Helicopter vibration active control system actuator frequency anomaly detection and positioning method

Abstract

The present application belongs to the field of helicopter vibration active control, and relates to a method for detecting and positioning frequency abnormality of actuators of a helicopter vibration active control system. The method comprises the following steps: collecting vibration sensor data of each latter half period of n continuous control periods, and splicing the data into a measured matrix of n / 2 control periods; performing zero padding on the measured matrix of n / 2 control periods to obtain a matrix with a frequency resolution less than 0.1 Hz; performing FFT processing on the matrix to obtain an acceleration response amplitude and a frequency; comparing the frequency with a standard execution frequency f0 of actuators of the helicopter vibration active control system; and if the error between the two is greater than 0.1 Hz, it is considered that there is an actuator with abnormal execution output force frequency in the system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of helicopter vibration active control, and relates to a method for detecting and positioning frequency abnormalities of an actuator of a helicopter vibration active control system. BACKGROUND

[0002] The vibration problem of a helicopter has been an important technical bottleneck that has plagued and hindered the development of the helicopter. An excessive vibration environment can reduce the reliability of the use of on-board equipment, increase the fatigue of the pilot and passengers, and even cause structural damage and endanger the safety of the helicopter. The vibration control system is used to reduce the vibration of the helicopter body and improve the vibration environment of the on-board equipment and the pilot and passengers. After the vibration active control system is applied, a comfortable experience is often brought.

[0003] The vibration active control system includes an actuator, a controller, a sensor and the like. The controller is used to calculate and send an output force command, and the sensor is used to collect a vibration acceleration signal. The actuator serves as an execution mechanism and is responsible for outputting an actuating force of a certain frequency and amplitude calculated according to an adaptive control algorithm, so as to offset the vibration response generated by the transmission of the rotor load of the helicopter to the fuselage. It can be seen that the accuracy and response speed of the actuating force output by the actuator will directly affect the vibration reduction effect of the system. If the frequency or amplitude deviation of the actuating force output by the actuator is large, the system may diverge and even become a vibration exciter, and cannot play a vibration reduction effect.

[0004] In the present application, the actuator can be divided into a centrifugal actuator from the configuration angle. The centrifugal actuator adopts a direct current motor to drive an eccentric mass block as an output force component, so that the output force frequency of the actuator is determined by the rotating speed of the direct current motor. For a helicopter, the main vibration response borne by the body is generally of a fixed frequency, so that only the abnormal frequency detection needs to be performed for a certain specific frequency. The motor driving of the actuator generally adopts a PID control mode for driving. In order to execute quickly, some loops are often sacrificed, so that the outermost loop of the actuator control is open loop. Therefore, the target rotating speed of the execution is determined by the parameters and robustness of the control law, and the deviation of the execution frequency of the actuator cannot be identified from the inside of the actuator. The present application is an important supplementary detection means for the vibration active control system actuator in addition to the conventional detection of the internal circuit and signal of the actuator, and has high engineering practical value. SUMMARY

[0005] The purpose of the present application is to adopt a fast and efficient method to identify whether the output frequency of the actuator is abnormal by judging the response characteristics of the signal collected by the sensor after the execution of the actuator. Meanwhile, for the case that multiple actuators exist in the vibration active control system, the execution problems of one or several actuators can also be accurately judged.

[0006] The technical solution of the present application is:

[0007] A method for detecting and locating abnormal actuator frequencies in a helicopter vibration active control system, comprising:

[0008] Vibration sensor data are collected for the second half of each of n consecutive control cycles and spliced ​​together to form a measured matrix for n / 2 control cycles.

[0009] Zero-padding is performed on a segment of the measured matrix spanning n / 2 control cycles to obtain a matrix with a frequency resolution less than 0.1 Hz. FFT processing is then applied to this matrix to obtain the acceleration response amplitude and frequency.

