A stability test method for a helicopter hub top-mounted active vibration control system

Abstract

The application provides a stability test method for a helicopter hub top-mounted vibration active control system. The method comprises the following steps: determining a stability test item, wherein the stability test item comprises a constant-speed system stability test, a variable-speed system stability test, a dangerous-speed-range stability test and an actuator power-off stability test. The constant-speed system stability test is used to simulate a constant-speed working state of a helicopter hub and to check whether the hub top-mounted vibration active control system is stable. The variable-speed system stability test is used to simulate a variable-speed working state of the helicopter hub and to check whether the hub top-mounted vibration active control system is stable. The dangerous-speed-range stability test is used to obtain an inherent frequency of a coupled rotor system formed after the hub top-mounted vibration active control system is installed on a test device and to check whether the coupled rotor system is stable when passing through the inherent frequency. The actuator power-off stability test is used to simulate an actuator power-off fault and to check whether the hub top-mounted vibration active control system is stable. The method can effectively check the stability of the hub top-mounted vibration active control system.

Description

Technical Field

[0001] This invention belongs to the field of active vibration control technology for helicopters, specifically relating to a stability test method for an active vibration control system for a helicopter rotor hub. Background Technology

[0002] Vibration active control based on rotor hub top is an advanced technology in the international helicopter field. It targets the vibration source rotor hub to reduce vibration and "counteracts vibration with vibration", which can comprehensively reduce the vibration load transmitted to the fuselage.

[0003] Since the system's actuators are mounted on the helicopter rotor hub and rotate with it, it is necessary to conduct system stability tests to study the system's impact on the overall aircraft safety. Conducting stability tests before performing vibration reduction tests on the rotor hub-mounted vibration control system is a crucial step in the development of this active vibration control system and a necessary prerequisite for successful vibration control.

[0004] Regarding rotor system stability testing methods, publicly available information shows that stability testing relies on a single speed frequency sweep without considering load conditions. For the rotor hub top vibration active control system, there is no complete and scientific stability testing method yet, and it is necessary to develop a targeted stability testing method.

[0005] CN119512025A discloses a test device and method for active vibration control based on a top-mounted propeller hub. It outlines the test device and method, including the system interface, components, and basic testing procedures. However, it does not specify detailed stability testing procedures for system stability assessment, nor does it address the criteria for system stability judgment. Summary of the Invention

[0006] The purpose of this invention is to provide a stability test method for an active vibration control system for a helicopter rotor hub, focusing on solving the following key problems: how to determine the stability test items, how to determine the external excitation and operating conditions, and how to define the system stability criteria.

[0007] To address the aforementioned technical issues, a stability testing method for a helicopter rotor hub-top vibration active control system is proposed. This method utilizes a rotor hub-top-based vibration active control testing device as described in patent application CN119512025A, and includes the following steps:

[0008] Step 1: Install the active vibration control system for the top of the propeller hub to be tested onto the test bench in the test apparatus;

[0009] Step 2: Confirm the test conditions, which include the test site environment, whether the test equipment is qualified, and the functional check of the test equipment;

[0010] Step 3: Determine the stability test items based on the principle of comprehensively covering the working state of the helicopter rotor hub. The stability test items include constant speed system stability test (used to simulate the helicopter rotor hub's constant speed working state and assess whether the rotor hub top vibration active control system is stable), variable speed system stability test (used to simulate the helicopter rotor hub's variable speed working state and assess whether the rotor hub top vibration active control system is stable), speed danger zone stability test (conducting this test can obtain the main natural frequency of the rotor hub top vibration active control system after it is installed on the test bench and assess whether the rotor hub top vibration active control system is stable when passing through the natural frequency), and actuator power failure stability test (used to simulate the actuator power failure and assess whether the rotor hub top vibration active control system is stable). The above test items can simulate the main speed states that the rotor hub top vibration active control system may face after it is installed on the helicopter rotor hub. Assessing its stability is an important prerequisite for ensuring system safety.

[0011] Step 4: Conduct the constant speed system stability test, variable speed system stability test, speed danger zone stability test, and actuator power-off stability test according to the stability test items determined in Step 3, and record the test data;

[0012] Step 5: Perform comprehensive processing and analysis on the test data of each test item obtained in Step 4, and evaluate the overall stability of the rotor top vibration active control system based on the test data of each test item.

[0013] In one possible embodiment, in step two, the test site environment is free of obvious obstructions, and a metal protective net is set up within a 2-meter radius of the test bench for installing the hub-top vibration active control system to be tested. The protective net is higher than the height of the hub-top vibration active control system to be tested after installation.

