Robot non-interference grinding and polishing posture multi-target planning method and device and medium

Abstract

The invention discloses a robot non-interference grinding and polishing posture multi-target planning method and device and a medium. The method comprises the steps that a non-interference configuration space of a robot abrasive belt grinding and polishing narrow component is defined; establishing a virtual workstation for grinding and polishing the narrow component by a robot abrasive belt; building a robot non-interference configuration space simulation platform; according to the rule that the non-interference configuration space continuously changes along the tool path, the robot non-interference configuration space is converted into a series of binary images; establishing a robot non-interference configuration space rapid calculation model based on image edge detection on the basis of a simulation platform; establishing a robot non-interference grinding and polishing posture multi-target optimization model; and a grinding and polishing attitude optimization solution algorithm based on the non-interference configuration space is designed, so that autonomous generation and multi-target optimization of the non-interference grinding and polishing attitude of the robot under the constraint of the narrow space of the tool can be achieved. The method is of great significance in improving the robot non-interference trajectory planning efficiency of narrow components such as an aeroengine blisk and an integral impeller.

Description

Technical Field

[0001] The present invention relates to the field of digital manufacturing of high-end equipment robots, and in particular to a method, equipment and medium for multi-objective planning of robot non-interference grinding and polishing postures. Background Art

[0002] As the new generation of national strategic equipment such as aerospace, national defense, military and nuclear power energy continues to develop towards lightweight, high speed, long life and high reliability, a large number of precision and complex components with high processing difficulty and demanding performance indicators have emerged, such as aircraft engine integral blades, centrifugal impellers and closed impellers. These components are usually composed of a large number of highly twisted, mutually concealed, complex streamlined surfaces involving aerodynamics. Their processing channels are narrow and deep, and the tool accessibility is poor. It is extremely easy to cause various types of processing interference. They are typical difficult-to-process parts (this invention refers to this type of components as narrow components). Their manufacturing level is a concentrated reflection of the country's comprehensive strength and scientific and technological level.

[0003] Belt grinding and polishing is widely used as the last integrated "shape" control process of parts to remove milling marks, reduce residual stress and improve surface quality. For a long time, the grinding and polishing of narrow components can only be completed by experienced workers through manual grinding and polishing. The processing efficiency is low, the consistency is poor and the environment is harmful. It cannot meet the production needs of modern industry for high precision, high efficiency and consistency. Industrial robots are known as the "crown jewel of the manufacturing industry". Compared with CNC machine tools, they have the advantages of large working space, high flexibility, strong processing flexibility and low price. In recent years, they have been widely used to replace manual work to achieve high-precision and efficient automatic grinding and polishing of parts.

[0004] Robotic grinding and polishing trajectory planning, including tool path generation and processing posture planning, is the most critical step in realizing automated grinding and polishing of parts, and directly determines the surface quality of the parts. However, for narrow components such as integral impellers and blades, various types of processing interference are extremely likely to occur due to their twisted and narrow processing channels. At present, even the internationally renowned commercial offline programming software cannot realize the autonomous generation of robot interference-free grinding and polishing postures. After detecting interference, it can only rely on tedious and time-consuming manual interaction to correct the interference point by point, and cannot achieve global optimal control of grinding and polishing performance. Moreover, there is no report on methods that comprehensively consider various processing performance indicators and support the autonomous generation and multi-objective optimization of robot interference-free grinding and polishing postures for narrow components in the world. Summary of the invention

[0005] In order to solve at least one of the technical problems existing in the prior art to a certain extent, the object of the present invention is to provide a method, device and medium for multi-objective planning of robot interference-free grinding and polishing posture.

[0006] The first technical solution adopted by the present invention is:

[0007] A multi-objective planning method for robot non-interference grinding and polishing posture, comprising the following steps:

[0008] Define the interference-free configuration space for robotic belt grinding of narrow components;

[0009] Establish a virtual workstation for robotic belt grinding and polishing of narrow components;

[0010] Build a robot non-interference configuration space simulation platform;

[0011] According to the law of continuous change of the non-interference configuration space along the tool path, the robot non-interference configuration space is converted into a series of binary images;

[0012] Based on the constructed simulation platform, a fast calculation model of the robot's non-interference configuration space based on image edge detection was established;

[0013] Establish a multi-objective optimization model for robot non-interference grinding and polishing posture;

[0014] An optimization algorithm for grinding and polishing posture based on non-interference configuration space is designed to realize autonomous generation and multi-objective optimization of the robot's non-interference grinding and polishing posture under the constraint of narrow space where the tool can reach.

