Friction force identification method for trailing edge flap driving mechanism with bearing

Abstract

The invention provides a friction force identification method for a trailing edge flap driving mechanism with a bearing, and the method comprises the steps: applying a series of improved triangular waves with different speeds to a driver, carrying out the closed-loop control, carrying out the zero-phase digital filtering of a collected flap angle signal, and suppressing the interference of random noise to the signal, adjusting a buffeting phenomenon of a derivation step length inhibition speed to obtain a flap angular speed, then intercepting a constant-speed ascending section and a constant-speed descending section, then assigning a series of angular speeds, carrying out friction model identification on a relation between friction force and the speed, and then identifying a relation between parameters obtained by identification and a flap angle; finally, the friction force about the flap angle and the flap angular velocity in the flap driving mechanism is obtained.

Description

Technical Field

[0001] The present application belongs to the technical field of active control of trailing edge flap rotors, and in particular, relates to a friction force identification method for a trailing edge flap drive mechanism with a bearing. Background Art

[0002] The vibration and noise caused by the rotor are the main sources of vibration and noise during helicopter flight, which seriously affects the service life of instruments and meters and the comfort of passengers. Active trailing edge flap control (ACF), an active control technology for helicopter vibration and noise developed in the past decade, has become one of the current research hotspots. The ACF rotor drives the additional flap at the trailing edge of the blade to deflect according to a given law through an actuator, thereby changing the aerodynamic distribution of the rotor, thereby reducing the alternating load at the hub or suppressing the noise of the rotor disc, achieving the purpose of vibration reduction or noise reduction.

[0003] The trailing edge flap drive mechanism is generally located at the outer end of the blade and integrated into the box cavity formed by the blade airfoil. The flap driver is generally a piezoelectric actuator installed inside the blade, one end of which is fixed and the other end is connected to the trailing edge flap through a drive rod. The trailing edge flap is fixed to the blade through a bearing or a flexible mechanism. When working, the trailing edge flap is driven by voltage to perform a flapping motion at a given frequency (single frequency or multi-frequency). In the working state, the flap drive mechanism must withstand the huge centrifugal force caused by the rotation of the blade, and the flap flapping motion must also overcome complex aerodynamic loads.

[0004] In order to realize the flapping motion, the connection between the two ends of the driving connecting rod and the flap and the blade is often designed with spherical bearings, thrust bearings, ball bearings, self-lubricating bushing bearings, etc. When the flap is working with a sinusoidal excitation voltage, due to the existence of bearing friction, when the flap is flapping at a low frequency, the sinusoidal flapping motion waveform of the flap often has a flat top phenomenon at the wave crest, introducing undesirable frequency components such as 2nd and 3rd frequencies.

[0005] It is difficult to eliminate this phenomenon through control laws such as PID. Therefore, it is necessary to identify the friction in the flap drive mechanism. On the one hand, it can guide the design of the flap drive mechanism and minimize the influence of friction on the flap flapping motion. On the other hand, in the servo closed-loop control of the flap, a friction model based on identification can be introduced to compensate for the friction, reduce or eliminate the flat top phenomenon at the peak of the sine wave, and improve the control accuracy.

[0006] Different from conventional motor control based on speed control, the friction in motor speed control is generally only related to speed, and the load of the motor may also change randomly, but it is generally only a change in torque, and the normal force between the stator and the mover of the rotating parts does not change much. In the deflection movement of the trailing edge flap, the plane movement of the driver passes through the driving connecting rod and the flap's lever arm, and is converted into deflection movement, which also plays an amplifying role. The load of the flap generally changes with the change of angle, causing the normal force of the friction surface such as the bearings at both ends of the driving connecting rod to change.

[0007] Therefore, the friction force of the trailing edge flap drive mechanism with bearings is not only a function of the flap flapping speed, but also a function of the angle. In addition, due to the opposite direction of the friction force in the flap ascending section (positive speed) and the descending section (negative speed), the flap driving force will change suddenly, so that the friction model parameters of the positive speed and negative speed will also be very different.

[0008] In addition, unlike the continuous rotation of loads such as motors, the flapping motion of the flap is a reciprocating motion, which makes it difficult to implement conventional friction identification based on constant speed tracking in the flap flapping motion. Summary of the invention

[0009] Purpose of the invention: A method for identifying the friction force of a trailing edge flap drive mechanism with a bearing is proposed, aiming to provide an identification method for the friction force that varies with angle and angular velocity under reciprocating motion.

