A XCP probe spin speed video measurement device and method

Abstract

The present application discloses a video measurement device and method for the spin speed of an XCP probe, and relates to the field of ocean velocity profile measurement. The video measurement device for the spin speed of an XCP probe includes a test water tower platform, a high-speed image acquisition module, and a data processing module; the test water tower platform is used to draw test water of different depths as needed to simulate the ocean environment of different depths; a plurality of observation windows of transparent materials are provided at different heights on the test water tower platform; a light-weight highlight mark point is provided on the XCP probe; during measurement, the high-speed image acquisition module is placed directly opposite the observation window to collect the motion sequence image of the XCP probe during the free fall process in the test water tower platform; the data processing module is used to process the motion sequence image and calculate the spin speed of the XCP probe. The video measurement device and method for the spin speed of an XCP probe of the present application can realize non-contact measurement of the spin speed of the XCP probe, greatly improving the measurement accuracy.

Description

Technical Field

[0001] The present application relates to the technical field of ocean velocity profile measurement, and in particular to a device and method for measuring the spin velocity of an XCP probe through video. Background Art

[0002] The expendable current profiler (XCP) is a disposable current profile observation instrument. It measures the seawater flow rate by measuring the weak induced electromotive force generated by the cutting of the geomagnetic field when the seawater flows. It can be carried on aircraft, ships, submarines and other platforms, and has broad application prospects in the fields of ocean survey, marine environmental forecast, scientific research and military applications. Since the induced electromotive force is generally at the nanovolt level, the XCP probe cannot directly measure the weak induced electromotive force, and the electromotive force signal needs to be modulated into an AC signal through high-speed spinning for measurement. The flow velocity measurement principle of the XCP determines that the high-speed spinning of its probe is a necessary prerequisite for measurement. The rotation speed directly affects the accuracy and vertical resolution of the measurement data, and the stability of the rotation speed directly determines the quality of the measurement data. How to design an XCP probe structure that can perform stable high-speed spinning in seawater is one of the difficulties and key technologies in the design of XCP. Therefore, in the process of designing the XCP probe structure, it is necessary to measure the spin speed of the XCP probe and analyze its spin stability through experiments. Furthermore, the design and optimization of the XCP probe structure depends on the measurement of the spin speed of the XCP probe in water. By measuring and analyzing the spin speed of the XCP probe, experimental data support can be provided for the design, adjustment and optimization of the XCP probe structure.

[0003] The existing XCP probe spin speed measurement solution mainly adds an angular velocity sensor module to the XCP probe. When the XCP probe falls, the angular velocity sensor records the spin angle of the XCP probe and then calculates the spin speed. However, the above measurement solution changes the weight and center of gravity distribution of the XCP probe itself, making it difficult to accurately obtain the spin speed of the XCP probe itself. Summary of the invention

[0004] In view of the XCP measurement principle and characteristics, the present application provides an XCP probe spinning speed video measurement device and method to achieve non-contact measurement of the XCP probe spinning speed and improve measurement accuracy.

[0005] To achieve the above objectives, this application provides the following solutions.

[0006] On the one hand, the present application provides an XCP probe spin speed video measurement device, comprising: a test water tower platform, a high-speed image acquisition module and a data processing module;

[0007] The test water tower platform is used to pump test water of different depths as needed to simulate marine environments of different depths; a plurality of observation windows made of transparent materials are arranged at different heights on the test water tower platform; the high-speed image acquisition module is communicatively connected with the data processing module; the frame rate of the high-speed image acquisition module is greater than or equal to 1000f / s, and the image resolution is greater than or equal to 1280×1024; a light-weight highlight mark point is arranged on the XCP probe;

[0008] During measurement, the high-speed image acquisition module is facing the observation window, and is used to collect the motion sequence images of the XCP probe during its free fall in the test water tower platform and send them to the data processing module; the data processing module is used to process the motion sequence images and calculate the spin speed of the XCP probe.

[0009] Optionally, the lightweight highlight mark point provided on the XCP probe is a lightweight highlight circular reflective paint mark point sprayed at the center of the XCP probe head using a highlight reflective paint spraying device.

[0010] Optionally, the XCP probe spin speed video measurement device further includes: a light source; a plurality of fill-light windows made of transparent material are provided at different heights on the test water tower platform; during measurement, the light source is directly opposite to the fill-light window for supplementary lighting in dim light conditions.

