HK1202328B - A system and method for detecting an aircraft jitter - Google Patents

Abstract

The present invention relates to a system and method for detecting an aircraft jitter. The aircraft jitter detection system comprises: a jitter detection apparatus, which detects accelerations of pitch and yaw of the aircraft; a data acquisition apparatus, which obtains accelerations in two directions detected by the jitter detection apparatus; and a jitter determination apparatus, which extracts frequency spectrum and energy information of the jitter according to the accelerations in two directions obtained by the data acquisition apparatus, and determines whether the aircraft jitters.

Description

Airplane shake detection system and method

Technical Field

The present invention relates to an onboard system and method, and more particularly, to an aircraft shake detection system and method.

Background

During the climbing or cruising phase, the aircraft shakes due to the aerodynamic effect as a result of the free travel of the components of the aircraft such as the doors, the cover plate under the belly, the ailerons and flaps of the aircraft, the doors of the landing gear, and the flight control surfaces, which cause an abnormal oscillation of some of these components with the airflow. The feel of the aircraft's flutter is particularly pronounced at the cockpit and tail. Although such jitter does not affect flight safety, it greatly affects the ride comfort of the crew and passengers. The crew can not focus attention on completing driving and service work due to airplane shaking, and passengers can feel irritated and uneasy due to airplane shaking.

In the prior art, the judgment of airplane jitter mainly depends on reports of crew members according to personal feelings. However, because the personal experience in the reports is often inaccurate, it sometimes happens that no faults actually occur or that a full check of the aircraft is required due to an inability to confirm the source of the jitter. Such inspection is labor intensive and difficult to implement. In order to avoid this, the repair engineering department may shorten the repair interval of parts, resulting in a large increase in repair costs.

Disclosure of Invention

In view of the above technical problems in the prior art, according to an aspect of the present invention, an aircraft shake detection system is provided, which includes: a shake detection device that detects accelerations of the aircraft in pitch and yaw; data acquisition means that acquires accelerations in two directions detected by the shake detection means; and the jitter determining device is used for extracting jittered frequency spectrum and energy information according to the accelerations in the two directions acquired by the data acquisition device and judging whether the airplane jitters.

The system as described above, further comprising: and the pattern comparison device is used for comparing the frequency and direction information of the airplane jitter with the jitter caused by a known jitter source and estimating a component with the jitter.

The system as described above, wherein the shake detection apparatus comprises an inertial navigation computer of the aircraft, an inertial navigation platform, or an accelerometer with a three-axis gravitational acceleration sensor.

The system as described above, wherein the data acquisition device comprises a DMU, QAR or FDR of the aircraft, or a separate hardware device for high frequency sampling.

The system further comprises a message generating device and a communication device, wherein the message generating device generates a jitter data message according to the acceleration data of the airplane in two directions, which is acquired by the data acquiring device; the communication device transmits the jitter packets to the jitter determination device on the ground through an air-to-ground data link.

The system as described above, further comprising a jitter recording initiating means.

The system as described above, wherein the jitter detection device, the data acquisition device, or the message generation device initiates jitter detection during the aircraft climbing or cruising phase.

The system as described above, wherein the jitter detection apparatus, the data acquisition apparatus, or the message generation apparatus starts jitter detection at the same time as or after about 10 seconds or 20 seconds from the start of climbing; or when the airplane climbs at a speed of over 260 knots, the jitter detection device, the data acquisition device or the message generation device starts jitter detection; or, the jitter detection device, the data acquisition device or the message generation device starts jitter detection after the aircraft is in the cruising steady state or after the aircraft is in the cruising steady state for about 40 seconds.

The system as described above, wherein the jitter determining means determines the frequency spectrum and energy information of jitter according to the acceleration in two directions for a certain time acquired by the data acquiring means.

The system as described above, wherein the jitter determining means processes the acceleration data of the aircraft in both pitch and yaw directions for the certain time period by fourier transform to obtain a frequency spectrum distribution of jitter.

The system as described above, wherein the jitter determining means processes the acceleration data of the aircraft at the certain time in both pitch and yaw directions by smooth pseudo-Wigner-ville distribution and/or wavelet transform to obtain jitter energy distribution.

The system as described above, wherein the jitter determining means confirms that jitter occurs when the jitter energy exceeds a preset threshold.