[0015] Furthermore, the narrow component refers to a complex component such as an integral blade disk of an aircraft engine, a centrifugal impeller, etc., whose processing channels are twisted and narrow and whose tool accessibility is poor.

[0016] Furthermore, the interference-free configuration space of the robot's belt grinding and polishing of narrow components is defined as a set of robot joint configurations corresponding to all grinding and polishing postures when processing a certain tool contact point. The configuration space is a high-dimensional space composed of multiple degrees of freedom of the robot (the degrees of freedom are greater than or equal to 6), which can be represented in the robot joint space and Cartesian space respectively.

[0017] Furthermore, the virtual workstation for robot belt grinding and polishing of narrow components is composed of a robot, a small belt grinder and polisher, a workbench and a narrow component; wherein the belt grinder and polisher is installed at the end of the robot, and the narrow component is fixed on the workbench; the robot clamps the belt grinder and polisher to penetrate into the cavity of the narrow component, and completes its grinding and polishing process using the abrasives distributed on the belt.

[0018] Furthermore, the robot interference-free configuration space simulation platform is built based on the IntelliCAM microkernel and the CoppeliaSim robot open source simulation library; wherein, the IntelliCAM microkernel is responsible for the planning of the grinding and polishing trajectory, while the CoppeliaSim robot open source library is responsible for the robot kinematics, dynamics simulation and interference detection, and the two realize the collaborative simulation of grinding and polishing trajectory planning, robot kinematics and interference detection through Socket communication. The simulation platform can realize the simulation calculation of the interference-free configuration space of each tool contact of the robot grinding and polishing.

[0019] Furthermore, the step of converting the robot interference-free configuration space into a series of binary images includes:

[0020] The three parameters ψ, α and d that determine the polishing posture are uniformly discretized into a set S ψ ={ψ i |i=1,2,…,M},S β ={α j |j=1,2,…,N} and S d ={d q |q=1,2,…,D};

[0021] After discretization, the three-dimensional continuous configuration space composed of parameters ψ, α and d is transformed into a space composed of D different parameters d q ∈S d The corresponding two-dimensional configuration space consists of M×N grids (ψ i ,α j ), where (ψ i ,α j )'s subscripts i and j represent their positions in the set S ψ and S α The index in ;

[0022] For each grid point (ψ i ,α j ), and regard it as a pixel point with image coordinates (i, j); if the grid point (ψ i ,α j ) If there is interference in the polishing posture corresponding to the pixel (i, j), the gray value of the pixel (i, j) is set to 1; otherwise, it is set to 0;

[0023] After each two-dimensional configuration space is converted into a binary image, the binary image consists of M and N pixels in the horizontal and vertical directions respectively.

[0024] Furthermore, the working mode of the robot non-interference configuration space fast calculation model based on image edge detection is as follows:

[0025] The first knife contact point is obtained by searching the robot non-interference configuration space simulation platform. The non-interference configuration space is denoted as RCS1;

[0026] Let k = 1, and change the k+1th knife contact The initial value of the robot's non-interference configuration space is set to RCS k ;

[0027] RCS k Convert to a series of binary images, and use the Soble edge detection operator to detect the edge pixels corresponding to each binary image;

[0028] Determine the grinding and polishing posture set GPB corresponding to all edge pixels k , using the built non-interference configuration space simulation platform to analyze each boundary posture Λ∈GPB k Grinding and polishing the k+1th tool contact point Interference check and kinematic simulation are performed at the same time, and the k+1th tool contact point is updated Robot configuration space RCS k+1 The interference state in these boundary grinding and polishing postures;

[0029] The search is iterated until the robot interference-free configuration space of all knife contact points is obtained.

[0030] Furthermore, the multi-objective optimization model of the robot's interference-free grinding and polishing posture is based on the constraints of avoiding interference, avoiding robot singularity, ensuring high rigidity during robot processing, and the performance limit of the robot joint motor drive, and the geometric smoothness of the grinding and polishing posture and the smoothness of the robot's kinematic performance are used as optimization goals.

