shown, the data post-processing program runs on the same computer or a separate computer and performs operations such as integration, fitting, and efficiency calculation on the stored raw data.

[0096] Next, refer to Figures 8 to 16 A detailed description is provided of a test method for the power system of an flapping-wing aircraft based on the above-described test system, which is an exemplary embodiment of the present invention.

[0097] like Figure 8 As shown, the testing method includes the following steps:

[0098] Step S1: Install the power system of the flapping-wing aircraft under test onto the installation interface of the wind tunnel test platform.

[0099] Specifically, the assembled flapping wing mechanism and power system components are fixed to the wind tunnel test platform support 11 via the main connecting plate 443, ensuring that the six-dimensional force sensor 441 is correctly connected and that each measuring unit is reliably connected to its corresponding measuring point.

[0100] Step S2: Use the motor characteristic test platform to obtain the correspondence between the output torque of the motor under test and the line current and line voltage.

[0101] Specifically, the motor under test is fixed in the motor mounting position of the motor characteristic testing platform 2; multiple different load torques are applied to the motor under test through a loading device (eddy current dynamometer); the output torque, speed, line current, and line voltage under each load torque are recorded through a measuring device; and the correspondence between the output torque and the line current and line voltage is obtained by fitting the recorded data. Figure 9 As shown, the fitted relationship obtained in this embodiment is:

[0102]

[0103] In the formula, This refers to the motor's output torque, expressed in mN·m. This is the motor line current, in amperes (A). This is the motor line voltage, in volts (V).

[0104] Step S3: Synchronously collect the electrical power, motor current, motor voltage, motor speed, rocker arm angle, rocker arm torque, lift and net thrust of the power system of the flapping-wing aircraft under test during operation through the signal measurement module 4.

[0105] Before proceeding to step S3, the rocker arm torque measurement unit needs to be calibrated. See [link / reference]. Figure 10 The calibration steps include: adjusting the rocker arm 331 to a horizontal position and restricting its rotation; inserting the calibration rod 432 into the flapping wing mounting hole of the rocker arm 331, the calibration rod 432 having a scale; suspending weights 433 in ascending order of scale, and recording the output voltage of the rocker arm torque measuring unit at each scale mark. Reverse the flapping wing mechanism by 180° and repeat the above operation; based on the calibration data, fit the relationship between the actual torque and the output voltage when the rocker arm is horizontally upward and horizontally downward respectively. Figure 11 The strain gauge calibration results diagram in this embodiment of the invention is shown, along with the specific fitting curve and the actual torque of the rocker arm. Calculated using the following formula:

[0106]

[0107] In the formula, , and , They are respectively Figure 11 The fitting slope and intercept parameters obtained from the calibration; The force in the z-direction of the flapping wing mechanism body axis system measured during the lift and net thrust measurement steps (i.e., when collecting lift and net thrust in step S3, under the conditions of wing installation, wind speed setting, and flapping frequency setting), in N; The angle of rotation of the rocker arm is expressed in radians.

[0108] After calibration, formal measurements are performed. First, the angle of attack of the wind tunnel test platform is set (12° in this embodiment). Then, lift and net thrust are collected according to the following sub-steps:

[0109] Setting the angle of attack of the wind tunnel test platform (12° in this embodiment);

[0110] Record the forces in the x and z directions of the mechanism's axis system under conditions of no wings and zero wind speed. , It should be noted here that the origin of the mechanism's axis system is set at the center of the top surface of the MINI40 six-dimensional force sensor 441. The x-axis is parallel to the long side of the base plate 45, the y-axis is parallel to the short side of the base plate 45, and the z-axis is parallel to the thickness direction of the base plate 45. The positive directions of each axis are as follows: Figure 3 As shown;

[0111] With the wing installed and the wind speed at zero, record the forces in the x and z directions of the mechanism's axis system. , ;

[0112] Under conditions where no wings are installed and a set wind speed (10 m / s in this embodiment), the forces in the x and z directions of the mechanism's axis system are recorded. , ;

[0113] Under the conditions of installing the wings, setting the wind speed, and setting the flapping frequency (9 Hz in this embodiment), the forces in the x and z directions of the mechanism's axis system are recorded. , ;

[0114] Based on the data from the four records mentioned above, through calculation... , By removing the interference of gravity and wind resistance, the force generated by the flapping wing is calculated.