[0011] In a second aspect, the present application further provides an XCP probe spinning speed video measurement method, based on the XCP probe spinning speed video measurement device; the XCP probe spinning speed video measurement method comprises:

[0012] Selecting the starting segment sequence image, the middle segment sequence image and the ending segment sequence image from the motion sequence images acquired by the high-speed image acquisition module;

[0013] Performing image preprocessing on the starting segment sequence image and the ending segment sequence image to obtain a preprocessed starting segment sequence image and a preprocessed ending segment sequence image;

[0014] For each frame of the preprocessed start segment sequence image and the preprocessed end segment sequence image, extract the XCP probe central axis and the center of the landmark point;

[0015] Calculate the distance from the center of the mark point to the central axis in each frame image, and obtain a distance sequence from the center of the mark point to the central axis in the preprocessed starting segment sequence image and the preprocessed ending segment sequence image;

[0016] Perform singular value detection and elimination on the two distance sequences respectively to obtain two distance data sequences after post-processing;

[0017] According to the two distance data sequences, the minimum distance from the center of the marker point to the central axis and the corresponding frame in the preprocessed starting segment sequence image and the preprocessed ending segment sequence image are calculated respectively;

[0018] The XCP probe spin speed is calculated based on the corresponding frame of the minimum distance from the center of the marker point to the central axis in the preprocessed start segment sequence image and the preprocessed end segment sequence image.

[0019] Optionally, the step of selecting a starting segment sequence image, a middle segment sequence image and an ending segment sequence image from the motion sequence images acquired by the high-speed image acquisition module specifically includes:

[0020] As the XCP probe rotates, the marker point on the XCP probe gradually enters the field of view of the high-speed image acquisition module from the back to the high-speed image acquisition module. When the marker point becomes complete in the image, the frame image is taken as the first image in the starting segment sequence image, and the frame number is recorded as As the XCP probe continues to rotate, the marker point gradually moves out of the field of view of the high-speed image acquisition module. The image in which the marker point retains its complete shape in the image is taken as the last image in the starting segment sequence image, and the frame number is recorded as ; then the set of all image frames in the starting sequence image is ;

[0021] Will The first image after the frame image is taken as the first image in the middle segment sequence image, and the frame number is recorded as As the XCP probe continues to rotate, the marker disappears and reappears in the field of view of the high-speed image acquisition module. When the marker becomes complete in the image again, the frame image is taken as the first image in the end segment sequence image, and the frame number is recorded as ,Will The previous frame image is taken as the last image in the middle segment sequence image, and the frame number is recorded as ; then the set of all image frames in the middle sequence image is ;

[0022] As the XCP probe continues to rotate, the marker point gradually moves out of the field of view of the high-speed image acquisition module again. The image in which the marker point finally maintains its complete shape in the image is taken as the last image in the end segment sequence image, and the frame number is recorded as ; then the set of all image frames in the end segment sequence image .

[0023] Optionally, the performing image preprocessing on the starting segment sequence images and the ending segment sequence images to obtain the preprocessed starting segment sequence images and the preprocessed ending segment sequence images specifically includes:

[0024] For each frame of the starting segment sequence image and the ending segment sequence image, the spatial domain median filtering method is used to smooth the image, and the image contrast is adjusted using the image enhancement method to obtain the preprocessed starting segment sequence image and the preprocessed ending segment sequence image.

[0025] Optionally, extracting the XCP probe central axis and the center of the landmark for each frame of the preprocessed start segment sequence image and the preprocessed end segment sequence image specifically includes:

[0026] For each frame of the preprocessed start segment sequence image and the preprocessed end segment sequence image, a Kalman filter-based method is used to track and predict the position of the XCP probe in the image coordinate system in the next frame of the image, and an area of ​​interest for searching the XCP probe in the next frame of the image is set;

[0027] The background image constructed by the statistical averaging method was subtracted by the background difference method to remove the background, and then the difference image was segmented in the region of interest using the threshold segmentation method to obtain a binary image containing the XCP probe;

[0028] Morphological filtering was used to eliminate noise and smooth the edges of each region in the binary image containing the XCP probe, and then the connected region-based marker segmentation method was used to segment the binary image, retaining only the connected regions with an area greater than the area threshold;

[0029] Traverse all connected areas, identify the XCP probe connected areas based on the morphological characteristics of the connected areas and extract the central axis. The central axis equation is recorded as ;in is a constant, Respectively represent the horizontal and vertical coordinates in the image coordinate system;

[0030] In the connected area of ​​the XCP probe, the original image is segmented using the threshold segmentation method to obtain a binary image containing the landmark points;

[0031] The arithmetic mean method is used to obtain the coordinates of the center point of the binary image containing the marker point, which is recorded as the center of the marker point .