[0031] Furthermore, the grinding and polishing posture optimization solution algorithm converts the optimization problem of the grinding and polishing posture into a problem of selecting a suitable grinding and polishing posture in the non-interference configuration space of each tool contact point to optimize the optimization target within the calculated robot non-interference configuration space. It is a typical combinatorial optimization problem and is solved by Dijkstra algorithm, particle swarm optimization algorithm or discrete differential evolution algorithm.

[0032] The second technical solution adopted by the present invention is:

[0033] An electronic device comprises a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement a robot non-interference grinding and polishing posture multi-objective planning method as described above.

[0034] The fourth technical solution adopted by the present invention is:

[0035] A computer-readable storage medium stores at least one instruction, at least one program, a code set or an instruction set, wherein the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by a processor to implement a robot non-interference grinding and polishing posture multi-objective planning method as described above.

[0036] The fifth technical solution adopted by the present invention is:

[0037] A computer program product or a computer program, the computer program product or the computer program includes computer instructions, the computer instructions are stored in a computer-readable storage medium. A processor of a computer device can read the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the above-mentioned robot non-interference grinding and polishing posture multi-objective planning method.

[0038] The beneficial effects of the present invention are as follows: the present invention first proposes the definition and representation method of the non-interference configuration space of robot belt grinding and polishing, builds a virtual workstation for robot belt grinding and polishing of narrow components and a simulation platform for the non-interference configuration space, reveals the phenomenon of continuous change of the non-interference configuration space along the tool path, and establishes a fast calculation model of the non-interference configuration space based on image edge detection. On this basis, a multi-objective optimization model and solution algorithm for grinding and polishing posture are proposed, and the autonomous generation and multi-objective optimization of the robot's non-interference grinding and polishing posture under the constraint of the narrow space accessible by the tool are realized, which is of great significance to promoting the efficiency of robot non-interference grinding and polishing trajectory planning for narrow components such as integral blades and centrifugal impellers of aircraft engines, and improving the grinding and polishing surface quality of core components of large-scale power machinery equipment and the service performance of the whole machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the embodiments of the present invention or the drawings of related technical solutions in the prior art are introduced below. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 is a flowchart of the steps of a multi-objective planning method for non-interference grinding and polishing posture of a robot in an embodiment of the present invention;

[0041] Figure 2 Schematic diagram of the contact point coordinate system of the abrasive belt grinding and polishing tool and the workpiece coordinate system in an embodiment of the present invention;

[0042] Figure 3It is a schematic diagram of the definition and representation of the non-interference configuration space of the robot belt grinding and polishing in an embodiment of the present invention;

[0043] Figure 4 Schematic diagram of a robot non-interference configuration space simulation platform constructed in an embodiment of the present invention;

[0044] Figure 5 Schematic diagram of the spatial evolution law of the non-interference configuration of the robot in an embodiment of the present invention;

[0045] Figure 6 Schematic diagram of the conversion between the robot non-interference configuration space and the binary image in an embodiment of the present invention;

[0046] Figure 7 2 is a schematic diagram of the calculation result of the non-interference configuration space of the robot grinding and polishing of the integral blade disk in an embodiment of the present invention;

[0047] Figure 8 Schematic diagram of the optimization result of the non-interference grinding and polishing posture of the blisk robot in an embodiment of the present invention;

[0048] Fig. 9 It is a schematic diagram of the kinematic performance of the robot joint corresponding to the non-interference grinding and polishing posture in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limitations of the present invention. For the step numbers in the following embodiments, they are only provided for the convenience of explanation, and the order between the steps is not limited in any way, and the execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0050] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0051] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0052] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0053] In view of the defects and improvement needs in the prior art, the present invention proposes a multi-objective planning scheme for robot non-interference grinding and polishing posture. The scheme first proposes the definition and representation method of the non-interference configuration space of robot belt grinding and polishing, builds a virtual workstation for robot belt grinding and polishing of narrow components and a simulation platform for the non-interference configuration space, reveals the phenomenon of continuous change of the non-interference configuration space along the tool path, and establishes a fast calculation model of the non-interference configuration space based on image edge detection. On this basis, a multi-objective optimization model and solution algorithm for grinding and polishing posture are proposed, which realizes the autonomous generation and multi-objective optimization of the robot non-interference grinding and polishing posture under the constraint of the narrow space accessible by the tool, which is of great significance to promoting the efficiency of robot non-interference trajectory planning for narrow components such as integral blades and integral impellers of aircraft engines.