[0115] Then, based on the set angle of attack... Converting forces under the body axis into lift under the wind axis. and net thrust The wind axis system is defined as follows: its origin coincides with the origin of the body axis system; the x-axis is parallel to the direction of the wind tunnel flow and points towards the wind tunnel entrance; the z-axis is vertically upward; and the y-axis is in the same direction as the y-axis of the body axis system. Simply put, it is the body axis system rotated around its positive y-axis by an angle of attack. get. Figure 12 The figure shows the lift and net thrust values ​​measured in this embodiment of the invention. It illustrates the curves of lift and net thrust changing with time, where the average lift period is 201.5 g and the average net thrust period is 7.3 g.

[0116] While collecting lift and net thrust data, the battery output power and electronic speed controller output power are recorded via the electric power measurement unit, the motor speed is recorded via the motor speed measurement unit, and the rocker arm angle is recorded via the rocker arm angle measurement unit. The output voltage of the strain gauge circuit is recorded by the rocker arm torque measurement unit. . Figure 13 The graph shows the effective values ​​of motor line current and line voltage measured in this embodiment of the invention, illustrating the real-time changes in motor current and voltage.

[0117] The output voltage of the rocker arm torque measurement unit was collected. and rocker arm angle and obtain Then, the actual torque of the rocker arm is calculated using the above formula. , Figure 14 This is a diagram showing the measured rocker arm rotation angle and torque in an embodiment of the invention, illustrating the rocker arm rotation angle. and the calculated rocker arm torque A curve that changes over time.

[0118] All signals are acquired synchronously by data acquisition hardware and displayed and saved by host computer software.

[0119] Step S4: Calculate the motor output torque based on the obtained correspondence and the collected motor current and motor voltage.

[0120] The motor line current measured in step S3 and line voltage Substituting the corresponding relationship (motor model) obtained in step S2, the output torque of the motor in actual operation can be calculated. In this embodiment, Figure 15 This is a graph showing the measured motor torque and speed in an embodiment of the present invention.

[0121] Step S5: Based on the collected electrical power, motor speed, rocker arm angle, rocker arm torque, and calculated motor output torque, calculate the efficiency of each component, the overall efficiency, and the force efficiency of the power system of the flapping-wing aircraft under test.

[0122] First, calculate the instantaneous input power and output power of each component:

[0123] Electronic speed controller: The input power is the battery output power (directly measured by the power measurement unit), and the output power is the motor input power (the three-phase power on the output side of the electronic speed controller is measured by the power measurement unit).

[0124] Motor: Input power is the output power of the electronic speed controller, and output mechanical power is the motor output torque multiplied by the motor speed.

[0125] Flapping mechanism: The input power is the mechanical power output by the motor, and the output mechanical power is twice the rocker arm torque multiplied by the rocker arm speed (the rocker arm speed is obtained by the rocker arm angle difference).

[0126] Then, in a complete flapping wing motion cycle The instantaneous power is integrated and averaged to obtain the periodic average input power and periodic average output power of each component. Figure 16 The figures shown are power graphs measured in the embodiments of the present invention, including real-time curves of battery output power, electronic speed controller output power, motor output mechanical power, and flapping wing mechanism output mechanical power.

[0127] The efficiency of each component is calculated using the following formula:

[0128]

[0129] In the formula, Indicates the component number (electronic speed controller, motor, flapping wing mechanism). For the first The efficiency of each component For the first The instantaneous output power of each component, For the first The instantaneous input power of each component.

