Cabin section pose docking method based on vision and laser

Abstract

The invention discloses a cabin section pose docking method based on vision and laser, which comprises the following steps: performing vision measurement on poses of two cabin sections to be docked to obtain a vision measurement result; preliminarily adjusting the poses of the two to-be-butted cabin sections according to a visual measurement result, and adjusting the two to-be-butted cabin sections to a pre-butted position; performing laser measurement on the poses of the two to-be-butted cabin sections to obtain a laser measurement result; the laser measurement result comprises cabin section distance information; and according to cabin section distance information in a laser measurement result, the poses of the two cabin sections to be butted are accurately adjusted. The method has the advantages of low cost, high butt joint precision and the like.

Description

Technical Field

[0001] The present invention mainly relates to the field of spacecraft technology, and in particular to a cabin attitude docking method based on vision and laser. Background Art

[0002] The docking of cabins of aircraft, missiles and other spacecraft is a key link in their processing and manufacturing. The quality of cabin docking determines the quality of its assembly, and the assembly quality is closely related to the overall performance of the product. With the continuous development of the national defense industry, cabin products have shown the characteristics of small batches and many types, and the diversification of product appearance has put forward higher requirements for the measurement of cabin posture in the automatic docking system.

[0003] The existing in-situ measurement methods for cabins can be divided into two categories according to the type of sensors used: visual measurement using cameras and laser measurement using laser sensors. The field of view and resolution of a camera are mutually constrained, which makes it difficult to achieve large field of view and high-resolution imaging. Actual measurement systems usually use large field of view cameras to obtain images with richer information to facilitate the calculation of the target's posture. Since it is difficult for cameras to accurately measure depth information, the accuracy of posture measurement is low, and high-precision posture measurement cannot be achieved. In addition, traditional visual measurement is insensitive to depth information, and the accuracy of spatial posture measurement is low. To achieve high-precision measurement of spatial posture, a point cloud reconstruction method is required. The equipment is large in size and high in cost, which is not convenient for in-situ measurement.

[0004] The cabin posture measurement based on laser sensors is mainly divided into posture measurement based on laser scanners and posture measurement based on laser displacement sensors. Among them, the posture measurement using laser scanners has certain requirements for the surface quality of the target to be measured, and the sensor needs to move during the measurement process. Its motion accuracy will also have a great impact on the measurement results, and it is difficult to achieve in-situ measurement. The posture measurement using laser displacement sensors mainly measures the cabin axis through the principle of three-point fitting circle, and then solves the cabin posture, which is difficult to accurately reflect the spatial posture information. Usually, the position of the laser displacement sensor measurement point is fixed. Therefore, this method has certain requirements for the initial posture of the cabin, and its accuracy is inversely proportional to the range, and its applicability is poor.

[0005] As mentioned above, the existing docking method has the following shortcomings, specifically:

[0006] (1) The existing cabin posture measurement methods have a single measurement method and poor universality

[0007] In the vision-based cabin position and attitude measurement method, the deviation between the initial position and attitude of the cabin to be measured and the target position and attitude has little impact on the measurement result. However, the measurement accuracy of this method is limited and cannot meet the requirements of precise docking of the cabin. The laser-based cabin position and attitude measurement method can use a high-precision laser displacement sensor to achieve high-precision measurement of the cabin position and attitude. However, the measuring range of the high-precision laser displacement sensor is small. Therefore, the deviation between the initial position and attitude of the cabin to be measured and the target position and attitude needs to be within the measuring range of the sensor, and it is impossible to measure the cabin position and attitude with a large position and attitude deviation.

[0008] (2) The existing in-situ measurement methods have low accuracy and cannot achieve high-precision position and attitude measurement.

[0009] Limited by space, high-precision space position and attitude measurement methods such as point cloud reconstruction are used for in-situ measurement. Visual measurement is a commonly used in-situ measurement method. Although its planar measurement accuracy is relatively high, it is difficult to achieve high-precision space position and attitude measurement. When using a high-precision laser displacement sensor for measurement, the depth information of a certain point on the cabin is obtained, and it is difficult to measure the space position and attitude of the cabin.