[0054] Example 1

[0055] like Figure 1 As shown, this embodiment provides a robot non-interference grinding and polishing posture multi-objective planning method, which specifically includes the following steps:

[0056] S1. Definition and representation of the interference-free configuration space for robot belt grinding and polishing of narrow components.

[0057] The narrow components refer to complex components such as integral blade disks of aircraft engines and centrifugal impellers, whose processing channels are twisted and narrow and whose tool accessibility is poor; the robot belt grinding and polishing interference-free configuration space is defined as the set of robot joint configurations corresponding to all grinding and polishing postures when processing a certain tool contact point. The configuration space is a high-dimensional space composed of multiple degrees of freedom (≥6) of the robot, which can be represented in the robot joint space and Cartesian space respectively.

[0058] join Figure 2 In some embodiments, the abrasive belt polishing process generally uses an abrasive belt wrapped around an elastic contact wheel, and the workpiece is indirectly in contact with the contact wheel and the abrasive grains on the abrasive belt are used to remove the workpiece material. Assume that the wrap angle of the abrasive belt on the contact wheel is In order to describe the grinding and polishing posture of the workpiece, at each tool contact point Establish a local coordinate system of the knife contact point in The axis is the knife contact curve The tangent direction of the point, The axis is the workpiece surface The normal direction of a point, At the same time, at the center point o of the abrasive belt in contact with the contact wheel T Establish a grinding and polishing tool coordinate system {T} = o T x T y T z T , where x T Axis is along the contact wheel axis, z T The axis points to the cylindrical surface of the contact wheel at o T The radial direction of the point, y T =z T × T After establishing the above coordinate system, the grinding and polishing posture of the tool contact point can actually be uniquely determined by the parameters ψ, α, and d. represents the translation distance of the workpiece along the contact wheel axis, W is the contact wheel width; α (-π≤α≤π) is the local coordinate system of the workpiece around the tool contact point The rotation angle of the axis α; is the rotation angle ψ of the workpiece around the contact wheel axis, is the contact wheel wrap angle. Therefore, when interference occurs during the grinding and polishing process, the posture can be corrected in the three-dimensional space composed of parameters ψ, α, and d to avoid interference. In order to promote the optimization of the robot's non-interference grinding and polishing posture, this embodiment proposes the concept of the robot's non-interference configuration space, which is specifically defined as follows:

[0059] Define the robot's non-interference configuration space: Figure 3 As shown, for a given knife contact Three parameters will describe the polishing posture α(-π≤α≤π) and Uniformly discretize into a set S ψ ={ψ i |i=1,2,…,M},S α ={α j |j=1,2,…,N} and S d ={d q |q=1,2,…,D}, after discretization, the tool posture of each tool contact point can be obtained by the set S (ψ,α,d) ={(ψ i ,α j ,d q )|ψ i ∈Sψ ,α j ∈S α ,d q ∈S d} approximate representation. For each discrete posture Λ k =(ψ i ,α j ,d q )∈S (ψ,ɑ,d) , which can be obtained by the robot inverse kinematics algorithm and Λ k The corresponding joint configuration θ(Λ k )={θ1,θ2,…,θ F}. In this joint configuration θ(Λ k ), if there is no interference between the robot and the grinding and polishing tools, workpieces, and other obstacles, it means that the configuration θ(Λ k ) is feasible. The robot non-interference configuration space is defined as the space consisting of all non-interference discrete postures Λ k The corresponding robot configuration θ(Λ k ) is a high-dimensional space composed of multiple degrees of freedom of the robot.

[0060] S2. Establish a virtual workstation for robot belt grinding and polishing of narrow components.

[0061] Based on the CoppeliaSim robot open source simulation library, a virtual workstation for robot belt grinding and polishing of narrow components was built. The workstation consists of a robot, a small belt grinding and polishing machine, a workbench, and narrow components such as integral impellers. The belt grinding machine is installed at the end of the robot, and narrow components such as integral impellers are fixed on the workbench. The robot clamps the belt grinding machine and penetrates into the complex cavity of the narrow component to complete its grinding and polishing through the abrasive particles distributed on the belt.

[0062] S3. Build a robot non-interference configuration space simulation platform.