The system as described above, wherein the preset threshold is that the energy density of the jitter is greater than 150 db, and the amplitude after the fourier transform is greater than 0.0003 m/s.

The system as described above, wherein the pattern comparing means determines the source of the jitter by combining the position information of the jitter.

According to another aspect of the present invention, an aircraft shake detection method is provided, including: detecting the acceleration of the aircraft in pitch and yaw; acquiring accelerations in two directions detected by the shake detection device; and extracting the frequency spectrum and energy information of the jitter according to the accelerations in the two directions acquired by the data acquisition device, and judging whether the airplane jitters.

The method as described above, further comprising a component for estimating the presence of jitter from frequency and direction information of aircraft jitter, compared to jitter caused by known sources of jitter.

The method further comprises generating a jitter data message according to the acceleration data of the airplane in two directions acquired by the data acquisition device.

The method as described above, further comprising transmitting the jitter packets to the surface via an air-to-ground data link.

The method as described above, further comprising initiating jitter detection during a climb or cruise phase of the aircraft.

The method as described above, wherein the jitter detection is initiated at the same time as the start of the climb or about 10 seconds or 20 seconds after the start of the climb; or, when the airplane climbs at a speed of over 260 knots, starting jitter detection; alternatively, the jitter detection may be initiated after the aircraft is at or about 40 seconds after the aircraft is at cruise steady state.

The method as described above, further comprising processing the acceleration data of the aircraft in both pitch and yaw directions over the time period by fourier transform to obtain a frequency spectrum distribution of the jitter.

The method further comprises processing the acceleration data of the airplane in the pitching and yawing directions at the certain time by smooth pseudo Wigner-ville distribution and/or wavelet transformation to obtain jitter energy distribution.

The method as described above, further comprising confirming that jitter occurs when the jitter energy exceeds a preset threshold.

The method as described above, wherein the predetermined threshold is that the energy density of the jitter is greater than 150 db, and the amplitude after the fourier transform is greater than 0.0003 m/s.

The method as described above, further comprising determining a source of the jitter in conjunction with the location information of the jitter.

According to another aspect of the invention, a method for repairing an aircraft shake fault is provided, which comprises the following steps: acquiring jitter data, wherein the jitter data comprises acceleration of the airplane in two directions of pitching and yawing for a certain time; and obtaining the frequency spectrum and energy distribution information of the jitter to determine whether the jitter really occurs.

The method as described above, further comprising deriving a likely source of jitter failure based on the frequency and direction of jitter.

The method as described above, further comprising deriving a likely source of jitter failure based on the frequency and direction of jitter and the location information of jitter.

The method as described above, further comprising performing maintenance on the aircraft for the flutter fault based on the derived source of the possible flutter fault.

According to another aspect of the invention, a method of aircraft maintenance is provided, comprising: establishing an aircraft shake monitoring system as described above, or applying an aircraft shake monitoring method as described above; and to extend the replacement time of components on the aircraft where flutter may occur.

The method as described above, wherein the component in which jitter may occur is one or more selected from the group consisting of: the rod end of the rudder, the actuator cylinder of the rudder and the rod end of the elevator.

Drawings

Preferred embodiments of the present invention will now be described in further detail with reference to the accompanying drawings, in which:

FIG. 1 is a schematic structural view of an aircraft elevator;

FIG. 2 is a schematic structural view of an aircraft rudder;

FIG. 3 is a schematic diagram of a configuration of an aircraft shake detection system according to an embodiment of the invention;

FIG. 4 is a flow diagram of an aircraft jitter monitoring method according to one embodiment of the present invention;

FIG. 5 is spectral data obtained by Fourier transforming the jitter data in pitch (i.e., up-down direction) and yaw (i.e., left-right direction) according to one embodiment of the present invention;

FIG. 6 is a schematic diagram of the amplitude (i.e., energy) distribution of the dithered data of the embodiment of FIG. 5 after being processed by a smooth pseudo Wigner-ville distribution;

FIG. 7 is a schematic diagram of the energy density distribution obtained after the distribution of the embodiment shown in FIG. 6 is further processed by wavelet transform;

FIG. 8 is a method of servicing an aircraft shudder fault according to one embodiment of the invention;

FIG. 9 is a method of aircraft maintenance according to one embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the following detailed description, reference is made to the accompanying drawings that form a part hereof and in which is shown by way of illustration specific embodiments of the application. In the drawings, like numerals describe substantially similar components throughout the different views. Various specific embodiments of the present application are described in sufficient detail below to enable those skilled in the art to practice the teachings of the present application. It is to be understood that other embodiments may be utilized and structural, logical or electrical changes may be made to the embodiments of the present application.