[0032] Optionally, the calculating of the distance from the center of the marker point to the central axis in each frame image to obtain a distance sequence of the distance from the center of the marker point to the central axis in each frame image in the preprocessed starting segment sequence image and the preprocessed ending segment sequence image specifically includes:

[0033] Using formula Calculate the distance from the center of the marker point to the central axis in each frame of the image ; will target Frame image calculation Recorded as , ; Then the distance sequence of the center of each frame image mark point to the central axis in the preprocessed starting segment sequence image is , the distance sequence of the center of each frame image mark point to the central axis in the end segment sequence image after preprocessing .

[0034] Optionally, the performing singular value detection and elimination on the two distance sequences respectively to obtain two distance data sequences after post-processing specifically includes:

[0035] For distance series ,in , using polynomial fitting to determine its changing trend ;

[0036] Using formula Calculate the residual sequence of the distance sequence ;

[0037] calculate The mathematical expectation of and its standard deviation ;

[0038] Check one by one Whether it falls on Within the range, if so, keep the current , and order , continue testing Whether it falls within the interval; otherwise, And order , continue testing Whether it falls within the interval; until all After checking, two distance data sequences are obtained after post-processing. .

[0039] Optionally, the step of respectively calculating the minimum distance from the center of the marker point to the central axis and the corresponding frame in the preprocessed start segment sequence image and the preprocessed end segment sequence image according to the two distance data sequences specifically includes:

[0040] For distance data series And the corresponding frame number Perform quadratic polynomial fitting to obtain a quadratic equation ;in are the coefficient of the quadratic term, the coefficient of the linear term and the constant term respectively;

[0041] when When using the formula and Calculate the minimum distance from the center of the marker point to the central axis in the preprocessed starting segment sequence image And the corresponding frame ;

[0042] when When using the formula and Calculate the minimum distance from the center of the marker point to the central axis in the end segment sequence image after preprocessing And the corresponding frame .

[0043] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0044] In a video measuring device and method for the self-spinning speed of an XCP probe provided in the present application, the video measuring device for the XCP rotation speed involved mainly includes a test water tower platform, a high-speed image acquisition module, and a data processing module; the present application uses a high-speed image acquisition module to collect a motion sequence image of an XCP probe with a lightweight highlight mark point in the test water tower platform, extracts the central axis of the XCP probe and the center of the mark point by a digital image processing method, calculates the moment when the center of the mark point passes through the central axis of the probe twice in a row, and thus realizes the measurement and calculation of the self-spinning speed of the XCP probe. The present application realizes low-cost, high-precision, contactless measurement of the spin speed of the XCP probe, can provide experimental means support for the design and optimization of the XCP probe structure, and assists in the research and development and manufacturing of XCP equipment, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 It is a structural schematic diagram of the XCP probe spin speed video measurement device;

[0047] Figure 2 Schematic diagram of the screening process of the starting segment sequence images, the middle segment sequence images and the ending segment sequence images. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0049] In view of the XCP measurement principle and characteristics, this application proposes a video measurement device and method for the XCP probe spinning speed, which realizes the non-contact measurement of the high-speed rotation speed of the XCP probe in water, improves the measurement accuracy of the XCP probe spinning speed, can meet the XCP indoor testing needs, and can provide experimental data support for the XCP probe structure design, adjustment and optimization.

[0050] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0051] like Figure 1 As shown, in an exemplary embodiment, the present application provides an XCP probe spin speed video measurement device, comprising: a test water tower platform 1, a high-speed image acquisition module 2 and a data processing module 3. In another exemplary embodiment, the XCP probe spin speed video measurement device may also include a light source 4. The test water tower platform 1 is used to pump test water of different depths as needed to simulate the marine environment of different depths. A plurality of observation windows 101 and fill light windows 102 made of transparent materials are provided at different heights on the test water tower platform 1. The high-speed image acquisition module 2 is communicatively connected to the data processing module 3. The frame rate of the high-speed image acquisition module 2 is greater than or equal to 1000f / s, and the image resolution is greater than or equal to 1280×1024.