[0010] The present application provides a method for identifying friction force of a trailing edge flap drive mechanism with a bearing, the method comprising:

[0011] According to the angle range and deflection frequency of the flap deflection according to the sine law, the angular velocity range of the theoretical flap deflection is calculated;

[0012] According to the angular velocity range of the theoretical flap deflection, an improved triangular wave is used to apply excitation to the flap drive mechanism, and a PI closed-loop control is adopted to obtain a series of flap angle response signals and PI control output signals under positive and negative flap deflection speeds;

[0013] selecting a cutoff frequency based on the flap angle response signal;

[0014] Using a 0-phase digital low-pass filter to filter the flap angle response signal according to the cutoff frequency to obtain a filtered flap angle response signal;

[0015] Selecting a derivation step length, and using the derivation step length to derive the filtered flap angle response signal to obtain an angular velocity of actual flap deflection;

[0016] According to the angular velocity of the actual flap deflection, intercepting the uniform ascending segment and descending segment signals in the filtered response signal and the corresponding PI control output signals;

[0017] Fitting the uniform speed ascending segment and descending segment signals with the PI control output signal to obtain the relationship between the uniform speed ascending segment and descending segment signals and the PI control output signal;

[0018] Based on the relationship between the uniform speed ascending section and descending section signals and the PI control output signal, the stiffness and friction force of the flap elastic load are obtained.

[0019] Preferably, the method further comprises:

[0020] Selecting a friction model based on a curve of the friction force changing with the angular velocity of the actual flap deflection;

[0021] Based on the friction model, the relationship between the friction force and the angular velocity of the actual flap deflection is identified.

[0022] Preferably, the method further comprises:

[0023] Based on the relationship between the friction force and the actual angular velocity of the flap deflection, the relationship between the friction force and the actual flap deflection angle and the actual angular velocity of the flap deflection is identified.

[0024] Preferably, the angular velocity range of theoretical flap deflection is calculated based on the angle range and deflection frequency of the flap deflected according to the sinusoidal law, including:

[0025] Obtain the deflection frequency of the flap deflected according to the sine law, the flap angle offset and the amplitude of the flap sinusoidal motion;

[0026] The circular frequency of the flap is calculated according to the deflection frequency of the flap deflected according to the sinusoidal law;

[0027] Calculating a theoretical flap deflection angle based on the flap circular frequency, the flap angle offset and the amplitude of the flap sinusoidal motion;

[0028] Based on the theoretical flap deflection angle, an angular velocity range of the theoretical flap deflection is obtained.

[0029] Preferably, the improved triangular wave is characterized in that the peaks and troughs are modified to be sinusoidal waves, and the connection with the rising and falling sections of the triangular wave is smooth and the first-order derivative is smooth.

[0030] Preferably, the improved triangle wave formula is as follows:

[0031] u=A sin +A sin*cos(2πft-π),t≤T sin

[0032] u=V*(tT sin +T1),T sin <t≤T2-T sin

[0033] u=A tri -A sin +A sin *cos(2πf(t-T2)),T2-T sin <t≤T2+T sin

[0034] u=A tri -V*(t-T2-T sin +T1),T2+T sin <t≤2T2-T sin

[0035] u=A sin +A sin *cos(2πf(t-2T2)-π),T2+T sin <t≤2T2-T sin

[0036] Among them, u represents the command signal, A tri Indicates the amplitude of the triangle wave, A sin represents the amplitude of the sine wave at the peak and trough of the improved triangular wave, V represents the speed of the slope section of the triangular wave, T sin It represents half of the duration of the sine wave at the peak or trough, T1 represents the time difference when u of the original triangle wave and the improved triangle wave are equal in the uniform rising section, and T2 represents half of the period of the improved three-level wave.

[0037] Preferably, selecting a cutoff frequency based on the response signal comprises:

[0038] Select the 0-phase digital low-pass filter;

[0039] The response signal is filtered by using the 0-phase digital low-pass filter, and the cutoff frequency is selected by comparing the signals before and after filtering to see whether the amplitude is attenuated.