There are many causes for causing jitter on an aircraft. As described in the background, the free travel of aircraft doors, under-the-belly flaps, ailerons and flaps of aircraft, landing gear doors, and flight control surfaces may cause aircraft flutter. The following description will take two components, i.e., an elevator and a rudder, which are most prone to flutter, as an example to explain some characteristics of aircraft flutter.

Fig. 1 is a schematic structural view of an aircraft elevator. As shown in fig. 1, an elevator is installed on each of the left and right sides of the tail of the aircraft. The angle of the control surface of the elevator is controlled by the actuating cylinder of the elevator through the hinge, so that the aircraft can ascend and descend. For elevators, the release of both the ram and the hinge can occur and free travel can occur, even if the clearance between the ram and the hinge is too great. The occurrence of these free strokes can cause the aircraft to flutter.

Fig. 2 is a schematic structural view of an aircraft rudder. As shown in fig. 2, a rudder is installed in the middle of the tail of the airplane. The actuating cylinder of the rudder controls the angle of the rudder surface of the rudder through a hinge to realize the steering of the airplane. Likewise, the rudder actuator and hinge may come loose and have a free stroke, causing the aircraft to flutter.

The doors of aircraft, the flaps under the belly, the ailerons and flaps of aircraft, and the doors of landing gear may be free-running due to the release of certain components on these devices, or may be improperly operated with some components not in place, causing the aircraft to flutter.

The inventor of the present application has found through research that the shaking of different parts or different components has respective characteristics. For example, they differ greatly in the frequency and direction of the jitter. Hatch or cover plate, the frequency is very high, generally above 100 Hz; the frequency of the vibration of the control surface is generally not high and is below 20 Hz. Further, there is also a difference in the direction of the jitter. For example, the direction of the rudder shake is up and down, and the direction of the rudder shake is left and right. If combined with the situation that the jitter appears at different parts of the airplane, different causes of the jitter can be distinguished, and therefore the position of the possible fault can be determined. Therefore, the troubleshooting time of the airplane shaking fault can be greatly reduced, the airworthiness time of the airplane is improved, the fixed maintenance period of the part is prolonged, and the maintenance cost is reduced. The invention is exemplified by an a320 series aircraft, and other types of aircraft or similar systems may employ the invention.

Fig. 3 is a schematic structural diagram of an aircraft shake detection system according to an embodiment of the invention. As shown in fig. 3, the aircraft shake detection system 300 includes a shake detection device 301, a data acquisition device 302, a shake determination device 303, and a pattern comparison device 304.

The shake detection device 301 detects the acceleration of the aircraft in pitch (i.e., up-down direction) and yaw (i.e., left-right direction). The change of the acceleration in the directions can reflect the shake of the airplane in the directions.

The data acquisition means 302 acquires accelerations in two directions detected by the shake detection means 301, and can store these pieces of acceleration information. The shake determination means 303 extracts the frequency spectrum and energy information of the shake from the accelerations in the two directions acquired by the data acquisition means 302, and determines whether the aircraft shakes based on the extracted information. The pattern comparison means 304 estimates the components causing the jitter by comparing the frequency and/or position information of the aircraft jitter with the jitter caused by known sources of jitter.

An example of the jitter detection device 301 is an inertial navigation computer of an aircraft, according to an embodiment of the present invention. The inertial navigation computer of an aircraft is an important component on the aircraft, and comprises a laser gyro and a three-axis accelerometer. During the flight of the aircraft, the inertial navigation computer calculates the acceleration of the aircraft in pitch (i.e. up-down direction) and yaw (i.e. left-right direction) according to the position of the aircraft relative to a reference plane defined by the activated gyro at every moment, thereby determining the attitude of the aircraft and providing the information of the attitude of the aircraft to a cockpit of the aircraft. Therefore, the inertial navigation computer of the airplane can be applied to the technical scheme of the invention to detect the relevant information of the jitter.