[0063] Based on the computer-aided manufacturing microkernel IntelliCAM and the CoppeliaSim robot open source simulation library independently developed by the team, a spatial simulation platform for non-interference configuration of robot grinding and polishing of narrow components was built. Figure 4 As shown. The IntelliCAM microkernel is responsible for grinding and polishing trajectory planning, while the CoppeliaSim end is responsible for robot kinematics, dynamics simulation and interference detection. The two realize collaborative motion simulation of grinding and polishing trajectory planning, robot kinematics and interference detection through Socket communication. After the simulation, the CoppeliaSim end will send the joint configuration and interference detection results of each tool contact point of the robot's grinding and polishing back to the IntelliCAM end. Based on the constructed simulation platform, the present invention carried out an experiment to explore the evolution law of the non-interference configuration space along the tool path when the robot polishes narrow components. The experiment is as follows Figure 4 Taking the robot belt grinding and polishing of the integral blade disk shown in (b) as an example, several knife contact point trajectories are first planned for it, and then two groups of knife contact points are randomly selected, each group of knife contact points consists of 5 adjacent knife contact points. Then each knife contact point and all the discrete postures Λ when grinding and polishing the knife contact point are calculated. k =(ψ i ,α j ,d q )∈S (ψ,α,d) The robot is sent to CoppeliaSim for robot kinematics simulation and interference detection. After the simulation, all non-interference robot configurations for each tool contact point can be obtained, that is, the robot non-interference configuration space for each tool contact point. Figure 5 The figure shows the non-interference configuration space of the robot with two sets of knife contacts. Each row represents a knife contact point. The horizontal axis in the figure is different ψ i Value, the vertical axis is α j Value, black indicates the polishing posture in this area (ψ i ,α j ,d) There is no interference; while white means there is interference in this area. By observing the boundary between the black area and the white area from top to bottom, it can be found that the non-interference configuration space changes continuously along the tool path when the robot is grinding and polishing narrow components.

[0064] S4. According to the law of continuous change of the non-interference configuration space along the tool path, the robot non-interference configuration space is converted into a series of binary images.

[0065] As mentioned above, the parameters ψ, α and d that determine the polishing posture are discretized into a set S ψ ={ψ i |i=1,2,…,M},S α ={α j |j=1,2,…,N} and S d ={d q |q=1,2,…,D}, the three-dimensional continuous configuration space composed of parameters ψ, α and d can actually be transformed into Figure 6 The three-dimensional discrete configuration space shown can be further viewed as a discrete distance d with D different translations. q ∈S d The corresponding two-dimensional configuration space consists of M×N grids (ψ i ,α j ), where (ψ i ,α j )'s subscripts i and j represent their positions in the set S ψ and S α Each two-dimensional C space describes the index of a given translation distance d. q In the case of different rotation angles ψi ∈S ψ and ψ i ∈S α The corresponding robot grinding and polishing posture interference. For each grid point (ψ i ,α j ), which can be regarded as a pixel with image coordinates (i, j). i ,α j ) corresponding to the polishing posture, the gray value of the pixel point (i, j) is set to 1; otherwise, it is set to 0. In this way, each two-dimensional configuration space can be converted into a Figure 6 The binary image shown in FIG. 1 is composed of M and N pixels in the horizontal and vertical directions respectively. Finally, the three-dimensional configuration space of the knife contact point can be converted into D corresponding binary images.

[0066] S5. Based on the constructed simulation platform, a fast calculation model of the robot's non-interference configuration space based on image edge detection is established.

[0067] Since the robot non-interference configuration space of adjacent tool contacts is continuously changing, after calculating the non-interference configuration space of the previous tool contact, the calculation of the non-interference configuration space of the next tool contact does not need to perform an interference check on all discrete grinding and polishing postures, but only needs to perform interference checks on some grinding and polishing postures on the boundary of the non-interference configuration space of the previous tool contact, which can greatly reduce the number of interference detections. Based on this idea, the embodiment of the present invention proposes a fast calculation algorithm for the robot non-interference configuration space based on the image edge detection operator, and the main steps of the algorithm are as follows:

[0068] (1) Discrete the knife contact curve evenly into a series of points At the same time, the grinding and polishing posture parameters ψ, α and d are uniformly discretized into a set S according to the specified discrete numbers M, N and D ψ ={ψ i |i=1,2,…,M},S β ={α j |j=1,2,…,N} and S d ={d q |q=1,2,…,D}. Then, all possible tool postures when polishing each tool contact point can be obtained by the set S (ψ,α,d) ={(ψ i ,α j ,d q )|ψ i ∈S ψ ,α j ∈S α ,d q ∈S d}express.

