CN112828892A

CN112828892A - Workpiece grabbing method and device, computer equipment and storage medium

Info

Publication number: CN112828892A
Application number: CN202110088039.3A
Authority: CN
Inventors: 高磊; 秦继昊; 田希文
Original assignee: Seizet Technology Shenzhen Co Ltd
Current assignee: Seizet Technology Shenzhen Co Ltd
Priority date: 2021-01-22
Filing date: 2021-01-22
Publication date: 2021-05-25
Anticipated expiration: 2041-01-22
Also published as: CN112828892B; WO2022156749A1

Abstract

The invention discloses a workpiece grabbing method, which comprises the following steps: s1, acquiring an original point cloud of a workpiece; s2, segmenting and identifying the original point cloud of the workpiece to obtain preliminary workpiece information; s3, identifying the preliminary workpiece information one by one to obtain workpiece information; s4, acquiring a first sequence, and performing grabbing planning judgment by a first grabbing planning module according to the first sequence polling workpiece point cloud, wherein the grabbing planning judgment comprises at least two types of cylindrical surface grabbing postures, included angles in each type of cylindrical surface grabbing postures are different, and if the cylindrical surface grabbing postures correspond to the workpiece point cloud, the workpiece point cloud is output outwards through grabbing planning; if the data are not processed through the grabbing plan, the step is switched to S5; s5, acquiring a second sequence, polling the preliminary workpiece point cloud according to the second sequence through a second grabbing planning module to carry out grabbing planning judgment, wherein the grabbing planning judgment comprises at least one type of end face grabbing gesture, and if the end face grabbing gesture corresponds to the preliminary workpiece point cloud and passes through grabbing planning, outputting the preliminary workpiece point cloud outwards; if the grabbing planning is not finished, the method can effectively improve the grabbing success rate and realize the grabbing of the workpieces in a completely disordered state.

Description

Workpiece grabbing method and device, computer equipment and storage medium

Technical Field

The invention relates to a system for grabbing parts from a material frame and a control method, in particular to a workpiece grabbing method, a workpiece grabbing device, computer equipment and a storage medium.

Background

In the industrial manufacturing field, the traditional feeding and discharging system is realized based on an automatic tool or a manual mode, a workpiece is heavy, the labor intensity of manual operation is high, and corresponding recruitment is difficult. With the popularization of industrial 3D cameras and the rising of 3D vision algorithms, the 3D vision-based unordered sorting and feeding system is expected to realize intellectualization of the past manual or automatic mode and industrial upgrading of the automatic feeding and feeding system.

The 3D vision guide is used for grabbing parts, grabbing from a material frame stack, grabbing from a stacking chain and grabbing parts in an EHB conveying system, the positioning is accurate, and the high-efficiency automation rate is realized. The workpiece is most complicated to grab from the stacking material frame, particularly the deep material frame, the workpiece in the material frame is usually in a scattered and disordered state, the position of the workpiece is not only required to be positioned when the part material frame is grabbed, but also the position of the workpiece is required to be judged, and in addition, the problems of multiple types of workpieces, different work sizes and the like are required to be faced.

The complexity faced by the unordered sorting puts more and higher requirements on the robot, and currently, the three following problems are mainly faced: firstly, workpieces in a material frame are usually in a scattered and disordered state, which means that an industrial robot cannot continue to execute work by means of a set program, but needs to sense and analyze an external environment through 3D vision and then make a judgment, so that pain points of unordered sorting in aspects of low scene material matching degree, fast product type iteration, low system adjustment adaptability and the like are solved. Secondly, because the workpieces are randomly placed, the situations of overlapping, shielding, shadows, complex backgrounds and the like of a large number of workpieces in the material frame easily exist, complete point cloud data of the workpieces cannot be acquired through a camera, and then related workpieces cannot be identified, so that the workpieces cannot be grabbed. Thirdly, in the current unordered sorting, the common motion planning means that a mechanical arm extends into a material frame, grabbing depends on a mechanical arm body kinematics model, a tail end of a robot is designed to be a long straight rod, and grabbing strategies are that the tail end is perpendicular to the surface of a workpiece to be sucked, when the size of the material frame is large or the material frame is relatively far away from the robot, the robot is prone to generating the problem of insufficient arm extension, and the posture (straight rod angle) of the robot cannot meet the requirement within 30 degrees sometimes. As shown in fig. 1 and 2, the proximal robot pose can reach 30 °, but the distal robot pose can only reach 15 °.

Disclosure of Invention

The invention aims to provide a workpiece grabbing method to solve the problems in the prior art.

In order to achieve the purpose, the invention provides a workpiece grabbing method, which comprises the steps of grabbing a workpiece by using a tail-end claw, wherein the tail-end claw comprises a straight rod and a claw component, the claw component and the straight rod are arranged in an included angle, the included angle is adjustable, the straight rod is used for being connected with an external mechanical arm so that the mechanical arm is positioned outside a material frame, and the claw component is arranged perpendicular to the workpiece to be grabbed;

the workpiece grabbing method comprises the following steps:

s1, acquiring an original point cloud of a workpiece;

s2, segmenting and identifying the workpiece original point cloud to obtain preliminary workpiece information, and turning to S3, wherein the preliminary workpiece information comprises a preliminary workpiece point cloud and a preliminary workpiece pose, and if the identification fails, the operation is finished;

s3 identifying the preliminary workpiece information one by one to acquire workpiece information including a cloud of workpiece points and a workpiece pose, and proceeding to step S4; if the identification fails, the process proceeds to step S5;

s4, polling the workpiece point clouds through a first grabbing planning module to carry out grabbing planning judgment, wherein the first grabbing planning module comprises at least two types of cylindrical surface grabbing postures, grabbing points of the cylindrical surface grabbing postures are located at cylindrical surfaces of the workpiece, included angles between the claw assemblies and the straight rod in each type of cylindrical surface grabbing postures are different, and if a group of workpiece point clouds corresponding to one cylindrical surface grabbing posture passes through grabbing planning, the workpiece information and the corresponding cylindrical surface grabbing postures are output; if all the workpiece point clouds corresponding to all the cylindrical surface grabbing postures do not pass the grabbing planning, the step S5 is executed;

s5, polling the preliminary workpiece point cloud through a second grabbing planning module to carry out grabbing planning judgment, wherein the second grabbing planning module comprises at least one type of end face grabbing postures, grabbing points of the end face grabbing postures are located at the end faces of the workpieces, included angles between the gripper components and the straight rod in each type of end face grabbing postures are different, and if a group of preliminary workpiece point clouds corresponding to one end face grabbing posture passes through grabbing planning, outputting preliminary workpiece information and the corresponding end face grabbing postures to carry out workpiece disturbance; and if all the preliminary workpiece point clouds corresponding to all the end face grabbing postures do not pass the grabbing planning, ending the process.

Preferably, the step S4 is preceded by spatially sorting the workpiece point clouds according to the workpiece poses to obtain a first sorting, and in the step S4, the workpiece point clouds are polled by a first capture planning module according to the first sorting to perform capture planning determination;

the step S5 is preceded by spatially sorting the preliminary workpiece point clouds according to the preliminary workpiece poses to obtain a second sorting, and in step S5, the preliminary workpiece point clouds are polled by a second grab planning module according to the second sorting to make a grab planning determination.

Preferably, in step S4, a plurality of cylindrical surface grabbing postures are arranged in series, each cylindrical surface grabbing posture polls the workpiece point clouds according to the first sequence to perform grabbing planning judgment, if all the workpiece point clouds corresponding to the previous cylindrical surface grabbing posture do not pass through grabbing planning, the next cylindrical surface grabbing posture is shifted to perform grabbing planning judgment, and until a group of workpiece point clouds corresponding to one of the cylindrical surface grabbing postures pass through grabbing planning, the workpiece information and the corresponding cylindrical surface grabbing posture are output;

and/or in step S5, a plurality of end face grabbing postures are arranged in series, and each end face grabbing posture polls the preliminary workpiece point cloud according to the second sequence to perform grabbing planning judgment: and if all the initial workpiece point clouds corresponding to the previous end face grabbing gesture do not pass the grabbing planning, switching to the next end face grabbing gesture to carry out grabbing planning judgment, and outputting the initial workpiece information and the corresponding end face grabbing gesture until a group of initial workpiece point clouds corresponding to one end face grabbing gesture pass the grabbing planning.