[0010] To sum up, limited by space, the in-situ measurement method of the cabin position and attitude cannot use high-precision measurement means such as point cloud reconstruction. The existing in-situ measurement technologies mostly use sensors such as cameras and lasers for position and attitude measurement. For example, vision measurement based on cameras and laser measurement based on laser displacement sensors. However, vision measurement is difficult to achieve high-precision measurement, laser measurement has the problem of small measuring range, and the laser displacement sensor can only achieve point measurement. Multiple sensors need to be set up to achieve space position and attitude measurement, resulting in the existing in-situ measurement methods being unable to balance the requirements of low cost and high precision.

[0011] The invention patent with the patent application number 201811090767.2 and the name "Dual-camera Measuring Device and Measuring Method for the Docking Angle of Cabin Pin Holes" discloses a dual-camera measuring device and measuring method for the docking angle of cabin pin holes. It uses binocular camera measurement technology and optimizes the structural design of the camera support frame to solve the problem of measuring the docking angle of cabin pin holes under space-limited conditions. According to the introduction in the patent specification, the contour of the pins and holes on the docking end face of the cabin is detected by binocular cameras, and the docking angle of the cabin is measured by calculating the center positions of the pins and holes. This method can only measure the deviation of the cabin's rotational degree of freedom along the axis and does not meet the docking requirements of the cabin under general working conditions.

[0012] The invention patent with the patent application number CN202110005821.4 and the title "A Cabin Position and Attitude Measurement and Alignment System, Control Method and Application" discloses a cabin position and attitude measurement and alignment system, control method and application. The surface of the cabin is scanned by a linear scanning method to obtain point cloud information, and the position and attitude information of the cabin is obtained by a comprehensive method of axis fitting and generatrix fitting. According to the introduction of the patent specification, this method can achieve non-contact, non-target, large-scale, automated and robust position and attitude measurement. However, this method has high requirements for the surface accuracy of the cabin and the motion accuracy of the scanning sensor.

[0013] The invention patent with the patent application number CN202410931331.0 and the title "A Vertical Thin Cabin Docking Device Based on Three-Camera Measurement and a Method for Adjusting Pose and Docking" discloses a vertical thin cabin docking device based on three-camera measurement and a method for adjusting pose and docking, which realizes in-situ measurement and high-precision, high-efficiency and rapid docking of vertical thin cabins. According to the introduction of the patent specification, this method sets up a target to guide the camera to perform position and attitude measurement, and an additional target needs to be placed. Moreover, the placement accuracy of the target affects the measurement accuracy. In addition, only cameras are used for measurement, and it is difficult to achieve high-precision position and attitude measurement with a large field-of-view camera when the cabin volume is large. Summary of the Invention

[0014] Aiming at the technical problems existing in the prior art, the present invention provides a vision- and laser-based cabin position and attitude docking method with low cost and high docking accuracy.

[0015] In order to solve the above technical problems, the technical solution proposed by the present invention is as follows:

[0016] A vision- and laser-based cabin position and attitude docking method, comprising the steps of:

[0017] Performing vision measurement on the positions and attitudes of two cabins to be docked to obtain vision measurement results;

[0018] Preliminarily adjusting the positions and attitudes of the two cabins to be docked according to the vision measurement results to adjust them to the pre-docking position;

[0019] Performing laser measurement on the positions and attitudes of the two cabins to be docked to obtain laser measurement results; the laser measurement results include cabin distance information;

[0020] Precisely adjusting the positions and attitudes of the two cabins to be docked according to the cabin distance information in the laser measurement results.

[0021] Preferably, the specific process of precisely adjusting the poses of two to-be-docked cabin sections according to the cabin section distance information in the laser measurement results is as follows: Set the correspondence between the camera pixels and the spatial distance, that is, the camera compensation coefficient, according to the distance information measured by the laser displacement sensor, and establish a non-linear function between the distance and the camera compensation coefficient.

[0022] Preferably, based on the non-linear function, precisely adjust the poses of the two to-be-docked cabin sections, specifically:

[0023] Based on each feature circle with known shape and size, solve the three-dimensional coordinates of the center of each feature circle in its camera coordinate system; where each feature map is the flange hole of the cabin section measured by each camera.

[0024] According to the relative position relationship between the cameras, convert the centers of each feature circle to a unified coordinate system to obtain the converted center coordinates.

