Calibration device and method for underwater vision measurement system

Abstract

The invention provides a calibration device and method of an underwater vision measurement system. The calibration device of the underwater vision measurement system comprises a base, a standard object movement mechanism, a vision measurement system movement mechanism, a standard object, a vision measurement system, a water tank, a control box and a control terminal. The water tank is located under the base and used for containing liquid to form an underwater environment, and the internal space is a calibration space. The base is composed of a lower structure, a supporting column and an upper structure, and the lower structure is used for being connected with the ground. The supporting column is connected between the lower structure and the upper structure. The standard object movement mechanism and the vision measurement system movement mechanism are arranged on the upper structure in parallel. According to the underwater calibration device, the water tank is used for simulating the underwater environment, and the dual-motion mechanism, the control box, the control terminal and other devices are matched with one another, so that the problems that an existing underwater calibration device cannot perform large-range multi-pose calibration, cannot be linked with an underwater vision measurement system and cannot simulate the underwater special environment are solved.

Description

Technical Field

[0001] The present application belongs to the technical field of calibration of underwater vision measurement systems, and specifically relates to a calibration device and method for underwater vision measurement systems. Background Art

[0002] With the development of marine resources, marine energy, water conservancy, hydropower, nuclear power and other industries, the application of underwater high-precision visual measurement systems is becoming more and more widespread. Underwater visual measurement systems include imaging, laser triangulation, stereo vision, structured light, photogrammetry and other measurement equipment that use light perception principles.

[0003] Calibration is a key link in the use of underwater vision measurement systems, which directly determines the measurement accuracy of the system. According to experience, it is helpful to improve the calibration effect by selecting multiple positions and multiple postures covering the entire space as much as possible in the measurement space and maintaining sufficient stability. Calibration not only includes system parameter calibration based on calibration plates and standard objects, but also includes system accuracy testing based on standard objects. With the improvement of the measurement accuracy of underwater vision measurement systems and the expansion of measurement space, the traditional pure manual calibration method or manual assisted calibration method can no longer meet actual needs. It not only has the disadvantages of low efficiency, poor accuracy, inconvenience and safety risks, but also cannot simulate the actual underwater measurement environment. The pure manual calibration method is to manually adjust the relative posture in the ocean, lake, swimming pool or test pool. The posture adjustment operation during the calibration process is cumbersome, and it is difficult to ensure posture stability. The manual assisted calibration method has improved the calibration efficiency and accuracy to a certain extent through the calibration tooling with control, but the following problems still exist:

[0004] 1) It cannot meet the needs of large-scale multi-pose calibration. The existing calibration device only supports the position adjustment of the calibration plate or standard object relative to the fixed visual measurement system, and only supports within 3 degrees of freedom, that is, it does not realize the flexible adjustment of the two relative to 6 degrees of freedom. It can neither meet the high-precision calibration needs under multiple poses in the entire measurement range, nor meet the measurement pose requirements recommended by relevant specifications, such as VDI / VDE2634.2-2012, 2012 "Optical 3D Measurement System: Part 2: Optical System Based on Area Scanning", VDI / VDE 2634.3-2008 "Optical 3D Measurement System: Part 3: Multi-view System Based on Area Scanning", JJF 1951-2021 "Calibration Specification for Optical 3D Measurement System Based on Structured Light Scanning";

[0005] 2) It does not have the function of non-drainage above-water and underwater calibration. Due to the influence of refraction of multi-layer media, high-precision underwater visual measurement systems generally need to calibrate camera parameters above water first, and then calibrate sealing window parameters underwater. Some even need to ensure that the relative posture above water and underwater remains unchanged. Switching between above-water and underwater environments by filling and draining or entering and exiting water through the calibration device is not only time-consuming and cumbersome to operate, but may also waste precious water resources;

[0006] 3) It does not have the function of simulating special underwater environments. For the marine energy industry, the underwater environment has flow and high turbidity; for the nuclear power industry, the underwater environment has flow and thermal disturbance and low turbidity. The calibration device cannot simulate the special environment required for the actual calibration process and cannot meet the needs of high-precision calibration;

[0007] 4) It does not have a semi-automatic or fully automatic calibration function linked to the measurement system. For multiple postures that cannot be automatically adjusted to the correct position to trigger acquisition directly or prompt manual acquisition, the staff is generally required to manually control the calibration plate to adjust the position, then manually confirm whether it is in place and stable, and finally manually control the measurement system to collect. The whole process is cumbersome and inefficient, and one-click automatic calibration cannot be achieved.