Preferably, in the step S4, the step of polling the workpiece point cloud for grabbing plan determination according to the first sequence by each cylindrical surface grabbing gesture includes the following steps:

s41, acquiring the angle theta of the straight rod according to the current cylindrical surface grabbing posture and the current position and posture of the workpiece to be grabbed;

s42, if the angle theta of the straight rod is not larger than a preset angle, simulating and grabbing the workpiece point cloud by using the current cylindrical surface grabbing posture for collision avoidance detection:

if the collision avoidance detection is passed, outputting the workpiece information and the corresponding cylindrical surface grabbing gesture;

if the current cylindrical surface grabbing gesture does not pass the collision avoidance detection, rotating for k times around the z axis of the workpiece point cloud coordinate system by a rotation angle of 360 degrees/k according to the current cylindrical surface grabbing gesture, performing collision avoidance detection once every rotation, and outputting the workpiece information and the corresponding cylindrical surface grabbing gesture until one rotation angle passes the collision avoidance detection, wherein k is a preset value; if the point cloud is judged not to be grabbed after rotating for 360 degrees, polling the next workpiece point cloud according to the first sequence to carry out grabbing planning judgment;

s43, if the angle theta of the straight rod is larger than a preset angle, directly polling the next workpiece point cloud according to the first sequence to carry out grabbing planning judgment;

and/or in the step S5, polling the preliminary workpiece point cloud according to the second sequence by each of the end face grasp postures to perform grasp planning determination includes the following steps:

s51, determining the angle theta of the straight rod according to the current end face grabbing posture and the current primary workpiece posture;

s52, if the angle theta of the straight rod is not larger than a preset angle, the initial workpiece point cloud is simulated and grabbed in the grabbing posture of the current end face to carry out collision avoidance detection:

if the collision avoidance detection is passed, outputting the preliminary workpiece information and the corresponding end face grabbing gesture;

if the current end face grabbing gesture does not pass the collision avoidance detection, rotating for k times around the z axis of the preliminary workpiece point cloud coordinate system by a rotation angle of 360 degrees/k according to the current end face grabbing gesture, performing collision avoidance detection once every rotation until one rotation angle passes the collision avoidance detection, and outputting the preliminary workpiece information and the corresponding end face grabbing gesture, wherein k is a preset value; if the point cloud cannot be grabbed after rotating for 360 degrees, polling the next preliminary workpiece point cloud according to the second sequence to carry out grabbing planning judgment;

and S53, if the angle theta of the straight rod is larger than a preset angle, directly polling the next workpiece point cloud according to the first sequence to perform grabbing planning judgment.

Further: the preset angle is 15 degrees.

Preferably, the included angle of the tail end paw is 15 degrees and 45 degrees;

the first grabbing planning module comprises a first cylindrical surface grabbing posture and a second cylindrical surface grabbing posture, and in the first cylindrical surface grabbing posture, the claw assembly and the straight rod form an included angle of 15 degrees; in the second cylindrical surface grabbing posture, the claw assembly and the straight rod form an included angle of 45 degrees;

the second grabbing planning module comprises a first-class end face grabbing posture, and in the first-class end face grabbing posture, the claw assembly and the straight rod form an included angle of 15 degrees.

Preferably, the first grabbing planning module comprises a first cylindrical surface grabbing gesture and a second cylindrical surface grabbing gesture, the first cylindrical surface grabbing gesture and the second cylindrical surface grabbing gesture respectively comprise a forward cylindrical surface middle grabbing gesture and a reverse cylindrical surface middle grabbing gesture, when the cylindrical surface grabbing gestures are the forward cylindrical surface middle grabbing gestures, the gripper assembly is forward vertical to the cylindrical surface of the workpiece, and the grabbing point is located in the middle of the center of the workpiece; when the cylindrical surface grabbing gesture is the middle grabbing gesture of the reversed cylindrical surface, the paw component is reversely vertical to the cylindrical surface of the workpiece, and the grabbing point is located in the middle of the cylindrical surface of the workpiece;

and/or the second grabbing planning module comprises a first cylindrical surface grabbing gesture, the first end surface grabbing gesture comprises a positive end surface middle grabbing gesture and a reverse end surface middle grabbing gesture, when the end surface grabbing gesture is the positive end surface middle grabbing gesture, the gripper assembly is perpendicular to the end surface of the workpiece in the positive direction, and the grabbing point is located in the middle of the workpiece; when the end face grabbing posture is a reverse end face middle grabbing posture, the tail end of the hand grab is reversely perpendicular to the end face of the workpiece, and the grabbing point is located in the middle of the end face of the workpiece.

Preferably, the first-class cylindrical surface grabbing postures and the second-class cylindrical surface grabbing postures further respectively comprise one or more combinations of a forward cylindrical surface middle left grabbing posture, a forward cylindrical surface middle right grabbing posture, a reverse cylindrical surface middle left grabbing posture and a reverse cylindrical surface middle right grabbing posture; when the cylindrical surface grabbing gesture is a positive cylindrical surface middle left grabbing gesture, the positive direction of the claw assembly is perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located in the workpiece middle left part; when the cylindrical surface grabbing gesture is a positive cylindrical surface middle right grabbing gesture, the positive direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located on the right part in the middle of the workpiece; when the cylindrical surface grabbing gesture is a reverse cylindrical surface middle left grabbing gesture, the paw component is reversely vertical to the cylindrical surface of the workpiece, and the grabbing point is located on a workpiece middle left part; when the cylindrical surface grabbing gesture is a right grabbing gesture in the middle of the reverse cylindrical surface, the paw component is reversely perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located on the right part in the middle of the workpiece.

According to another aspect of the invention, a workpiece grasping device is disclosed that performs workpiece grasping using a distal gripper including a straight bar and a gripper assembly coupled to the straight bar; the gripper assembly and the straight rod are arranged in an included angle, the included angle is adjustable, the straight rod is used for being connected with an external mechanical arm to enable the mechanical arm to be located outside the material frame, and the gripper assembly is arranged perpendicular to a workpiece to be grabbed;

the work gripping device includes:

the workpiece original point cloud obtaining module is used for obtaining a workpiece original point cloud;

the preliminary workpiece information acquisition module is used for segmenting and identifying the workpiece original point cloud to acquire preliminary workpiece information and transferring the preliminary workpiece information to the workpiece information acquisition module, wherein the preliminary workpiece information comprises a preliminary workpiece point cloud and a preliminary workpiece pose;

the workpiece information acquisition module is used for identifying the preliminary workpiece information one by one to acquire workpiece information and transferring the workpiece information to the first sequencing acquisition module, wherein the workpiece information comprises workpiece point cloud and workpiece pose; if the identification fails, switching to a second grabbing planning module for processing;

the first grabbing planning module is used for carrying out grabbing planning judgment on the preliminary workpiece point cloud, the first grabbing planning module comprises at least two types of cylindrical surface grabbing postures, grabbing points of the cylindrical surface grabbing postures are located at cylindrical surfaces of the workpiece, included angles between the claw assemblies and the straight rod in each type of cylindrical surface grabbing postures are different, and if a group of workpiece point clouds corresponding to one cylindrical surface grabbing posture passes through grabbing planning, the workpiece information and the corresponding cylindrical surface grabbing postures are output; if all the workpiece point clouds corresponding to all the cylindrical surface grabbing postures do not pass through the grabbing planning, switching to a second grabbing planning module;

the second grabbing planning module is used for polling the preliminary workpiece point clouds to carry out grabbing planning judgment, the second grabbing planning module comprises at least one type of end face grabbing postures, grabbing points of the end face grabbing postures are located at the end faces of the workpieces, and if a group of preliminary workpiece point clouds corresponding to one end face grabbing posture pass through grabbing planning, the preliminary workpiece information and the corresponding end face grabbing postures are output to carry out workpiece disturbance; and if all the preliminary workpiece point clouds corresponding to all the end face grabbing postures do not pass the grabbing planning, ending the process.

According to another aspect of the invention, there is provided a computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of any of the methods described above when executing the computer program.

According to another aspect of the invention, a computer-readable storage medium is provided, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method of any of the above.

According to the workpiece grabbing method, the workpiece grabbing device, the computer equipment and the storage medium, the tail-end paw is provided with the included angle, the included angle is adjustable, the grabbing success rate can be effectively improved through the matching of the tail-end paw with the changeable included angle and the grabbing strategies of the first grabbing planning module and the second grabbing planning module, the grabbing of workpieces in a completely disordered state is realized, meanwhile, the grabbing of the workpieces with the inclination angle within +/-90 degrees is completed by the robot in a posture within +/-15 degrees, compared with a straight-bar paw design, the robot arm spread is saved, and the robot posture singularity is avoided more.