[0025] Based on the unified coordinate system, complete the fitting of the spatial circle where the converted center coordinates are located, and then complete the solution of the normal vector of the spatial circle passing through the center, and calculate the pose of the cabin section; where the center normal vector is the axis of the cabin section.

[0026] Preferably, the visual measurement results include the relative position relationship between the cameras, including the internal parameters and external parameters of the cameras.

[0027] The present invention further discloses a cabin section pose docking device based on vision and laser, including a control unit, a plurality of visual detection units, and a laser detection unit; the plurality of visual detection units and the laser detection unit are located on the docking flange side of the to-be-docked cabin section; the control unit is connected to the plurality of visual detection units and the laser detection unit, and is used to adjust the pose of the to-be-docked cabin section according to the visual measurement results and the laser measurement results.

[0028] Preferably, the visual detection unit is a camera; the laser detection unit is a laser displacement sensor.

[0029] The present invention further discloses a computer program product, including a computer program, and the computer program executes the steps of the above-mentioned method when being run by a processor.

[0030] The present invention also discloses a computer-readable storage medium, on which a computer program is stored, and the computer program executes the steps of the above-mentioned method when being run by a processor.

[0031] The present invention further discloses a cabin section pose docking system based on vision and laser, including a memory and a processor connected to each other, a computer program is stored on the memory, and the computer program executes the steps of the above-mentioned method when being run by the processor.

[0032] Compared with the prior art, the advantages of the present invention are as follows:

[0033] The method of the present invention is realized by relying on a camera, a laser displacement sensor and a posture adjustment mechanism. The processing surface features of the docking end of the cabin section are detected by a multi-view camera, and the posture of the cabin section is measured based on the prior knowledge of the feature size and the multi-view geometry knowledge. The measurement information is fed back to the posture adjustment mechanism to realize the preliminary docking of the cabin section. After the preliminary docking is completed, multiple high-precision laser displacement sensors are used to measure the depth information to correct the corresponding camera, realizing the high-precision measurement of the cabin section posture. The measurement information is fed back to the posture adjustment mechanism to realize the precise docking of the cabin section.

[0034] The present invention combines the advantages of a camera and a laser displacement sensor, uses the camera for rough measurement and rough adjustment of the cabin section posture, adjusts it to the pre-docking position. To solve the problem that the posture measurement is inaccurate due to the poor depth measurement accuracy of the camera, the laser displacement sensor is used to correct the depth information measured by the camera, realizing the high-precision measurement of the cabin section posture at the pre-docking position, and adopting the method of camera measurement and laser compensation to realize the low-cost and high-precision measurement of the cabin section posture.

[0035] The present invention overcomes the problems of low precision in the posture measurement method based on a large field-of-view camera and small measurement range and poor applicability in the posture measurement method based on a high-precision laser displacement sensor, and improves the applicability of the high-precision in-situ measurement method for the cabin section posture. Description of the Drawings

[0036] Figure 1 It is a flowchart of the cabin section posture docking method of the present invention in an embodiment.

[0037] Figure 2 It is an embodiment diagram of the cabin section posture docking method of the present invention in specific application.

[0038] Figure 3 It is a structural diagram of the cabin section posture docking device of the present invention in an embodiment.

[0039] Figure 4 It is a calibration coefficient-distance curve graph in the present invention. Detailed Embodiment

[0040] The present invention will be further described below in conjunction with the drawings in the specification and specific embodiments.

[0041] As Figure 1 and Figure 2 shown, the vision and laser-based cabin section posture docking method provided by the embodiment of the present invention includes the steps of:

[0042] Visually measure the postures of two cabin sections to be docked to obtain the visual measurement results;

[0043] Based on the visual measurement results, preliminarily adjust the poses of the two docking sections to be docked to the pre-docking position.

[0044] Perform laser measurement on the poses of the two docking sections to be docked to obtain laser measurement results; the laser measurement results include section distance information.

[0045] According to the section distance information in the laser measurement results, precisely adjust the poses of the two docking sections to be docked.

