Visual positioning method of mobile manipulator

A technology of visual positioning and mobile operation, applied in the directions of manipulators, program-controlled manipulators, chucks, etc., can solve the problems of bonding phenomenon, improper placement of workpieces, positioning errors, etc., to ensure material transportation, stabilize material transportation, and improve robustness. performance effect

Inactive Publication Date: 2015-12-30
INST OF AUTOMATION CHINESE ACAD OF SCI
5 Cites 1 Cited by

AI-Extracted Technical Summary

Problems solved by technology

[0002] In the process of repeatedly picking and placing workpieces, the mobile manipulator will cause positioning errors due to some internal factors or external interference, so that it cannot pick and place workpieces stably and reliably, and may even cause some accidents. Therefore, mobile manipulators are used in industrial material transportation. Positioning is needed to eliminate this error in
In material transportation, for some specific workpieces, it is necessary to add specific materials (such as polyester sheets) to the clamping fingers to improve the friction with the surface of the workpiece and prevent accidents caused by the workpiece falling during transportation; however, due to Due to the action of the clamping force, the workpiece may be bonded to the added material of the...
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Method used

Adopt camera to carry out plane vision positioning, can guarantee that the position and attitude of workpiece 2 grasping and placing are within the required scope of regulation; Then adopt flexible mechanism to carry out depth vision positioning compensation, can guarante...
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Abstract

The invention discloses a visual positioning method of a mobile manipulator. The visual positioning method at least comprises the following steps: performing planar visual positioning by a camera, wherein the planar visual positioning comprises positioning of two translation degrees of freedom and one rotation degree of freedom; performing deep visual positioning compensation by a flexible mechanism, wherein the deep visual positioning comprises positioning of translation degree of freedom, preferably, the planar visual positioning comprises a step of obtaining an error of the translation degrees of freedom and an error of the rotation degree of freedom through a template matching mode. According to the visual positioning method, the technical problem of how to improve the robustness of the mobile manipulator is at least solved.

Application Domain

Technology Topic

Template matchingRotational degrees of freedom +6

Image

  • Visual positioning method of mobile manipulator
  • Visual positioning method of mobile manipulator
  • Visual positioning method of mobile manipulator

Examples

  • Experimental program(1)