Drawings

FIG. 1 is a schematic diagram of a structure of a robot with a limited arm spread during distal grabbing;

FIG. 2 is a schematic diagram of a structure of a robot with a limited arm spread when the robot grips at a near end;

FIG. 3 is a schematic flowchart of a workpiece grabbing method according to an embodiment of the present invention;

FIG. 4 is a schematic view of an embodiment of a grasping end;

FIG. 5 is a schematic view of a working flow of an embodiment of a first capture plan determination module;

FIG. 6 is a schematic view of a grabbing structure in operation of the workpiece grabbing method of the present invention;

FIG. 7 is a schematic view of a work flow of the gripping planning judgment of the gripping posture of the cylindrical surface;

FIG. 8 is a schematic view of a structure of a grabbing posture in the middle of a first class of forward cylindrical surfaces, wherein an included angle is 15 degrees;

FIG. 9(a) is a schematic structural diagram of grabbing a workpiece with an inclination angle of 0 ° by using the tail end of the gripper shown in FIG. 8 in a grabbing posture in the middle of a first type of positive cylinder;

FIG. 9(b) is a schematic structural diagram of grabbing a workpiece with an inclination angle of 15 degrees by using the tail end of the gripper shown in FIG. 8 in a grabbing posture in the middle of a first type of forward cylindrical surface;

FIG. 9(c) is a schematic structural diagram of grabbing a workpiece with an inclination angle of 30 ° by using the tail end of the gripper shown in FIG. 8 in a grabbing posture of the middle of a first type of positive cylinder;

FIG. 10 is a schematic view of a first type of inverted cylindrical surface intermediate grabbing attitude structure, wherein the included angle is 15 degrees;

fig. 11(a) is a schematic structural view of grabbing a workpiece with an inclination angle of 30 ° using the tail end of the gripper shown in fig. 10 in a first-type inverted cylindrical surface middle grabbing posture;

FIG. 11(b) is a schematic structural diagram of workpiece grabbing at an inclination angle of 15 ° using the end of the gripper shown in FIG. 10 in a first-type inverted cylindrical surface intermediate grabbing attitude;

FIG. 11(c) is a schematic structural diagram of workpiece grabbing at an inclination angle of 0 ° using the end of the gripper shown in FIG. 10 in a first-type inverted cylindrical intermediate grabbing attitude;

FIG. 12 is a schematic view of a second type of positive cylinder intermediate grabbing attitude structure, wherein the included angle is 45 degrees;

fig. 13(a) is a schematic structural view of grabbing a workpiece with an inclination angle of 30 ° using the tail end of the gripper shown in fig. 12 in a middle grabbing posture of a second type of forward cylindrical surface;

fig. 13(b) is a schematic structural view of grabbing a workpiece with an inclination angle of 45 ° using the tail end of the gripper shown in fig. 12 in the middle of the second type of forward cylindrical surface for grabbing;

fig. 13(c) is a schematic structural view of grabbing a workpiece with an inclination angle of 60 ° using the tail end of the gripper shown in fig. 12 in the middle of the second type of forward cylindrical surface for grabbing;

FIG. 14 is a structural diagram of a first type of inverted cylindrical surface intermediate grabbing attitude, wherein the included angle is 45 degrees;

fig. 15(a) is a schematic structural view of grabbing a workpiece with an inclination angle of 60 ° in a second type of inverted cylindrical surface middle grabbing posture by using the tail end of the gripper shown in fig. 14;

FIG. 15(b) is a schematic structural view of grabbing a workpiece with an inclination angle of 45 ° in a second type of inverted cylindrical surface middle grabbing posture by using the tail end of the gripper shown in FIG. 14;

FIG. 15(c) is a schematic structural view of a gripper using the distal end of the gripper shown in FIG. 14 to grip a workpiece having an inclination of 30 ° in a second-type inverted cylindrical intermediate gripping attitude;

fig. 16(a) is a schematic structural diagram of the first-type cylindrical surface grabbing gesture being a positive cylindrical surface middle left grabbing gesture;

fig. 16(b) is a structural diagram illustrating a first-type cylindrical surface grabbing posture being a forward cylindrical surface middle right-leaning grabbing posture;

fig. 16(c) is a structural diagram illustrating the first-type cylindrical surface grabbing posture being a reverse cylindrical surface middle left-leaning grabbing posture;

fig. 16(d) is a structural diagram illustrating the first-type cylindrical surface grabbing posture being a reverse cylindrical surface middle right-leaning grabbing posture;

fig. 17(a) is a structural schematic diagram of a second-class cylindrical surface grabbing gesture which is a positive cylindrical surface middle leftward grabbing gesture;

fig. 17(b) is a structural diagram illustrating a second-class cylindrical surface grabbing posture being a forward cylindrical surface middle right-leaning grabbing posture;

fig. 17(c) is a structural diagram illustrating a second-type cylindrical surface grabbing posture being a reverse cylindrical surface middle left-leaning grabbing posture;

FIG. 17(d) is a structural diagram of a second-type cylindrical surface grabbing posture being a reverse cylindrical surface middle right-leaning grabbing posture;

fig. 18 is a schematic view of a workflow for planning and judging the gripping of the end face gripping attitude;

FIG. 19 is a structural diagram of a middle grabbing posture of a first type of forward end face, wherein an included angle is 15 degrees;

FIG. 20(a) is a schematic structural view showing the gripping of a workpiece with an inclination of 60 ° using the distal end of the gripper shown in FIG. 19 in a forward end surface intermediate gripping attitude;

FIG. 20(b) is a schematic structural view showing the gripper of FIG. 19 using the distal end of the gripper to grip a workpiece with an inclination of 75 ° in the middle of the forward cylinder;

FIG. 20(c) is a schematic structural view showing the gripper of FIG. 19 using the distal end of the gripper to grip a workpiece at an inclination of 90 ° in the middle of the forward cylinder;

FIG. 21 is a structural diagram of a middle grabbing posture of a first type of reverse end face, wherein an included angle is 15 degrees;

FIG. 22(a) is a schematic structural view of a gripper using the distal end of the gripper shown in FIG. 21 for gripping a workpiece with an inclination of 60 ° in a first-type inverted end surface intermediate gripping attitude;

FIG. 22(b) is a schematic structural diagram of workpiece grabbing at an inclination angle of 75 ° in a first-type reverse cylindrical surface middle grabbing posture by using the tail end of the gripper shown in FIG. 21;

FIG. 22(c) is a schematic structural view of a gripper using the distal end of the gripper shown in FIG. 21 to grip a workpiece with an inclination angle of 90 ° in a first-type inverted cylindrical intermediate gripping attitude;

FIG. 23 is a schematic structural view of an embodiment of a workpiece handling device according to the present invention;

FIG. 24 is a hardware architecture of one embodiment of a computer device of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of the invention in any way.

Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items. In the drawings, the thickness, size, and shape of an object have been slightly exaggerated for convenience of explanation. The figures are purely diagrammatic and not drawn to scale.

It will be further understood that the terms "comprises," "comprising," "includes," "including," "has," "includes" and/or "including," when used in this specification, specify the presence of stated features, steps, integers, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, integers, operations, elements, components, and/or groups thereof.

The terms "substantially", "about" and the like as used in the specification are used as terms of approximation and not as terms of degree, and are intended to account for inherent deviations in measured or calculated values that would be recognized by one of ordinary skill in the art.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The invention discloses a workpiece grabbing method, which comprises the steps of grabbing a workpiece by using a tail-end paw, wherein the tail-end paw comprises a straight rod and a paw component, an included angle is formed between the paw component and the straight rod, the included angle is adjustable, the straight rod is used for connecting an external mechanical arm to enable the mechanical arm to be positioned outside a material frame, and the paw component is arranged perpendicular to the workpiece to be grabbed;

as shown in fig. 3, the workpiece gripping method includes the steps of:

s1, acquiring an original point cloud of a workpiece;

s2, segmenting and identifying the workpiece original point cloud to obtain preliminary workpiece information, and turning to S3, wherein the preliminary workpiece information comprises the preliminary workpiece point cloud and a preliminary workpiece pose, and if the identification fails, the process is ended;

s4, performing spatial ordering on the workpiece point cloud according to the workpiece pose to obtain a first order, polling the workpiece point cloud according to the first order through a first grabbing planning module to perform grabbing planning judgment, wherein the first grabbing planning module comprises at least two types of cylindrical grabbing postures, the grabbing points of the cylindrical grabbing postures are located at the cylindrical surface of the workpiece, included angles between the claw assemblies and the straight rod in each type of cylindrical grabbing postures are different, and if one group of workpiece point clouds corresponding to one cylindrical grabbing posture passes through grabbing planning, outputting the workpiece information and the corresponding cylindrical grabbing postures; if all the workpiece point clouds corresponding to all the cylindrical surface grabbing postures do not pass the grabbing planning, the step S5 is carried out;

s5, performing spatial sorting on the preliminary workpiece point cloud according to the preliminary workpiece pose to obtain a second sorting, polling the preliminary workpiece point cloud according to the second sorting through a second grabbing planning module to perform grabbing planning judgment, wherein the second grabbing planning module comprises at least two types of end face grabbing postures, the grabbing points of the end face grabbing postures are located at the end faces of the workpieces, included angles between the gripper components and the straight rod in each type of end face grabbing postures are different, and if one group of preliminary workpiece point clouds corresponding to one end face grabbing posture passes through grabbing planning, outputting preliminary workpiece information and the corresponding end face grabbing postures to perform workpiece disturbance; and if all the preliminary workpiece point clouds corresponding to all the end face grabbing postures do not pass the grabbing planning, ending the process.

According to the workpiece grabbing method disclosed by the invention, the tail-end gripper is provided with the included angle, the included angle is adjustable, the grabbing success rate can be effectively improved through the matching of the tail-end gripper with the first grabbing planning module and the second grabbing planning module, the grabbing strategies are switched, the grabbing strategies are completely disordered, the grabbing of the workpieces with the inclination angle within +/-90 degrees can be realized by the robot within +/-15 degrees, and compared with a straight-rod gripper design, the arm spread of the robot is saved, and the gesture singularity of the robot is avoided more.