[0008] After searching the patent "201710292067.0 A self-adaptive underwater camera calibration device for water quality" only proposes that the motor drives the calibration plate to move relative to the camera through a connecting rod, but does not specify the relative freedom of movement, and requires that the camera and the calibration plate be relatively fixed when calibrating from air to water, but no solution is provided. More importantly, the entire calibration device needs to be immersed in water, which has high requirements for the device itself to be waterproof or in a pool; the patent "CN201910838562.6 A underwater structured light measurement calibration device" achieves underwater measurement results relative to surface measurement results by adjusting the relative distance between the sensor and the target Simple compensation does not involve sensor parameter calibration based on the principle; Patent "202323149270.2 An underwater camera calibration device" only solves the automatic adjustment of the relative distance and height between the camera and the calibration plate during the calibration process, and cannot solve the relative posture adjustment; Patent "202311056582.0 Underwater measurement and calibration device for inner surface defects of pressure vessels in nuclear power plants" only solves the manual adjustment of the relative distance and height between the scanner and the calibration block during the calibration process; Patent "202320069504.3 An underwater camera calibration device" only solves the two-dimensional posture of the calibration plate relative to the camera, and cannot solve the relative position adjustment. Summary of the invention

[0009] In view of this, the present application is committed to providing a calibration device and method for an underwater vision measurement system, which uses a water tank to simulate the underwater environment and utilizes the mutual cooperation of various devices such as a dual motion mechanism, a control box, and a control terminal to solve the problems of existing underwater calibration devices that are unable to calibrate in a large range of multiple postures, unable to be linked with an underwater vision measurement system, and unable to simulate special underwater environments.

[0010] The first aspect of the present application provides a calibration device for an underwater visual measurement system, which comprises a base, a standard object motion mechanism, a visual measurement system motion mechanism, a standard object, a visual measurement system, a water tank, a control box and a control terminal. The water tank is located directly below the base and is used to load liquid to form an underwater environment, and the internal space is a calibration space. The base is composed of a lower structure, a support column and an upper structure, and the lower structure is used to establish a connection with the ground. The support column is connected between the lower structure and the upper structure. The standard object motion mechanism and the visual measurement system motion mechanism are arranged in parallel on the upper structure. The standard object motion mechanism is connected to the standard object and is used to control the multi-degree-of-freedom motion of the standard object. The visual measurement system motion mechanism is connected to the visual measurement system and is used to independently control the multi-degree-of-freedom motion of the visual measurement system. The control box is connected to the base, the visual measurement system motion mechanism, the standard object motion mechanism and the visual measurement system, and is used to directly control the mechanism movement, acquisition start and stop and data transmission, providing a basis for semi-automatic or fully automatic calibration. The control terminal is installed with calibration software and visual measurement system software for human-computer interaction and automatic control during the calibration process. The control terminal has one or more of the following modes: manual calibration mode, semi-automatic calibration mode, and fully automatic calibration mode.

[0011] In a specific embodiment of the present application, the lower structure is fixedly connected to the ground via bolts or movably connected to the ground via rollers.

[0012] In a specific embodiment of the present application, the upper structure adopts a guide rail structure, and the guide rail structure is used to provide a one-dimensional motion track for the visual measurement system motion mechanism and the standard object motion mechanism.

[0013] In a specific embodiment of the present application, the visual measurement system motion mechanism includes a multi-joint serial robot arm or a linear and joint combination robot arm. The end of the visual measurement system motion mechanism is connected to the visual measurement system using a quick-connect structure. The visual measurement system motion mechanism is used to achieve independent multi-degree-of-freedom motion of the visual measurement system.

[0014] In a specific embodiment of the present application, the standard object motion mechanism includes a multi-joint serial robot arm or a linear and joint combined robot arm. The end of the standard object motion mechanism is connected to the standard object using a quick-connect structure, and the standard object motion mechanism is used to achieve independent multi-degree-of-freedom motion of the standard object.

[0015] In a specific embodiment of the present application, the water tank includes a mobile module, a stirring module, a thermal disturbance module and a circulation module. The mobile module is arranged at the bottom of the water tank, and is used to quickly switch between the mobile state and the fixed state. The stirring module is arranged at the four corners of the bottom of the water tank, and generates water flow through rotating blades to simulate the actual water flow environment. The thermal disturbance module is arranged at the bottom of the water tank, and is composed of a plurality of independent electric heating plates or heat exchange tubes. It controls the constant temperature heating of the electric heating plates to generate heat exchange with the water body, or controls the constant temperature hot water to flow through the heat exchange tube and generate heat exchange with the water body, so as to simulate the actual thermal disturbance environment. The circulation module includes a circulation pipeline, a circulation water pump, a filter, and an air cooler, which are used to actively purify the water body to avoid repeated water changes, and to reduce the average temperature of the water body in the water tank to ensure the thermal disturbance effect.

[0016] In a specific implementation of the present application, calibration software is installed on the control terminal. The calibration software has the functions of importing and exporting models and importing and exporting posture data.

[0017] A second aspect of the present application provides a calibration method for an underwater vision measurement system. The calibration method for an underwater vision measurement system is performed using the calibration device for an underwater vision measurement system in the above-mentioned embodiment.

[0018] In a specific embodiment of the present application, if the calibration device is in a semi-automatic calibration mode, the calibration method of the underwater vision measurement system includes:

[0019] 10a: Import the 3D model of the standard object and the visual measurement system to provide input for the 3D simulation and proceed to 11a.