[0052] XCP usually consists of an XCP probe (referred to as the probe) 501, a buoy 502 and a ship-borne receiving device (not shown in the figure). Before use, the XCP probe 501 is built into the buoy 502 and connected to the buoy 502 via a data transmission line 503. After the survey ship arrives at the predetermined sea area, the buoy 502 (including the XCP probe 501) is thrown into the sea. After that, the XCP probe 501 leaves the buoy 502 and falls freely in the seawater. During the falling process, the seawater flow rate is measured, and the measurement signal is transmitted to the sea surface buoy 502 via the data transmission line 503. The sea surface buoy 502 transmits the measurement signal to the ship-borne receiving device wirelessly.

[0053] The unique design of the XCP probe 501 of the present application is that before measurement, a light highlight mark point 504 is added to the XCP probe 501, such as Figure 2 Among them, "lightweight" means that the mark point has almost no weight, and "highlight" means that the mark point has a high brightness due to high reflectivity or other reasons, and can be greater than a certain brightness threshold in the captured image, so it can be clearly identified through threshold segmentation.

[0054] During measurement, ensure that a light-weight highlight mark point 504 is provided on the XCP probe 501. The mark point 504 may be a light-weight highlight circular reflective paint mark point sprayed at the center of the head of the XCP probe 501 using a highlight reflective paint spraying device.

[0055] During measurement, the high-speed image acquisition module 2 needs to face the observation window 101 to collect the motion sequence images of the XCP probe 501 in the free fall process in the test water tower platform 1 and send them to the data processing module 3. In the case of low light, it is also necessary to place a light source 4 at the fill light window 102, and the light source 4 is preferably facing the fill light window 102 to supplement the light. The data processing module 3 is used to process the motion sequence images and calculate the spin speed of the XCP probe.

[0056] In an exemplary embodiment, the test water tower platform 1 is a cylindrical test platform with a height of 20m and a diameter of 2m, which is divided into 7 layers according to different heights, and each layer is provided with a transparent observation window 101 and a fill-in light window 102 made of acrylic material with a diameter of 60cm. Of course, in practical applications, the observation window 101 and the fill-in light window 102 can also be used universally. The test water tower platform 1 can also be provided with other layers. Test water of different depths can be pumped into the test water tower platform 1 as needed, which can simulate the test environment of the ocean shallower than 20m.

[0057] In another exemplary embodiment, the test water tower platform 1 can also be set to be a fully transparent acrylic material, but during construction, it is also necessary to evenly distribute the observation window 101 and the fill-in light window 102 on the 20m test water tower platform 1 according to actual conditions.

[0058] In an exemplary embodiment, the high-speed image acquisition module 2 may use a frame rate of not less than 1000 f / s (frames per second) and a high-speed industrial camera with an image resolution of not less than 1280×1024, such as the Y3-S1 high-speed industrial camera produced by IDT. The high-speed image acquisition module 2 is mainly used to acquire the motion sequence images of the XCP probe 501 during the free fall process in the test water tower platform 1.

[0059] During measurement, the high-speed image acquisition module 2 needs to face the observation window 101. When measuring the spin speed of the XCP probe, only one high-speed image acquisition module 2 needs to be placed in the observation window 101 at the bottom of the test water tower platform 1, or a high-speed image acquisition module 2 can be placed on each layer, so that the entire process of the XCP probe from entering the water to reaching a stable falling state can be measured.

[0060] The data processing module 3 is mainly used to process the motion sequence image information obtained by the high-speed image acquisition module 2 and calculate the XCP probe spin speed. The data processing module 3 can be a computer equipped with data processing software compiled based on the method of the present application.

[0061] Light source 4 is a LED bowl-shaped light source, which is used to supplement the light in dim conditions to obtain high-quality images. Figure 1 As shown, the fill light window 102 can be directly opposite to the observation window 101, or can be located in a vertical direction of the observation window 101. During measurement, the light source 4 can be directly opposite to the fill light window 102. According to the preliminary test results, fill light is usually required.

[0062] High-gloss reflective paint spraying equipment can be used to spray lightweight high-gloss circular reflective paint marking points on the XCP probe, adding high-precision feature points to the XCP probe without almost changing the weight and center of gravity distribution of the XCP probe.

[0063] Based on the XCP probe spinning speed video measuring device, the present application also provides an XCP probe spinning speed video measuring method, including the following S1 to S7.