[0130] The overall efficiency of the power system is defined as the ratio of the periodic average output power of the flapping wing mechanism to the periodic average output power of the battery.

[0131] Force efficiency is divided into lift force efficiency. and net thrust efficiency Calculate using the following formulas respectively:

[0132]

[0133]

[0134] In the formula, and These are instantaneous lift and instantaneous net thrust, respectively. This refers to the instantaneous output power of the battery.

[0135] Based on the above measurement data, the average power per cycle of each component was calculated as follows: battery average output power 20.917 W, electronic speed controller average output power 20.321 W, motor average output power 14.676 W, and flapping wing mechanism average output power 9.434 W. Therefore, the efficiency of the electronic speed controller is 0.972, the motor efficiency is 0.722, the flapping wing mechanism efficiency is 0.643, the overall efficiency is 0.451, the lift efficiency is 9.634 g / W, and the net thrust efficiency is 0.349 g / W.

[0136] The measurement results of the above specific embodiments fully demonstrate that the present invention can comprehensively reveal the energy flow and loss of each component within the power system of a flapping-wing aircraft, providing designers with accurate quantitative data to guide the optimization and improvement of the power system. Furthermore, since the system and method do not depend on a specific motor type or flapping wing mechanism form, they possess good versatility and scalability for power systems using pure flapping wing mechanisms.

[0137] Finally, it should be noted that the features mentioned and / or shown in the above description of exemplary embodiments of the present invention can be combined in the same or similar manner with one or more other embodiments, combined with or substituted for corresponding features in other embodiments. These combined or substituted technical solutions should also be considered to be included within the scope of protection of the present invention.

Claims

1. A test system for the power system of an flapping-wing aircraft, characterized in that: It includes a wind tunnel testing platform, a signal measurement module, a motor characteristic testing platform, and a data acquisition and analysis module; The wind tunnel test platform has an installation interface for installing the power system of the flapping-wing aircraft under test, and is used to provide test conditions for the power system of the flapping-wing aircraft under test. The signal measurement module is used to connect to multiple measurement points of the power system of the flapping-wing aircraft under test, so as to collect the electrical and mechanical signals generated by the power system of the flapping-wing aircraft under test during operation, and convert the electrical and mechanical signals into voltage signals; The motor characteristic testing platform is set up independently of the wind tunnel test platform and is used to conduct offline testing of the motor in the power system of the flapping-wing aircraft under test. The motor characteristic testing platform has a motor mounting position for fixing the motor under test, a loading device for applying an adjustable load to the motor under test, and a measuring device for measuring the output torque, speed, line current and line voltage of the motor under test. The motor characteristic testing platform is used to output the correspondence between the output torque of the motor under test and the line current and line voltage. The data acquisition and analysis module is connected to the output terminal of the signal measurement module and the output terminal of the motor characteristic test platform, respectively. It is used to acquire the voltage signal and receive the corresponding relationship to calculate the output torque of the motor under test, and then analyze and obtain the component efficiency, overall efficiency and force efficiency of the power system of the flapping-wing aircraft under test.

2. The testing system according to claim 1, characterized in that, The signal measurement module includes: The electric power measurement unit is used to measure the battery output power and electronic speed controller output power of the power system of the flapping-wing aircraft under test. The motor current and voltage measurement unit is used to measure the line current and line voltage of the motor of the power system of the flapping-wing aircraft under test when it is running under wind tunnel test conditions. The motor speed measurement unit is used to measure the motor speed of the power system of the flapping-wing aircraft under test when it is running under wind tunnel test conditions. The rocker arm rotation angle measuring unit is used to measure the rotation angle of the rocker arm of the flapping wing mechanism in the power system of the flapping wing aircraft under test; The rocker arm torque measurement unit is used to measure the torque of the rocker arm of the flapping wing mechanism; The lift and net thrust measurement unit is used to measure the lift and net thrust generated by the flapping wing mechanism.