[0020] 11a: The pose point sequence x1' of the visual measurement system in the unified coordinate system by importing the pose file or 3D simulation input calibration process i ,y1' i ,z1' i ,α1' i ,β1' i ,γ1' i and the pose point sequence x2' of the standard object i ,y2' i ,z2' i ,α2' i ,β2' i ,γ2' i , the total number of marked postures is m, i takes the value of 0-m, and proceed to 12a.

[0021] 12a: Use a 3D physics engine based on a three-dimensional model to detect whether there is interference. If yes, proceed to 13a; if not, proceed to 14a.

[0022] 13a: Sound and light alarms are issued to remind the user of interference and wait for manual processing.

[0023] 14a: Set the positioning attitude count variable J to 1 and proceed to 15a.

[0024] 15a: According to the calibration position, the standard object and the visual measurement system are controlled to move to 16a.

[0025] 16a: According to And max[α1' i -α1|,|β1' i -β1|,γ1' i -γ1]≤θ, judge whether the motion mechanism 12 of the visual measurement system is in place and stable, and the judgment standard of the motion mechanism 11 of the calibration object is similar. If not, go to 15a, if yes, go to 17a. x1, y1, z1, α1, β1, γ1 are the real-time measurement poses of the end of the motion mechanism of the visual measurement system;

[0026] 17a: Manually fine-tune the positions of the standard object 13 and the visual measurement system 14 according to the actual relative positions, and proceed to 18a.

[0027] 18a: Manually set the visual measurement system parameters and start acquisition, then go to 19a.

[0028] 19a: Manually determine that the Jth collection is completed and J>m. If yes, proceed to 20a; if not, proceed to 21a.

[0029] 20a: All calibrations are completed and the operation is ended.

[0030] 21a: J=J+1, go to 15a and start calibration of a new pose.

[0031] In a specific embodiment of the present application, if the calibration device of the underwater vision measurement system is in the fully automatic calibration mode, the calibration method of the underwater vision measurement system includes:

[0032] 10b: Import the 3D model of the standard object and the visual measurement system to provide input for the 3D simulation and proceed to 11b.

[0033] 11b: The pose point sequence x1' of the visual measurement system in the same coordinate system by importing the pose file or 3D simulation input calibration process i ,y1' i ,z1' i ,α1' i ,β1' i ,γ1' i and the pose point sequence x2' of the standard object i ,y2' i ,z2' i ,α2' i ,β2' i ,γ2'i , the total number of marked postures is m, i takes the value of 0-m, and proceed to 12b.

[0034] 12b: Use a 3D physics engine based on a three-dimensional model to detect whether there is interference. If yes, go to 13b; if not, go to 14b.

[0035] 13b: Sound and light alarms are issued to remind the user of interference and wait for manual processing.

[0036] 14b: Set the positioning attitude count variable J to 1 and proceed to 15b.

[0037] 15b: According to the calibration posture, the movement of the standard object and the visual measurement system are controlled respectively and then transferred to 16b.

[0038] 16b: According to And max[|α1' i -α1|,|β1' i -β1|,|γ1' i -γ1|]≤θ, determine whether the visual measurement system 12 is in place and stable, and the determination criteria for the calibration object motion mechanism 11 are similar. If not, proceed to 15b, if yes, proceed to 17b. x1, y1, z1, α1, β1, γ1 are the real-time measurement poses of the end of the visual measurement system motion mechanism based on the sensor;

[0039] 17b: Automatically set the visual measurement system according to default parameters and collect multiple images, and then go to 18b.

[0040] 18b: Evaluate the image quality and calculate the best parameters. Automatically set the visual measurement system according to the best parameters and trigger the acquisition to go to 19b.

[0041] 19b: Automatically determine whether the Jth collection is completed and J>m. If yes, proceed to 20b; if not, proceed to 21b.

[0042] 20b: Complete all calibrations and end the job.

[0043] 21b: J=J+1, go to 15b and start calibration of a new pose.

[0044] The beneficial effect of the technical solution of the present application is that by using a water tank to simulate an underwater environment, and by utilizing the mutual cooperation of various devices such as the dual motion mechanism (i.e., the standard object motion mechanism and the visual measurement system motion mechanism) in the calibration device, the control box, and the control terminal, the relative posture of the visual measurement system and the calibration object in a large calibration space with or without water can be adjusted, which can not only meet the corresponding posture requirements of high-precision calibration, but also meet the measurement posture requirements recommended by relevant specifications. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1Shown is a schematic structural diagram of a calibration device for an underwater vision measurement system provided in one embodiment of the present application.

[0046] Figure 2 Shown is a schematic structural diagram of a calibration device for an underwater vision measurement system provided in another embodiment of the present application.

[0047] Figure 3 Shown is a schematic structural diagram of a calibration device for an underwater vision measurement system provided in yet another embodiment of the present application.

[0048] Figure 4 Shown is a schematic structural diagram of a calibration device for an underwater vision measurement system provided in yet another embodiment of the present application.

[0049] Figure 5 Shown is a schematic diagram of an implementation of a heat disturbance module.