[0046] As Figure 3 shown, an embodiment of the present invention further provides a docking system for the pose of a section based on vision and laser, including a control unit, multiple vision detection units, and a laser detection unit; the multiple vision detection units and the laser detection unit are located on the docking flange side of the docking section to be docked; the control unit is connected to the multiple vision detection units and the laser detection unit for adjusting the pose of the docking section to be docked according to the visual measurement results and the laser measurement results. Among them, the docking section to be docked is adjusted in pose through a pose adjustment mechanism, and the pose adjustment mechanism is a standardized six-degree-of-freedom pose adjustment mechanism (conventional structure, not described in detail here).

[0047] Specifically, the above-mentioned vision detection unit is a camera, and the laser detection unit is a laser displacement sensor, and the number of each is three. Among them, a single camera and a single laser displacement sensor form a measurement component, namely measurement component A, measurement component B, and measurement component C; the above-mentioned measurement components are evenly distributed on the circumference of the flange section of the docking section to be docked.

[0048] In specific applications, as Figure 1 shown, first use a camera to preliminarily measure the poses of the two docking sections to be docked, and feed the measurement results back to the pose adjustment mechanism. The pose adjustment mechanism adjusts the poses of the two sections according to the measurement results (in this process, one of the sections can be fixed, and the pose of the other section is adjusted, reducing the computational amount of the pose adjustment system).

[0049] Then use a high-precision laser displacement sensor to measure the depth information of the current section, correct the depth information measured by the camera, and then realize the high-precision pose measurement of the docking section to be docked according to the preset feature circle information. The pose adjustment mechanism adjusts the pose of the section according to the precise measurement results to complete the precise docking of the section.

[0050] The method of the present invention is realized relying on a camera, a laser displacement sensor, and a pose adjustment mechanism. The processing surface features of the docking end of the section are detected by a multi-view camera, and the pose of the section is measured based on the prior knowledge of the feature size and the multi-view geometry knowledge. The measurement information is fed back to the pose adjustment mechanism to realize the preliminary docking of the section; after the preliminary docking is completed, multiple high-precision laser displacement sensors are used to measure the depth information to correct the corresponding camera, realizing the high-precision pose measurement of the section. The measurement information is fed back to the pose adjustment mechanism to realize the precise docking of the section.

[0051] The present invention combines the advantages of a camera and a laser displacement sensor. The camera is used for rough measurement and rough attitude adjustment of the cabin position, and it is adjusted to the pre-docking position. To solve the problem that the poor depth measurement accuracy of the camera leads to inaccurate position and attitude measurement, a laser displacement sensor is used to correct the depth information measured by the camera, and high-precision measurement of the cabin position and attitude is realized at the pre-docking position. The method of using camera measurement and laser compensation is adopted to achieve low-cost and high-precision measurement of the cabin position and attitude.

[0052] The present invention overcomes the problems of low accuracy in the position and attitude measurement method based on a large-field-of-view camera and the small measurement range and poor applicability in the position and attitude measurement method based on a high-precision laser displacement sensor, and improves the applicability of the high-precision in-situ measurement method for the cabin position and attitude.

[0053] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings of the specification and specific implementation manners.

[0054] 1) Install cameras A, B, and C, and calculate the relative position relationship (R, T matrix) between cameras A, B, and C through the camera calibration process;

[0055] 2) Use a laser displacement sensor to calibrate the camera compensation coefficient, specifically: set the correspondence between the camera pixels and the spatial distance (i.e., the camera compensation coefficient) according to the distance information measured by the laser displacement sensor, and establish a non-linear function between the distance and the camera compensation coefficient, as Figure 4 shown;

[0056] 3) Based on the feature circles a, b, and c with known shapes and sizes, solve the three-dimensional coordinates of the centers a, b, and c in their camera coordinate systems;

[0057] 4) Convert the centers a, b, and c to a unified coordinate system according to the relative position relationship between cameras A, B, and C, denoted as a', b', and c';

[0058] 5) Based on the unified coordinate system, complete the fitting of the spatial circles where a', b', and c' are located, and then complete the solution of the normal vector (cabin axis) passing through the center of the spatial circle, and calculate and obtain the cabin position and attitude.

