Rotor common taper measurement method, system, device and storage medium

Abstract

The present invention discloses a method, system, device and storage medium for measuring rotor common taper, wherein the method comprises: during the rotation of the blade, generating a trigger signal according to the azimuth angle, and controlling the camera to capture the foreground image of each blade according to the trigger signal; if in the current shooting cycle, the triggering sequence of the trigger signal and the photo sequence of the foreground image are synchronized, all the photos in the current shooting cycle are determined to be a continuous foreground image group, and the triggering sequence and the photo sequence are set to zero. The flight attitude corresponding to the foreground image in the continuous foreground image group is obtained, and the foreground image is analyzed differently according to the flight attitude, so as to calculate the flapping height of different blades of the aircraft in the current shooting cycle, and determine the rotor common taper of the aircraft in the current shooting cycle according to the flapping height. The embodiment of the present application helps to reduce the measurement deviation caused by the rotor speed jump in different shooting cycles, so as to improve the measurement accuracy of the rotor common taper.

Description

Technical Field

[0001] The present application relates to the field of helicopter rotor monitoring, and in particular to a rotor common taper measurement method, system, device and storage medium. Background Art

[0002] Rotorcraft is an important branch of aircraft, and helicopters are a typical type of rotorcraft. As a separate system, the rotor makes the helicopter controllable and provides propulsion and load-bearing functions for the helicopter, so the rotor is the most critical component of the helicopter.

[0003] In the production and maintenance of helicopters, an important inspection item is the rotor taper. The rotor taper is a major indicator of rotor dynamic balance measurement, which is directly related to the performance of the helicopter. The main methods for measuring rotor taper are infrared measurement, laser measurement or universal track equipment measurement. However, since the taper measurement is performed under the high-speed rotation of the rotor, the above measurement methods have the problems of high measurement difficulty and poor measurement accuracy. With the development of optoelectronic technology, electronic technology, and especially image processing technology, image-based rotor taper measurement technology has the advantages of non-contact, high accuracy, and easy computer processing.

[0004] However, since the measurement of rotor taper needs to be performed when the blades are rotating at high speed, with the current limited hardware resources, it is difficult for the camera to capture a complete circle of blade images, which affects the accuracy of the taper measurement.

[0005] The images of blades taken by the camera are easily interfered by background interference such as trees, buildings and dark clouds. The background reconstruction, foreground / background segmentation and other related technologies are prone to cause blade recognition errors, resulting in a decrease in the measurement accuracy of the rotor common taper measurement. Summary of the invention

[0006] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present application proposes a rotor common taper measurement method, system, device and storage medium, which can effectively improve the measurement accuracy of the rotor common taper.

[0007] In the first aspect, an embodiment of the present application provides a method for measuring the common taper of a rotor, comprising: when the blades of an aircraft rotate, controlling a camera to capture a foreground image of each blade according to a trigger signal; if within the current shooting cycle, the triggering sequence of the trigger signal and the photo sequence of the foreground image are synchronized, determining a continuous foreground image group within the current shooting cycle, and setting the triggering sequence and the photo sequence to zero; determining the flight attitude of the foreground image; based on the flight attitude and the continuous foreground image group, determining the flapping heights of different blades of the aircraft within the current shooting cycle; based on several flapping heights, determining the common taper of the rotor of the aircraft within the current shooting cycle; wherein the continuous foreground image group includes a first number of foreground images; wherein the shooting cycle is the time length taken for the triggering number of the trigger signal to reach a first number; wherein the trigger signal is triggered by an azimuth angle; wherein the first number is equal to the number of blades of the aircraft.

[0008] Optionally, the measurement method further includes: if the trigger sequence and the photo sequence are not synchronized in the current shooting cycle, discarding the foreground image in the current shooting cycle, and setting the trigger sequence and the photo sequence to zero.

[0009] Optionally, determining the flapping heights of different blades of the aircraft in a current shooting cycle according to the flight attitude and the continuous foreground image group includes: determining a basic phase according to the flight attitude; determining an optical model according to the basic phase; and determining the flapping height according to the optical model and the continuous foreground image group.

[0010] Optionally, determining the basic phase according to the flight attitude includes: obtaining the flight attitude of the aircraft, the flight attitude including a ground small-pitch attitude, a hovering attitude and a level flight attitude; when the aircraft is in one of the flight attitudes, the camera captures a number of first blade images at different shooting angles; if the blade tip in the current first blade image is imaged at the center of the image, determining that the current camera parameters are the basic phase corresponding to the current flight attitude; determining the basic phases corresponding to all the flight attitudes; wherein the camera parameters include the lens elevation angle and the camera focal length.