An example of the shake detection apparatus 301 is an inertial navigation platform of an aircraft, according to an embodiment of the present invention. The inertial navigation platform is a device applied to early airplanes, has functions similar to those of an existing inertial navigation computer, and can also be applied to the invention.

An example of the shake detection apparatus 301 is a stand-alone hardware device including an accelerometer with a three-axis gravity acceleration sensor, according to one embodiment of the invention. Accelerometers may also be used to detect acceleration of the aircraft in both directions, and may also be used in the solution of the invention.

According to one embodiment of the invention, the invention utilizes the digital flight Data interface and Management component FDIMU (flight Data interface and Management Unit) of the aircraft. The FDIMU receives aircraft state data from onboard sensors or other devices. The data acquisition subsystem of the FDIMU converts acquired aircraft state data into digital signals for broadcast. The broadcast aircraft status data is received and stored by the quick Access recorder qar (quick Access recorder). In this case, a part of the Data is stored in a flight Data recorder fdr (flight Data recorder), namely a "black box", so that the Data can be investigated and analyzed by the relevant personnel after an emergency event occurs in the aircraft.

An aircraft Condition Monitoring system ACMS (aircraft Condition Monitoring System) also receives broadcast aircraft Condition data from the data acquisition subsystem of the FDIMU. ACMS monitors, collects, records aircraft status data, and outputs predetermined aircraft status data under certain trigger conditions for use by flight and crew personnel in daily monitoring of aircraft status and performance. It is called a message because its data content and format can be changed by the user.

ACMS messages are generated under control of integrated application software. The messages are triggered by thresholds of specific aircraft state parameters or by combinatorial logic of a plurality of specific aircraft state parameters, i.e. specific message trigger logic. ACMS messages generated by the message trigger logic designed and tested by the ACMS manufacturer are called basic messages. Many basic messages have become standards prescribed by the civil aviation administration. Taking an air passenger A320 series airplane as an example, more than 20 ACMS basic messages are used.

Customized messages can be generated by self-writing ACMS message trigger logic. Customized messages may enable those skilled in the art to be directly confronted with tens of thousands of aircraft state parameters without being limited by parameters in the basic message. This allows for better monitoring of the state of the aircraft.

An example of data acquisition device 302 is a DMU, QAR, or FDR of an FDIMU of an aircraft, according to one embodiment of the invention.

An example of data acquisition device 302 is a hardware-independent volatile or non-volatile data storage device, according to one embodiment of the present invention. Since the sampling frequency of the DMU of the FDIMU is limited, typically no greater than 32Hz (i.e., 32 times per second), some high frequency jittered data cannot be acquired. This problem is avoided by using a data acquisition device that can sample at high frequencies.

An example of the jitter determining means 303 is a main control computer, an auxiliary computer of an aircraft, ACMS of an FDIMU or other on-board computer or a ground computing platform according to an embodiment of the present invention.

An example of the mode comparison device 304 is a main control computer, an auxiliary computer, an ACMS or other on-board computer of an aircraft or a ground computer according to an embodiment of the present invention. In other words, data acquisition device 302 and pattern comparison device 304 may be implemented by the same on-board computing platform or by different computing platforms.

According to an embodiment of the present invention, the jitter determining means 303 and the pattern comparing means 304 are preferably computing platforms on the ground, since the main control computer, the auxiliary computer on the aircraft, the ACMS of the FDIMU or other on-board computers have their own tasks without more computing resources, and obtaining the spectrum and energy information of the jitter requires a lot of computation.

According to one embodiment of the invention, the aircraft jitter detection system 300 comprises a message generation means 305 and a communication means 306. The message generating device 305 generates a jitter data message based on the acceleration data in two directions of the aircraft acquired by the data acquiring device 302. According to an embodiment of the present invention, since the acceleration data amount is relatively large, in order to ensure smooth message transmission, the message generation apparatus generates more than one jitter data message. The communication means 306 transmit the message to the jitter determining means 303.

An example of the message generating device 305 is an ACMS of an FDIMU, or other onboard message generating device, according to one embodiment of the invention. According to one embodiment of the present invention, an example of the communication device 306 is a ground-to-air data link such as the ACARS system, and the anti-icing shutter performance message is transmitted to a ground workstation via the ground-to-air data link and further transmitted to a ground computing platform or server of an airline company.