[0040] Preferably, the expression for the relationship between the uniform rising and falling segment signals and the PI control output signal is:

[0041] f = k flap θ flap -u PI

[0042] Where f represents friction, kflap represents the stiffness of the elastic load in the flap drive mechanism related to the flap angle, u PI represents the PI control output signal, θ flap Represents the flap angle response signal of the uniform ascent and descent phases.

[0043] Beneficial technical effects of this application:

[0044] 1. Under the condition that the flap flapping motion angle range is limited, the improved triangular wave can be used to increase the angle range of the flap angle uniform change section under closed-loop control to improve the recognition accuracy;

[0045] 2. When only the flap angle can be measured but the angular velocity cannot be directly measured, the random noise of the signal can be suppressed by means of zero-phase digital low-pass filtering and derivative step setting to improve the speed identification accuracy;

[0046] 3. A friction force identification method related to angle and angular velocity is proposed. Conventional friction identification of rotating mechanisms is only related to angular velocity. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A friction force identification flow chart of a trailing edge flap drive mechanism with a bearing;

[0048] Figure 2 This is a comparison diagram between the improved triangle wave signal and the conventional triangle wave signal;

[0049] Figure 3 To improve the schematic diagram of each time node in the triangular wave signal;

[0050] Figure 4 is a schematic diagram of the trailing edge flap driving mechanism;

[0051] Among them: 1, diamond-shaped piezoelectric actuator; 2, driving connecting rod; 3, trailing edge flap; 4, flap rotation axis. DETAILED DESCRIPTION

[0052] The present application provides a friction force identification method for a trailing edge flap drive mechanism with a bearing, aiming to provide an identification method for the friction force that varies with angle and angular velocity in a reciprocating motion situation.

[0053] The present invention proposes a friction force identification method for a trailing edge flap drive mechanism with a bearing, which applies a series of improved triangular waves of different speeds to the driver and performs closed-loop control, then performs zero-phase digital filtering on the collected flap angle signal to suppress the interference of random noise on the signal, adjusts the derivative step length to suppress the vibration phenomenon of the speed to obtain the flap angular velocity, then intercepts the uniform ascending section and the uniform descending section, and then specifies a series of angular velocities, performs friction model identification on the relationship between friction force and speed, and then identifies the relationship between the identified parameters and the flap angle, and finally obtains the friction force on the flap angle and flap angular velocity in the flap drive mechanism. The specific steps are as follows:

[0054] Step 1, according to the angle range and deflection frequency of the flap deflection according to the sine law, calculate the angular velocity range of the flap deflection;

[0055] θ=θ0+θ amp sin(ωt)

[0056]

[0057] In the above formula, θ represents the flap angle, represents the flap angular velocity, ω represents the flap circular frequency, θ0 represents the flap angle offset, θ amp Represents the amplitude of the sinusoidal motion of the flap.

[0058] Step 2: According to the angular velocity range obtained in step 1, an improved triangular wave is used to apply excitation to the flap drive mechanism, and PI closed-loop control is used to obtain a series of responses under positive and negative flap deflection speeds;

[0059] The improved triangular wave is characterized by the modification of the peak and trough to a sine wave transition, and the connection with the rising and falling sections of the triangular wave is smooth and the first-order derivative is smooth, which can avoid or reduce the oscillation phenomenon of the closed-loop controller at the peak and trough, and increase the angle range of the uniform speed control section. The improved triangular wave formula is as follows:

[0060] u=u amp +u amp *cos(2πft-π),t≤T sin

[0061] u=V*(tT sin +T1),T sin <t≤T2-T sin

[0062] u=Au amp +u amp *cos(2πf(t-T2)),T2-T sin <t≤T2+T sin

[0063] u=AV*(t-T2-T sin +T1),T2+T sin <t≤2T2-T sin

[0064] u=u amp +u amp *cos(2πf(t-2T2)-π),T2+T sin <t≤2T2-T sin

[0065] In the above formula, A represents the amplitude of the triangle wave, u amp The amplitude of the sine wave at the peak and trough of the improved triangular wave, V represents the speed of the slope section of the triangular wave, T sin It represents half of the duration of the sine wave transitioning at the peak or trough, T1 represents the time from the minimum angle of the uniform rising section in the improved triangular wave to the 0 angle, and T2 represents half of the period of the improved tertiary wave.

[0066] Step 3: Filter the signal using a 0-phase digital filter. By comparing the signal before and after filtering to see if the amplitude is attenuated, select a suitable low-pass filter cutoff frequency (to suppress noise interference in the signal without generating phase delay).