[0050] Figure 6 Shown is a schematic diagram of another embodiment of a heat disturbance module.

[0051] Figure 7 Shown is a schematic diagram of the circulation module structure.

[0052] Figure 8 The figure is a flow chart of a calibration method for an underwater vision measurement system provided in one embodiment of the present application.

[0053] Fig. 9 Shown is a flow chart of a calibration method for an underwater vision measurement system provided in another embodiment of the present application. DETAILED DESCRIPTION

[0054] 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.

[0055] At least one embodiment of the present application provides a calibration device for an underwater visual measurement system, such as Figures 1 to 4 As shown, the calibration device of the underwater vision measurement system includes a base 10, a standard object motion mechanism 11, a vision measurement system motion mechanism 12, a standard object 13, a vision measurement system 14, a water tank 15, a control box 16 and a control terminal 17. The water tank 15 is located directly below the base 10 and is used to load liquid to form an underwater environment, and the internal space is a calibration space.

[0056] The base 10 is composed of a lower structure 101, a support column 102, and an upper structure 103. The lower structure 101 is used to establish a connection with the ground. The support column 102 is connected between the lower structure 101 and the upper structure 103. The standard object motion mechanism 11 and the visual measurement system motion mechanism 12 are arranged in parallel on the upper structure 103. The standard object motion mechanism 11 is connected to the standard object 13 to control the multi-degree-of-freedom motion of the standard object 13. The visual measurement system motion mechanism 12 is connected to the visual measurement system 14 to independently control the multi-degree-of-freedom motion of the visual measurement system 14. The control box 16 is used to be connected to the base 10, the visual measurement system motion mechanism 12, the standard object motion mechanism 11 and the visual measurement system 14, and is used to directly control the start and stop of acquisition and data transmission, providing a basis for semi-automatic or fully automatic calibration. The control terminal 17 is installed with calibration software and visual measurement system software for human-computer interaction and automatic control during the calibration process.

[0057] It should be noted that the visual measurement system 14 may include a camera, a line laser scanner, a grating scanner, a binocular measuring instrument, etc., covering other underwater measurement equipment using the principle of light perception such as imaging method, laser triangulation method, stereoscopic vision method, structured light method, photogrammetry method, etc. The size of the water tank 15 can be selected according to the maximum measurement space of the visual measurement system 14. The control box 16 includes the necessary power module, controller, driver, IO module, communication module, and reserves a network port and IO interface for mutual communication with the visual measurement system 14. The control box 16 can also realize power supply, communication and corresponding control for various connected devices such as the base 10, the visual measurement system motion mechanism 12, the standard object motion mechanism 11 and the visual measurement system 14. The control terminal 17 can be a computer.

[0058] According to the technical solution provided in the embodiment of the present application, by using a water tank 15 to simulate an underwater environment, and by utilizing the mutual cooperation of various devices such as the dual motion mechanism (i.e., the standard object motion mechanism 11 and the visual measurement system motion mechanism 12), the control box 16, and the control terminal 17 in the calibration device, the relative posture of the visual measurement system and the calibration object in a large calibration space can be adjusted, which can meet the corresponding posture requirements of high-precision calibration and the measurement posture requirements recommended by relevant specifications.

[0059] In at least one embodiment of the present application, the lower structure 101 is fixedly connected to the ground by bolts or is movably connected to the ground. For example, the lower structure 101 represented by a track or roller is movably connected to the ground, which can realize the overall one-dimensional movement of the support column 102 and the upper structure 103. At the same time, the mobile base 10 can also realize the rapid switching of the above-water or underwater calibration environment without drainage. In addition, the base motion and dual motion mechanism combination technology is further conducive to realizing the free adjustment of the relative posture of the visual measurement system and the calibration object in a large calibration space, which can not only meet the corresponding posture requirements of high-precision calibration, but also meet the measurement posture requirements recommended by relevant specifications.

[0060] The upper structure 103 is fixedly connected or movably connected to the visual measurement system motion mechanism 12 and the standard object motion mechanism 11. For example, in at least one embodiment of the present application, the upper structure 103 adopts a guide rail structure, and the guide rail structure is used to provide a one-dimensional motion track for the visual measurement system motion mechanism 12 and the standard object motion mechanism 11. In this way, the motion range of the visual measurement system motion mechanism 12 and the standard object motion mechanism 11 in the calibration space can be expanded.

[0061] The standard object 13 is used for parameter calibration or accuracy test of the visual measurement system 14. The standard object 13 can be set according to actual needs, and the embodiment of the present application does not specifically limit this. For example, in at least one embodiment of the present application, the standard object 13 includes but is not limited to a calibration plate, a standard single ball, a standard double ball, a standard plane or a standard cylinder.