Because the included angle of the end paw is adjustable, the cylindrical surface grabbing postures and the end surface grabbing postures in the first grabbing planning module and the second grabbing planning module can be further subdivided into n types of grabbing postures according to the difference of the set number n of the included angles, wherein the n types of cylindrical surface grabbing postures are used for grabbing conventional workpieces; the n-type end face grabbing postures are used for solving the workpiece grabbing scheme under the conditions of overlapping, shielding, shading, complex background and the like in a material frame, when workpieces are grabbed, after workpiece point clouds of workpiece original point clouds are preprocessed and identified to form workpiece point clouds containing complete or more complete cylindrical surface information, the n-type cylindrical surface grabbing postures are used for grabbing and judging, when the machine works, each cylindrical surface grabbing posture polls the identified workpiece point clouds, so that the grabbed workpieces and corresponding grabbing postures (including corresponding end-end paw included angles) are finally determined and output to a robot for workpiece grabbing, and workpiece grabbing under most disordered states in the material frame can be finished through the cylindrical surface grabbing postures shown by the invention; and (3) for the situations of overlapping, shielding, shading, complex background and the like of the workpieces in the material frame, namely when the plurality of cylindrical surface grabbing postures judge that no workpieces can be grabbed or the original workpiece point cloud cannot identify the workpiece point cloud through preprocessing, turning to end surface grabbing posture processing, wherein the end surface grabbing postures are used for disturbing the workpieces, realizing the movement of the positions of the workpieces in the material frame, and then photographing again for carrying out the next round of workpiece grabbing planning. The grabbing planning judgment object of the N types of end face grabbing postures is used for carrying out grabbing planning on a preliminary workpiece point cloud (preliminarily divided point cloud), and the preliminary workpiece point cloud (workpiece point cloud cluster) is identified through polling of each end face grabbing posture so as to judge whether a workpiece capable of being grabbed exists or not and a corresponding end face grabbing posture (including a corresponding terminal paw included angle); if the workpiece position is the same as the position of the workpiece, outputting the workpiece position to an external robot, and carrying the tail end paw by the external robot to carry out workpiece disturbance so as to realize the movement of the workpiece position.

The working principle of the workpiece grabbing method shown in the present invention will be further explained by taking an example that the workpiece grabbing of the cylindrical rod in the deep material frame and the included angle between the end claws is switchable between 15 degrees and 45 degrees.

In this embodiment, a terminal paw is used for grabbing a workpiece, as shown in fig. 4, the terminal paw includes a straight rod and a paw component, the paw component and the straight rod form an included angle, and the included angle is switchable between 15 degrees and 45 degrees, the straight rod is used for connecting an external robot arm so that the robot arm is located outside a material frame, and the paw component is arranged perpendicular to the workpiece to be grabbed; the first grabbing planning module comprises a first cylindrical surface grabbing posture and a second cylindrical surface grabbing posture, and in the first cylindrical surface grabbing posture, the claw assembly and the straight rod form an included angle of 15 degrees; in the second cylindrical surface grabbing posture, the claw assembly and the straight rod form an included angle of 45 degrees; the second grabbing planning module also comprises a first end face grabbing posture, wherein in the first end face grabbing posture, the claw assembly and the straight rod form an included angle of 15 degrees, and the robot can grab workpieces with postures within +/-90 degrees in postures within +/-15 degrees.

As shown in fig. 5, the workpiece grabbing method disclosed by the invention comprises the following steps:

s110, acquiring an original point cloud of a workpiece; in the step S110, a 3D camera is matched with a light source to photograph a workpiece in a charging basket so as to obtain an original point cloud of the workpiece;

s120, segmenting and identifying the workpiece original point cloud to obtain preliminary workpiece information, and turning to the step S3, wherein the preliminary workpiece information comprises a preliminary workpiece point cloud and a preliminary workpiece pose, and if the identification fails, ending the process;

as a preferred scheme, in this embodiment, segmenting and identifying the workpiece original point cloud to obtain preliminary workpiece information includes the following steps:

s121, setting a grabbing space, and adjusting the length, width, height, thickness and pose of the virtual material frame to cut out an actual material frame area so as to obtain a cut point cloud;

and S122, primarily dividing the cut point cloud, and acquiring the divided point cloud, namely the primary workpiece information.

S130, identifying the preliminary workpiece information one by one to acquire workpiece information, and turning to S4, wherein the workpiece information comprises workpiece point clouds and workpiece poses; if the identification fails, the process proceeds to step S5;

in the step S130, the preliminary workpiece point cloud is further processed to obtain an accurate workpiece point cloud profile, in this embodiment, the cylinder recognition tool is used to recognize the divided preliminary workpiece information one by one to obtain each piece of workpiece information, that is, the corresponding workpiece point cloud and the corresponding workpiece pose are obtained, the cylinder recognition result is as shown in fig. 6, the z-axis of the workpiece coordinate system is along the axial direction of the workpiece, the x-axis is along the radial direction of the workpiece, and the x-y-z-axis forms a right-hand coordinate system.

S140, space sequencing is carried out on the workpiece point clouds according to the workpiece poses to obtain a first sequence, the workpiece point clouds are polled according to the first sequence through a first grabbing planning module to carry out grabbing planning judgment, and when grabbing planning, if a group of workpiece point clouds corresponding to one cylindrical surface grabbing gesture passes through grabbing planning, the workpiece information and the corresponding cylindrical surface grabbing gesture are output; if all the workpiece point clouds corresponding to all the cylindrical surface grabbing postures do not pass the grabbing planning, the step S150 is carried out;

in the step S140, spatial sorting is performed according to the workpiece pose information of the identified workpiece point clouds, wherein the sorting principle is that the z-axis direction is prior to the x-axis direction and the y-axis direction, then the x-axis direction and finally the y-axis direction, namely, for the identified workpiece point clouds, sorting is performed on the basis of the height of the workpiece point clouds in the z-axis direction, the higher the height in the z-axis direction is, the more forward the sorting is, if the heights of the workpiece point clouds in the z-axis direction are the same, sorting is performed according to the size in the x-axis direction, and the larger the value is, the more forward the sorting is; if the numerical values of the workpiece point clouds in the x-axis direction are the same, continuing to sort based on the size of the y-axis direction, and thus obtaining the spatial sorting of the workpiece point clouds;

after the first sequence of the workpiece point cloud is obtained, transferring to a first grabbing planning module for grabbing judgment, wherein the first grabbing planning module is a conventional grabbing attitude judgment module, in the embodiment, the first grabbing planning module comprises a first cylindrical surface grabbing attitude and a second cylindrical surface grabbing attitude, and in the first cylindrical surface grabbing attitude, an included angle of 15 degrees is formed between the paw assembly and the straight rod; in the grabbing posture of the second cylindrical surface, the claw assembly and the straight rod form an included angle of 45 degrees. The grabbing points of the grabbing postures of the two types of cylindrical surfaces are positioned on the cylindrical surfaces of the workpieces, so that the size and the adsorption area of the tail-end paw are larger, and the workpieces can be grabbed more effectively.

Each cylindrical surface grabbing gesture is correspondingly set as one grabbing planning unit, a plurality of grabbing planning units are arranged in series, when a first grabbing planning module carries out grabbing judgment, the grabbing judgment is carried out by polling all the workpiece point clouds according to the first sequence from the first cylindrical surface grabbing gesture according to internal sequencing until one group of workpiece point clouds passes the grabbing judgment, the workpiece information and the corresponding grabbing gesture are output, if the workpiece point clouds which can pass the grabbing judgment are not found, the next cylindrical surface grabbing gesture is carried out, and all the workpiece point clouds are continuously polled according to the first sequence to carry out grabbing judgment; and if all the workpiece point clouds corresponding to all the cylindrical surface grabbing postures are judged to be not grabbed, the step S150 is carried out. And if the included angle is judged to be 15 degrees by the last grabbing plan, the first-class cylindrical surface grabbing gesture is obtained, and if the included angle is judged to be 45 degrees by the current grabbing plan, the second-class cylindrical surface grabbing gesture is obtained, the robot end sends a switching instruction to drive the gripper component to switch the grabbing angle, and then the current grabbing is carried out.

As a preferred scheme, as shown in fig. 7, in order to obtain a graspable workpiece point cloud as much as possible when performing the grasp planning determination each time, the step of polling the workpiece point cloud to perform the grasp planning determination according to the first sequence by each cylindrical surface grasping attitude includes:

s141, acquiring the angle theta of the straight rod according to the current cylindrical surface grabbing posture and the current position and posture of the workpiece to be grabbed;

and S142, if the angle theta of the straight rod is not larger than the preset angle, simulating and grabbing the workpiece point cloud according to the current cylindrical surface grabbing posture for collision avoidance detection.

As described above, when the material frame is large in size or the material frame is relatively far from the robot, the robot is still likely to have a problem of insufficient arm extension even when the robot posture (straight bar angle θ) is 30 °. Preferably, in the present embodiment, the preset angle is 15 degrees.

s143, if the angle theta of the straight rod is larger than a preset angle, the next workpiece point cloud is polled directly according to the first sequence to perform grabbing planning judgment.

By rotating a plurality of angles, when one group of workpiece point clouds are grabbed and planned in the current cylindrical surface grabbing gesture, more possible grabbing gestures can be obtained, and the vast majority of workpieces in the material frame can be grabbed.

