CN111354036B - Underwater optical positioning method applied to pressure container environment - Google Patents

Underwater optical positioning method applied to pressure container environment Download PDF

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CN111354036B
CN111354036B CN201811565142.7A CN201811565142A CN111354036B CN 111354036 B CN111354036 B CN 111354036B CN 201811565142 A CN201811565142 A CN 201811565142A CN 111354036 B CN111354036 B CN 111354036B
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rov
camera
angle
calculating
pressure vessel
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CN111354036A (en
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陈姝
魏文斌
张志义
冯美名
张益成
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Research Institute of Nuclear Power Operation
China Nuclear Power Operation Technology Corp Ltd
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Research Institute of Nuclear Power Operation
China Nuclear Power Operation Technology Corp Ltd
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/70—Determining position or orientation of objects or cameras
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C11/00—Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/003—Remote inspection of vessels, e.g. pressure vessels
    • G21C17/01—Inspection of the inner surfaces of vessels
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/003—Remote inspection of vessels, e.g. pressure vessels
    • G21C17/013—Inspection vehicles
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10004—Still image; Photographic image
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

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  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Multimedia (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Theoretical Computer Science (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The invention belongs to an underwater positioning technology, and particularly relates to an underwater optical positioning algorithm applied to a pressure container environment. Under existing inspection conditions, positioning of the underwater ROV must first be achieved to make it possible to guide the ROV to a specified location. The method comprises the following steps: step 1, inputting the length a and radius data r of a pressure vessel bus, a vertical field angle A of a camera and the height B of a CCD target surface of the camera; step 2, solving a critical angle; step 3, calculating an angle theta corresponding to the unit radial length of the image plane of the camera 0 (ii) a Step 4, turning on an LED lamp on the ROV; step 5, adjusting the pitch angle alpha of a camera arranged in the center of the remote control platform according to the principle from large to small until a bright spot enters the central line of the field of view of the camera, wherein the rotation angle at the moment is the azimuth angle of the ROV; step 6 record the bright spot location (0,y) 0 ) And calculating the central variable. Step 7 calculates the depth x of the ROV. By using the method, the position of the ROV can be obtained by using the LED lamp on the ROV under the assistance of the camera.

Description

Underwater optical positioning method applied to pressure container environment
Technical Field
The invention belongs to an underwater positioning technology, and particularly relates to an underwater optical positioning method applied to a pressure container environment.
Background
A nuclear reactor pressure vessel is generally formed by an upper cylinder and a lower hemisphere, with a water inlet and outlet on the sides of the cylinder. FIG. 1 is a schematic cross-sectional view of a nuclear reactor pressure vessel. The pressure vessel has welding seams at the junction of the water outlet, the water inlet, the cylinder body and the bottom hemisphere and other specific positions. If these welds are damaged, there is a greater risk of continued use at high temperatures and pressures. Therefore, periodic inspection and repair of the pressure vessel is required. Usually, an underwater remote control underwater vehicle (ROV) has to carry out ultrasonic detection on a welding seam at a specified position to check whether a damage defect exists. For this purpose, the positioning of the underwater ROV must first be achieved, in order to be able to guide the ROV to a given location.
In order to realize the positioning of the ROV, a camera is arranged on a central beam remote control platform above the pressure container, the underwater vehicle ROV is arranged in the pressure container, and an LED lamp is arranged on the ROV. The camera on the remote platform has azimuth rotation and pitch adjustment functions, see fig. 2.
The position of the ROV can be obtained by using an LED lamp on the ROV with the assistance of a camera.
Disclosure of Invention
The invention aims to provide an underwater ROV optical positioning method applied to a pressure vessel environment, which can establish a mathematical model by utilizing the size parameters of the pressure vessel, the installation position of a camera and the parameters of LED lamp light on an ROV on a CCD target surface of a camera to obtain the accurate position of an ROV of a submersible vehicle.
The technical scheme of the invention is as follows:
an underwater ROV optical positioning method applied to a pressure container environment comprises the following steps:
step 1) inputting the length a (m) and radius data r (m) of a pressure vessel bus, a vertical field angle A (rad) (or a horizontal field angle) of a camera and the height B (mm) (or width) of a CCD target surface of the camera;
step 2) solving the critical angle
Figure BDA0001914339290000021
Step 3) calculating the angle theta corresponding to the unit radial length of the image plane of the camera 0 (rad)
Figure BDA0001914339290000022
Step 4), turning on an LED lamp on the ROV;
step 5) adjusting the pitch angle alpha rad of the camera arranged in the center of the remote control platform according to the principle from large to small, wherein the times are not more than
Figure BDA0001914339290000023
Which comprises
Figure BDA0001914339290000024
(not adjusted) and
Figure BDA0001914339290000025
rotating until the bright spot enters the central line of the camera view field, wherein the rotating angle is the azimuth angle of the ROV;
step 6) recording the position of the bright spot (0,y) 0 ) To find the central variable
Figure BDA0001914339290000026
Step 7) the depth x (m) of the ROV is calculated by the following algorithm:
Figure BDA0001914339290000027
the invention has the remarkable effects that: according to the underwater ROV optical positioning method for the pressure container environment, the position of the submersible vehicle ROV can be accurately obtained by utilizing the size parameters of the pressure container, the installation position parameters of the camera and the LED bright light on the ROV, the method is scientific, the detection has full coverage, and the calculation real-time performance is strong.
Drawings
FIG. 1 is a schematic cross-sectional view of a nuclear reactor pressure vessel
FIG. 2 a schematic diagram of sectional view camera and ROV measurement of a nuclear reactor pressure vessel
FIG. 3 is a graph of variable θ as a function of depth x
FIG. 4 is a schematic view of sectional view of a nuclear reactor pressure vessel, showing the camera shooting and ROV measuring angles
Detailed Description
The following detailed description of the patent refers to the accompanying drawings and specific embodiments:
the invention is described in further detail below with reference to the figures and the embodiments.
An underwater ROV optical positioning method applied to a pressure container environment comprises the following steps:
for a pressure vessel shaped as in fig. 2, knowledge about the analytical geometry is used to establish a relationship between the variable θ and the depth x, see fig. 3.
Taking O as a coordinate origin, OC as an x axis and OA as a y axis, establishing a rectangular coordinate system Oxy, and then the following points and coordinates thereof are as follows: o (0,0), O x (a, 0), a (0,r), B (a, r), C (a + r, 0). If the abscissa of the point D between AB is x and the angle COD = theta, then
Figure BDA0001914339290000031
If the abscissa of the point E on the arc BC is x, the ordinate is y, and the angle COE = θ, then:
Figure BDA0001914339290000032
and (x-a) 2 +y 2 ＝r 2 . Obtaining a result according to the characteristic that the E point is positioned at the upper right
Figure BDA0001914339290000041
At the point of the boundary B,
Figure BDA0001914339290000042
the above discussion illustrates the basic principle of solving for the depth x of an ROV.
Step 1) inputting the length a (m) and radius data r (m) of a pressure vessel bus, a vertical field angle A (rad) (or a horizontal field angle) of a camera and the height B (mm) (or width) of a CCD target surface of the camera; the data can be obtained through parameter introduction on a product specification;
step 2) solving the critical angle of the depth formula according to the length and radius data of the pressure vessel bus
Figure BDA0001914339290000043
Step 3) calculating the angle corresponding to the unit radial length of the CCD target surface of the camera by using the view field of the camera and the size of the CCD target surface
Figure BDA0001914339290000044
Step 4), turning on an LED lamp on the ROV for the camera to search ROV target information;
step 5) adjusting the pitch angle alpha rad of the camera arranged in the center of the remote control platform according to the principle from large to small, wherein the times do not exceed the number of times
Figure BDA0001914339290000045
Which comprises
Figure BDA0001914339290000046
(not to adjust) and
Figure BDA0001914339290000047
rotating until the bright spot enters the central line of the camera view field, wherein the rotating angle is the azimuth angle of the ROV;
step 6) recording the position of the bright spot (0,y) 0 ) To find out the variables
Figure BDA0001914339290000048
y 0 The positive and negative of (a) reflect the up-and-down position relation between the position D of the ROV and the intersection point Ox of the normal line of the mirror surface of the camera and the curved surface of the container, as shown in FIG. 4;
step 7) the depth x (m) of the ROV is calculated by using a plane analytic geometry method:
Figure BDA0001914339290000051
in the above steps, step 1) is to obtain the known parameters required by the algorithm: pressure vessel generating line length and radius, cameraAngle of view parameters and camera image plane size. And 2) solving the critical angle by utilizing the length and the radius of the pressure vessel bus. Step 3) calculating an angle theta corresponding to the unit radial length of the CCD target surface of the video camera according to the field angle and the size of the image plane of the video camera 0 (rad), for example, when the camera angle of view is 60 ° × 45 °, and the camera CCD target surface is 6mm × 4.5mm, a length of 1mm corresponds to a 10 ° angle of view. Steps 4) and 5) are operations performed to measure the orientation and depth of the ROV, from which the orientation of the ROV is obtained simultaneously. Step 6) and step 7) are key algorithms for solving the depth of the ROV.