[0011] Optionally, determining the flapping height according to the optical model and the continuous foreground image group includes: determining the center point of the foreground image as a first reference position; determining a blade tip position according to the foreground image, and determining a first distance between the first reference position and the blade tip position; determining a second distance between the blade tip height of the aircraft and a second reference position according to the optical model and the first distance, the second distance being the flapping height; wherein the second reference position is a horizontal position where the rotor rotation center of the aircraft is located;

[0012] Optionally, the measurement method also includes: obtaining a common taper set, the common taper set including the rotor common tapers corresponding to multiple shooting cycles; determining a number of normal common tapers in the common taper set; and determining the rotor common taper of the aircraft based on the several normal common tapers.

[0013] Optionally, the measurement method also includes: acquiring an exposure data set; training an optimal exposure model based on the exposure data set; acquiring current lighting of the environment in which the aircraft is located; determining an optimal exposure time based on the current lighting and the optimal exposure model; determining shooting parameters of the camera based on the optimal exposure time; and capturing the foreground image by the camera based on the shooting parameters.

[0014] Optionally, the method further includes: acquiring a background image; and preprocessing the continuous foreground image group according to the flight posture and the background image.

[0015] In a second aspect, an embodiment of the present application provides a rotor taper measurement system, comprising: a first module, a second module, a third module, a fourth module and a fifth module; the first module is used to control the camera to capture a foreground image of each blade according to a trigger signal when the blades of the aircraft rotate; the second module is used to determine a continuous foreground image group in the current shooting cycle if the triggering sequence of the trigger signal and the photo sequence of the foreground image are synchronized within the current shooting cycle, and reset the triggering sequence and the photo sequence to zero; the third module is used to determine the flight attitude of the foreground image; the fourth module is used to determine the flapping height of different blades of the aircraft in the current shooting cycle according to the flight attitude and the continuous foreground image group; the fifth module determines the rotor taper of the aircraft in the current shooting cycle according to several flapping heights; wherein the continuous foreground image group includes a first number of foreground images; wherein the shooting cycle is the time taken for the triggering number of the trigger signal to reach a first number; wherein the trigger signal is triggered by an azimuth angle; wherein the first number is equal to the number of blades of the aircraft.

[0016] In a third aspect, an embodiment of the present application provides a device comprising: at least one processor; at least one memory for storing at least one program; when the at least one program is executed by the at least one processor, the at least one processor implements the rotor common taper measurement method as described in the first aspect.

[0017] In a fourth aspect, an embodiment of the present application provides a computer storage medium, which stores a program executable by a processor, and when the program executable by the processor is executed by the processor, it is used to implement the method for measuring the rotor common taper as described in the first aspect.

[0018] The beneficial effects of the embodiments of the present application are as follows: the embodiments of the present application synchronize the trigger sequence calculated by the hardware circuit and the photo sequence calculated by the software, which helps to obtain the foreground image of all blades in the same circle, thereby reducing the measurement deviation caused by the rotor speed jump in different shooting cycles, so as to improve the measurement accuracy of the rotor common taper; and, the embodiments of the present application propose different analyses of the foreground image according to the different flight attitudes corresponding to different foreground images, which also helps to improve the calculation accuracy of the blade flapping height, thereby improving the measurement accuracy of the common taper. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide further understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0020] Figure 1 is a flowchart of the steps of the method for measuring the rotor common taper provided in an embodiment of the present application;

[0021] Figure 2 A top view of a foreground image captured in an embodiment of the present application;

[0022] Figure 3 A flowchart of the steps for determining the blade flapping height provided in an embodiment of the present application;

[0023] Figure 4 The blade images taken by the camera in the three flight postures provided in the embodiment of the present application;

[0024] Figure 5 A schematic diagram of an optical model provided in an embodiment of the present application;

[0025] Figure 6 A flowchart of the steps for establishing an optimal exposure model provided in an embodiment of the present application;

[0026] Figure 7 A schematic diagram of a rotor common taper measurement system provided in an embodiment of the present application;

[0027] Figure 8 A schematic diagram of a device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] It should be noted that, although the functional modules are divided in the system schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the system or the order in the flowchart. The terms "first", "second", etc. in the specification, claims and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0030] The embodiments of the present application are further described below in conjunction with the accompanying drawings.

[0031] refer to Figure 1 , Figure 1 : is a flowchart of the steps of the rotor common taper measurement method provided in an embodiment of the present application, the method includes but is not limited to steps S100-S140:

[0032] S100, when the blades of the aircraft rotate, controlling the camera to capture a foreground image of each blade according to a trigger signal;

[0033] Specifically, refer to Figure 2 , Figure 2 A top view of a foreground image captured in an embodiment of the present application. Figure 2 In the figure, reference numeral 210 denotes the fuselage of the aircraft, reference numeral 220 denotes the tail of the aircraft, and Figure 2 The nose of the aircraft is in the horizontal right direction, and the tail is in the horizontal left direction; in addition, Figure 2 In the figure, reference numeral 230 denotes a blade, reference numeral 240 denotes a reflective sticker, reference numeral 250 denotes an azimuth sensor, and reference numeral 260 denotes a measuring device for the rotor conicity; Figure 2 The craft shown has 6 blades.