Furthermore, in this embodiment, the first kind of cylindrical surface grabbing postures include a first kind of forward cylindrical surface intermediate grabbing posture and a first kind of reverse cylindrical surface intermediate grabbing posture, and the second kind of cylindrical surface grabbing postures include a second kind of forward cylindrical surface intermediate grabbing posture and a second kind of reverse cylindrical surface intermediate grabbing posture, respectively.

As shown in fig. 8, when the cylindrical surface grabbing gesture is a first type of positive cylindrical surface grabbing gesture, the positive direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, the grabbing point is located at the middle position of the workpiece, and the gripper assembly and the straight rod form an included angle of 15 degrees. When the workpiece is grabbed, as shown in fig. 9(a), when the inclination angle of the workpiece is 0 °, the angle θ of the straight rod is 15 °; as shown in fig. 9(b), when the workpiece inclination angle is 15 °, the straight bar angle θ is 0 °; as shown in fig. 9(c), the straight bar angle θ is-15 ° when the workpiece tilt angle is 30 °. The 15-degree tail end paw is designed to match with the middle grabbing posture of the first type of positive cylindrical surface, and the angle theta of the straight rod is gradually reduced along with the gradual increase of the inclination angle of the workpiece.

As shown in fig. 10, when the cylindrical surface grabbing posture is the middle grabbing posture of the first reverse cylindrical surface, the gripper assembly is reversely perpendicular to the cylindrical surface of the workpiece, the grabbing point is located at the middle of the workpiece, and the gripper assembly and the straight rod form an included angle of 15 degrees. When the workpiece is grabbed, as shown in fig. 11(a), when the inclination angle of the workpiece is 0 °, the angle θ of the straight rod is-15 °; as shown in fig. 11(b), when the workpiece inclination angle is-15 °, the straight bar angle θ is 0 °; as shown in fig. 11(c), the straight bar angle θ is 15 ° when the workpiece tilt angle is-30 °. The 15-degree tail end paw is designed to match with the middle grabbing posture of the first reverse cylindrical surface, and the angle of the straight rod is gradually increased along with the gradual reduction of the inclination angle of the workpiece.

As shown in fig. 12, when the cylindrical surface grabbing gesture is a grabbing gesture in the middle of the second type of positive cylindrical surface, the positive direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, the grabbing point is located in the middle of the center of the workpiece, and the gripper assembly and the straight rod form an included angle of 45 degrees. When the workpiece is grabbed, as shown in fig. 13(a), when the inclination angle of the workpiece is 30 °, the angle θ of the straight rod is 15 °; as shown in fig. 13(b), when the workpiece inclination angle is 45 °, the straight bar angle θ is 0 °; as shown in fig. 13(c), the straight bar angle θ is-15 ° when the workpiece tilt angle is 60 °. The 45-degree tail end paw is designed to match with the middle grabbing posture of the first type of positive cylindrical surface, and the angle of the straight rod is gradually reduced along with the gradual increase of the inclination angle of the workpiece.

As shown in fig. 14, when the cylindrical surface grabbing posture is a second-type reverse cylindrical surface middle grabbing posture, the gripper assembly is reversely perpendicular to the cylindrical surface of the workpiece, the grabbing point is located at the middle of the center of the workpiece, and the gripper assembly and the straight rod form an included angle of 45 degrees. When the workpiece is grabbed, as shown in fig. 15(a), when the inclination angle of the workpiece is-30 degrees, the angle theta of the straight rod is-15 degrees; as shown in fig. 15(b), when the workpiece inclination is-45 °, the straight bar angle θ is 0 °; as shown in fig. 15(c), when the workpiece tilt angle is-60 °, the straight bar angle θ is 15 °. The 45-degree tail end paw is designed to match with the middle grabbing posture of the first reverse cylindrical surface, and the angle of the straight rod is gradually reduced along with the gradual increase of the inclination angle of the workpiece.

In order to match the point cloud of the workpiece with a more suitable grabbing attitude, in the embodiment, on the basis of the 4 cylindrical surface grabbing attitudes, the relative positions of the grabbing points on the cylindrical surfaces are limited, and the first cylindrical surface grabbing attitude and the second cylindrical surface grabbing attitude further comprise one or more combinations of a forward cylindrical surface middle left-leaning grabbing attitude, a forward cylindrical surface middle right-leaning grabbing attitude, a reverse cylindrical surface middle left-leaning grabbing attitude and a reverse cylindrical surface middle right-leaning grabbing attitude;

as shown in fig. 16(a), when the gripping posture of the first-class cylindrical surface is a forward cylindrical surface middle left gripping posture, the forward direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, the gripping point is located at a workpiece middle left position, and an included angle of 15 degrees is formed between the gripper assembly and the straight rod; as shown in fig. 16(b), when the grabbing posture of the first-class cylindrical surface is a forward cylindrical surface middle right-hand grabbing posture, the forward direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, the grabbing point is located at a workpiece middle right-hand part, and an included angle between the gripper assembly and the straight rod is 15 degrees. As shown in fig. 16(c), when the grabbing posture of the first-class cylindrical surface is a reverse cylindrical surface middle left grabbing posture, the gripper assembly is reversely perpendicular to the cylindrical surface of the workpiece, the grabbing point is located at a workpiece middle left part, and an included angle of 15 degrees is formed between the gripper assembly and the straight rod; as shown in fig. 16(d), when the grabbing posture of the first-class cylindrical surface is a posture that the middle of the reverse cylindrical surface is inclined to the right, the gripper assembly is reversely perpendicular to the cylindrical surface of the workpiece, the grabbing point is located at the right part of the middle of the workpiece, and an included angle of 15 degrees is formed between the gripper assembly and the straight rod.

As shown in fig. 17(a), when the gripping posture of the second-type cylindrical surface is a forward cylindrical surface middle left gripping posture, the forward direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, the gripping point is located at a workpiece middle left position, and an included angle of 45 degrees is formed between the gripper assembly and the straight rod; as shown in fig. 17(b), when the gripping posture of the second-class cylindrical surface is a forward cylindrical surface middle right-hand gripping posture, the forward direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, the gripping point is located at a workpiece middle right-hand position, and an included angle of 45 degrees is formed between the gripper assembly and the straight rod. As shown in fig. 17(c), when the gripping posture of the second-type cylindrical surface is a left-to-right gripping posture in the middle of the reverse cylindrical surface, the gripper assembly is reversely perpendicular to the cylindrical surface of the workpiece, the gripping point is located on the left-to-right position in the middle of the workpiece, and an included angle of 45 degrees is formed between the gripper assembly and the straight rod; as shown in fig. 17(d), when the gripping posture of the second-class cylindrical surface is a posture of gripping the middle of the reverse cylindrical surface to the right, the gripper assembly is reversely perpendicular to the cylindrical surface of the workpiece, the gripping point is located at the right part of the middle of the workpiece, and an included angle of 45 degrees is formed between the gripper assembly and the straight rod.

In this embodiment, the first grabbing planning module sets the above 12 cylindrical grabbing postures, each cylindrical grabbing posture corresponds to one grabbing planning unit, each grabbing planning unit is in a serial relationship, when each grabbing planning unit performs grabbing planning, the grabbing planning unit uses the corresponding cylindrical grabbing posture m (m is 1, …,12), and calculates the straight rod angle θ of the hand grab according to the recognized workpiece posture and the grabbing posture m from the first workpiece point cloud with i being 1: if theta is not greater than 15 degrees, carrying out collision avoidance detection; if the collision is avoided, outputting the information of the graspable workpiece; if the collision avoidance does not pass, rotating the attitude m around the z axis of the workpiece coordinate system for k times, wherein the rotation angle is 360 DEG/k each time, performing collision avoidance detection each time, and outputting workpiece information which can be grasped until an angle is found to pass the collision avoidance; and if no workpiece can be grabbed after the rotation of 360 degrees, jumping to the next identified workpiece point cloud. If no workpiece can be grabbed in the grabbing postures 1-12, triggering another grabbing strategy, namely, turning to the step S150.

S150, performing spatial ordering on the preliminary workpiece point cloud according to the preliminary workpiece pose to obtain a second ordering, polling the preliminary workpiece point cloud according to the second ordering through a second grabbing planning module to perform grabbing planning judgment, wherein the second grabbing planning module comprises at least two types of end face grabbing postures, the grabbing points of the end face grabbing postures are located at the end faces of the workpieces, the included angle theta between the gripper component and the straight rod in each type of end face grabbing posture is different, and if a group of preliminary workpiece point clouds corresponding to one end face grabbing posture passes through grabbing planning, outputting preliminary workpiece information and the corresponding end face grabbing postures to perform workpiece disturbance; and if all the preliminary workpiece point clouds corresponding to all the end face grabbing postures do not pass the grabbing planning, ending the process.