[0059] The present invention realizes low-cost and high-precision measurement of the cabin position and attitude based on a camera and a laser displacement sensor, and adopts a rough and fine composite measurement method; rough measurement: combined with laser displacement sensor compensation, use a camera to realize rough measurement of the cabin position and attitude, and adjust the cabin to the pre-docking position; fine measurement: use a high-precision laser displacement sensor to measure the depth information of the cabin at the pre-docking position, compensate for the missing high-precision depth information during camera measurement, and then realize accurate measurement of the cabin position and attitude.

[0060] The present invention further discloses a computer program product, including a computer program which, when run by a processor, executes the steps of the method as described above. The present invention also discloses a computer-readable storage medium, on which a computer program is stored, and the computer program, when run by a processor, executes the steps of the method as described above. The present invention further discloses a vision- and laser-based cabin position and attitude docking system, including a memory and a processor connected to each other, where the memory stores a computer program, and the computer program, when run by the processor, executes the steps of the method as described above. The products, media, and systems of the present invention all correspond to the above method and have the same advantages as those of the above method.

[0061] The implementation of all or part of the processes in the method of the above embodiments of the present invention can also be completed by hardware related to computer program instructions. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the above method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable storage medium includes: any entity or device capable of carrying computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. The memory is used to store computer programs and / or modules, and the processor realizes various functions by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory. The memory can include high-speed random access memory, and can also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one magnetic disk storage device, flash device, or other volatile solid-state storage devices, etc.

[0062] The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, several improvements and refinements made without departing from the principle of the present invention should be regarded as within the protection scope of the present invention.

Claims

1. A vision- and laser-based docking method for the cabin's position and orientation, characterized in that, Including the steps: Visually measure the poses of two docking sections to obtain visual measurement results; Preliminarily adjust the poses of the two docking sections according to the visual measurement results to adjust them to the pre-docking positions; Laser measure the poses of the two docking sections to obtain laser measurement results; the laser measurement results include section distance information; Precisely adjust the poses of the two docking sections according to the section distance information in the laser measurement results.

2. The method for docking the cabin position and attitude based on vision and laser according to claim 1, characterized in that The specific process of precisely adjusting the poses of the two docking sections according to the section distance information in the laser measurement results is: set the correspondence between the camera pixels and the spatial distance, that is, the camera compensation coefficient, according to the distance information measured by the laser displacement sensor, and establish a non-linear function between the distance and the camera compensation coefficient.

3. The method for docking the cabin position and attitude based on vision and laser according to claim 2, wherein Precisely adjust the poses of the two docking sections based on the non-linear function, specifically: Based on each feature circle with known shape and size, solve the three-dimensional coordinates of the center of each feature circle in its camera coordinate system; where each feature map is the flange hole of the section measured by each camera; Convert the center of each feature circle to a unified coordinate system according to the relative position relationship between the cameras to obtain the converted center coordinates; Complete the fitting of the spatial circle where the converted center coordinates are located based on the unified coordinate system, and then complete the solution of the normal vector of the spatial circle passing through the center of the circle, and calculate and obtain the section pose; where the normal vector of the center of the circle is the axis of the section.

4. The vision- and laser-based cabin attitude and position docking method according to claim 1 or 2 or 3, characterized in that, The visual measurement results include the relative position relationship between each camera, including the internal parameters and external parameters of the camera.

5. A vision- and laser-based docking device for the cabin position and attitude, characterized in that, Including a control unit, multiple visual detection units, and a laser detection unit; multiple said visual detection units and laser detection unit are located on the docking flange side of the docking section; the control unit is connected to multiple said visual detection units and laser detection unit, and is used to adjust the pose of the docking section according to the visual measurement results and laser measurement results.

6. The visual and laser-based cabin pose docking device according to claim 5, characterized in that, The visual detection unit is a camera.

7. The vision and laser-based cabin position and attitude docking device according to claim 5, characterized in that, The laser detection unit is a laser displacement sensor.

8. A computer program product comprising a computer program, characterized in that, When the computer program is run by a processor, it executes the steps of the method according to any one of claims 1-4.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is run by a processor, it executes the steps of the method according to any one of claims 1-4.

10. A vision- and laser-based cabin attitude and position docking system, comprising a memory and a processor connected to each other, wherein a computer program is stored on the memory, and is characterized in that, When the computer program is run by a processor, it executes the steps of the method according to any one of claims 1-4.

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