[0069] (2) Searching for the first knife contact point using the robot non-interference configuration space simulation platform The non-interference configuration space is denoted as RCS1.

[0070] (3) Let k = 1, and set the k+1th knife contact The robot non-interference configuration space (denoted as RCS k+1 ) is set to RCS k .

[0071] (4) RCS k Convert it into a series of binary images, and use the Soble edge detection operator to detect the edge pixels corresponding to each binary image.

[0072] (5) Determine the polishing posture set GPB corresponding to all edge pixels k , the robot non-interference configuration space simulation platform built by the present invention is used to calculate each boundary posture Λ∈GPB k Grinding and polishing the k+1th tool contact point Interference check and kinematic simulation are performed at the same time, and the k+1th tool contact point is updated Robot configuration space RCS k+1 Interference states in these boundary grinding and polishing postures.

[0073] (6) Use the above steps to iterate the search until the robot interference-free configuration space of all knife contact points is obtained. Figure 7 The figure shows the interference-free configuration space of the robot grinding and polishing the integral impeller calculated by the method of the present invention. It can be seen from the figure that each calculated robot configuration has no interference, which can illustrate the effectiveness of the method of the present invention.

[0074] S6. Establish a multi-objective optimization model for the robot’s non-interference grinding and polishing posture.

[0075] Based on the calculation of the robot's non-interference configuration space, the multi-objective optimization model of the robot's grinding and polishing posture for narrow components can be established by comprehensively considering the indicators such as non-interference, non-singularity, coordinated smoothness of the grinding and polishing posture and the robot's kinematic performance. The details are as follows:

[0076] In terms of singularity, compared with CNC machine tools, robots are more susceptible to singularity due to their special structure. When the robot is in a singular configuration, its joint angular velocity will tend to infinity, which may cause the robot to vibrate violently and change its processing posture suddenly. Therefore, the optimization of grinding and polishing posture needs to consider singularity avoidance. k A discrete polishing posture Λ k =(ψ i ,α j ,dq ), which should satisfy the following constraints to avoid singularities:

[0077]

[0078] In the above formula, θ k =(θ1,θ2,θ3,θ4,θ5,θ6) represents the robot inverse kinematics algorithm f -1 (·) obtained with posture Λ k =(ψ i ,α j ,d q ) corresponds to the robot shutdown angle. The grinding and polishing robot used in this paper has 6 rotational degrees of freedom; J(θ k ) represents the robot Jacobian matrix; k(Λ k ) represents the robot's dexterity, and 1≤k(J)≤+∞. k(Λ k ) is smaller, the higher the dexterity is and the farther away from the singular configuration is; η represents the dexterity threshold, which can be set according to actual conditions.

[0079] In addition to avoiding singularity, the grinding and polishing posture along the entire tool contact trajectory should also change smoothly, otherwise the sudden change of the grinding and polishing posture will seriously damage the surface quality and surface accuracy. After the robot has an interference-free configuration space, the present invention proposes the following grinding and polishing posture smoothness measurement index, that is, the total amount of change in the grinding and polishing posture along the entire knife contact curve is minimized to ensure smooth changes in the grinding and polishing posture.

[0080]

[0081] In the above formula, Δψ, Δα and Δd represent the maximum thresholds of the grinding and polishing posture parameters ψ, α and d allowed to change between two adjacent tool contact points respectively; OCF(Λ k ,Λ k+1 ) represents the function for evaluating the change in the grinding and polishing posture between two adjacent tool contact points. Considering the grinding and polishing posture parameter ψ k ,α k and d k With different dimensions, in order to eliminate the influence of different dimensions on the cost function, the present invention first uses the following formula to normalize these parameters:

[0082]

[0083] In the above formula, x represents the value before normalization; x * is the normalized value; x min and x max are the minimum and maximum values ​​of these parameters respectively. After normalization, OCF(Λ k ,Λk+1 ) can be calculated by the following formula:

[0084]