[0034] like Figure 2 As shown, a reflective sticker is attached to one of the blades, and this blade is used as the reference blade. When the reference blade rotates, the reflective sticker reflects light to the azimuth sensor set on the fuselage. After receiving the reflected light, the azimuth sensor sends a signal to the measuring device. The measuring device multiplies the signal according to the number of blades of the current aircraft to generate a trigger signal, thereby controlling the camera to capture the image of the blade according to the trigger signal. Figure 2If the aircraft in the image has 6 blades, the trigger signal will control the camera to take a picture of each blade. When the azimuth sensor receives the reflected light again, it means that the reference blade has made a circle. The camera should take six blade images corresponding to different blades, and then start the next shooting cycle. Therefore, in the embodiment of the present application, the shooting cycle is the time taken for the trigger signal to trigger the number of blades. In the embodiment of the present application, the number of blades is the first number. In this step, during the current shooting cycle, the camera is controlled to take multiple foreground images including the blades according to the trigger signal.

[0035] S110, if in the current shooting cycle, the triggering sequence of the trigger signal and the photo sequence of the foreground image are synchronized, determining a continuous foreground image group in the current shooting cycle;

[0036] Specifically, it is mentioned in the above content that the trigger signal is triggered by the azimuth angle. In the embodiment of the present application, the trigger signal is triggered by Figure 1 For example, the measuring device is provided with an FPGA (Field Programmable Gate Array) control board and a CPU (central processing unit). When the azimuth sensor receives the reflected light and sends a signal to the FPGA, the FPGA generates a trigger signal by multiplying the number of blades, drives the camera to shoot the blades, and sends a trigger sequence to the CPU through its own GPIO (General-purpose input / output). The trigger sequence represents which signal the trigger signal is in the current shooting cycle. Since the trigger signal is triggered by a hardware circuit, the order of the trigger signal can be regarded as a kind of "hard count".

[0037] The camera is controlled by the trigger signal to capture the foreground image containing the blades. Every time an image is successfully acquired, the CPU will accumulate the count to obtain the photo sequence, which represents the photo number taken in the current shooting cycle. Since the photo sequence is calculated by the CPU, the sorting of foreground photos can be regarded as a "soft count".

[0038] In an embodiment of the present application, the blade image taken by the camera is used to calculate the rotor co-taper. The purpose of the rotor co-taper measurement is mainly to measure the height difference of the flapping heights of different blades when the blade rotates one circle (that is, corresponding to one shooting cycle). If it is not in the same rotation cycle, due to the high-speed rotation of the rotor, the fluctuation of the rotor speed will cause a large deviation in the co-taper, making it difficult to reflect the actual co-taper state of the rotor system. Therefore, whether the foreground image taken by the camera can fully reflect the situation of the blade rotating one circle (that is, corresponding to one shooting cycle) is very important for improving the measurement accuracy of the co-taper.

[0039] Therefore, in this step, the trigger sequence and the photo sequence in the current shooting cycle are synchronously compared. For example, the current aircraft has 6 blades. In the current shooting cycle, the trigger sequence is 1, and the corresponding photo sequence is also 1, which means that the first foreground photo is taken according to the first trigger signal. Compare the next 5 trigger sequences and 5 photo sequences one by one. If they all correspond, it means that in the current shooting cycle, the trigger sequence and the photo sequence are synchronized, which means that: in the current shooting cycle, the camera completely captures 6 blades, one photo for each blade. Therefore, these 6 photos are defined as a continuous foreground image group, which includes 6 foreground images. After determining the continuous foreground image group corresponding to the current shooting cycle, it is necessary to set the trigger sequence and the photo sequence to zero in order to synchronize the next shooting cycle.

[0040] Since this step is to compare the "soft count" and "hard count" synchronously, when GPIO is always valid, it can be determined that each of the continuous foreground image groups obtained contains different blade images in the same circle. Therefore, the subsequent common taper operation based on the continuous foreground image group can ensure to the greatest extent that the calculated rotor common taper can reflect the actual common taper state of the rotor system, thereby providing more reliable data support for rotor system design, adjustment, and maintenance.