[0064] S1. Filtering a starting segment sequence image, a middle segment sequence image and an ending segment sequence image from the motion sequence images acquired by the high-speed image acquisition module.

[0065] Before the test, a light-weight, high-gloss silver-white circular reflective paint mark is sprayed on the center of the head of the experimental XCP probe using a high-gloss reflective paint spraying device. During the test, turn on the light source 4 and align it with the fill light window 102 of the test water tower platform 1. Place the high-speed image acquisition module 2 vertically and align it with the observation window 101 of the test water tower platform 1 and connect it to the data processing module 3. Set the image acquisition frame rate of the high-speed image acquisition module 2 and start collecting images. The frame rate is set to more than 1000 frames per second, the higher the better. The XCP buoy 502 (including the XCP probe 501) is dropped from the top of the test water tower platform 1. After the XCP probe 501 falls to the bottom of the test water tower platform 1, turn off the high-speed image acquisition module 2. The trajectory of the XCP probe 501 spinning down is spiral as a whole. It will spin around its own central axis while falling in the sea water.

[0066] Then, the starting segment sequence images, the middle segment sequence images and the ending segment sequence images are screened from all the motion sequence images acquired by the high-speed image acquisition module 2, specifically including:

[0067] S1.1, if Figure 2As shown in the figure, the marker point 504 on the XCP probe 501 (the following description will not be labeled for language simplicity) gradually enters the field of view of the high-speed image acquisition module from the back to the high-speed image acquisition module as the XCP probe rotates. When the marker point becomes complete in the image, the frame image is taken as the first image in the starting segment sequence image, and the frame number is recorded as As the XCP probe continues to rotate, the marker point gradually moves out of the field of view of the high-speed image acquisition module. The image in which the marker point retains its complete shape in the image is taken as the last image in the starting segment sequence image, and the frame number is recorded as ; then the set of all image frames in the starting sequence image is .

[0068] S1.2. The first image after the frame image is taken as the first image in the middle segment sequence image, and the frame number is recorded as ; As the XCP probe continues to rotate, the marker disappears and then reappears in the field of view of the high-speed image acquisition module; when the marker becomes complete in the image again, the frame image is taken as the first image in the end segment sequence image, and the frame number is recorded as ;Will The previous frame image is taken as the last image in the middle segment sequence image, and the frame number is recorded as ; then the set of all image frames in the middle sequence image is ;

[0069] S1.3, as the XCP probe continues to rotate, the marker point gradually moves out of the field of view of the high-speed image acquisition module again, and the image in which the marker point finally maintains its complete shape in the image is taken as the last image in the end segment sequence image, and the frame number is recorded as ; then the set of all image frames in the end segment sequence image .

[0070] Due to the use of a high-speed image acquisition module and preliminary tests, the XCP probe spins at a speed of about 15 revolutions per second and falls at a speed of about 5 m / s. The XCP probe makes one rotation and falls 0.33 m. This ensures that the starting segment sequence images, middle segment sequence images and ending segment sequence images can be screened out from all the motion sequence images captured by the high-speed image acquisition module.

[0071] S2. Perform image preprocessing on the starting segment sequence image and the ending segment sequence image to obtain a preprocessed starting segment sequence image and a preprocessed ending segment sequence image.

[0072] Each frame of the starting segment sequence image and the ending segment sequence image is recorded as frame image, where ; Corresponding to the starting segment sequence image, Corresponding to the end segment sequence image. The frame image is smoothed by using the spatial median filtering method to reduce the influence of camera shake and high-frequency noise; and the image enhancement method is used to adjust the image contrast and improve the image quality for subsequent processing; thus, the preprocessed starting segment sequence image and the preprocessed ending segment sequence image are obtained.

[0073] S3, for each frame of the preprocessed start segment sequence image and the preprocessed end segment sequence image, extract the XCP probe central axis and the center of the landmark point, specifically including:

[0074] S3.1, for each frame of the preprocessed starting segment sequence image and the preprocessed ending segment sequence image, that is, Frame image, using Kalman filtering to track and predict the position of the XCP probe in the image coordinate system in the next frame image, and set the region of interest (ROI) for searching the XCP probe in the next frame image to reduce the amount of calculation;

[0075] S3.2, removing the background by subtracting the background image constructed by the statistical averaging method through the background difference method, and then segmenting the difference image in the region of interest using the threshold segmentation method to obtain a binary image containing the XCP probe;