[0014] In one possible embodiment, in step two, the testing device has been verified and qualified by the metrology department and is within the qualification period.

[0015] In one possible embodiment, in step four, the test data for each test item includes test bench base vibration data and test bench shaft rotation speed data. The base vibration is collected by a base vibration sensor and is the main data used in the system stability discrimination formula. The shaft rotation speed is collected by a rotation speed sensor and is used to record the system rotation speed state.

[0016] In one possible embodiment, step four of the constant speed system stability test specifically includes the following steps:

[0017] The actuator of the active vibration control system for the top-mounted rotor hub under test is not started, but the exciter is started. The test state is set according to the test state table, and the test state includes shaft speed, loading frequency, and horizontal loading amplitude. Vertical loading amplitude Test and record experimental data under each experimental condition;

[0018] The shaft rotation speed includes the rated speed, the ground idle speed, and the critical speed of the hub-top vibration active control system.

[0019] The rated speed refers to 100% of the rated speed of the helicopter main rotor shaft;

[0020] The ground-stable speed refers to the stable operating speed of the helicopter main rotor shaft on the ground.

[0021] The critical speed of the rotor hub top vibration active control system refers to the resonance phenomenon that occurs when the shaft speed reaches the critical speed, and the vibration amplitude of the test bench increases rapidly. Numerically, the critical speed corresponds to the modal natural frequency of the rotor hub top vibration active control system.

[0022] The loading frequency refers to the operating frequency of the exciter in the test device;

[0023] Horizontal loading amplitude Vertical loading amplitude The calculation formula is , ,in, The x-axis load component is located at the center of the helicopter rotor hub. This refers to the y-axis rotor load component at the center of the helicopter rotor hub, which is obtained through simulation evaluation or helicopter testing. The weight of the test bench installed for the rotor hub top-mounted vibration active control system. The normal weight of the helicopter is used, and the load amplitude is equal to the helicopter rotor hub load amplitude.

[0024] To observe the stability of the system under constant speed conditions, and considering the large vibration near the critical speed, the test bench shaft is required to run at a stable speed for 5 to 10 seconds in each test condition, and the test data are recorded.

[0025] In one possible embodiment, step four of the transmission system stability test specifically includes the following steps:

[0026] Start the actuator, start the vibrator, set the test state according to the test state table, test and record the test data under each test state;

[0027] Within a 20% range before and after the rated speed and the ground idle speed, the vibration active control system follows the speed change and provides real-time control.

[0028] The load amplitude is the horizontal load amplitude. Vertical loading amplitude It is determined according to the following process;

[0029] Horizontal loading amplitude Vertical loading amplitude The calculation formula is , ,in, The x-axis load component is located at the center of the helicopter rotor hub. This refers to the y-axis rotor load component at the center of the helicopter rotor hub, which is obtained through simulation evaluation or helicopter testing. The weight of the test bench installed for the rotor hub top-mounted vibration active control system. The normal weight of the helicopter is used, and the load amplitude is equal to the helicopter rotor hub load amplitude.

[0030] The required change time of the test bench shaft speed in each state is determined according to the actual time of helicopter state switching, with a time range of approximately 5 to 10 seconds.

[0031] In one possible embodiment, step four, the speed danger zone stability test specifically includes the following steps:

[0032] If the actuator and exciter do not start, conduct a speed-up and speed-down frequency sweep test and record the test data.

[0033] This experiment can obtain the modal natural frequencies of the active vibration control system at the top of the propeller hub after it is installed on the test bench. The modal natural frequencies of the system refer to the resonance phenomenon in which the vibration amplitude of the test bench increases rapidly when a certain speed is reached during the steady increase or decrease of the shaft speed. This speed is the critical speed of the system and corresponds to the modal natural frequency of the system.

[0034] The required speed change time within the specified speed range is 90 seconds.

[0035] In one possible embodiment, step four, the actuator power-off stability test, specifically includes the following steps:

[0036] The actuator starts, the exciter starts, and under steady-state conditions at each speed, the actuator changes from the working state to the power-off state. Test and record the test data.

[0037] Based on the actual power failure of the actuator, the actuator speed switching time for each state should be less than 3 seconds.

[0038] In one possible embodiment, the actuator power-off stability test further includes recording the position of the actuator eccentric mass block before and after the power failure.