[0041] In some embodiments, in actual application environments, even if GPIO is always valid, the camera may miss or take multiple shots. The above content also mentioned that ensuring the continuity of the foreground image is of great significance to improving the accuracy of common cone measurement. Therefore, if the triggering sequence of the trigger signal and the photo sequence of the foreground image are not synchronized in the current shooting cycle, all foreground images in the current shooting cycle are discarded, that is, the entire circle of foreground images are discarded and no longer processed, and the triggering sequence and the picture sequence are set to zero to enter the synchronous comparison of the next shooting cycle.

[0042] For example, in the current shooting cycle, if the aircraft has 6 blades, there are 6 trigger signals, but the maximum order of photos in the current shooting cycle is 5, that is, the trigger signal with a trigger order of 6 has no corresponding photo order. In this case, the camera missed a foreground image, so all the images in the current circle need to be discarded. In other cases, for example, there are 6 trigger signals, but the maximum order of photos in the current shooting cycle is 7. In this case, the camera took an extra foreground image, and all the images in the current shooting cycle also need to be discarded.

[0043] S120, determining the flight posture of the foreground image;

[0044] Specifically, the rotation of the aircraft's blades will be different under different flight attitudes. Since the camera's focal length, shooting angle, etc. are limited, the camera needs to adjust parameters under different flight attitudes to obtain a higher quality foreground image. Different camera parameters affect the extraction method of blade features in the foreground image, so it is necessary to distinguish the foreground image and perform different analysis and calculations on the foreground image according to different flight attitudes.

[0045] S130, determining the swinging heights of different blades of the aircraft in the current shooting cycle according to the flight attitude and the continuous foreground image group;

[0046] Specifically, the flight attitudes corresponding to all foreground images in the current continuous foreground image group are determined, and all foreground images in the continuous foreground image group are analyzed according to different flight attitudes. First, the foreground image is processed using relevant technologies. The image processing process can be specifically related technologies such as background segmentation and feature extraction. Through image processing, the geometric features of the blades in the foreground image are extracted, and these geometric features are analyzed to determine the swinging heights of different blades of the aircraft in the current shooting cycle. The specific process of determining the swinging height in this step will be described below.

[0047] It is understandable that the flight attitude of the aircraft will change from takeoff to steady flight, and the blades are still rotating during the change of flight attitude. Therefore, it is possible that the flight attitudes corresponding to different foreground images are different within a shooting cycle. In order to reduce the rotor vibration, rotor speed change, etc. caused by the change of flight attitude, when the flight attitudes corresponding to the images in a continuous foreground image group are not completely consistent within a shooting cycle, the continuous foreground image group can be discarded to improve the accuracy of the rotor common taper.

[0048] S140, determining the rotor taper of the aircraft in the current shooting cycle according to a number of flapping heights;

[0049] Specifically, according to the flapping heights of different blades in the same circle, the rotor taper of the aircraft in the current shooting cycle can be determined.

[0050] Through steps S100-S140, the embodiment of the present application provides a method for measuring the common taper of the rotor. First, during the rotation of the blade, a trigger signal is generated according to the azimuth angle, and the camera is controlled to capture the foreground image of each blade according to the trigger signal; if in the current shooting cycle, the triggering sequence of the trigger signal and the photo sequence of the foreground image are synchronized, all the photos in the current shooting cycle are determined to be a continuous foreground image group, and the triggering sequence and the photo sequence are set to zero. The flight attitude corresponding to the foreground image in the continuous foreground image group is obtained, and the foreground image is analyzed differently according to the flight attitude, so as to calculate the swinging height of different blades of the aircraft in the current shooting cycle, and determine the common taper of the rotor of the aircraft in the current shooting cycle according to the swinging height of different blades of the aircraft in the same circle.

[0051] The embodiment of the present application synchronizes the trigger sequence calculated by the hardware circuit and the photo sequence calculated by the software, which helps to obtain the foreground images of all blades in the same circle, thereby reducing the measurement deviation caused by the rotor speed jump in different shooting cycles, so as to improve the measurement accuracy of the rotor common taper; and the embodiment of the present application proposes to analyze the foreground image differently according to the different flight attitudes corresponding to different foreground images, which also helps to improve the calculation accuracy of the blade flapping height, thereby improving the measurement accuracy of the common taper. In some embodiments, when the trigger sequence and the photo sequence are not synchronized, all foreground pictures in the current shooting cycle are discarded, which also helps to obtain the foreground image of the blades in the same circle.

[0052] In some embodiments, Figure 1 The rotor common taper measurement method shown also includes steps S150-S160:

[0053] S150, obtaining a common taper set, where the common taper set includes rotor common tapers corresponding to a plurality of shooting cycles;

[0054] Specifically, according to the method in steps S100-S140, the rotor common tapers corresponding to multiple shooting cycles can be obtained, and the set of these rotor common tapers is a common taper set. It can be understood that the number of common tapers in the common taper set depends on the maximum number of photos that the camera can store. In the actual common taper measurement process, many foreground images will be discarded due to multiple shots, missed shots, or poor quality after image preprocessing by the camera, so it is necessary to collect as many foreground images as possible during the shooting process.