According to one embodiment of the invention, the aircraft jitter detection system 300 includes a jitter recording initiation means 307. Jitter does not occur every moment but has a certain randomness. Therefore, in addition to the jitter detection accidents at times when the aircraft is relatively prone to jitter, such as during climb and cruise, an additional jitter recording activation device 307 may be activated by the flight crew or flight crew to obtain jitter data at the time of jitter. According to an embodiment of the invention the jitter recording initiating means 307 is connected to the jitter detection means 301 to initiate the whole jitter detection process, which is very useful when the jitter detection means 301 is a stand-alone hardware. According to an embodiment of the present invention, the jitter recording initiating means 307 is connected to the data acquisition means 302 to initiate the whole jitter detection process, which is very useful when the data acquisition means 302 is a stand-alone hardware. According to an embodiment of the invention the jitter recording initiating means 307 is connected to the message generating means 305 for initiating the jitter data acquisition and jitter message generation process.

FIG. 4 is a flow diagram of an aircraft jitter monitoring method according to one embodiment of the present invention. As an application, the aircraft shake monitoring method of fig. 4 can be applied to the aircraft shake monitoring system of the embodiment shown in fig. 3.

As shown in fig. 4, the aircraft jitter monitoring method 400 includes: at step 410, it is determined whether the aircraft is in a climb or cruise condition; in step 420, if the aircraft is in the climbing state or the cruising state, the jitter detection apparatus 301, the data acquisition apparatus 302 or the message generation apparatus 305 is activated to start jitter detection.

According to one embodiment of the invention, jitter detection is initiated at the same time as the start of the climb or after a certain time, preferably 10 seconds or 20 seconds, after the start of the climb. According to one embodiment of the invention, the jitter detection is initiated when the aircraft is climbing at a speed greater than 260 knots. According to one embodiment of the invention, after the aircraft is in a cruise steady state, jitter detection is initiated; or to initiate jitter detection after the aircraft has been at cruise steady state for a period of time, preferably 40 seconds or more.

Alternatively, in step 430, the flight crew or the flight attendant manually activates the jitter detection device 301, the data acquisition device 302, or the message generation device 305 using the jitter record activation device 307 to start jitter detection.

After the start of the jitter detection, the data acquisition device 302 obtains a time of jitter data of the aircraft from the jitter detection device at fixed time intervals in step 440. Alternatively, the message generating device 305 obtains the time jitter data of the airplane from the data obtaining device 302, such as the DMU, QAR, or FDR of the FDIMU, or the data obtaining device 302 of the independent hardware.

The jitter data includes, but is not limited to, acceleration of the aircraft in both pitch (i.e., up-down) and yaw (i.e., left-right). According to an embodiment of the present invention, the acceleration in the front-back direction has little influence on the situation of the shake, and may be obtained or omitted. As previously mentioned, if the jitter recording device is the DMU, QAR or FDR of the FDIMU, the sampling frequency of these devices is limited in many current aircraft, up to 32 times per second, i.e., 32 Hz. If the data acquisition device 302 is hardware or software specifically designed for jitter recording, aircraft jitter over a wider frequency range can be detected without being limited by the sampling frequency.

In order to determine the pattern of jitter, data acquisition device 302 acquires 20-120 seconds of jitter data, according to one embodiment of the present invention; preferably 20-60 seconds or 20-40 seconds of jitter data.

At step 450, the jitter record data including acceleration in pitch (i.e., up and down) and yaw (i.e., left and right) is transmitted through the communication device 306 to a workstation on the ground using an air-to-ground data link, such as ACARS, and further transmitted to an airline computing platform or data server.

Because the main control computer, the auxiliary computer, the ACMS or other onboard computers on the airplane have respective tasks in the flight process, a large amount of computing resources are needed for processing the jitter data, and the jitter generally does not affect the flight safety, the transmission of the jitter data to the ground server for processing is a good choice. Of course, step 450 is optional and these calculations may be performed on an on-board computer.

According to an embodiment of the present invention, the message generating apparatus 305 transmits the recorded jitter data for a certain time to a server on the ground through a series of messages. For example, the shake data including the acceleration in both the pitch (i.e., up-down direction) and yaw (i.e., left-right direction) directions is transmitted to the server on the ground through 5 shake messages.