[0010] Will Compared with the standard execution frequency f0 of the actuator in the active vibration control system of a helicopter,

[0011] If the error between the two is greater than 0.1Hz, it is considered that there is an actuator in the system with an abnormal frequency of output force.

[0012] The method further includes:

[0013] Obtain the desired output force F sent by the system to the actuator. (2m×1) m is the number of actuators;

[0014] Obtain the transfer function matrix T of the system from the actuator to the sensor. (2k×2m) k is the number of sensors;

[0015] Based on the transfer function matrix T (2k×2m) Calculate the response Z of the actuator at the sensor under the desired output force. 0(2k×1) This allows us to obtain the desired phase value at each sensor; the desired output force is given in advance.

[0016] The measured matrix is ​​processed by DFT, and the average value is taken to obtain the measured phase value at each sensor.

[0017] Take the absolute value of the difference between the expected phase value and the measured phase value at the sensor.

[0018] Based on the transfer function matrix T (2k×2m) The absolute value is used to calculate the evaluation value for each actuator;

[0019] If the evaluation value of the i-th actuator is greater than 2π×0.1 / f0, then the frequency of the i-th actuator is found to be abnormal.

[0020] The method further includes:

[0021] The positioning results are verified based on the measured matrix and the transfer matrix.

[0022] According to the measured matrix and the transfer matrix, the positioning result of this time is checked, including:

[0023] According to the checking formula, the actual actuator output force is calculated The checking formula is: The measured matrix is;

[0024] The correlation analysis is performed on and F (2m×1) According to the actuator number, if the correlation of the corresponding actuator number is less than the preset threshold, it is checked that there is no error, and the actuator is the output force frequency anomaly.

[0025] The preferred value of n is 4.

[0026] The frequency resolution of the matrix is 0.05Hz.

[0027] Z 0(2k×1) =T (2k×2m)× F (2m×1) .

[0028] The helicopter vibration active control system actuator frequency anomaly detection and positioning method has the advantages that the vibration active control system actuator frequency anomaly can be quickly and accurately identified, and the actuator position can be accurately positioned. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The helicopter vibration active control system actuator frequency anomaly detection and positioning method has the advantages that the vibration active control system actuator frequency anomaly can be quickly and accurately identified, and the actuator position can be accurately positioned. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0031] The method is applied to detect the vibration active control system actuator output force frequency anomaly, and position the abnormal output actuator number, and its essence is to realize by comparing the angle deviation of the actual output force signal of each actuator and the expected output force signal in the force stable output section (generally considered in the second half of the control cycle, the actuator adjustment process needs to be discarded) in the whole control cycle. As shown in the formula (1), the implementation process is as follows: Figure 1

[0032] ​The sampling rate of the vibration sensor for general control is set to 1024 Hz, and the vibration sensor data of the last half of each control cycle length of 4 control cycles, i.e. the data of the stable stage of the actuator output, is collected and spliced into a real measured matrix for subsequent processing. For example, if the control cycle is 1 s, 0.5 s of data is taken respectively, and a total of 2 s of data length is spliced;

[0033] The collected data is subjected to FFT (Fast Fourier Transform) processing to obtain the acceleration response amplitude frequency To obtain accurate frequency values, the data needs to be zero-padded before FFT to lengthen the data length to 20 s, ensuring a frequency resolution of 0.05 Hz;

[0034] The signal frequency obtained is compared with the standard execution frequency f0 of the actuator of the vibration active control system. If the error exceeds 0.1 Hz, it is considered that the execution output force frequency of one or more actuators in the system is abnormal;

[0035] The control instruction sent by the system to the actuator is

[0036] F (2m×1) =[F 1c , F 1s , F 2c , F 2s , …, F mc , F ms ] 1)

[0037] The transfer function matrix of the system from the actuator to the sensor is

[0038]

[0039] The response of the actuator at the sensor under the expected output force is calculated by the formula Z = T x F

[0040] Z 0(2k×1) =[Z 01c , Z 01s , Z 02c , Z 02s , …, Z 0kc , Z 0ks ] T 3)