[0055] S160, determining a number of normal common tapers in the common taper set;

[0056] Specifically, a variety of conditions can be set to filter the common tapers in the common taper set. For example, the common tapers of other aircraft of the same model are used as a reference to determine the numerical range of normal common tapers, and the common tapers that are not within the numerical range are discarded; or the mean of all common tapers can be calculated, and the common tapers that differ too much from the mean are discarded. The screening conditions for common tapers can be set as needed, and the embodiments of the present application are not limited. When the abnormal common tapers in the common tapers are discarded, the remaining ones are normal common tapers.

[0057] S170. Determine the rotor taper of the aircraft based on a number of normal tapers.

[0058] Specifically, the rotor taper of the aircraft is determined according to the normal taper obtained in step S160. For example, the rotor taper of the aircraft may be the mean or median of these normal tapers.

[0059] Through steps S150-S170, the embodiment of the present application proposes obtaining the rotor common taper within multiple shooting cycles, filtering these common tapers through preset filtering conditions, and finally obtaining the rotor common taper corresponding to the aircraft.

[0060] In some embodiments, step S130 may be performed by Figure 3 To achieve this, refer to Figure 3 , Figure 3 A flowchart of the steps for determining the blade flapping height provided in an embodiment of the present application, the method includes but is not limited to steps S300-S320:

[0061] S300, determining a basic phase according to the flight attitude;

[0062] Specifically, the flight attitude of the aircraft can be divided into ground small pitch attitude, hovering attitude and level flight attitude. In the process of shooting the foreground image, since the setting position of the camera is fixed, the blades will have different images on the same size image under different flight attitudes. Figure 4 , Figure 4 The foreground images captured by the camera under three flight postures provided in the embodiments of the present application are as follows: Figure 4 As shown in the figure, it is not difficult to see that under the same camera parameters, the foreground images captured under different flight attitudes have relatively large deviations in the imaging area of ​​the blades, which is obviously not conducive to unified image processing. Moreover, maintaining uniform camera parameters to shoot the blades may also cause image quality to deteriorate due to reasons such as camera focal length, which will also affect the accuracy of image processing. Therefore, it is necessary to first determine the basic phase under different flight states. The basic phase represents the optimal shooting parameters of the camera under this flight state.

[0063] In some embodiments, the flight state corresponding to the image can be stored in the image information, and after the flight attitude is obtained, the basic phase corresponding to the flight attitude can be determined. When the aircraft is in one of the flight attitudes, the camera adjusts the camera parameters such as the lens elevation angle and the camera focal length, shoots the rotating blades, and captures several first blade images corresponding to different camera parameters. For example, in one of the first blade images, the blade tip is imaged in the center of the image, and the camera parameters corresponding to the first blade image are determined as the basic phase, and the camera parameters include but are not limited to the lens elevation angle, the camera focal length, and the like. In other words, when the flight is in a certain flight state, the corresponding basic phase is determined, and the foreground image is captured using the optimal shooting parameters represented by the basic phase.

[0064] S310, determining an optical model according to a basic phase;

[0065] Specifically, the camera parameters can be determined based on the basic phase. In addition, since the camera is fixed on the fuselage, the distance between the camera lens and the horizontal plane where the blade rotation center is located can also be determined. Through these parameters, the optical model of camera imaging in this flight mode can be determined. The following takes the camera shooting blades as an example to illustrate the process of building the optical model.

[0066] Reference Figure 5 , Figure 5 A schematic diagram of an optical model provided in an embodiment of the present application, such as Figure 5 As shown in the figure, AB is the actual object height, as the reference point, point M is imaged at the center of the picture, CD is the imaging plane parallel to the camera through point M, point O is the equivalent optical center of the lens, and OM is the optical center axis of the camera. A'B' is the CCD imaging plane of the camera. The angle between the camera optical axis and the horizontal is α, and the angles between the light rays OA and OB and the optical center axis are β and γ.

[0067] Before deducing the relationship, the coordinate system used in the derivation process is first explained. The right side takes a certain point M on the object to be measured as the origin, and the image of point M is located at the center of the image. The vertical axis direction corresponds to the height of the actual object to be measured. The coordinate system on the left side has the lens center point O as the origin, and the horizontal and vertical directions are the plane coordinate system of the x and y axes. Points A and B in the object are mapped to points A' and B' in the image respectively, and point M is mapped to point M'. Point X is the center of rotation of the rotor, and the dotted line represents a schematic diagram of the blades and their flapping.