According to one embodiment of the invention, a jitter packet comprises three parts: the first part includes message preset parameters, such as: machine number, flight number, airspeed, engine speed, etc. The second part includes: the flight phase of the aircraft, the start time, the end time of the jitter recording, etc. The third part is the body part of the message, including the acceleration of the aircraft in both the pitch (i.e., up and down) and yaw (i.e., left and right) directions at different times.

Returning to fig. 4, at step 460, the jitter determining means 303 processes the jitter data in each direction to obtain the spectral characteristics of the jitter data. According to an embodiment of the invention, the data acquisition means further acquires an energy characteristic of the jitter data. As previously mentioned, the jitter caused by different jitter sources has a relatively unique frequency, and the pattern of the jitter can be determined by the spectral characteristics of the jitter data. Whether the airplane is really shaken or not can be determined through the energy characteristics of the shaking data, so that interference vibration with low shaking energy can be omitted, and false alarm is avoided.

According to one embodiment of the invention, acceleration data of an originally sampled airplane in two directions of pitching (namely, the up-down direction) and yawing (namely, the left-right direction) is processed through Fourier transformation, smooth pseudo Wigner-ville distribution and wavelet transformation, and a jittering frequency spectrum and jittering energy distribution are obtained. It will be appreciated by those skilled in the art that the above analysis method is for exemplary purposes only, and that other spectral analysis, analog methods, and/or numerical analysis methods may be applied to the analysis of the jitter data to obtain the frequency and energy characteristics of the jitter data.

At step 470, the jitter determining means 303 determines whether the aircraft is jittered. According to one embodiment of the present invention, the jitter is confirmed to occur when the energy density of the jitter is greater than 150 db (preferably 200 db) and the amplitude after fourier transform is greater than 0.0003 (preferably 0.0005) square meter/second. Different types of aircraft may have different thresholds for determining the presence of jitter due to differences in size and configuration. Most of the low energy disturbances can be rejected, via step 470, to determine the true presence of jitter.

Fig. 5 is spectral data obtained by fourier transforming the shake data in pitch (i.e., up-down direction) and yaw (i.e., left-right direction) according to an embodiment of the present invention. This was done as an example of a test in which a 2Hz vertical vibration source was introduced on the wing of the aircraft. The dither data at this vibration source was obtained using the aforementioned system and method of the present invention.

As shown in fig. 5, the spectral data obtained by fourier transforming the jitter data in the pitch (i.e., the up-down direction) shows a peak in the region around 2 Hz. The spectral data obtained by fourier transforming the jitter data in the yaw (i.e., the left-right direction) does not have any peak. Therefore, the possibility that the jitter on the airplane is about 2Hz can be judged.

Fig. 6 is a schematic diagram of an amplitude (i.e., energy) distribution obtained after the jitter data of the embodiment shown in fig. 5 is subjected to a smooth pseudo-Wigner-ville distribution process. As shown in fig. 6, the highest energy density is found in the region around 2 Hz.

Fig. 7 is a schematic diagram of the energy density distribution obtained after the distribution of the embodiment shown in fig. 6 is further subjected to wavelet transform. As can be seen more clearly in fig. 7, there is a high energy jitter around 2 Hz.

Referring to fig. 5, the amplitude of the dither after fourier transform is greater than 0.0003 square meters per second; and referring to fig. 8, the energy density of the dither is greater than 150 db. Therefore, a jitter source of up-down direction jitter of about 2Hz can be determined to be really existed on the airplane.

Returning to fig. 4, at step 480, the jitter direction and frequency characteristics obtained by the jitter determining means 303 are compared with the known jitter pattern at the pattern comparing means 304 to determine the possible source of the failure. As previously described, the source of the fault may be preliminarily determined based on a known jitter pattern. Such as hatches or covers, the dithering frequency is very high, typically above 100 Hz; the frequency of the vibration of the control surface is generally not high, and is about 20 Hz. In the direction of the judder, for example, the judder direction of the elevator is up-down, and the judder direction of the rudder is left-right.