[0039] Calculate the included angle of the eccentric mass block using the actuator before and after power failure. The included angle is calculated within the range of 0 to 180°; it can be observed whether the actuator can maintain stability when it suddenly loses power and rotates with the shaft; the judgment criterion is: when The actuator is self-stabilizing; when The eccentric mass block of the actuator will generate eccentric excitation on the propeller hub platform, and the stability of the actuator needs to be addressed as a key concern.

[0040] In one possible embodiment, in step four, a safety inspection is carried out before each test. The inspection items include the debugging of the hub load simulation loading system, the coordination and function check of the rotor structure in non-rotating state, and the coordination and function check of the rotor structure in rotating state.

[0041] The specific debugging of the rotor hub load simulation loading system includes: debugging and checking the maximum stroke, repeatability, and linear velocity of the rotor hub load simulation loading system; checking the excitation amplitude and excitation force range of the rotor hub load simulation loading system, ensuring that the frequency and excitation force amplitude range meet the test requirements, and checking for interference and jamming phenomena; and checking the coordinated loading function of the rotor hub load simulation loading system.

[0042] The non-rotating rotor structure coordination and functional inspection specifically refers to: loading the rotor hub within the simulated load range on the test bench and checking for abnormal deformation, component interference, or other phenomena within the load range; manually rotating the rotor shaft to check for structural interference, minimum clearance between adjacent components, and motion coordination;

[0043] The rotor structure coordination and function check in the rotating state specifically refers to: checking for abnormal vibration or abnormal noise when the rotating shaft is rotating; and checking for interference, functional coordination, and whether the fasteners are loose after the rotating shaft stops rotating.

[0044] In one possible embodiment, the stability of the rotor hub top vibration active control system in step five means that the stability of the rotor hub top vibration active control system refers to the system's ability to follow the control system's instructions, reach the specified rotational speed through the shaft, or reach the specified output force through the rotor hub actuator under the set test conditions, without excessive vibration during the process and the dwell phase, and to resist the disturbance and remain stable when encountering excitation disturbance.

[0045] In one possible embodiment, in step five, the system stability judgment condition...

[0046] Wherein, S is the system stability coefficient proposed in this invention. The vibration amplitude of the test bench base in the recorded test data. This represents the average amplitude of the data segment. and The unit is acceleration in m / s². 2 , n is the number of test data points, and s0 is the stability coefficient under the maximum allowable speed and maximum excitation load conditions when the test bench is not equipped with the top-mounted vibration active control system.

[0047] In summary, the beneficial effects of the present invention are as follows:

[0048] This invention proposes a stability testing method for a helicopter rotor hub-top vibration active control system. It clarifies the stability test items, establishes principles for determining external excitation and operating conditions, proposes system stability evaluation criteria, and plans a rigorous and comprehensive test procedure, effectively assessing the stability of the rotor hub-top vibration active control system. The test system established on the test bench constructs the coupled stability relationship between the rotor hub-top vibration active control system, the test bench, and the exciter. It can simulate helicopter ground slowness and flight conditions on the test bench, simulating the effects of different speeds, rapid speed changes, and actuator power failure on the stability of the test system. This allows for early verification of the stability of the rotor hub-top vibration active control system under different operating conditions after installation on a helicopter. This is an essential test during the laboratory development phase of the rotor hub-top vibration active control system, laying the foundation for the system's installation and development phase. Attached Figure Description

[0049] Figure 1 This is a flowchart of a preferred embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram of the test apparatus according to a preferred embodiment of the present invention. Detailed Implementation

[0051] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0052] like Figure 1 As shown, a stability test method for an active vibration control system for a helicopter rotor hub is presented. The method includes the following steps:

[0053] S1. Preparation of instruments required for the test: including a hub load simulation loading system, a data acquisition and integrated monitoring system, a vibration acceleration sensor, a speed sensor, and a bilinear pendulum test bench; among which, the vibration acceleration sensor should be installed on the horizontal support of the bilinear pendulum test bench, and the speed sensor should be installed close to the test bench's rotating shaft;

[0054] S2, Test conditions and requirements for test pieces

[0055] S2-1, The test site should be free of obvious obstructions. A metal protective net should be installed within a 2-meter radius of the test bench. The protective net should be higher than the height of the test piece after installation.

[0056] S2-2, The test bench and testing instruments have been verified and qualified by the metrology department and are within the qualification period.

[0057] S2-3, Safety inspections are conducted before the test. The inspection items include the debugging of the rotor hub load simulation loading system, the coordination and function check of the rotor structure in non-rotating state, and the coordination and function check of the rotor structure in rotating state.