[0068] Suppose the number of vertical pixels from point A' to the horizontal center line of the image is N1, and the number of vertical pixels from point B' to the horizontal center line of the image is N2. The vertical coordinates of points A, B and M are ha, hb and 0 respectively. The following derivation process is to derive the corresponding relationship between N1 and AM, and the corresponding relationship between N2 and MB, so that the mathematical relationship between the number of pixels between A'B' and the actual object height difference AB (ha-hb) can be obtained.

[0069] When the image point is located in the upper half of the image, it is known that the actual physical size of each pixel on the CCD is L (um) and the focal length of the lens is OM'. Let the number of pixels from the image center of point A to point A' be N1. In the triangle A'M'O, there is

[0070]

[0071] Then there is

[0072] β=ac tan(N1×L×10 -3 / OM')

[0073] In the triangle AOM, applying the law of sines, we have:

[0074]

[0075] Among them, the length of OM and the size of the installation pitch angle α can be determined by the actual installation position, which can be simplified to

[0076]

[0077] From the above formula, the mapping relationship between the number of pixels N1 from the imaging point A' to the image center and the actual height difference AM (ha) from the point A to the reference point M can be obtained.

[0078] In triangle B'M'O, when the image point is in the lower half of the image:

[0079]

[0080] Then there is

[0081]

[0082] In the triangle AOM, applying the law of sines, we have:

[0083]

[0084] Among them, the length of OM and the size of the installation pitch angle α can be determined by the actual installation position, which can be simplified to

[0085]

[0086] From the above formula, it can be obtained that the correspondence between the number of pixels N2 of the imaging point B' of point B from the center of the image and the actual height difference MB(hb) of point B from the reference point M is obtained.

[0087] Therefore, since the blade tip is imaged in the center of the image in the basic phase, according to the above optical model, the center point of the foreground image taken by the camera can be set as the first reference position (that is, point M'), and the position of the blade in the blade image (that is, point A' or point B') is confirmed. The first distance between the first reference position and the blade position can be obtained. The first distance is actually the number of pixels between the first reference position and the blade position (that is, N1 or N2). Then, according to the optical model determined by the above formula, the second distance between the blade tip height of the aircraft (that is, point A or point B) and the second reference position (that is, point M) can be calculated. The second distance is the flapping height of the blade, and the second reference position is the horizontal position where the rotor rotation center of the aircraft is located.

[0088] S320: Determine a waving height according to the optical model and the continuous foreground image group.

[0089] Specifically, all foreground images in the continuous foreground image group are analyzed and calculated according to the optical model determined in step S310, so as to determine the flapping heights corresponding to all foreground images, and thus determine the rotor taper of the aircraft according to the plurality of flapping heights.

[0090] Through steps S300-S320, the embodiment of the present application provides a method for establishing an optical model according to a basic phase and calculating a blade flight height corresponding to a foreground image.

[0091] In some embodiments, Figure 3 The method for calculating the blade swing height shown in the figure also includes the step of preprocessing the foreground image. It is understandable that the camera is generally set at a position obliquely below the blade. When the camera shoots the blade upward, the image obtained may include obstacles such as raindrops, clouds, and flying birds in addition to the blade. In the process of image processing, the background will have a certain impact on the extraction of the blade. And because the characteristics of the background in the blade image are different under different flight attitudes, for example, under the ground small pitch and hovering attitude, the movement of the aircraft is very small, so the background is relatively stable. Under these two flight attitudes, the relevant technology can be used to combine the acquired background image to segment the foreground image and complete the image preprocessing. In the level flight attitude, the background corresponding to the blade will change all the time, so the background image cannot be used for simple foreground and background segmentation. This embodiment wants to illustrate that the foreground image can be preprocessed accordingly according to the flight attitude of the aircraft to extract more accurate blades, thereby improving the calculation accuracy of the common cone.

[0092] In actual measurement scenarios, the measurement environment may not be conducive to camera shooting. For example, when the measurement environment is poorly illuminated, using a single automatic exposure mode to shoot a high-speed rotating blade is likely to cause tailing, which will also affect the accuracy of the common taper measurement.

[0093] Therefore, in some embodiments, the rotor common taper measurement method proposed in the embodiment of the present application further includes the step of establishing an optimal exposure model, referring to Figure 6 , Figure 6 The flowchart of the steps of establishing the optimal exposure model provided in the embodiment of the present application includes but is not limited to steps S600-S640.

[0094] S600, obtaining an exposure data set;

[0095] Specifically, foreground images under different lighting conditions, different exposure times, and different flight states are acquired as exposure data sets.