According to an embodiment of the invention, the source of the jitter can be judged more accurately by combining the position information of the jitter. In general, jitter from different sources, the flight crew or passengers feel different at different locations in the aircraft cabin. This information is relatively accurate. Thus, crew reports may be incorporated in the determination of the source of the fault. According to one embodiment of the invention, the general orientation of the dither may be determined from sensors at different locations on the aircraft. This information is more accurate and therefore can also be used as a basis for determining the source of jitter failure.

According to one embodiment of the invention, the source of jitter failure is determined with reference to the following table: (the shaking is dependent on the aircraft construction, A320 series of shaking characteristics are listed below)

FIG. 8 is a method of repairing aircraft flutter faults in accordance with an embodiment of the present invention. As shown in fig. 8, a method 800 for repairing a flutter fault of an aircraft includes: at step 810, jitter data is obtained when the aircraft has a jitter fault, wherein the jitter data includes acceleration of the aircraft in both pitch (i.e., up and down) and yaw (i.e., left and right) directions for a certain time. The systems and methods described in the embodiments described herein above may be used to obtain jitter data in the present embodiment.

In step 820, the spectrum and energy distribution information of the jitter are obtained to determine whether the jitter actually occurs. The systems and methods described in the embodiments described herein above may be used to obtain information on whether jitter has occurred in the present embodiment.

At step 830, a possible source of jitter failure is derived based on the frequency and direction of jitter, and optionally the location information of the jitter. The systems and methods described in the embodiments described herein above may be used to obtain information on the source of jitter faults in the present embodiment.

At step 840, the aircraft's shudder failure is repaired based on the possible shudder failure sources obtained at step 830.

FIG. 9 is a method of aircraft maintenance according to one embodiment of the invention. As shown in fig. 9, a method 900 of aircraft maintenance includes: at step 910, an aircraft shake monitoring system as described above in the present application is built for an aircraft, or an aircraft shake monitoring method as described above in the present application is applied. At step 920, the replacement time for components on the aircraft where flutter may occur is extended. For example, for the rod end and ram of the rudder, the maintenance interval is 1 recommended maintenance cycle and is changed to 4 cycles. The rod end of 4 elevators needs to be replaced at a time, and the recommended interval for the maintenance interval is 2 cycles, and is modified into 4 cycles. With the application of the scheme of the invention, the cost of materials is only one, and the lowest cost of each airplane is reduced to 35,000 CNY/year.

The method can help maintenance personnel to accurately judge the possible source of the jitter fault by accurately reducing the acceleration state of each axis and the frequency spectrum and energy distribution when the airplane jitters, obviously reduce the troubleshooting time of the jitter fault, prolong the maintenance period of parts which are easy to have the jitter fault and reduce the maintenance cost of the airplane.

The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the scope of the present invention, and therefore, all equivalent technical solutions should fall within the scope of the present invention.

Claims (29)

1. An aircraft jitter detection system comprising:

a shake detection device that detects accelerations of the aircraft in pitch and yaw directions;

data acquisition means that acquires accelerations in two directions detected by the shake detection means;

the jitter determining device extracts the frequency spectrum and energy information of jitter according to the accelerations in two directions acquired by the data acquiring device and judges whether the airplane jitters; and

and the pattern comparison device is used for comparing the frequency and direction information of the airplane jitter with the jitter caused by a known jitter source and estimating a component with the jitter.

2. The system of claim 1, wherein the jitter detection device comprises an inertial navigation computer of the aircraft, an inertial navigation platform, or an accelerometer with a three-axis gravitational acceleration sensor.

3. The system of claim 1, wherein the data acquisition device comprises an aircraft DMU, QAR or FDR, or a stand-alone hardware device of high frequency sampling.

4. The system according to claim 1, further comprising a message generating device and a communication device, wherein the message generating device generates a jitter data message according to the acceleration data of the airplane in two directions acquired by the data acquiring device; the communication device transmits the jitter packets to the jitter determination device on the ground through an air-to-ground data link.

5. The system of claim 1, further comprising a jitter recording initiating means.

6. The system of claim 1, wherein the jitter detection means or data acquisition means initiates jitter detection during a climb or cruise phase of the aircraft.

7. The system according to claim 4, wherein the message generating means initiates jitter detection during the aircraft climb or cruise phase.