Example Embodiment

[0034] The technical problems solved by the embodiments of the present invention, the technical solutions adopted and the technical effects achieved are clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. Apparently, the described embodiments are only some of the embodiments of the present application, not all of them. Based on the embodiments in the present application, all other equivalent or obviously modified embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention. Embodiments of the invention can be embodied in many different ways as defined and covered by the claims.
[0035] It should be noted that, in the following description, many specific details are given for the convenience of understanding. It may be evident, however, that the present invention may be practiced without these specific details.
[0036] It should be noted that, in the case of no explicit limitation or conflict, various embodiments of the present invention and technical features therein can be combined with each other to form a technical solution.
[0037] In the industry, the repeated operation of the mobile manipulator on the workpiece will cause positioning errors due to some internal factors or external interference. At this time, it is necessary to compensate the positioning of the workpiece to ensure accurate and reliable pick and place of the workpiece. To this end, an embodiment of the present invention provides a visual positioning method for a mobile operating machine, such as figure 1 As shown, the method may at least include:
[0038] S102: Using a camera to perform plane vision positioning, wherein the plane vision positioning includes two translation degrees of freedom positioning and one rotation degree of freedom positioning;
[0039] S104: Using a flexible mechanism to perform depth vision positioning compensation, wherein the depth vision positioning includes translation degree of freedom positioning.
[0040] Using the camera for plane visual positioning can ensure that the position and posture of the workpiece 2 are within the specified requirements; then using a flexible mechanism for depth visual positioning compensation can ensure that the workpiece 2 can be reliably placed in place relative to different workbenches. Especially for the case where the workbench is inclined. Through the above improvements, the robust performance of the mobile manipulator 3 is improved, which can ensure stable material transportation.
[0041] In an optional embodiment, the planar vision positioning includes: acquiring a translation degree of freedom error and a rotation degree of freedom error by means of template matching.
[0042] Specifically, the above-mentioned embodiment may include: obtaining a calibration file at a certain positioning height, and the calibration file is related to the feature points whose actual relative positions are known; The image of the feature point, and select the image of the feature point to be matched in the image; according to the calibration file and the coordinate value of the current feature point, the error of the translation degree of freedom and the error of the rotation degree of freedom are obtained.
[0043] In an optional embodiment, obtaining the calibration file includes: positioning the height of the camera; printing feature points whose relative positions are known, and establishing a coordinate system; collecting a picture currently containing feature points, and calibrating the picture according to the actual coordinate values ​​of the feature points The pixel value of each feature point in .
[0044] In this embodiment, first determine the positioning height of the camera, adjust the focal length of the camera and the coverage of the light source to ensure that the feature points are clear and the brightness is moderate. In order to improve the positioning accuracy and reliability, the lines of the feature points should be as thin and clear as possible.
[0045] In the case of keeping the camera positioning height unchanged, first make the calibration file of the camera. Specifically: print a series of feature points whose actual relative positions are known, select one of the points as the origin, establish a coordinate system, and paste these feature points on the worktable. Then, turn on the camera, collect a picture that currently contains a series of feature points, and calibrate the pixel value of each feature point in the picture according to the actual coordinate value of each feature point, and then generate a calibration file at this positioning height.
[0046]After the calibration file is obtained, only one required feature point is left on the worktable, and the image of the feature point is still collected under the condition that the camera positioning height remains unchanged. First, circle the feature point images that need to be matched in the image, and define the qualified matching degree. Then import the calibration file, and define the relative difference output of two translation degrees of freedom and one rotation degree of freedom according to the coordinate values ​​of the current feature points. Finally, define the output protocol and trigger to get the template file.
[0047] After obtaining the template file, the mobile manipulator 3 continues to teach the pick-and-place position of the workpiece 2 on the basis of the positioning point position, and this series of processes are all completed at one time, and the base of the manipulator is guaranteed to be fixed .
[0048] In an optional embodiment, the active position of the flexible mechanism is located at a special part of the workpiece 2 to ensure that an elastic force is obtained after the workpiece 2 is clamped. The special part is preferably a step. The flexible mechanism is preferably a flexible finger 1 .
[0049] figure 2 It is a schematic structural diagram of an end effector of a mobile manipulator according to an exemplary embodiment. image 3 It is an assembly schematic diagram of a mobile operating machine shown according to an exemplary embodiment. figure 2 The positional relationship between the flexible finger 1 and the workpiece 2 is shown. image 3 The positional relationship between the mobile manipulator 3 and the end effector 4 is shown. like figure 2 As shown, in order to ensure the normal and reliable operation of the flexible finger 1 when picking and placing the workpiece, the position where the flexible finger 1 acts needs to be at a special position, such as a step, to ensure that the required elastic force F can be obtained. This elastic force can be divided into two component forces. One of the component forces is used to push the workpiece away from the finger friction plate to prevent sticking; the other component force is used to prevent the workpiece from falling vertically to assist the release of the workpiece 2 (as in the case of an inclined table). exist figure 2 In the middle, the component force F1 pushes the workpiece away from the finger friction plate to prevent adhesion, and the component force F2 can prevent the workpiece 2 from falling vertically, and assist in releasing the workpiece 2 to the inclined table. For the case where the workbench is on a horizontal plane, the position of the flexible finger 1 can be changed so that the component force F1 is equal to F, and only the workpiece 2 is pushed away from the friction plate to eliminate the influence of the component force F2. Through the function of the flexible finger 1 , it can make up for the deficiency in plane visual positioning, and reduce the influence of the height of the workpiece 2 from the table top on the positioning and placement of the workpiece 2 as much as possible.
[0050] In this embodiment, the various steps are described according to the above sequence. Those skilled in the art can understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in this order, and they can be executed simultaneously or The order is reversed, and these simple changes are all within the protection scope of the present invention.
[0051] The technical solutions provided by the embodiments of the present invention have been introduced in detail above. Although this paper uses specific examples to illustrate the principles and implementation methods of the present invention, the description of the above-mentioned embodiments is only applicable to help understand the principles of the embodiments of the present invention; meanwhile, for those skilled in the art, according to this In the embodiment of the invention, changes may be made within the scope of specific implementation and application.
[0052] It should be noted that: the symbols in the drawings are only for illustrating the present invention more clearly, and are not regarded as improperly limiting the protection scope of the present invention.
[0053] The terms "comprising", "comprising" or any other similar terms are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus/device comprising a set of elements includes not only those elements, but also items not expressly listed. Other elements, or also include elements inherent in these processes, methods, articles, or devices/devices. Without further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional elements in the process, method, article, or apparatus/device comprising said element, i.e. "comprising a The meaning of " also covers the meaning of "including another".
[0054] The various steps of the present invention can be realized with general-purpose computing devices, for example, they can be concentrated on a single computing device, such as: personal computer, server computer, handheld device or portable device, tablet type device or multi-processor device, also may be distributed over a network of multiple computing devices, which may perform the steps shown or described in a different order than here, or they may be fabricated as individual integrated circuit modules, or multiple modules of them may be Or the steps are fabricated into a single integrated circuit module to realize. Accordingly, the invention is not limited to any specific hardware and software or combination thereof.
[0055] The method provided by the present invention can be implemented using programmable logic devices, and can also be implemented as computer program software or program modules (which include routines, programs, objects, components, or data structures that perform specific tasks or implement specific abstract data types, etc. ), for example, according to an embodiment of the present invention may be a computer program product, and the execution of the computer program product causes a computer to execute the exemplified method. The computer program product comprises a computer readable storage medium having computer program logic or code portions embodied thereon for implementing the method. The computer-readable storage medium may be a built-in medium installed in the computer or a removable medium detachable from the main body of the computer (for example, a storage device using a hot-swappable technology). The built-in medium includes but not limited to rewritable non-volatile memory, such as RAM, ROM, flash memory and hard disk. The removable media include but not limited to: optical storage media (such as: CD-ROM and DVD), magneto-optical storage media (such as: MO), magnetic storage media (such as: magnetic tape or mobile hard disk), with built-in Media that writes non-volatile memory (eg: memory card) and media with built-in ROM (eg: ROM cartridge).
[0056] The present invention is not limited to the above-mentioned embodiments, and without departing from the essence of the present invention, any deformation, improvement or replacement conceivable by those skilled in the art falls within the scope of the present invention.
[0057] While the foregoing has shown, described and indicated a detailed description of the essential novel features of the invention as applicable to various embodiments, it will be appreciated that those skilled in the art can make changes to the system without departing from the intent of the invention. various omissions, substitutions and changes in form and detail.
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Description & Claims & Application Information

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