[0076] S3.3, using morphological filtering to eliminate noise and smooth the edges of each region of the binary image containing the XCP probe, and then using a connected region-based marker segmentation method to segment the resulting binary image, retaining only connected regions whose area is greater than an area threshold;

[0077] S3.4, traverse all connected areas, identify the XCP probe connected areas based on the morphological characteristics of the connected areas and extract the central axis. The central axis equation is recorded as ;in is a constant, Respectively represent the horizontal and vertical coordinates in the image coordinate system;

[0078] S3.5, in the XCP probe connected area, the original image is segmented using the threshold segmentation method to obtain a binary image containing the landmark points, such as Figure 2 As shown;

[0079] S3.6, then use the arithmetic mean method to obtain the coordinates of the center point of the marker point in the binary image containing the marker point, recorded as the marker point center .

[0080] S4, calculating the distance from the center of the mark point to the central axis in each frame image, and obtaining a distance sequence from the center of the mark point to the central axis in the preprocessed starting segment sequence image and the preprocessed ending segment sequence image, specifically including:

[0081] Using formula Calculate the distance from the center of the marker point to the central axis in each frame of the image , will target Frame image calculation Recorded as , Then the distance sequence of the center of each frame image mark point to the central axis in the preprocessed starting segment sequence image is , the distance sequence of the center of each frame image mark point to the central axis in the end segment sequence image after preprocessing .

[0082] S5. Perform singular value detection and elimination on the two distance sequences respectively to obtain two distance data sequences after post-processing. The post-processing process specifically includes:

[0083] S5.1. Record the distance sequence from the center of the marker point to the central axis in each frame image as ,in ; For distance sequence , using polynomial fitting to determine its changing trend ;

[0084] S5.2. Use formula Calculate the residual sequence of the distance sequence ;

[0085] S5.3. Calculation The mathematical expectation of and its standard deviation ;

[0086] For the distance sequence , The mathematical expectation of , standard deviation ; For the distance sequence , The mathematical expectation of , standard deviation ;

[0087] S5.4. Check each one Whether it falls on Within the range, if so, keep the current , and order , continue testing Whether it falls within the interval; otherwise, And order , continue testing Whether it falls within the interval; until all After checking, two distance data sequences are obtained after post-processing. . The distance data sequence after singular value detection and elimination It can be assumed to contain only random errors.

[0088] S6, respectively calculating the minimum distance from the center of the marker point to the central axis and the corresponding frame in the preprocessed start segment sequence image and the preprocessed end segment sequence image according to the two distance data sequences, specifically including:

[0089] S6.1. Distance data series And the corresponding frame number Perform quadratic polynomial fitting to obtain a quadratic equation ;in are the coefficient of the quadratic term, the coefficient of the linear term and the constant term respectively; the minimum distance from the center of the marker point to the central axis in each frame image and the corresponding number of frames can be calculated based on the characteristics of the quadratic equation;

[0090] S6.2: When using the formula and Calculate the minimum distance from the center of the marker point to the central axis in the preprocessed starting segment sequence image And the corresponding frame ;

[0091] S6.3. When When using the formula and Calculate the minimum distance from the center of the marker point to the central axis in the end segment sequence image after preprocessing And the corresponding frame .

[0092] S7, calculating the XCP probe spinning speed according to the corresponding frame of the minimum distance from the center of the marker point to the central axis in the preprocessed start segment sequence image and the preprocessed end segment sequence image.

[0093] Using formula Calculation of XCP probe spin speed , the unit is ; is the frame rate of the high-speed image acquisition module.

[0094] By repeating S1-S7, the spin speed of the XCP probe can be measured and calculated multiple times. , … , Nis the number of measurements. The spin speed obtained by analyzing multiple measurements , … , and the stability of the XCP probe's spin speed can also be explored. The purpose of multiple measurements is to explore whether the XCP probe's spin is stable. The head, height, and measurement position of the XCP probe should be kept the same during multiple measurements. This is how we can study whether the XCP probe's falling speed is consistent each time it is dropped. If the spin speed is measured multiple times, , … If the spin speeds are the same, it indicates that the XCP probe spin is stable; if the spin speed is unstable, then there will be large differences in the spin speeds measured multiple times.