3. The testing system according to claim 2, characterized in that, The rocker arm torque measurement unit includes strain gauges attached to the rocker arm and a double-arm half-bridge measurement circuit connected to the strain gauges.

4. The testing system according to claim 1, characterized in that, The data acquisition and analysis module includes data acquisition hardware, host computer software, and data post-processing program. The data acquisition hardware includes a data acquisition card. The host computer software is used to display and save the acquired signals. The data post-processing program is used to analyze and calculate the signals saved by the host computer software to obtain various characteristics of the power system of the flapping-wing aircraft under test.

5. A method for testing the power system of an flapping-wing aircraft based on the test system according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Install the power system of the flapping-wing aircraft under test onto the mounting interface of the wind tunnel test platform; Step 2: Use the motor characteristic testing platform to obtain the correspondence between the output torque of the motor under test and the line current and line voltage; Step 3: Synchronously collect the electrical power, motor current, motor voltage, motor speed, rocker arm angle, rocker arm torque, lift and net thrust of the power system of the flapping-wing aircraft under test during operation through the signal measurement module; Step 4: Calculate the motor output torque based on the aforementioned correspondence and the collected motor current and motor voltage. Step 5: Based on the collected electrical power, motor speed, rocker arm angle, rocker arm torque, and calculated motor output torque, calculate the efficiency of each component, the overall efficiency, and the force efficiency of the power system of the tested flapping-wing aircraft.

6. The test method according to claim 5, characterized in that, Step 2 specifically includes: The motor to be tested is fixed in the motor mounting position; The loading device applies multiple different load torques to the motor under test. The measuring device records the output torque, speed, line current, and line voltage under each load torque. The relationship between output torque and line current and line voltage was obtained by fitting the recorded data.

7. The test method according to claim 5, characterized in that, Before acquiring the rocker arm torque in step 3, the process also includes calibrating the rocker arm torque measurement unit, specifically including: Adjust the rocker arm to a horizontal position and restrict its rotation; A weight is suspended on the rocker arm for loading, and the output voltage of the rocker arm torque measurement unit is recorded at different loading positions. The flapping wing mechanism was reversed, and weights were suspended on the rocker arm again for loading. The output voltage of the rocker arm torque measurement unit was recorded at different loading positions. Based on the calibration data, the relationship between the actual torque and the output voltage when the rocker arm is horizontally upward and downward is fitted respectively.

8. The test method according to claim 5, characterized in that, Step 3, which involves collecting lift and net thrust, specifically includes: Set the angle of attack for the wind tunnel test platform; Record the forces in the x and z directions of the mechanism's axis system under conditions where no wings are installed and the wind speed is zero; Under the condition of installing the wing and zero wind speed, record the forces in the x and z directions of the mechanism's axis system; Record the forces in the x and z directions of the mechanism's axis system under the condition that the wings are not installed and the wind speed is set; Under the conditions of installing the wings, setting the wind speed, and setting the flapping frequency, record the forces in the x and z directions of the mechanism's axis system; Based on the data recorded in the four instances above, the force generated by the flapping wing was calculated. Based on the set angle of attack, the force generated by the flapping wing is converted into lift and net thrust.

9. The test method according to claim 5, characterized in that, The efficiency of each component in step 5 is calculated using the following formula: In the formula, Indicates the component number. For the first The efficiency of each component For flapping wing motion period; for electronic speed controller, For battery output power, This refers to the input power to the motor; for a motor, For the output power of the electronic speed controller, This is the product of the motor's output torque and its speed; for flapping wing mechanisms, It is the product of the motor output torque and the motor speed. It is twice the product of the rocker arm torque and the rocker arm speed.

10. The test method according to claim 5, characterized in that, The formula for calculating force efficiency in step 5 is: In the formula, and These are lift efficiency and net thrust efficiency, respectively. For the flapping wing motion period, and These are instantaneous lift and instantaneous net thrust, respectively. This refers to the instantaneous output power of the battery.

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