When all the identified cloud workpieces of each point cannot be grabbed through the first grabbing planning module or primary cloud workpiece points are not identified, it is indicated that no suitable workpiece to be grabbed exists in the material frame at this time, and if the workpiece is located at the corner of the material frame and the workpiece is overlapped, the situation that cylindrical point clouds of the workpiece cannot be effectively obtained is existed, at this time, the step S150 is carried out, the second grabbing planning judging module selects a suitable workpiece to be disturbed through the adsorption end face, namely, the suitable grabbing gesture and the grabbing workpiece are selected through the grabbing strategy shown in the step S150, the gesture of the workpiece is disturbed after the workpiece is adsorbed by the end claw, the workpiece is recovered to be in a grabbing state, then the image is taken again, the workpiece is grabbed, and the workpiece is accurately grabbed after the workpiece is repositioned through the first grabbing planning module.

In step S150, firstly, spatial ordering is performed according to the pose information of the preliminary point cloud workpiece identified in step S120; most of workpieces in the material frame are sorted completely through the first grabbing and planning module, and when the rest workpieces are identified, only end surface point clouds and part of wall surface point clouds can be obtained, so that the second grabbing and planning module carries out space sequencing on the workpieces based on the primary point clouds, and the sequencing principle is that the z-axis direction is prior to the x-axis direction and the y-axis direction; firstly, sorting a plurality of identified preliminary workpiece point clouds based on the height of the preliminary workpiece point clouds in the z-axis direction, wherein the sorting is more advanced when the height of the z-axis direction is higher, and if the heights of the z-axes of the plurality of preliminary workpiece point clouds are the same, the sorting is performed according to the size of the x-axis direction, and the sorting is advanced when the numerical value is larger; and if the numerical values of the primary workpiece point clouds in the x-axis direction are also the same, sequencing is continuously performed on the basis of the size of the y-axis direction, so that the spatial sequencing of the primary workpiece point clouds is obtained.

And after a second ordering result of the preliminary workpiece point cloud is obtained, the workpiece point cloud is transferred to a second planning and grabbing module to select a proper workpiece and a corresponding grabbing posture for workpiece position disturbance. In this embodiment, the second grabbing planning module includes a first-class end surface grabbing posture in which the gripper assembly and the straight rod form an included angle of 15 degrees; the grabbing point of the end face grabbing gesture is located at the end face of the workpiece and used for sucking the workpiece to disturb the workpiece.

In the second grabbing planning module, all grabbing postures are also arranged in series, when grabbing judgment is carried out, one end face grabbing posture is selected firstly, and for any end face grabbing posture in the second grabbing planning module, the preliminary workpiece point clouds are polled according to the second sequence for grabbing judgment, and when one group of preliminary workpiece point clouds passes the grabbing judgment, the preliminary workpiece information and the corresponding end face grabbing posture are output to carry out workpiece disturbance; if all the preliminary workpiece point clouds in the current grabbing attitude do not pass the grabbing judgment, switching to the next end face grabbing attitude, polling the preliminary workpiece point clouds according to the second sequence to carry out grabbing judgment until one group of the preliminary workpiece point clouds pass the grabbing judgment, and outputting the preliminary workpiece information and the corresponding end face grabbing attitude to carry out workpiece disturbance; and if all the initial workpiece point clouds corresponding to all the grabbing postures in the second grabbing planning module cannot be grabbed, ending the grabbing judgment and reporting an error outwards.

Because the workpiece is not suitable for grabbing in the current material frame, if the second grabbing planning module does not find the suitable workpiece for grabbing, the whole system is finished, and the workpiece in the material frame can be grabbed as far as possible, so that when the second grabbing planning module grabs the planning judgment every time, various possible grabbing postures are tried as much as possible through the rotating angle.

As shown in fig. 18, each grasping plan judgment in the second grasping plan module includes the following steps:

s151, determining the angle theta of the straight rod according to the current end face grabbing posture and the current primary workpiece posture;

s152, if the angle theta of the straight rod is not larger than the preset angle, the initial workpiece point cloud is captured in a simulated mode according to the current end face capturing posture to perform collision avoidance detection. In the present embodiment, the preset angle is preferably 15 degrees.

and S153, if the angle theta of the straight rod is larger than a preset angle, directly polling the next workpiece point cloud according to the first sequence to perform grabbing planning judgment.

Furthermore, in this embodiment, the first type of end face grabbing postures include a first type of forward end face middle grabbing posture and a first type of reverse end face middle grabbing posture.

As shown in fig. 19, when the end face grabbing posture is the first-type forward end face grabbing posture, the forward direction of the gripper assembly is perpendicular to the end face of the workpiece, the grabbing point is located at the middle position of the workpiece, and the gripper assembly and the straight rod form an included angle of 15 degrees. When the workpiece is grabbed, as shown in fig. 20(a), when the inclination angle of the workpiece is-90 °, the angle θ of the straight rod is 15 °; as shown in fig. 20(b), when the workpiece inclination angle is-75 °, the straight bar angle θ is 0 °; as shown in FIG. 20(c), when the workpiece tilt angle is-60, the straight bar angle θ is-15. The 15-degree tail end paw is designed to match with the middle grabbing posture of the first type of positive end face, and the angle of the straight rod is gradually reduced along with the gradual increase of the inclination angle of the workpiece.

As shown in fig. 21, when the end face grabbing posture is the first-type reverse end face middle grabbing posture, the gripper assembly is reversely perpendicular to the end face of the workpiece, the grabbing point is located at the middle of the workpiece, and the gripper assembly and the straight rod are also at an included angle of 15 degrees. When the workpiece is grabbed, as shown in fig. 22(a), when the workpiece inclination angle is 60 °, the straight bar angle θ is 15 °; as shown in fig. 32(b), when the workpiece inclination angle is 75 °, the straight bar angle θ is 0 °; as shown in fig. 32(c), when the workpiece inclination angle is 90 °, the straight bar angle θ is-15 °. The 15-degree tail end paw is designed to match with the middle grabbing posture of the first reverse end face, and the angle of the straight rod is gradually reduced along with the gradual increase of the inclination angle of the workpiece.

In this embodiment, the second grabbing planning module sets up that the above 2 end faces grab the gesture and grab gesture 1, 2, each end face grabbing gesture corresponds to one respectively and grabs the planning unit, each grabs and is the series relation between the planning unit, when every grabs the planning unit and snatchs the planning, it uses and correspondingly grabs gesture m (m 1, 2) to snatch the planning unit, starts from the first preliminary work piece point cloud that i 1 becomes, calculates the straight-bar angle θ of holding according to the work piece gesture that discerns and grabbing gesture m: if theta is not greater than 30 degrees, collision avoidance detection is carried out; if the collision is avoided, outputting the information of the graspable workpiece; if the collision avoidance does not pass, rotating the attitude m around the z axis of the workpiece coordinate system for k times, wherein the rotation angle is 360 degrees/k each time, performing collision avoidance detection each time, and outputting workpiece grippable information until one angle is found to pass the collision avoidance; and if no workpiece can be grabbed after the rotation of 360 degrees, jumping to the next identified workpiece point cloud. If the grippable workpieces are not recognized in the gripping postures 1 and 2, the fact that no grippable workpieces exist in the material frame is indicated, the gripping judgment is finished, and an error is reported outwards.

According to the workpiece grabbing method disclosed by the invention, when the inclination angle of the workpiece is within +/-30 degrees, the grabbing tail end of the gripper with the included angle of 15 degrees is matched with the grabbing posture of the first-class cylindrical surface, so that the robot can grab the workpiece within +/-15 degrees. The inclination angle of the workpiece is 30-60 degrees, -60-30 degrees, and the tail end of the gripper with an included angle of 45 degrees is matched with the gripping posture of the second cylindrical surface, so that the robot can finish gripping in a posture within +/-15 degrees; when the inclination angle of the workpiece is 60-90 degrees, -90-60 degrees, and the tail end of the 15-degree hand grab is matched with the grabbing posture of the first end face, the robot can grab the workpiece in a posture within +/-15 degrees. Therefore, the 15-45-degree two-gear switching gripper tail end design is matched with the first gripping planning module and the second gripping planning module, so that the robot can grip workpieces with postures within +/-90 degrees in postures within +/-15 degrees. Compared with a straight-bar hand grab and a 30-degree hand grab design, the robot arm spread is saved, and the robot posture singularity is avoided more.