[0096] S610, obtaining an optimal exposure model according to the exposure data set training;

[0097] Specifically, the exposure data set obtained in step S600 is used to train the optimal exposure model. The specific training conditions may be, for example, scoring different foreground images taken at different exposure times under the same lighting conditions, and the exposure time corresponding to the foreground image with the highest score is the optimal exposure time. The model is mainly used to determine the exposure time corresponding to different exposure levels.

[0098] S620, obtaining the current illumination of the environment where the aircraft is located and the flight attitude of the aircraft;

[0099] Specifically, the current lighting conditions and flight attitude of the measurement environment where the aircraft is located are obtained.

[0100] S630, determining the optimal exposure time of the camera according to the current illumination and the optimal exposure model;

[0101] Specifically, the current lighting and flight attitude are input into the optimal exposure model, and the model can output the corresponding optimal exposure time, that is, self-learning exposure can be completed.

[0102] S640: The camera captures a foreground image according to the optimal exposure time.

[0103] Specifically, when the camera is shooting the foreground image, the current lighting and flight posture are obtained in real time, and the camera's shooting state is adjusted according to the optimal exposure time, so that the camera can capture a clear foreground without tailing.

[0104] Through steps S600-S640, the embodiment of the present application provides a solution for establishing an optimal exposure model so that the camera can achieve self-learning exposure. According to this solution, the quality of images taken by the camera can be improved and the generation of images of blade trailing can be minimized.

[0105] Reference Figure 7 , Figure 7A schematic diagram of a rotor taper measurement system provided in an embodiment of the present application, the system 700 includes a first module 710, a second module 720, a third module 730, a fourth module 740 and a fifth module 750; the first module is used to control the camera to capture a foreground image of each blade according to a trigger signal when the blades of the aircraft rotate; the second module is used to determine a continuous foreground image group in the current shooting cycle if the triggering sequence of the trigger signal and the photo sequence of the foreground image are synchronized in the current shooting cycle, and reset the triggering sequence and the photo sequence to zero; the third module is used to determine the flight attitude of the foreground image; the fourth module is used to determine the flapping height of different blades of the aircraft in the current shooting cycle according to the flight attitude and the continuous foreground image group; the fifth module determines the rotor taper of the aircraft in the current shooting cycle according to a number of flapping heights; wherein the continuous foreground image group includes a first number of foreground images; wherein the shooting cycle is the time length used for the triggering number of the trigger signal to reach the first number; wherein the trigger signal is triggered by the azimuth; wherein the first number is equal to the number of blades of the aircraft.

[0106] refer to Figure 8 , Figure 8 A schematic diagram of a device provided in an embodiment of the present application, wherein the device 800 includes at least one processor 810 and at least one memory 820 for storing at least one program; Figure 8 A processor and a memory are taken as an example.

[0107] The processor and the memory may be connected via a bus or other means. Figure 8 The example of connecting through bus is taken in the following.

[0108] The memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer executable programs. In addition, the memory may include a high-speed random access memory, and may also include a non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory may optionally include a memory remotely disposed relative to the processor, and these remote memories may be connected to the device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0109] Another embodiment of the present application further provides a device, which can be used to execute the control method in any of the above embodiments, for example, to execute the control method described above. Figure 1 The method steps in .

[0110] The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0111] An embodiment of the present application further discloses a computer storage medium, in which a program executable by a processor is stored, characterized in that the program executable by the processor is used to implement the rotor common taper measurement method proposed in the present application when executed by the processor.

[0112] It will be appreciated by those skilled in the art that all or some of the steps and systems in the disclosed method above may be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or may be implemented as hardware, or may be implemented as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or a non-transitory medium) and a communication medium (or a temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that may be used to store desired information and may be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0113] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the above-mentioned implementation mode. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the present application. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. A method for measuring rotor taper, characterized in that: include: When the propeller blades of the aircraft rotate, the camera is controlled to capture the foreground image of each propeller blade according to the trigger signal; If in the current shooting cycle, the triggering sequence of the trigger signal and the photo sequence of the foreground image are synchronized, determining a continuous foreground image group in the current shooting cycle, and setting the triggering sequence and the photo sequence to zero; Determining the flight attitude of the foreground image; Determine the swinging heights of different blades of the aircraft in a current shooting cycle according to the flight posture and the continuous foreground image group; The step of determining the flapping heights of different blades of the aircraft in a current shooting cycle according to the flight posture and the continuous foreground image group includes: determining a basic phase according to the flight attitude; The determining of the basic phase according to the flight attitude comprises: Acquire the flight attitude of the aircraft, wherein the flight attitude includes a ground small pitch attitude, a hovering attitude, and a level flight attitude; When the aircraft is in one of the flight attitudes, the camera captures a plurality of first blade images at different shooting angles; If the blade tip in the current first blade image is imaged at the center of the image, determining the current camera parameter to be the basic phase corresponding to the current flight attitude; Determine the basic phases corresponding to all the flight attitudes; Wherein, the camera parameters include lens elevation angle and camera focal length; determining an optical model according to the basic phase; determining the waving height according to the optical model and the set of continuous foreground images; Determine the rotor taper of the aircraft in a current shooting cycle according to a plurality of flapping heights; Wherein, the continuous foreground image group includes a first number of the foreground images; The shooting cycle is the time taken for the triggering number of the triggering signal to reach the first number; Wherein, the trigger signal is triggered by the azimuth angle; Wherein, the first number is equal to the number of blades of the aircraft; The measuring method further comprises: If the trigger sequence and the photo sequence are not synchronized in the current shooting cycle, the foreground image in the current shooting cycle is discarded, and the trigger sequence and the photo sequence are set to zero; If the flight postures corresponding to the images in the continuous foreground image group are not completely consistent within a shooting cycle, the continuous foreground image group within the shooting cycle is discarded.