[0085] In addition to ensuring the smoothness of the grinding and polishing posture, the smoothness of the robot's kinematic performance such as joint angular velocity, angular acceleration and angular jerk in the robot's joint space is also very important. This is of great significance for suppressing the sudden change of the dynamic load of the robot's joint motor and reducing system vibration and instability. To this end, the present invention further proposes a metric for the smoothness of the robot's kinematic performance. For the four adjacent knife contacts and Assume that their polishing postures are k , Λ k+1 , Λ k+2 and Λ k+3 , for each grinding and polishing posture The corresponding robot's six joint angles θ can be obtained k =(θ1,θ2,θ3,θ4,θ5,θ6). Assume that the knife contact point and The chord lengths between them are s k ,s k+1 and k+2 , and assuming that the robot grinding feed speed is f, the robot's i-th joint angular velocity, angular acceleration and angular jerk can be calculated by the following formula:

[0086]

[0087] In the above formula, Q i,1 =(s k+1 +s k )s k+1 s k , In order not to exceed the performance limit of the robot joint motor drive, the robot's shutdown angular velocity, angular acceleration, and angular jerk should also meet the following constraints:

[0088]

[0089] The above formula gives the kinematic performance index of each joint of the robot. The kinematic performance of the entire robot, that is, the composite angular velocity, angular acceleration and angular jerk, can be obtained by the following formula:

[0090]

[0091] In the above formula, F is the joint degree of freedom of the robot. In order to ensure that the joint angular velocity, angular acceleration and even angular jerk of the robot along the entire knife contact trajectory change smoothly, this embodiment proposes the following kinematic performance smoothness measurement index, that is, to minimize the angular jerk change of the robot along the entire knife contact trajectory:

[0092]

[0093] Based on the above indicators, the present invention takes non-interference and non-singularity as constraint conditions, and the robot polishing posture and robot kinematic performance coordinated smoothing as optimization goals, and establishes the following multi-objective optimization model:

[0094]

[0095] S7. Design an optimization solution algorithm for the grinding and polishing posture based on the non-interference configuration space to achieve autonomous generation and multi-objective optimization of the robot's non-interference grinding and polishing posture under the constraints of the narrow space that the tool can reach.

[0096] After obtaining the robot non-interference configuration space of all tool contact points, the optimization problem of non-interference grinding and polishing posture can be simplified to a combinatorial optimization problem of selecting a suitable grinding and polishing posture in the non-interference configuration space of each tool contact point to minimize the multi-objective objective function. This combinatorial optimization problem can be solved by Dijkstra algorithm, particle swarm optimization algorithm or discrete differential evolution algorithm.

[0097] like Figure 8 The figure shows the robot grinding and polishing posture of the integral blade disk based on the calculated non-interference configuration space of the robot, which is optimized by the above method. Figure 8 It can be seen that the grinding and polishing posture of the entire knife contact track before optimization is not smooth enough, and there are many mutations in the posture between two adjacent knife contacts. On the contrary, the grinding and polishing posture after optimization by the method of this embodiment not only has no interference, but also is very smooth along the entire knife contact track. Fig. 9 The figure shows the change of robot joint angle velocity corresponding to the grinding and polishing posture. Fig. 9 It can be seen that the kinematic performance of the robot corresponding to the polishing posture optimized by the method of this embodiment changes very smoothly, which further verifies the effectiveness and advantages of the method of the present invention.

[0098] Example 2

[0099] An embodiment of the present invention further provides an electronic device, the electronic device comprising a processor and a memory, the memory storing at least one instruction, at least one program, a code set or an instruction set, the at least one instruction, the at least one program, the code set or the instruction set being loaded and executed by the processor to implement the following Figure 1 A multi-objective planning method for robot non-interference grinding and polishing posture is shown.

[0100] It is understood that the memory may include a random access memory (RAM) or a read-only memory (ROM). Optionally, the memory includes a non-transitory computer-readable storage medium. The memory may be used to store instructions, programs, codes, code sets, or instruction sets. The memory may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function, instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area may store data created according to the use of the server, etc.