[0062] In at least one embodiment of the present application, the visual measurement system motion mechanism 12 includes a multi-joint serial robot arm or a linear and joint combined robot arm, and the end of the visual measurement system motion mechanism 12 is connected to the visual measurement system 14 using a quick-connect structure, which is used to independently control the multi-degree-of-freedom motion of the visual measurement system 14. In this way, by setting the visual measurement system motion mechanism 12 to include a multi-joint serial robot arm or a linear and joint combined robot arm, the visual measurement system motion mechanism 12 is used to independently control the multi-degree-of-freedom motion of the visual measurement system 14, and combined with the one-dimensional motion of the base 10, the position (x1, y1, z1) and posture (α1, β1, γ1) of the visual measurement system 14 can be adjusted in a large range of calibration space.

[0063] In at least one embodiment of the present application, the standard object motion mechanism 11 includes a multi-joint serial robot arm or a linear and joint combined robot arm. The end of the standard object motion mechanism 11 is connected to the standard object 13 using a quick-connect structure, and the standard object motion mechanism 11 is used to independently control the multi-degree-of-freedom movement of the standard object 13. In this way, by setting the standard object motion mechanism 11 to include a multi-joint serial robot arm or a linear and joint combined robot arm, the standard object motion mechanism 11 is used to independently control the multi-degree-of-freedom movement of the standard object 13, and then combined with the one-dimensional movement of the base 10, the position (x2, y2, z2) and posture (α2, β2, γ2) of the standard object 13 can be adjusted in a large range of calibration space.

[0064] In the above embodiment, the visual measurement system motion mechanism 12 is connected to the visual measurement system 14 through a quick connection structure, and is seated on the upper structure 103 of the base 10, and can drive the visual measurement system 14 to independently move with 6 degrees of freedom in the calibration space; the standard object motion mechanism 11 is connected to the standard object 13 through a quick connection structure, and is also seated on the upper structure 103 of the base 10, and can drive the standard object 13 to independently move with 6 degrees of freedom in the calibration space. Through the structural design of the standard object motion mechanism 11 and the visual measurement system 14, the relative posture between the visual measurement system 14 and the standard object 13 can be flexibly adjusted during the calibration process, and both can be adjusted simultaneously, or one can be fixed and the other can be relatively adjusted, so as to ensure that the visual measurement system 14 and the standard object 13 of different sizes and weights can be reached in any specified relative posture within a wide range of calibration.

[0065] In at least one embodiment of the present application, the water tank 15 includes a moving module 151, a stirring module 152, a thermal disturbance module 153 and a circulation module 154. The moving module 151 is arranged at the bottom of the water tank, and can use horizontal adjustment casters or jack lifting casters or locking track rollers to achieve rapid switching between the mobile state and the fixed state. The stirring module 152 is arranged at the four corners of the bottom of the water tank, and is used to generate water flow through rotating blades to simulate an actual water flow environment. The thermal disturbance module 153 is arranged at the bottom of the water tank 15, and is used to simulate an actual thermal disturbance environment, such as Figure 5 As shown, one embodiment can be composed of multiple independent 151-1 electric heating plates, and heat exchange is generated between the electric heating plate body and the water body by controlling the electric heating plate to heat at a constant temperature, such as Figure 6 As shown, another implementation method is composed of 151-2 heat exchange tubes arranged in parallel, preferably using thin-walled metal tubes to enhance heat exchange efficiency, and controlling the constant temperature hot water to flow through the heat exchange tubes to generate heat exchange between the heat exchange tubes and the water body. Figure 7 As shown, the circulation module 154 includes 154-1 circulation pipeline, 154-2 circulation water pump, 154-3 filter, and 154-4 air cooler, which are used for actively circulating and purifying water to avoid repeated water changes due to water contamination, and for reducing the average temperature of water in the water tank to ensure the thermal disturbance effect.

[0066] In the above embodiment, the mobile module 151 in the water tank 15 moves the water tank as a whole to realize non-drainage rapid switching of the above-water or underwater calibration environment switching, and the switching efficiency is high and the time is short. When the underwater calibration is completed and the visual measurement system motion mechanism 12 and the standard object motion mechanism 11 are adjusted to a non-interference posture, the water tank 15 is withdrawn as a whole. At this time, the visual measurement system motion mechanism 12 and the standard object motion mechanism 11 can be restored to the underwater calibration posture and the above-water calibration can be performed, thereby realizing rapid switching of the above-water and underwater environments without additional filling and drainage. In addition, the circulation module 154 can be used to effectively filter impurities, algae, bacteria, etc. in the water, so that the water body can be reused, and the water body can be repeatedly changed due to dirt after being used for a period of time. By adding different additives such as borax, milk, etc., underwater environments with different densities and different turbidities can be further simulated. The embodiment of the present application can simulate various special underwater environments through the combination of various modules. Stirring, heating, and adding additives are used to simulate various special underwater environments, such as superimposed water flow, turbid water environment with thermal disturbance, etc.

[0067] In at least one embodiment of the present application, the control terminal 17 has a standard object model. The calibration software has the functions of importing and exporting models and importing and exporting posture data. The visual measurement system supports universal formats and supports universal format posture files. In this way, the posture to be calibrated can be quickly imported through the pre-edited posture file, and the posture to be calibrated can also be quickly generated through three-dimensional simulation placement.