2. The method for measuring rotor common taper according to claim 1, characterized in that: The step of determining the waving height according to the optical model and the continuous foreground image group comprises: Determining a center point of the foreground image as a first reference position; determining a blade tip position according to the foreground image, and determining a first distance between the first reference position and the blade tip position; determining a second distance between a blade tip height of the aircraft and a second reference position according to the optical model and the first distance, wherein the second distance is the flapping height; The second reference position is the horizontal position of the rotor rotation center of the aircraft.

3. The method for measuring rotor common taper according to any one of claims 1 to 2, characterized in that: The measuring method further comprises: Get the exposure dataset; Obtaining an optimal exposure model through training according to the exposure data set; Obtaining the current lighting of the environment where the aircraft is located; Determining an optimal exposure time according to the current illumination and the optimal exposure model; Determining the shooting parameters of the camera according to the optimal exposure time; According to the shooting parameters, the camera shoots the foreground image.

4. The method for measuring rotor common taper according to claim 1, characterized in that: The method further comprises: Get the background image; The continuous foreground image group is preprocessed according to the flight posture and the background image.

5. A rotor taper measurement system, characterized in that: include: The first module, the second module, the third module, the fourth module and the fifth module; The first module is used to control the camera to capture the foreground image of each blade according to the trigger signal when the blades of the aircraft rotate; The second module is used for determining a continuous foreground image group in the current shooting cycle if the triggering sequence of the trigger signal and the photo sequence of the foreground image are synchronized in the current shooting cycle, and setting the triggering sequence and the photo sequence to zero; The third module is used to determine the flight attitude of the foreground image; The fourth module is used to determine the swinging heights of different blades of the aircraft in the current shooting cycle according to the flight posture and the continuous foreground image group; Determining the flapping heights of different blades of the aircraft in the current shooting cycle according to the flight attitude and the continuous foreground image group includes: determining a basic phase according to the flight attitude; determining the basic phase according to the flight attitude includes: acquiring the flight attitude of the aircraft, the flight attitude including a ground small pitch attitude, a hovering attitude and a level flight attitude; when the aircraft is in one of the flight attitudes, the camera captures a number of first blade images at different shooting angles; if the blade tip in the current first blade image is imaged at the center of the image, determining the current camera parameter to be the basic phase corresponding to the current flight attitude; determining the basic phases corresponding to all the flight attitudes; wherein the camera parameters include a lens elevation angle and a camera focal length; determining an optical model according to the basic phase; determining the flapping height according to the optical model and the continuous foreground image group; The fifth module determines the rotor taper of the aircraft in the current shooting cycle according to a plurality of flapping heights; Wherein, the continuous foreground image group includes a first number of the foreground images; The shooting cycle is the time taken for the triggering number of the triggering signal to reach the first number; Wherein, the trigger signal is triggered by the azimuth angle; Wherein, the first number is equal to the number of blades of the aircraft; The measuring system further comprises: If the trigger sequence and the photo sequence are not synchronized in the current shooting cycle, the foreground image in the current shooting cycle is discarded, and the trigger sequence and the photo sequence are set to zero; If the flight postures corresponding to the images in the continuous foreground image group are not completely consistent within a shooting cycle, the continuous foreground image group within the shooting cycle is discarded.

6. A device, characterized in that: include: at least one processor; at least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the rotor common taper measurement method according to any one of claims 1 to 4.

7. A computer storage medium storing a program executable by a processor, characterized in that: The program executable by the processor is used to implement the method for measuring the rotor common taper as described in any one of claims 1 to 4 when executed by the processor.

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