[0095] This application is aimed at the principle and characteristics that the XCP probe needs to maintain high-speed stable rotation in seawater to measure the current profile, and proposes a video measurement device and method for the rotation speed of the XCP probe. The high-speed image acquisition module is used to collect the motion sequence images of the XCP probe with lightweight highlight mark points in the test water tower platform, and the XCP probe central axis and the mark point center are extracted by digital image processing method. The moment when the mark point center passes through the probe central axis twice in a row is calculated, and the measurement and calculation of the XCP probe rotation speed is realized. This application can realize the low-cost, high-precision, non-contact measurement of the high-speed rotation speed of the XCP probe in water, which can meet the XCP indoor testing requirements, and can provide experimental means support for the design and optimization of the XCP probe structure, and help the research and development and manufacturing of XCP equipment. At the same time, the method of this application can also be used for the spin speed measurement and motion performance testing of other marine instruments with similar working modes, and has broad application prospects.

[0096] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for measuring the spin speed of an XCP probe by video, based on an apparatus for measuring the spin speed of an XCP probe by video, characterized in that: The XCP probe spin speed video measurement device comprises: a test water tower platform, a high-speed image acquisition module and a data processing module; The test water tower platform is used to pump test water of different depths as needed to simulate the marine environment of different depths; a plurality of observation windows made of transparent materials are arranged at different heights on the test water tower platform; the high-speed image acquisition module is in communication connection with the data processing module; the frame rate of the high-speed image acquisition module is greater than or equal to 1000 f / s , the image resolution is greater than or equal to 1280×1024; the XCP probe is provided with a light highlight mark point; During measurement, the high-speed image acquisition module faces the observation window and is used to acquire the motion sequence images of the XCP probe during free fall in the test water tower platform and send them to the data processing module; the data processing module is used to process the motion sequence images and calculate the spin speed of the XCP probe; The XCP probe spin speed video measurement method comprises: Selecting the starting segment sequence image, the middle segment sequence image and the ending segment sequence image from the motion sequence images acquired by the high-speed image acquisition module; Performing image preprocessing on the starting segment sequence image and the ending segment sequence image to obtain a preprocessed starting segment sequence image and a preprocessed ending segment sequence image; For each frame of the preprocessed start segment sequence image and the preprocessed end segment sequence image, extract the XCP probe central axis and the center of the landmark point; Calculate the distance from the center of the mark point to the central axis in each frame image, and obtain a distance sequence from the center of the mark point to the central axis in the preprocessed starting segment sequence image and the preprocessed ending segment sequence image; Perform singular value detection and elimination on the two distance sequences respectively to obtain two distance data sequences after post-processing; According to the two distance data sequences, the minimum distance from the center of the marker point to the central axis and the corresponding frame in the preprocessed starting segment sequence image and the preprocessed ending segment sequence image are calculated respectively; The XCP probe spin speed is calculated based on the corresponding frame of the minimum distance from the center of the marker point to the central axis in the preprocessed start segment sequence image and the preprocessed end segment sequence image.

2. The XCP probe spin speed video measurement method according to claim 1, characterized in that: The light-weight highlight mark point provided on the XCP probe is a light-weight highlight circular reflective paint mark point sprayed at the center of the XCP probe head by using a highlight reflective paint spraying device.

3. The XCP probe spin speed video measurement method according to claim 1, characterized in that: The XCP probe spin speed video measurement device also includes: a light source; a plurality of fill-in light windows made of transparent material are arranged at different heights on the test water tower platform; during measurement, the light source is directly opposite to the fill-in light window for supplementary illumination in dim light conditions.

4. The XCP probe spin speed video measurement method according to claim 1, characterized in that: The step of selecting the starting segment sequence images, the middle segment sequence images and the ending segment sequence images from the motion sequence images acquired by the high-speed image acquisition module specifically includes: As the XCP probe rotates, the marker point on the XCP probe gradually enters the field of view of the high-speed image acquisition module from the back to the high-speed image acquisition module. When the marker point becomes complete in the image, the frame image is taken as the first image in the starting segment sequence image, and the frame number is recorded as As the XCP probe continues to rotate, the marker point gradually moves out of the field of view of the high-speed image acquisition module. The image in which the marker point retains its complete shape in the image is taken as the last image in the starting segment sequence image, and the frame number is recorded as ; then the set of all image frames in the starting sequence image is ; Will The first image after the frame image is taken as the first image in the middle segment sequence image, and the frame number is recorded as As the XCP probe continues to rotate, the marker disappears and reappears in the field of view of the high-speed image acquisition module. When the marker becomes complete in the image again, the frame image is taken as the first image in the end segment sequence image, and the frame number is recorded as ,Will The previous frame image is taken as the last image in the middle segment sequence image, and the frame number is recorded as ; then the set of all image frames in the middle sequence image is ; As the XCP probe continues to rotate, the marker point gradually moves out of the field of view of the high-speed image acquisition module again. The image in which the marker point finally maintains its complete shape in the image is taken as the last image in the end segment sequence image, and the frame number is recorded as ; then the set of all image frames in the end segment sequence image .