[0068] It should be noted that the visual measurement system and standard object models that support common formats, such as stp or igs, also support common format pose files, such as .txt or .excel.

[0069] In at least one embodiment of the present application, the control terminal 17 has three calibration modes, including a manual calibration mode, a semi-automatic calibration mode, and a fully automatic calibration mode. In this way, the corresponding calibration mode can be selected according to actual needs. The semi-automatic and automatic calibration methods based on the linkage between the calibration device and the visual measurement system are used to improve the calibration efficiency.

[0070] Embodiment 1: A calibration device using a linear and joint combined robotic arm.

[0071] like Figure 2As shown, the base 10 is composed of a lower structure 101, a support column 102, and an upper structure 103. The lower structure 101 is fixedly connected to the ground through bolts and a bottom plate. The upper structure 103 adopts a guide rail structure to provide a one-dimensional motion track for the visual measurement system motion mechanism 12 and the standard object motion mechanism 11; the visual measurement system motion mechanism 12 adopts a mechanical arm composed of 2-dimensional linear motion and 3-dimensional joint motion, combined with the one-dimensional motion of the base 10, to form a 6-degree-of-freedom motion; the standard object motion mechanism 11 also adopts a mechanical arm composed of 2 linear motions and 3 joint motions, combined with the one-dimensional motion of the base 10, to form a 6-degree-of-freedom motion; the visual measurement system 14 is a 3D scanner; the standard object 13 is a standard ball.

[0072] Embodiment 2: A calibration device using a linear and joint combined robotic arm.

[0073] like Figure 3 As shown, the standard object motion mechanism 11 adopts a long rod structure that can slide on the upper structure 103. The position of the standard object motion mechanism is measured by a sensor, and relative posture adjustment and automatic calibration can be achieved on the basis of cost saving.

[0074] Embodiment 3: A calibration device using a multi-joint serial robot arm.

[0075] like Figure 4 As shown, the base 10 is composed of a lower structure 101, a support column 102, and an upper structure 103. The lower structure 101 is connected to the ground by 8 casters, and the upper structure 103 is fixedly connected to the visual measurement system motion mechanism 12 and the standard object motion mechanism 11. The visual measurement system motion mechanism 12 adopts a 6-joint serial robot arm to drive the visual measurement system 14 to move in the calibration space with 6 degrees of freedom. The standard object motion mechanism 11 also adopts a 6-joint serial robot arm to drive the standard object 13 to move in the calibration space with 6 degrees of freedom; the visual measurement system 14 is an underwater linear laser 3D scanner; and the standard object 13 is a checkerboard calibration plate.

[0076] At least one embodiment of the present application further provides a calibration method for an underwater vision measurement system. The calibration method for an underwater vision measurement system is executed using the underwater vision measurement system in the above embodiment.

[0077] If the calibration device is in semi-automatic calibration mode, the calibration method of the underwater vision measurement system is as follows: Figure 8 shown.

[0078] 10a: Import the 3D model of the standard object and the visual measurement system to provide input for the 3D simulation and proceed to 11a.

[0079] 11a: The pose point sequence x1' of the visual measurement system in the unified coordinate system by importing the pose file or 3D simulation input calibration processi ,y1' i ,z1' i ,α1' i ,β1' i ,γ1' i and the pose point sequence x2' of the standard object i ,y2' i ,z2' i ,α2' i ,β2' i ,γ2' i , the total number of marked postures is m, i takes the value of 0-m, and proceed to 12a.

[0080] 12a: Use a 3D physics engine based on a three-dimensional model to detect whether there is interference. If yes, proceed to 13a; if not, proceed to 14a.

[0081] 13a: Sound and light alarms are issued to remind the user of interference and wait for manual processing.

[0082] 14a: Set the positioning attitude count variable J to 1 and proceed to 15a.

[0083] 15a: According to the calibration position, the standard object and the visual measurement system are controlled to move to 16a.

[0084] 16a: According to And max[α1' i -α1|,|β1' i -β1|,γ1' i -γ1]≤θ, judge whether the motion mechanism 12 of the visual measurement system is in place and stable, and the judgment standard of the motion mechanism 11 of the calibration object is similar. If not, go to 15a, if yes, go to 17a. x1, y1, z1, α1, β1, γ1 are the real-time measurement postures of the end of the motion mechanism 12 of the visual measurement system based on the sensor;

[0085] 17a: Manually fine-tune the positions of the standard object 13 and the visual measurement system 14 according to the actual relative positions, and proceed to 18a.

[0086] 18a: Manually set the visual measurement system parameters and start acquisition. The system parameters include camera exposure time, camera threshold, line laser brightness, line laser light extraction threshold, etc. Go to 19a.

[0087] 19a: Manually determine that the Jth collection is completed and J>m. If yes, proceed to 20a; if not, proceed to 21a.

[0088] 20a: All calibrations are completed and the operation is ended.

[0089] 21a: J=J+1, go to 15a and start calibration of a new pose.