[0067] Step 4: Use a suitable derivation step length to derive the measured angle signal to obtain the angular velocity (a suitable derivation step length can suppress the chattering phenomenon that may be caused by the first-order derivative of the angle signal, that is, the angular velocity);

[0068] Step 5, according to the angular velocity obtained in step 4, intercept the uniform rising segment and falling segment of the triangular wave signal;

[0069] Step 6: For the uniform speed control segment signal intercepted in step 5, the relationship between the angle and the control output voltage (or the output force of the driver) is obtained by fitting. According to the formula f=k flap θ-u, calculate the stiffness k of the flap elastic load flap ;

[0070] In the formula, f represents the friction force, k flap represents the stiffness of the elastic load related to the flap angle in the flap drive mechanism, and u represents the actual control input;

[0071] Step 7, for the uniform speed control segment signal intercepted in step 5, fit the relationship between the angle and the control output voltage (or the output force of the driver) at different angular velocities, make the angle the same, calculate the positive speed friction force and the negative speed friction force corresponding to the different angular velocities at this angle, select a suitable friction model such as the friction model of Coulomb friction + viscous friction according to the curve of friction force changing with angular velocity, and identify the relationship between friction force and speed at this angle;

[0072] The relationship between the excitation voltage applied in the flap drive mechanism and the flap angle can be expressed as follows:

[0073]

[0074] F load =f+k flap θ

[0075] In the above formula, J represents the flap moment of inertia, represents the flap angular acceleration, F load Represents the load of the flap deflection motion.

[0076] In order to identify the friction force of the flap drive mechanism related to the recommended angular velocity and angle, the triangular wave closed-loop control of step 2 is applied and the uniform speed section under closed-loop control is selected. At this time, the flap angular acceleration have:

[0077] u=f+k flap θ

[0078] When the angle remains unchanged, for the friction model composed of Coulomb friction + viscous friction, the friction force f can be expressed as:

[0079]

[0080] In the above formula, represents the friction model coefficient when the speed is positive, The friction model coefficient when the velocity is negative

[0081] Step 8: According to the angle range of flap deflection, refer to step 7 to identify the relationship between friction force and angular velocity at different angles, and then identify the relationship between parameters and angles in the friction model on this basis.

[0082] Within the flap angle range, specifying different flap angles, it is obvious that it is easy to identify a series of friction model parameters Then the relationship between the parameters of this series of friction models and the flap angle is identified, and the following is obtained:

[0083]

[0084] In summary, the friction force related to the flap drive mechanism, flap angle, and flap angular velocity can be obtained through experimental identification.

[0085] In other embodiments of the present application, for a pair of 4 blades, the ACF rotor system with a base frequency of 6 Hz, the trailing edge flap drive mechanism (such as Figure 4 ) The flap deflection and drive rod adopt bearing connection structure. The maximum excitation frequency of the flap of 4 blades is generally 5 / rev, that is, 30Hz. If the flap deflection angle range is 0°~6°. The friction force of the mechanism within its working range is identified as follows:

[0086] Step 1: Calculate the flap circular frequency based on the maximum deflection frequency of the flap deflected according to the sine law. The formula is as follows:

[0087] ω=2πf

[0088] In the above formula, f represents the deflection frequency, ω represents the flap circular frequency, and π represents pi.

[0089] Step 2: According to the angle range and circular frequency of the deflection of the flap according to the sinusoidal law, the angular velocity range of the flap deflection is calculated as follows:

[0090] θ=θ0+θ amp sin(ωt)

[0091]

[0092] In the above formula, θ represents the flap angle, represents the flap angular velocity, ω represents the flap circular frequency, θ0 represents the flap angle offset, θ amp represents the amplitude of the sinusoidal motion of the flap, and t represents the time.