[0041] The expected phase value at each sensor is obtained from Z 0(2k×1)

[0042] θ 0(2k×1) =[θ 01 , θ 02 , …, θ 0k ​] T 4)

[0043] Respectively, the collected 4 data are processed by DFT (Discrete Fourier Transform) to obtain the phase value of each data segment, and the average value is obtained

[0044] θ 1(2k×1) =[θ 11 ,θ 12 …,θ 1k ] T 5)

[0045] The phase value θ 0(2k×1) in 4) and 5) is subtracted from θ 1(2k×1) to obtain the absolute value

[0046]

[0047] From θ and θ , the deviation value of the phase of the actual output force can be obtained by the formula Where T -1 is the actual output force of the actuator

[0048]

[0049] If

[0050] The positioning of the actuator frequency anomaly corresponding to the i number.

[0051] Usually, to accurately locate the abnormal frequency actuator number, it should also be checked

[0052] From θ , the actual actuator output force obtained by the vibration response inversion can be obtained The matrix correlation analysis of F and F in 4) is carried out, if the correlation of the corresponding actuator number is less than 0.9, the actuator is abnormal in output force frequency, otherwise, the actuator position determination result should be discarded, and only the actuator frequency abnormality fault is reported.

[0053] The above is only a specific embodiment of the present application, which is described in detail, and the part not described is a conventional technology. However, the protection scope of the present application is not limited to this, any change or replacement that can be easily thought of by those skilled in the art within the technical range disclosed by the present application should be covered in the protection scope of the present application. The protection scope of the present application should be subject to the protection scope of the claims.​

Claims

1. A method for detecting and locating abnormal actuator frequencies in a helicopter vibration active control system, characterized in that, include: Vibration sensor data are collected for the second half of each of n consecutive control cycles and spliced ​​together to form a measured matrix for n / 2 control cycles. Zero-padding is performed on a segment of the measured matrix spanning n / 2 control cycles to obtain a matrix with a frequency resolution less than 0.1 Hz. FFT processing is then applied to this matrix to obtain the acceleration response amplitude and frequency. ; Will Compared to the standard execution frequency φ0 of the helicopter vibration active control system actuator, If the error between the two is greater than 0.1Hz, it is considered that there is an actuator in the system with an abnormal frequency of output force.

2. The method according to claim 1, characterized in that, The method further includes: Obtain the desired output force sent by the system to the actuator. F (2m×1) m is the number of actuators; Obtain the transfer function matrix T of the system from the actuator to the sensor. (2k×2m) k is the number of sensors; Based on the transfer function matrix T (2k×2m) Calculate the response Z of the actuator at the sensor under the desired output force. 0(2k×1) This allows us to obtain the desired phase value at each sensor; the desired output force is given in advance. The measured matrix is ​​processed by DFT, and the average value is taken to obtain the measured phase value at each sensor. Take the absolute value of the difference between the expected phase value and the measured phase value at the sensor. Based on the transfer function matrix T (2k×2m) The absolute value is used to calculate the evaluation value for each actuator; If the evaluation value of the i-th actuator is greater than 2π×0.1 / f If the value is 0, then the frequency of the i-th actuator is abnormal.

3. The method according to claim 2, characterized in that, The method further includes: The positioning results are verified based on the measured matrix and the transfer matrix.

4. The method according to claim 3, characterized in that, Based on the measured matrix and the transfer matrix, the positioning results are verified, including: Calculate the actual actuator output force based on the verification formula. The verification formula is: ; This is the measured matrix; right and F (2m×1) If a correlation analysis is performed based on the actuator number, and the correlation of the corresponding actuator number is less than the preset threshold, then the verification is correct, and the actuator is indeed abnormal in output force frequency.

5. The method according to claim 1, characterized in that, The frequency resolution of this matrix is ​​0.05 Hz.

6. The method according to claim 2, characterized in that, Z 0(2k×1) = T (2k×2m)× F (2m×1) 。 7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1-6.

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