5. The XCP probe spin speed video measurement method according to claim 1, characterized in that: The performing image preprocessing on the starting segment sequence image and the ending segment sequence image to obtain the preprocessed starting segment sequence image and the preprocessed ending segment sequence image specifically includes: For each frame of the starting segment sequence image and the ending segment sequence image, the spatial domain median filtering method is used to smooth the image, and the image contrast is adjusted using the image enhancement method to obtain the preprocessed starting segment sequence image and the preprocessed ending segment sequence image.

6. The XCP probe spin speed video measurement method according to claim 4, characterized in that: The step of extracting the XCP probe central axis and the center of the landmark for each frame of the preprocessed start segment sequence image and the preprocessed end segment sequence image specifically includes: For each frame of the preprocessed start segment sequence image and the preprocessed end segment sequence image, a Kalman filter-based method is used to track and predict the position of the XCP probe in the image coordinate system in the next frame of the image, and an area of ​​interest for searching the XCP probe in the next frame of the image is set; The background image constructed by the statistical averaging method was subtracted by the background difference method to remove the background, and then the difference image was segmented in the region of interest using the threshold segmentation method to obtain a binary image containing the XCP probe; Morphological filtering was used to eliminate noise and smooth the edges of each region in the binary image containing the XCP probe, and then the connected region-based marker segmentation method was used to segment the binary image, retaining only the connected regions with an area greater than the area threshold; Traverse all connected areas, identify the XCP probe connected areas based on the morphological characteristics of the connected areas and extract the central axis. The central axis equation is recorded as ;in is a constant, Respectively represent the horizontal and vertical coordinates in the image coordinate system; In the connected area of ​​the XCP probe, the original image is segmented using the threshold segmentation method to obtain a binary image containing the landmark points; The arithmetic mean method is used to obtain the coordinates of the center point of the binary image containing the marker point, which is recorded as the center of the marker point .

7. The XCP probe spin speed video measurement method according to claim 6, characterized in that: The calculating of the distance from the center of the mark point to the central axis in each frame image to obtain a distance sequence from the center of the mark point to the central axis in each frame image of the preprocessed starting segment sequence image and the preprocessed ending segment sequence image specifically includes: Using formula Calculate the distance from the center of the marker point to the central axis in each frame of the image ; will target Frame image calculation Recorded as , ; Then the distance sequence of the center of each frame image mark point to the central axis in the preprocessed starting segment sequence image is , the distance sequence of the center of each frame image mark point to the central axis in the end segment sequence image after preprocessing .

8. The XCP probe spin speed video measurement method according to claim 7, characterized in that: The singular value detection and elimination are performed on the two distance sequences respectively to obtain two distance data sequences after post-processing, specifically including: For distance series ,in , using polynomial fitting to determine its changing trend ; Using formula Calculate the residual sequence of the distance sequence ; calculate The mathematical expectation of and its standard deviation ; Check one by one Whether it falls on Within the range, if so, keep the current , and order , continue testing Whether it falls within the interval; otherwise, And order , continue testing Whether it falls within the interval; until all After checking, two distance data sequences are obtained after post-processing. .

9. The XCP probe spin speed video measurement method according to claim 8, characterized in that: The step of calculating the minimum distance from the center of the marker point to the central axis and the corresponding frame in the preprocessed starting segment sequence image and the preprocessed ending segment sequence image respectively according to the two distance data sequences specifically includes: For distance data series And the corresponding frame number Perform quadratic polynomial fitting to obtain a quadratic equation ;in are the coefficient of the quadratic term, the coefficient of the linear term and the constant term respectively; when When using the formula and Calculate the minimum distance from the center of the marker point to the central axis in the preprocessed starting segment sequence image And the corresponding frame ; when When using the formula and Calculate the minimum distance from the center of the marker point to the central axis in the preprocessed end segment sequence image And the corresponding frame .

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