[0093] Step 3: According to the angular velocity range calculated in step 2, the flap drive mechanism is excited by using an improved triangular wave at a certain speed interval, and a series of flap angle response signals under positive and negative flap deflection speeds are obtained by using PI closed-loop control;

[0094] The improved triangular wave is characterized by modifying the peaks and troughs of the triangular wave to transition to a sine wave, and the connection with the rising and falling sections of the triangular wave is smooth and the first-order derivative is smooth, which can avoid or reduce the oscillation phenomenon of the closed-loop controller at the peaks and troughs, increase the angle range of the uniform speed control section, and prevent the piezoelectric driver from being damaged by the step response. The improved triangular wave formula is as follows:

[0095] u=A sin +A sin *cos(2πft-π),t≤T sin

[0096] u=V*(tT sin +T1),T sin <t≤T2-T sin

[0097] u=A tri -A sin +A sin *cos(2πf(t-T2)),T2-T sin <t≤T2+T sin

[0098] u=A tri -V*(t-T2-T sin +T1),T2+T sin <t≤2T2-T sin

[0099] u=A sin +A sin *cos(2πf(t-2T2)-π),T2+T sin <t≤2T2-T sin

[0100] In the above formula, u represents the command signal, A tri Indicates the amplitude of the triangle wave, A sin represents the amplitude of the sine wave at the peak and trough of the improved triangular wave, V represents the speed of the slope section of the triangular wave, T sin It represents half of the duration of the sine wave at the peak or trough, T1 represents the time difference when the original triangle wave and the improved triangle wave are equal in the uniform rising section, and T2 represents half of the period of the improved three-level wave. The various time quantities in the improved triangle wave and triangle wave signal can be seen in Figure 2 and Figure 3 .

[0101] PI closed-loop control is based on basic PID control. The discrete expression of PI control is:

[0102]

[0103] e′(k)=SP(k)-PV(k)

[0104] In the above formula, u PI (k) represents the PI control output signal of the kth control step in discrete control, Kp represents the proportional gain, Ki represents the integral gain, SP(k) represents the value of the improved triangular wave command signal u at the kth control step, PV(k) represents the value of the flap angle signal θ fed back at the kth control step, e′(k) represents the difference between the triangular wave command signal and the flap angle signal fed back at the kth control step, i.e., the control error, Represents the cumulative sum of errors from the 0th control step to the kth control step.

[0105] Step 4: Use a 0-phase digital low-pass filter to filter a series of flap angle response signals at positive and negative flap deflection speeds obtained in step 3. The cutoff frequency of the low-pass filter is selected by comparing whether the amplitude of the signal before and after filtering is significantly attenuated;

[0106] Step 5: Use a derivation step of appropriate length to derive a series of filtered flap angle signals obtained in step 4 to obtain a series of measured flap angular velocities. The derivation step is selected based on whether the flap angular velocity signal obtained by derivation has a buffeting phenomenon.

[0107] Step 6: Based on the series of measured flap angular velocities obtained in step 5, intercept the PI control output signal u in step 3 corresponding to the uniform ascending and descending segments in the angular velocity signal PI and flap angle response signal θ flap .

[0108] Step 7: PI control output signal u of a series of uniform speed control segments intercepted in step 6 PI The flap angle response signal is fitted according to the following formula to obtain a series of relationships between flap angles and control output voltage (or driver output force);

[0109] f = k flap θ flap -u PI

[0110] In the above formula, f represents friction, k flap Represents the stiffness of the flap drive mechanism's elastic load related to the flap angle.

[0111] Step 8: Let the flap angle in the relationship between the series of flap angles and the control output voltage obtained in step 7 take the same value, and then obtain a series of friction force values ​​at different flap angular velocities. For the friction force values ​​and flap angular velocity values ​​obtained at a series of different flap angular velocities, select a suitable friction model, such as a friction model composed of Coulomb friction + viscous friction, and identify the parameters of the friction model. The friction model is as follows:

[0112]

[0113] In the above formula, represents the friction model coefficient when the flap angular velocity is positive, represents the friction model coefficient when the flap angular velocity is negative, sgn is the sign function, It represents the flap angular velocity calculated based on the measured flap angle.

[0114] Step 9: Repeat step 8, and let the flap angle in step 8 take values ​​within the flap angle range obtained in step 2 at a certain step interval, and identify the friction model parameters between the friction force and the flap angular velocity at different flap angles. Then the relationship between this series of friction model parameters and the corresponding flap angles is identified through polynomial fitting, and the following is obtained:

[0115]

[0116] In the above formula, a n 、a0 represents With θ flap The polynomial coefficients obtained by fitting between n , b0 represents With θ flap The polynomial coefficients obtained by fitting between n 、c0 represents With θ flap The polynomial coefficients obtained by fitting between n , d0 represents With θ flap The polynomial coefficients obtained by fitting between .