Example two

The invention also discloses a workpiece grabbing device 10, which uses a tail end paw to grab a workpiece, wherein the tail end paw comprises a straight rod and a paw component connected with the straight rod; the gripper assembly and the straight rod are arranged in an included angle, the included angle is adjustable, the straight rod is used for being connected with an external mechanical arm to enable the mechanical arm to be located outside the material frame, and the gripper assembly is arranged perpendicular to a workpiece to be grabbed;

as shown in fig. 23, the work gripping apparatus 10 includes:

a workpiece original point cloud obtaining module 11, configured to obtain a workpiece original point cloud;

a preliminary workpiece information obtaining module 12, configured to segment and identify the workpiece original point cloud to obtain preliminary workpiece information, and transfer the preliminary workpiece information to the workpiece information obtaining module, where the preliminary workpiece information includes a preliminary workpiece point cloud and a preliminary workpiece pose;

the workpiece information acquisition module 13 is used for identifying the preliminary workpiece information one by one to acquire workpiece information and transferring the workpiece information to the first sequencing acquisition module, wherein the workpiece information comprises workpiece point cloud and workpiece pose; if the identification fails, switching to a second grabbing planning module for processing;

the first grabbing planning module 14 is configured to poll the preliminary workpiece point cloud to perform grabbing planning judgment, where the first grabbing planning module includes at least two types of cylindrical grabbing postures, grabbing points of the cylindrical grabbing postures are located at cylindrical surfaces of the workpiece, included angles between the gripper assemblies and the straight rod in each type of cylindrical grabbing postures are different, and if a group of workpiece point clouds corresponding to one of the cylindrical grabbing postures passes through grabbing planning, the workpiece information and the corresponding cylindrical grabbing posture are output; if all the workpiece point clouds corresponding to all the cylindrical surface grabbing postures do not pass the grabbing planning, the operation is switched to a second grabbing planning module 17;

the second grabbing planning module 15 is used for polling the preliminary workpiece point clouds to carry out grabbing planning judgment, the second grabbing planning module comprises at least one type of end face grabbing postures, grabbing points of the end face grabbing postures are located at the end faces of the workpieces, included angles between the gripper components and the straight rod in each type of end face grabbing postures are different, and if a group of preliminary workpiece point clouds corresponding to one end face grabbing posture passes through grabbing planning, the preliminary workpiece information and the corresponding end face grabbing postures are output to carry out workpiece disturbance; and if all the preliminary workpiece point clouds corresponding to all the end face grabbing postures do not pass the grabbing planning, ending the process.

According to the workpiece grabbing device 10, the tail-end claw is provided with the included angle, the included angle is adjustable, the tail-end claw with the switchable included angle is matched with the first grabbing planning module and the second grabbing planning module, the grabbing success rate can be effectively improved, the workpiece grabbing in a completely disordered state is realized, meanwhile, the robot can grab the workpiece with the inclination angle within +/-90 degrees in the posture within +/-15 degrees, compared with a straight-rod claw design, the arm spread of the robot is saved, and the posture singularity of the robot is avoided more.

Preferably, the workpiece gripping device 10 of the present invention further includes a first sequence acquiring module 16 and a second sequence acquiring module 17

The first ordering acquiring module 16 is configured to perform spatial ordering on the workpiece point cloud according to the workpiece pose to acquire a first ordering, and transfer the first ordering to a first grabbing and planning module for processing; the first grabbing planning module polls the preliminary workpiece point cloud according to the second sequence to carry out grabbing planning judgment;

the second ordering acquiring module 17 is configured to spatially order the preliminary workpiece point clouds according to the preliminary workpiece poses to acquire a second ordering; the second grabbing planning module polls the preliminary workpiece point cloud according to the second sequence to carry out grabbing planning judgment,

preferably, in the first grabbing planning module 14, a plurality of cylindrical grabbing postures are arranged in series, each cylindrical grabbing posture polls the workpiece point clouds according to the first sequence to perform grabbing planning judgment, if all the workpiece point clouds corresponding to the previous cylindrical grabbing posture do not pass through grabbing planning, the next cylindrical grabbing posture is switched to perform grabbing planning judgment, and until a group of workpiece point clouds corresponding to one of the cylindrical grabbing postures pass through grabbing planning, the workpiece information and the corresponding cylindrical grabbing posture are output;

and/or in the second grabbing planning module 15, a plurality of end face grabbing postures are arranged in series, and each end face grabbing posture polls the preliminary workpiece point cloud according to the second sequence to carry out grabbing planning judgment: and if all the initial workpiece point clouds corresponding to the previous end face grabbing postures do not pass the grabbing planning, switching to the next end face grabbing posture for grabbing planning judgment, and outputting the initial workpiece information and the corresponding end face grabbing postures to perform workpiece disturbance until a group of initial workpiece point clouds corresponding to one end face grabbing posture pass the grabbing planning.

Preferably, in the first grabbing planning module 14, each cylindrical surface grabbing posture judgment submodule includes:

the first straight rod angle acquisition unit is used for acquiring a straight rod angle theta according to the current cylindrical surface grabbing posture and the current workpiece posture to be grabbed;

the first collision avoidance detection judging unit is used for polling the next workpiece point cloud to perform grabbing planning judgment directly according to the first sequence if the angle theta of the straight rod is larger than a preset angle; if the angle theta of the straight rod is not larger than the preset angle, the straight rod is switched to a collision avoidance detection unit;

and the first collision avoidance detection unit is used for simulating and grabbing the workpiece point cloud in the current cylindrical surface grabbing posture to carry out collision avoidance detection: if the collision avoidance detection is passed, outputting the workpiece information and the corresponding cylindrical surface grabbing gesture; if the current cylindrical surface grabbing gesture does not pass the collision avoidance detection, rotating for k times around the z axis of the workpiece point cloud coordinate system by a rotation angle of 360 degrees/k according to the current cylindrical surface grabbing gesture, performing collision avoidance detection once every rotation, and outputting the workpiece information and the corresponding cylindrical surface grabbing gesture until one rotation angle passes the collision avoidance detection, wherein k is a preset value; if the point cloud is judged not to be grabbed after rotating for 360 degrees, polling the next workpiece point cloud according to the first sequence to carry out grabbing planning judgment;

as a preferable scheme, in the second grabbing planning module 15, each of the end face grabbing posture judgment submodules includes:

the second straight rod angle acquisition unit is used for confirming the straight rod angle theta according to the current end face grabbing posture and the current primary workpiece posture;

the second collision avoidance detection and judgment unit is used for directly polling the next workpiece point cloud according to the first sequence to perform grabbing planning judgment if the angle theta of the straight rod is larger than a preset angle; if the angle theta of the straight rod is not larger than the preset angle, switching to a second collision avoidance detection unit for collision avoidance detection:

the second collision avoidance detection unit is used for simulating and grabbing the preliminary workpiece point cloud according to the current end face grabbing posture to carry out collision avoidance detection; if the collision avoidance detection is passed, outputting the preliminary workpiece information and the corresponding end face grabbing gesture; if the current end face grabbing gesture does not pass the collision avoidance detection, rotating for k times around the z axis of the preliminary workpiece point cloud coordinate system by a rotation angle of 360 degrees/k according to the current end face grabbing gesture, performing collision avoidance detection once every rotation until one rotation angle passes the collision avoidance detection, and outputting the preliminary workpiece information and the corresponding end face grabbing gesture, wherein k is a preset value; and if the point cloud cannot be grabbed after rotating for 360 degrees, polling the next preliminary workpiece point cloud according to the second sequence to carry out grabbing planning judgment.

Further, the preset angle is 15 °.

Preferably, the included angle between the end paw is 15 degrees and 45 degrees, the first grabbing planning module 15 comprises a first cylindrical surface grabbing posture and a second cylindrical surface grabbing posture, and in the first cylindrical surface grabbing posture, the paw component and the straight rod form an included angle of 15 degrees; in the grabbing posture of the second cylindrical surface, the claw assembly and the straight rod form an included angle of 45 degrees.

Further, the first cylindrical surface grabbing gesture and the second cylindrical surface grabbing gesture respectively comprise a forward cylindrical surface middle grabbing gesture and a reverse cylindrical surface middle grabbing gesture, when the cylindrical surface grabbing gestures are forward cylindrical surface middle grabbing gestures, the gripper assembly is forward vertical to the cylindrical surface of the workpiece, and the grabbing point is located in the middle of the workpiece; when the cylindrical surface grabbing gesture is the grabbing gesture in the middle of the reversed cylindrical surface, the paw component is reversely perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located in the middle of the cylindrical surface of the workpiece.

Furthermore, the first-class cylindrical surface grabbing postures and the second-class cylindrical surface grabbing postures further respectively comprise one or more combinations of a forward cylindrical surface middle left grabbing posture, a forward cylindrical surface middle right grabbing posture, a reverse cylindrical surface middle left grabbing posture and a reverse cylindrical surface middle right grabbing posture; when the cylindrical surface grabbing gesture is a positive cylindrical surface middle left grabbing gesture, the positive direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located in the workpiece middle left part; when the cylindrical surface grabbing gesture is a positive cylindrical surface middle right grabbing gesture, the positive direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located in the workpiece middle right part; when the cylindrical surface grabbing gesture is a reverse cylindrical surface middle left grabbing gesture, the paw component is reversely vertical to the cylindrical surface of the workpiece, and the grabbing point is located on a workpiece middle left part; when the cylindrical surface grabbing gesture is a right grabbing gesture in the middle of the reverse cylindrical surface, the paw component is reversely perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located on the right part in the middle of the workpiece.

Preferably, the second grabbing planning module 15 comprises a first end face grabbing posture, and in the first end face grabbing posture, the claw assembly and the straight rod form an included angle of 15 degrees.

Furthermore, the first-class end face grabbing postures comprise a forward end face middle grabbing posture and a reverse end face middle grabbing posture, when the end face grabbing postures are the forward end face middle grabbing postures, the forward direction of the gripper component is perpendicular to the end face of the workpiece, and the grabbing point is located in the middle of the workpiece; when the end face grabbing posture is a reverse end face middle grabbing posture, the tail end of the hand grab is reversely perpendicular to the end face of the workpiece, and the grabbing point is located in the middle of the end face of the workpiece.