[0058] S2-4, the test specimen is a hub-mounted vibration active control system, including one hub actuator (including a driver), one slip ring, DC power supply, etc. Installation diagram is attached. Figure 2 As shown.

[0059] S2-5, all components included in the test piece are within the warranty period and have passed the inspection.

[0060] S-3, Determine the stability test items

[0061] The stability test project needs to cover the working state of the helicopter rotor hub, the actual working state of the rotor hub top vibration active control system, and the possible failure modes of the system.

[0062] S-4 conducts key project trials

[0063] S4-1, Stability Test of Constant Speed ​​System

[0064] S4-1-1, Actuator not started, exciter started. Test states are set according to Table 1. Test states need to include the helicopter's operating state, i.e., rated speed and ground idle speed. Additionally, considering the stability of the rotor hub-top vibration active control system near the critical speed, states 3 and 4 are set in this test. Specifically, the calculation formula for the load amplitude of the load loading system in each state is: where... ， , The x-axis load component at the center of the rotor hub of the background model helicopter. This refers to the y-axis rotor load component at the center of the helicopter rotor hub, which is obtained through simulation evaluation or helicopter testing. The weight of the test bench installed for the rotor hub top-mounted vibration active control system. The normal weight of the background model helicopter is given. When this system is installed on the background model helicopter, the load amplitude is equal to the helicopter rotor hub load amplitude.

[0065] S4-1-2, to observe the stability of the system in constant speed state, while considering the large vibration near the critical speed, the test bench shaft is required to run at a stable speed for 5 to 10 seconds in each state, and the test data is recorded.

[0066] Table 1. Stability Test Status Table of Constant Speed ​​System

[0067] S4-2, Transmission System Stability Test

[0068] S4-2-1, Actuator starts, exciter starts, set the test state according to Table 2. The test state is determined based on the following: In actual helicopter operation, within a 20% range before and after the rated speed and ground speed, the vibration active control system follows the speed change and controls in real time. The system should not experience stability problems.

[0069] S4-2-2, the required time for the test bench shaft speed change in each state is determined according to the actual time of helicopter state switching, approximately 5 to 10 seconds, and the test data is recorded.

[0070] Table 2. Stability Test Status of Transmission System

[0071] S4-3, Stability test in the hazardous speed zone

[0072] S4-3-1, Response test of the rotor speed through the critical speed of the rotor hub top vibration active control system. The actuator and exciter are not started. A speed-up / down frequency sweep test is conducted, and the test data is measured and recorded. This test obtains the main natural frequencies of the rotor hub top vibration active control system after it is installed on the test bench.

[0073] Table 3. Stability Test Status of Transmission System

[0074] S4-3-2 requires that the time for changing the speed within the speed range be 90s, and the test data be recorded.

[0075] S4-4, Actuator power-off stability test

[0076] S4-4-1, Actuator starts, vibrator starts, set the test state according to Table 4.

[0077] Table 4. Actuator Power-Off Stability Test Status Table

[0078] S4-4-2, based on the actual power failure of the actuator, the actuator speed switching time for each state must be less than 3 seconds. Record the test data. A key parameter added to this test is recording the position of the actuator's eccentric mass block before and after the power failure. Specifically, in this test, the included angle of the eccentric mass block is calculated using the position of the eccentric mass block before and after the power failure. The included angle is calculated to be within the range of 0 to 180°. It can be observed whether the actuator can maintain stability while rotating along the shaft after a sudden power outage. Judgment criterion: When... The actuator is self-stabilizing; when The eccentric mass block of the actuator will generate eccentric excitation on the propeller hub platform, and the stability of the actuator needs to be addressed as a key concern.

[0079] S5 performs comprehensive processing and analysis of the collected test data for each state, and evaluates the overall stability of the rotor hub top vibration active control system based on the results. The test data recorded under each test state includes the vibration of the test bench base and the rotational speed of the test bench shaft.

[0080] As a preferred embodiment of the above scheme, in step S1, the hub load simulation loading system consists of a hydraulically driven actuator and its operating system, which can apply the required vibration load to the shaft according to a given frequency and load spectrum. Main technical specifications: Number of actuators ≥ 2; Rated working pressure of actuator P = 21 MPa.