[0117] In summary, the relationship between the friction force of the flap drive mechanism and the flap angle and flap angular velocity was identified.

Claims

1. A method for identifying friction force of a trailing edge flap drive mechanism with a bearing, characterized in that: The method comprises: According to the angle range and deflection frequency of the flap deflection according to the sine law, the angular velocity range of the theoretical flap deflection is calculated; According to the angular velocity range of the theoretical flap deflection, an improved triangular wave is used to apply excitation to the flap drive mechanism, and a PI closed-loop control is adopted to obtain a series of flap angle response signals and PI control output signals under positive and negative flap deflection speeds; selecting a cutoff frequency based on the flap angle response signal; Using a 0-phase digital low-pass filter to filter the flap angle response signal according to the cutoff frequency to obtain a filtered flap angle response signal; Selecting a derivation step length, and using the derivation step length to derive the filtered flap angle response signal to obtain an actual angular velocity of flap deflection; According to the angular velocity of the actual flap deflection, intercepting the uniform ascending segment and descending segment signals in the filtered response signal and the corresponding PI control output signals; Fitting the uniform speed ascending segment and descending segment signals with the PI control output signal to obtain the relationship between the uniform speed ascending segment and descending segment signals and the PI control output signal; Based on the relationship between the uniform speed ascending section and descending section signals and the PI control output signal, the stiffness and friction force of the flap elastic load are obtained.

2. The method according to claim 1, characterized in that The method further comprises: Selecting a friction model based on a curve of the friction force changing with the angular velocity of the actual flap deflection; Based on the friction model, the relationship between the friction force and the angular velocity of the actual flap deflection is identified.

3. The method according to claim 2, characterized in that The method further comprises: Based on the relationship between the friction force and the actual angular velocity of the flap deflection, the relationship between the friction force and the actual flap deflection angle and the actual angular velocity of the flap deflection is identified.

4. The method according to claim 3, characterized in that: The angular velocity range of the theoretical flap deflection is calculated based on the angle range and deflection frequency of the flap deflected according to the sinusoidal law, including: Obtain the deflection frequency of the flap deflected according to the sine law, the flap angle offset and the amplitude of the flap sinusoidal motion; The circular frequency of the flap is calculated according to the deflection frequency of the flap deflected according to the sinusoidal law; Calculating a theoretical flap deflection angle based on the flap circular frequency, the flap angle offset and the amplitude of the flap sinusoidal motion; Based on the theoretical flap deflection angle, an angular velocity range of the theoretical flap deflection is obtained.

5. The method according to claim 3, characterized in that: The improved triangular wave is characterized in that the peaks and troughs are modified to be transitioned into sine waves, and the connection with the rising and falling sections of the triangular wave is smooth and the first-order derivative is smooth.

6. The method according to claim 5, characterized in that The improved triangle wave formula is as follows: u=A sin +A sin *cos(2πft-π),t≤T sin u=V*(tT sin +T1),T sin <t≤T2-T sin u=A tri -A sin +A sin *cos(2πf(t-T2)),T2-T sin <t≤T2+T sin u=A tri -V*(t-T2-T sin +T1),T2+T sin <t≤2T2-T sin u=A sin +A sin *cos(2πf(t-2T2)-π),T2+T sin <t≤2T2-T sin Among them, u represents the command signal, A tri Indicates the amplitude of the triangle wave, A sin represents the amplitude of the sine wave at the peak and trough of the improved triangular wave, V represents the speed of the slope section of the triangular wave, T sin It represents half of the duration of the sine wave at the peak or trough, T1 represents the time difference when u of the original triangle wave and the improved triangle wave are equal in the uniform rising section, and T2 represents half of the period of the improved three-level wave.

7. The method according to claim 3, characterized in that The step of selecting a cutoff frequency based on the response signal comprises: Select the 0-phase digital low-pass filter; The response signal is filtered by using the 0-phase digital low-pass filter, and the cutoff frequency is selected by comparing the signals before and after filtering to see whether the amplitude is attenuated.

8. The method according to claim 3, characterized in that The expression of the relationship between the uniform rising and falling segment signals and the PI control output signal is: f=k flap i flap -u PI Where f represents friction, k flap represents the stiffness of the elastic load in the flap drive mechanism related to the flap angle, u PI represents the PI control output signal, θ flap Represents the flap angle response signal of the uniform ascent and descent phases.

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