[0090] If the calibration device of the underwater vision measurement system is in the fully automatic calibration mode, the calibration method of the underwater vision measurement system is as follows: Fig. 9 shown.

[0091] 10b: Import the 3D model of the standard object and the visual measurement system to provide input for the 3D simulation and proceed to 11b.

[0092] 11b: The pose point sequence x1' of the visual measurement system in the unified coordinate system by importing the pose file or inputting the calibration process of 3D simulation placement i ,y1' i ,z1' i ,α1' i ,β1' i ,γ1' i and the standard object's pose point sequence x2' i ,y2' i ,z2' i ,α2' i ,β2' i ,γ2' i , the total number of marked postures is m, i takes the value of 0-m, and proceed to 12b.

[0093] 12b: Use a 3D physics engine based on a three-dimensional model to detect whether there is interference. If yes, go to 13b; if not, go to 14b.

[0094] 13b: Sound and light alarms are issued to remind the user of interference and wait for manual processing.

[0095] 14b: Set the positioning attitude count variable J to 1 and proceed to 15b.

[0096] 15b: According to the calibration posture, the movement of the standard object and the visual measurement system are controlled respectively and then transferred to 16b.

[0097] 16b: According to And max[|α1' i -α1|,|β1' i -β1|,|γ1' i -γ1|]≤θ, determine whether the visual measurement system 12 is in place and stable, and the determination criteria for the calibration object motion mechanism 11 are similar. If not, proceed to 15b, if yes, proceed to 17b. x1, y1, z1, α1, β1, γ1 are the real-time measurement poses of the end of the visual measurement system motion mechanism 12 based on the sensor;

[0098] 17b: Automatically set the visual measurement system according to default parameters and collect multiple images, and then go to 18b.

[0099] 18b: Evaluate the image quality and calculate the best parameters. Automatically set the visual measurement system according to the best parameters and trigger the acquisition to go to 19b.

[0100] 19b: Automatically determine whether the Jth collection is completed and J>m. If yes, proceed to 20b; if not, proceed to 21b.

[0101] 20b: Complete all calibrations and end the job.

[0102] 21b: J=J+1, go to 15b and start calibration of a new pose.

[0103] It should be noted that the combination of the various technical features in the embodiments of the present application is not limited to the combination described in the embodiments of the present application or the combination described in the specific embodiments, and all technical features described in the present application can be freely combined or combined in any way unless there is a contradiction between them.

[0104] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the term "comprising" only indicates that the steps and elements that have been clearly identified are included, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0105] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0106] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A calibration device for an underwater visual measurement system, characterized in that: It includes a base, a standard object motion mechanism, a visual measurement system motion mechanism, a standard object, a visual measurement system, a water tank, a control box and a control terminal. Among them, the water tank is located directly below the base, which is used to load liquid to form an underwater environment. The internal space is the calibration space. The base is composed of a lower structure, a support column, and an upper structure. The lower structure is used to establish a connection with the ground. The support column is connected between the lower structure and the upper structure. The standard object motion mechanism and the visual measurement system motion mechanism are arranged in parallel on the upper structure; the standard object motion mechanism is connected to the standard object to control the multi-degree-of-freedom motion of the standard object; the visual measurement system motion mechanism is connected to the visual measurement system to independently control the multi-degree-of-freedom motion of the visual measurement system; the control box is connected to the base, the visual measurement system motion mechanism, the standard object motion mechanism and the visual measurement system, which is used to directly control the start and stop of acquisition and data transmission; the control terminal is a computer, which is installed with calibration software and visual measurement system software for human-computer interaction and automatic control of the calibration process; the control terminal has one or more of manual calibration mode, semi-automatic calibration mode and fully automatic calibration mode.

2. The calibration device of an underwater vision measurement system according to claim 1, characterized in that: The substructure is fixedly connected to the ground via bolts or movably connected to the ground via rollers.

3. The calibration device of an underwater vision measurement system according to claim 1, characterized in that: The upper structure adopts a guide rail structure, which is used to provide a one-dimensional motion track for the visual measurement system motion mechanism and the standard object motion mechanism.

4. The calibration device of an underwater vision measurement system according to claim 1, characterized in that: The motion mechanism of the visual measurement system includes a multi-joint serial robot arm or a linear and joint combination robot arm. The end of the motion mechanism of the visual measurement system is connected to the visual measurement system by a quick-connect structure. The motion mechanism of the visual measurement system is used to independently control the multi-degree-of-freedom motion of the visual measurement system.

5. The calibration device for an underwater visual measurement system according to claim 1, characterized in that: The standard object motion mechanism includes a multi-joint serial robot arm or a linear and joint combined robot arm. The end of the standard object motion mechanism is connected to the standard object by a quick-connect structure. The standard object motion mechanism is used to independently control the multi-degree-of-freedom motion of the standard object.