Claims (2)

1. An underwater optical positioning method applied to a pressure vessel environment is characterized in that: the method comprises the following steps:
step 1, inputting the length a and radius data r of a pressure vessel bus, a vertical field angle A of a camera and the height B of a CCD target surface of the camera;
step 2, solving a critical angle;
step 3, calculating an angle theta corresponding to the unit radial length of the image plane of the camera 0 ；
Step 4, turning on an LED lamp on the ROV;
step 5, adjusting the pitch angle alpha of the camera arranged in the center of the remote control platform according to the principle from large to small until a bright spot enters the central line of the field of view of the camera, wherein the rotating angle at the moment is the azimuth angle of the ROV;
step 6 record the bright spot location (0,y) 0 ) Calculating a central variable;
step 7, calculating the depth x of the ROV;
the step 2: the specific way to solve the critical angle is as follows:
Figure FDA0003806297800000011
and step 5: the number of times of adjusting the pitch angle alpha is not more than
Figure FDA0003806297800000012
And step 5: adjusting the pitch angle alpha, whichIn
Figure FDA0003806297800000013
When in use
Figure FDA0003806297800000014
No adjustment is made;
the step 6: the specific way to find the central variable is
Figure FDA0003806297800000015
In step 7, the calculation method for calculating the depth x of the ROV is
Figure FDA0003806297800000021
2. An underwater optical locating method applied to a pressure vessel environment as claimed in claim 1, wherein: the step 3: calculating the angle theta corresponding to the unit radial length of the image plane of the camera 0 The concrete mode is as follows:
Figure FDA0003806297800000022
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Publication number Priority date Publication date Assignee Title
BR112015013804B1 (en) * 2012-12-14 2021-02-09 Bp Corporation North America Inc measuring system for three-dimensional measurement of an underwater structure, method for laser triangulation of an underwater structure and non-transient computer-readable medium coded with instructions
CN104464849A (en) * 2013-09-23 2015-03-25 核动力运行研究所 Device for checking reactor pressure vessel of nuclear power station
NO342795B1 (en) * 2016-07-28 2018-08-06 4Subsea As Method for detecting position and orientation of a subsea structure using an ROV
WO2018186750A1 (en) * 2017-04-05 2018-10-11 Blueye Robotics As Camera assisted control system for an underwater vehicle
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