8. The system of claim 7, wherein the jitter detection means, data acquisition means, or message generation means initiates jitter detection at the same time as or about 10 seconds or 20 seconds after the start of climb; or when the airplane climbs at a navigational speed of more than 260 knots, the jitter detection device, the data acquisition device or the message generation device starts jitter detection; or, the jitter detection device, the data acquisition device or the message generation device starts jitter detection after the aircraft is in the cruising steady state or after the aircraft is in the cruising steady state for about 40 seconds.

9. The system according to claim 1, wherein the jitter determining means determines the frequency spectrum and energy information of jitter from the acceleration in both directions for a certain time acquired by the data acquiring means.

10. The system of claim 9, wherein the jitter determining means processes the time of aircraft acceleration data in both pitch and yaw by fourier transform to obtain a spectral distribution of jitter.

11. The system of claim 9, wherein the jitter determining means processes the acceleration data of the aircraft over the time in both pitch and yaw directions by smoothing a pseudo-Wigner-ville distribution and/or a wavelet transform to obtain a jitter energy distribution.

12. The system according to claim 11, wherein the jitter determining means confirms that jitter occurs when jitter energy exceeds a preset threshold.

13. The system of claim 12, wherein the jitter energy exceeding the predetermined threshold is a jitter energy density of greater than 150 db and a fourier transformed amplitude of greater than 0.0003 m/s.

14. The system of claim 2, wherein the pattern comparison means determines the source of jitter in conjunction with position information of jitter.

15. An aircraft shake detection method, comprising:

detecting accelerations of the aircraft in pitch and yaw directions;

acquiring the detected accelerations in two directions;

extracting jittering frequency spectrum and energy information according to the obtained accelerations in the two directions, and judging whether the airplane jitters; and

and estimating the component in which the jitter occurs according to the frequency and direction information of the aircraft jitter and compared with the jitter caused by a known jitter source.

16. The method of claim 15, further comprising generating a jitter data message based on the acquired acceleration data for the aircraft in both directions.

17. The method of claim 16, further comprising transmitting the jitter packets to the surface over an air-to-ground data link.

18. The method of claim 15, further comprising initiating jitter detection during a climb or cruise phase of the aircraft.

19. The method of claim 18, wherein jitter detection is initiated at the same time as the climb begins or approximately 10 seconds or 20 seconds after the climb begins; when the airplane climbs at the speed of more than 260 knots, starting jitter detection; alternatively, the jitter detection may be initiated after the aircraft is at or about 40 seconds after the aircraft is at cruise steady state.

20. The method of claim 15, further comprising processing acceleration data of the aircraft in both pitch and yaw over a time period by fourier transform to obtain a frequency spectrum distribution of the jitter.

21. The method of claim 15, further comprising processing acceleration data of the aircraft in both pitch and yaw over time to obtain a jitter energy profile by smoothing the pseudo-Wigner-ville profile and/or wavelet transform.

22. The method of claim 21, further comprising confirming jitter is occurring when the jitter energy exceeds a preset threshold.

23. The method of claim 22, wherein the jitter energy exceeding the predetermined threshold is a jitter energy density of greater than 150 db and a fourier transformed amplitude of greater than 0.0003 m/s.

24. The method of claim 15, further comprising determining a source of jitter in conjunction with the location information of the jitter.

25. A method of repairing aircraft flutter faults, comprising:

acquiring jitter data, wherein the jitter data comprises acceleration of the airplane in two directions of pitching and yawing for a certain time;

obtaining the frequency spectrum and energy distribution information of jitter, and determining whether the jitter really occurs; and

and estimating the component in which the jitter occurs according to the frequency and direction information of the aircraft jitter.

26. The method of claim 25, further comprising deriving a likely source of jitter failure based on the frequency and direction of jitter and the location information of jitter.

27. The method of claim 26, further comprising repairing a shudder fault in an aircraft based on the derived source of the probable shudder fault.

28. A method of aircraft maintenance, comprising:

establishing an aircraft shake detection system according to any of claims 1-14 or applying an aircraft shake detection method according to claims 15-24; and

the replacement intervals of components on the aircraft where flutter may occur are extended.

29. The method of claim 28, wherein the component in which jitter is likely to occur is one or more selected from the group consisting of: the rod end of the rudder, the actuator cylinder of the rudder and the rod end of the elevator.