6. The calibration device of an underwater vision measurement system according to claim 1, characterized in that: The water tank includes a mobile module, a stirring module, a thermal disturbance module and a circulation module. The mobile module is arranged at the bottom of the water tank and is used for fast switching between the mobile state and the fixed state. The stirring module is arranged at the four corners of the bottom of the water tank and is used to generate water flow through rotating blades to simulate the actual water flow environment. The thermal disturbance module is arranged at the bottom of the water tank and is composed of multiple independent electric heating plates or heat exchange tubes. Heat exchange is generated between the electric heating plates and the water body by controlling the constant temperature heating of the electric heating plates, or heat exchange is generated between the constant temperature hot water flowing through the heat exchange tubes and the water body to simulate the actual thermal disturbance environment. The circulation module includes a circulation pipeline, a circulation water pump, a filter, and an air cooler, which are used to actively purify the water body to avoid repeated water changes, and to reduce the average temperature of the water body in the water tank to ensure the thermal disturbance effect.

7. A calibration device for an underwater vision measurement system according to any one of claims 1 to 6, characterized in that: The control terminal has a standard object model, and the calibration software has the functions of importing and exporting models and pose data. The visual measurement system supports universal formats and universal format pose files.

8. A calibration method for an underwater visual measurement system, characterized in that: A calibration device for an underwater vision measurement system as described in any one of claims 1 to 7 is used.

9. The calibration method of an underwater vision measurement system according to claim 8, characterized in that: If the calibration device is in the semi-automatic calibration mode, the calibration method of the underwater vision measurement system includes: 10a: Import the 3D model of the standard object and the visual measurement system to provide input for the 3D simulation and proceed to 11a; 11a: The pose point sequence x1' of the visual measurement system in the unified coordinate system by importing the pose file or 3D simulation input calibration process i ,y1' i ,z1' i ,α1' i ,β1' i ,γ1' i and the pose point sequence x2' of the standard object i ,y2' i ,z2' i ,α2' i ,β2' i ,γ2' i , the total number of marked postures is m, i takes the value of 0-m, and proceed to 12a; 12a: Use a 3D physical engine based on a three-dimensional model to detect whether there is interference. If yes, proceed to 13a; if not, proceed to 14a; 13a: Sound and light alarms are issued to remind the user of interference and wait for manual processing; 14a: The calibration attitude count variable J is set to 1, and the process goes to 15a; 15a: Control the movement of the standard object and the visual measurement system according to the calibration posture and enter 16a; 16a: According to And max[|α1' i -α1|,|β1' i -β1|,|γ1' i -γ1|]≤θ, judge whether the motion mechanism of the visual measurement system is in place and stable. The judgment standard of the motion mechanism of the calibration object is similar. If not, proceed to 15a, if yes, proceed to 17a; x1, y1, z1, α1, β1, γ1 are the real-time measurement poses of the end of the motion mechanism of the visual measurement system; 17a: Manually fine-tune the positions of the standard object and the visual measurement system according to the actual relative positions, and proceed to 18a; 18a: Manually set the visual measurement system parameters and start acquisition, and go to 19a; 19a: Manually determine that the Jth collection is completed and J>m, if yes, proceed to 20a, if not, proceed to 21a; 20a: Complete all calibrations and end the operation; 21a: J=J+1, go to 15a and start calibration of a new pose.

10. The calibration method of an underwater vision measurement system according to claim 8, characterized in that: If the calibration device of the underwater vision measurement system is in the fully automatic calibration mode, the calibration method of the underwater vision measurement system includes: 10b: Import the 3D model of the standard object and the visual measurement system to provide input for the 3D simulation and proceed to 11b; 11b: The pose point sequence x1' of the visual measurement system in the unified coordinate system by importing the pose file or 3D simulation input calibration process i ,y1' i ,z1' i ,α1' i ,β1' i ,γ1' i and the pose point sequence x2' of the standard object i ,y2' i ,z2' i ,α2' i ,β2' i ,γ2' i , the total number of marked postures is m, i takes the value of 0-m, and goes to 12b; 12b: Use a 3D physical engine based on a three-dimensional model to detect whether there is interference. If yes, go to 13b; if not, go to 14b; 13b: Sound and light alarms are issued to remind the user of interference and wait for manual processing; 14b: Set the positioning attitude count variable J to 1, and go to 15b; 15b: Control the movement of the standard object and the visual measurement system according to the calibration posture and enter 16b; 16b: According to And max[|α1' i -α1|,|β1' i -β1|,|γ1' i -γ1|]≤θ, judge whether the motion mechanism of the visual measurement system is in place and stable. The judgment standard of the motion mechanism of the calibration object is similar. If not, go to 15b, if yes, go to 17b; x1, y1, z1, α1, β1, γ1 are the real-time measurement poses of the end of the motion mechanism of the visual measurement system; 17b: Automatically set the visual measurement system according to default parameters and collect multiple pictures, and then go to 18b; 18b: Evaluate the image quality and calculate the best parameters, automatically set the visual measurement system according to the best parameters and trigger the acquisition to go to 19b; 19b: Automatically determine if the Jth collection is completed and J>m, if yes, proceed to 20b, if not, proceed to 21b; 20b: Complete all calibrations and end the operation; 21b: J=J+1, go to 15b and start calibration of a new pose.

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