Example four

Fig. 24 is a schematic structural diagram of a computer device according to an embodiment of the present invention, such as a smart phone, a tablet computer, a notebook computer, a desktop computer, a rack-mounted server, a blade server, a tower server, or a rack-mounted server (including an independent server or a server cluster formed by multiple servers) that can execute programs. The computer device 20 of the present embodiment includes at least, but is not limited to: a memory 21 and a processor 22 which can be communicatively connected to each other by a system bus, as shown in fig. 24. It is noted that fig. 24 only shows the computer device 20 with components 21-22, but it is understood that not all of the shown components are required to be implemented, and that more or fewer components may be implemented instead.

In this embodiment, the memory 21 (i.e., the readable storage medium) includes a Flash memory, a hard disk, a multimedia Card, a Card-type memory (e.g., SD or DX memory, etc.), a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a Read Only Memory (ROM), an Electrically Erasable Programmable Read Only Memory (EEPROM), a Programmable Read Only Memory (PROM), and the memory 21 may also be an external storage device of the computer device 20, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash Card (Flash Card), and the like, which are provided on the computer device 20. Of course, the memory 21 may also include both internal and external storage devices of the computer device 20. In this embodiment, the memory 21 is generally used for storing an operating system installed in the computer device 20 and various application software, such as program codes of the workpiece grasping method of the method embodiment. In addition, the memory 21 may also be used to temporarily store various types of data that have been output or are to be output.

Processor 22 may be a Central Processing Unit (CPU), controller, microcontroller, microprocessor, or other data Processing chip in some embodiments. The processor 22 is typically used to control the overall operation of the computer device 20. In this embodiment, the processor 22 is configured to execute the program code stored in the memory 21 or process data, for example, to operate the workpiece grasping apparatus 10, so as to implement the workpiece grasping method in the method embodiment.

EXAMPLE five

The present application also provides a computer-readable storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., SD or DX memory, etc.), a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a magnetic disk, an optical disk, a server, an App application mall, etc., on which a computer program is stored, which when executed by a processor implements corresponding functions. The computer-readable storage medium of the present embodiment is for storing program codes of a workpiece grasping apparatus, which when executed by a processor, implement the workpiece grasping method in the method embodiment.

It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A workpiece grabbing method is characterized in that a tail end paw is used for grabbing workpieces, and the workpiece grabbing method is characterized in that: the tail end paw comprises a straight rod and a paw component, an included angle is formed between the paw component and the straight rod, the included angle is adjustable, the straight rod is used for being connected with an external mechanical arm to enable the mechanical arm to be located outside the material frame, and the paw component is arranged perpendicular to a workpiece to be grabbed;

the workpiece grabbing method comprises the following steps:

s1, acquiring an original point cloud of a workpiece;

s3 identifying the preliminary workpiece information one by one to acquire workpiece information and turning to S4, wherein the workpiece information comprises workpiece point clouds and workpiece poses; if the identification fails, the process proceeds to step S5;

s4, polling the workpiece point clouds through a first grabbing planning module to carry out grabbing planning judgment, wherein the first grabbing planning module comprises at least two types of cylindrical surface grabbing postures, grabbing points of the cylindrical surface grabbing postures are located at cylindrical surfaces of the workpiece, included angles between the claw assemblies and the straight rod in each type of cylindrical surface grabbing postures are different, and if a group of workpiece point clouds corresponding to one cylindrical surface grabbing posture passes through grabbing planning, the workpiece information and the corresponding cylindrical surface grabbing postures are output; if all the workpiece point clouds corresponding to all the cylindrical surface grabbing postures do not pass the grabbing planning, the step S5 is carried out;

s5, polling the preliminary workpiece point clouds through a second grabbing planning module to carry out grabbing planning judgment, wherein the second grabbing planning module comprises at least one type of end face grabbing postures, grabbing points of the end face grabbing postures are located at the end faces of the workpieces, included angles between the gripper components and the straight rod in each type of end face grabbing postures are different, and if a group of preliminary workpiece point clouds corresponding to one end face grabbing posture passes through grabbing planning, outputting preliminary workpiece information and corresponding end face grabbing postures to carry out workpiece disturbance; and if all the preliminary workpiece point clouds corresponding to all the end face grabbing postures do not pass the grabbing planning, ending the process.

2. A workpiece gripping method according to claim 1, characterised in that: before the step S4, the method further includes spatially sorting the workpiece point clouds according to the workpiece poses to obtain a first sorting order, and in the step S4, the workpiece point clouds are polled by a first capture planning module according to the first sorting order to perform capture planning determination;

the step S5 is preceded by spatially sorting the preliminary workpiece point clouds according to the preliminary workpiece poses to obtain a second sort, and in step S5, the preliminary workpiece point clouds are polled by a second capture planning module according to the second sort to perform capture planning determination.

3. A workpiece gripping method according to claim 2, characterised in that: in the step S4, a plurality of cylindrical surface grabbing postures are arranged in series, each cylindrical surface grabbing posture polls the workpiece point clouds according to the first sequence to perform grabbing planning judgment, if all the workpiece point clouds corresponding to the previous cylindrical surface grabbing posture do not pass the grabbing planning, the next cylindrical surface grabbing posture is shifted to perform grabbing planning judgment, and until a group of workpiece point clouds corresponding to one of the cylindrical surface grabbing postures pass the grabbing planning, the workpiece information and the corresponding cylindrical surface grabbing posture are output;

in the step S5, a plurality of end face grabbing postures are arranged in series, and each end face grabbing posture polls the preliminary workpiece point cloud according to the second sequence to perform grabbing planning judgment: and if all the initial workpiece point clouds corresponding to the previous end face grabbing gesture do not pass the grabbing planning, switching to the next end face grabbing gesture to carry out grabbing planning judgment, and outputting the initial workpiece information and the corresponding end face grabbing gesture until a group of initial workpiece point clouds corresponding to one end face grabbing gesture pass the grabbing planning.

4. A workpiece gripping method according to claim 1, characterised in that: in the step S4, polling the workpiece point cloud for grabbing planning determination according to the first sequence by each cylindrical surface grabbing gesture includes the following steps:

and/or in the step S5, polling the preliminary workpiece point clouds by each of the end face grabbing poses according to the second sequence to perform grabbing planning determination includes the following steps:

s52, if the angle theta of the straight rod is not larger than a preset angle, the initial workpiece point cloud is captured in a simulated manner in the current end face capturing posture for collision avoidance detection:

5. A workpiece gripping method according to claim 4, characterised in that: the preset angle is 15 degrees.

6. A workpiece gripping method according to claim 1, characterised in that: the included angle of the tail end paw is 15 degrees and 45 degrees;

7. The workpiece grabbing method according to claim 1 or 6, wherein the first grabbing planning module comprises a first cylindrical surface grabbing posture and a second cylindrical surface grabbing posture, the first cylindrical surface grabbing posture and the second cylindrical surface grabbing posture respectively comprise a forward cylindrical surface middle grabbing posture and a reverse cylindrical surface middle grabbing posture, when the cylindrical surface grabbing posture is the forward cylindrical surface middle grabbing posture, the forward direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located in the middle of the workpiece; when the cylindrical surface grabbing gesture is the middle grabbing gesture of the reversed cylindrical surface, the paw component is reversely vertical to the cylindrical surface of the workpiece, and the grabbing point is located in the middle of the cylindrical surface of the workpiece;

8. The workpiece grabbing method according to claim 7, wherein the first cylindrical surface grabbing postures and the second cylindrical surface grabbing postures further respectively comprise one or more combinations of a forward cylindrical surface middle left grabbing posture, a forward cylindrical surface middle right grabbing posture, a reverse cylindrical surface middle left grabbing posture and a reverse cylindrical surface middle right grabbing posture; when the cylindrical surface grabbing gesture is a positive cylindrical surface middle left grabbing gesture, the positive direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located in the workpiece middle left part; when the cylindrical surface grabbing gesture is a positive cylindrical surface middle right grabbing gesture, the positive direction of the gripper assembly is perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located in the workpiece middle right part; when the cylindrical surface grabbing gesture is a reverse cylindrical surface middle left grabbing gesture, the paw component is reversely vertical to the cylindrical surface of the workpiece, and the grabbing point is located on a workpiece middle left part; when the cylindrical surface grabbing gesture is a right grabbing gesture in the middle of the reverse cylindrical surface, the paw component is reversely perpendicular to the cylindrical surface of the workpiece, and the grabbing point is located on the right part in the middle of the workpiece.

9. The utility model provides a work piece grabbing device, its uses terminal hand claw to snatch the work piece which characterized in that: the tail end paw comprises a straight rod and a paw assembly connected with the straight rod; the gripper assembly and the straight rod are arranged in an included angle, the included angle is adjustable, the straight rod is used for being connected with an external mechanical arm to enable the mechanical arm to be located outside the material frame, and the gripper assembly is arranged perpendicular to a workpiece to be grabbed;

the work gripping device includes:

10. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the method of any one of claims 1 to 8 when executing the computer program.

11. A computer-readable storage medium having stored thereon a computer program, characterized in that: the computer program when executed by a processor implements the steps of the method of any one of claims 1 to 8.