[0081] Frequency range ≥30Hz; excitation frequency: 0-30Hz; frequency accuracy: 0.05Hz; excitation force ≥2000N;

[0082] More preferably, in step S1, the data acquisition and integrated monitoring system has 96 acquisition and processing channels, an operating temperature of -10 to 55°C, a channel accuracy of 0.1%, a maximum sampling frequency of 10kHz, and is required to perform continuous synchronous acquisition, process and monitor key parameters in real time, display the parameters that need to be monitored in real time, and achieve a 100% inspection rate for the test instruments.

[0083] More preferably, in step S1, the vibration acceleration sensor has a range of not less than 5g and a measurement accuracy of ±3%.

[0084] As a preferred embodiment of the above scheme, the debugging of the rotor hub load simulation loading system in steps S2-3 specifically includes: debugging and checking the maximum stroke, repeatability, positioning accuracy, and linear velocity of the rotor hub load simulation loading system; checking the excitation amplitude and excitation force range of the rotor hub load simulation loading system, ensuring that the frequency and excitation force amplitude range meet the test requirements, and checking for interference and jamming phenomena; and checking the coordinated loading function of the rotor hub load simulation loading system.

[0085] Further preferably, in steps S2-3, the non-rotating rotor structure coordination and functional check specifically refers to: loading within the simulated load range of the rotor hub on the test bench, and checking for abnormal deformation, component interference, or other phenomena within the load range. Manually rotating the shaft is then performed to check for structural interference, the minimum clearance between adjacent components, and motion coordination.

[0086] More preferably, in step S2-3, the rotor structure coordination and function check in the rotating state specifically refers to: when the rotating shaft is rotating, checking for abnormal vibration or abnormal noise; after the rotating shaft stops rotating, checking for interference, functional coordination, and whether the fasteners are loose.

[0087] As a preferred embodiment of the above scheme, in step S5, the stability of the rotor hub top vibration active control system means that, under the set test conditions, the system can follow the control system instructions to reach the specified speed through the rotating shaft or the specified output force through the rotor hub actuator, without excessive vibration during the process and the dwell phase, and the system can resist the disturbance and maintain stability when encountering excitation disturbance.

[0088] More preferably, in step S5, the system stability judgment condition ,

[0089] Wherein, S is the system stability coefficient proposed in this invention. The vibration amplitude of the test bench base in the recorded test data. This represents the average amplitude of the data segment. and The unit is acceleration in m / s². 2 , n is the number of test data points, and s0 is the stability coefficient under the maximum allowable speed and maximum excitation load conditions when the test bench is not equipped with the top-mounted vibration active control system.

Claims

1. A stability test method for a helicopter rotor hub top-mounted vibration active control system, characterized in that, include: The stability test items are determined as follows: Constant speed system stability test, used to simulate the helicopter rotor hub operating at a constant speed, to assess the stability of the rotor hub top vibration active control system; variable speed system stability test, used to simulate the helicopter rotor hub operating at varying speeds, to assess the stability of the rotor hub top vibration active control system; speed danger zone stability test, used to obtain the natural frequency of the rotor hub top vibration active control system after it is installed in the test device, and to assess its stability when passing through the natural frequency; actuator power failure stability test, used to simulate the actuator power failure, to assess the stability of the rotor hub top vibration active control system; external excitation and operating conditions are determined: the test states for each test item are proposed, and the load amplitude calculation formula for the load loading system under each test state is given; the stability definition and stability judgment conditions of the rotor hub top vibration active control system are proposed. The stability of the rotor hub top vibration active control system refers to the system's ability to follow the control system commands to reach a specified speed or the actuator to reach a specified output force under the set test conditions, without excessive vibration during this process, and the system's ability to resist excitation disturbances and maintain stability.

2. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 1, characterized in that, It also includes the following steps: conducting stability tests, recording test data, and evaluating the overall stability of the hub-top vibration active control system based on the test data of each test project.

3. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 1, characterized in that, The stability test of the constant speed system specifically includes the following steps: The actuator of the active vibration control system for the rotor hub under test is not activated. The test conditions are set, including shaft speed, loading frequency, and horizontal loading amplitude. Vertical loading amplitude Test and record experimental data under each experimental condition; The shaft rotation speed includes the rated speed, the ground idle speed, and the critical speed of the hub-top vibration active control system. The rated speed refers to 100% of the rated speed of the helicopter main rotor shaft; The ground-stable speed refers to the stable operating speed of the helicopter main rotor shaft on the ground. The critical speed of the rotor top vibration active control system refers to the coupling system formed by the rotor top vibration active control test device. When the rotor speed reaches the critical speed, the coupling system exhibits a resonance phenomenon in which the vibration amplitude of the test bench increases rapidly. Numerically, the critical speed corresponds to the modal natural frequency of the coupling system. The loading frequency refers to the operating frequency of the exciter in the test device; Horizontal loading amplitude Vertical loading amplitude The calculation formula is , ,in, The x-axis load component is located at the center of the helicopter rotor hub. This refers to the y-axis rotor load component at the center of the helicopter rotor hub, which is obtained through simulation evaluation or helicopter testing. The weight of the test bench installed for the rotor hub top-mounted vibration active control system. The normal weight of the helicopter is used, and the load amplitude is equal to the helicopter rotor hub load amplitude. For each test condition, the test bench shaft is required to maintain a stable rotational speed for 5 to 10 seconds, and the test data should be recorded.

4. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 1, characterized in that, The stability test of the transmission system specifically includes the following steps: The actuator is started, the vibrator is started, the test state is set, and the test data is tested and recorded under each test state. Within a 20% range before and after the rated speed and the ground idle speed, the vibration active control system follows the speed change and controls it in real time; The required change time of the test bench shaft speed in each state is determined according to the actual time of helicopter state switching, with a time range of approximately 5 to 10 seconds.

5. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 1, characterized in that, The stability test in the dangerous speed zone specifically includes the following steps: If the actuator and exciter do not start, conduct a speed-up and speed-down frequency sweep test and record the test data. This test can obtain the modal natural frequencies of the active vibration control system installed on the test bench. The modal natural frequencies of the active vibration control system refer to the resonance phenomenon that occurs when the test bench vibration amplitude rapidly increases when a certain speed is reached during the steady increase or decrease of the shaft speed. This speed is the critical speed of the system and corresponds to the modal natural frequency of the system. The required speed change time within the specified speed range is 90 seconds.

6. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 1, characterized in that, The actuator power-off stability test specifically includes the following steps: The actuator starts, the exciter starts, and under steady-state conditions at each speed, the actuator changes from the working state to the power-off state. Test and record the test data. Based on the actual power failure of the actuator, the actuator speed switching time for each state should be less than 3 seconds.

7. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 1, characterized in that, The actuator power failure stability test also includes recording the position of the actuator eccentric mass block before and after power failure. Calculate the included angle of the eccentric mass block using the actuator before and after power failure. The included angle Calculate the range from 0 to 180°; observe whether the actuator can maintain stability when it suddenly loses power and rotates with the shaft; judgment criteria: when The actuator is self-stabilizing; when The eccentric mass block of the actuator will generate eccentric excitation on the propeller hub platform, and the stability of the actuator needs to be addressed as a key concern.

8. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 2, characterized in that, The overall stability of the rotor hub top vibration active control system was evaluated based on the test data from each test item, and the system stability judgment conditions were established. , Wherein, S is the system stability coefficient proposed in this invention. The vibration amplitude of the test bench base in the recorded test data. This represents the average amplitude of the data segment. and The unit is acceleration in m / s². 2 , n is the number of test data points, and s0 is the stability coefficient under the maximum allowable speed and maximum excitation load conditions when the test bench is not equipped with the top-mounted vibration active control system.

9. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 1, characterized in that, Safety inspections are conducted before each test, including debugging of the rotor hub load simulation loading system, checking the structural coordination and function of the rotor in non-rotating state, and checking the structural coordination and function of the rotor in rotating state.

10. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 9, characterized in that, The specific debugging of the rotor hub load simulation loading system includes: debugging and checking the maximum stroke, repeatability, positioning accuracy, and linear velocity of the rotor hub load simulation loading system; checking the excitation amplitude and excitation force range of the rotor hub load simulation loading system, ensuring that the frequency and excitation force amplitude range meet the test requirements, and checking for interference and jamming phenomena; and checking the coordinated loading function of the rotor hub load simulation loading system.

11. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 9, characterized in that, The non-rotating rotor structure coordination and function check specifically refers to: loading within the simulated load range of the rotor hub on the test bench, checking for abnormal deformation or interference of parts within the load range; manually rotating the shaft to check for structural interference, minimum clearance between adjacent components, and motion coordination.

12. The stability test method for a helicopter rotor hub top-mounted vibration active control system according to claim 9, characterized in that, The rotor structure coordination and function check in the rotating state specifically refers to: checking for abnormal vibration or abnormal noise when the rotating shaft is rotating; and checking for interference, functional coordination, and whether the fasteners are loose after the rotating shaft stops rotating.

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