[0101] The processor may include one or more processing cores. The processor uses various interfaces and lines to connect the various parts of the entire server, and executes various functions of the server and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory, and calling data stored in the memory. Optionally, the processor can be implemented in at least one hardware form of digital signal processing (DSP), field programmable gate array (FPGA), and programmable logic array (PLA). The processor can integrate one or a combination of a central processing unit (CPU) and a modem. Among them, the CPU mainly processes the operating system and application programs; the modem is used to process wireless communications. It can be understood that the above-mentioned modem may not be integrated into the processor, but implemented separately through a chip.

[0102] Since the electronic device is an electronic device corresponding to a robot non-interference grinding and polishing posture multi-objective planning method in an embodiment of the present invention, and the principle of solving the problem by the electronic device is similar to that of the method, the implementation of the electronic device can refer to the implementation process of the above-mentioned method embodiment, and the repeated parts will not be repeated.

[0103] Example 3

[0104] The embodiment of the present invention further provides a computer-readable storage medium, wherein the storage medium stores at least one instruction, at least one program, code set or instruction set, and the at least one instruction, the at least one program, the code set or instruction set is loaded and executed by a processor to implement the following Figure 1A multi-objective planning method for robot non-interference grinding and polishing posture is shown.

[0105] Those skilled in the art will appreciate that all or part of the steps in the various methods of the above embodiments may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, the storage medium including a read-only memory (ROM), a random access memory (RAM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a one-time programmable read-only memory (OTPROM), an electronically erasable programmable read-only memory (EEPROM), a compact disc (CD-ROM) or other optical disc storage, magnetic disk storage, magnetic tape storage, or any other computer-readable medium that can be used to carry or store data.

[0106] Since the storage medium is the storage medium corresponding to a robot non-interference grinding and polishing posture multi-objective planning method in an embodiment of the present invention, and the principle of solving the problem by the storage medium is similar to that of the method, the implementation of the storage medium can refer to the implementation process of the above-mentioned method embodiment, and the repeated parts will not be repeated.

[0107] Example 4

[0108] In some possible implementations, various aspects of the method of the embodiment of the present invention can also be implemented in the form of a program product, which includes a program code. When the program product is run on a computer device, the program code is used to enable the computer device to execute the steps of a robot non-interference grinding and polishing posture multi-objective planning method according to various exemplary embodiments of the present application described above in this specification. Among them, the executable computer program code or "code" used to execute each embodiment can be written in a high-level programming language such as C, C++, C#, Smalltalk, Java, JavaScript, Visual Basic, structured query language (e.g., Transact-SQL), Perl, or in various other programming languages.

[0109] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0110] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0111] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-objective planning method for robot non-interference grinding and polishing posture, characterized in that: The following steps are involved: Define the interference-free configuration space for robotic belt grinding of narrow components; Establish a virtual workstation for robotic belt grinding and polishing of narrow components; Build a robot non-interference configuration space simulation platform; According to the law of continuous change of the non-interference configuration space along the tool path, the robot non-interference configuration space is converted into a series of binary images; Based on the constructed simulation platform, a fast calculation model of the robot's non-interference configuration space based on image edge detection was established; Establish a multi-objective optimization model for robot non-interference grinding and polishing posture; An optimization algorithm for grinding and polishing posture based on non-interference configuration space is designed to realize autonomous generation and multi-objective optimization of the robot's non-interference grinding and polishing posture under the constraint of narrow space where the tool can reach.

2. According to claim 1, a robot non-interference grinding and polishing posture multi-objective planning method is characterized in that: The interference-free configuration space of the robot belt grinding and polishing narrow components is defined as the set of robot joint configurations corresponding to all grinding and polishing postures when processing a certain tool contact point. The configuration space is a high-dimensional space composed of multiple degrees of freedom of the robot and can be represented in the robot joint space and Cartesian space respectively.

3. The multi-objective planning method for robot non-interference grinding and polishing posture according to claim 1 is characterized in that: The virtual workstation for robot belt grinding and polishing of narrow components consists of a robot, a belt grinder and polisher, a workbench and a narrow component; wherein the belt grinder and polisher is installed at the end of the robot, and the narrow component is fixed on the workbench; the robot clamps the belt grinder and polisher to penetrate into the cavity of the narrow component, and completes the grinding and polishing process using the abrasive particles distributed on the belt.

4. The multi-objective planning method for robot non-interference grinding and polishing posture according to claim 1 is characterized in that: The robot non-interference configuration space simulation platform is built based on the IntelliCAM microkernel and the CoppeliaSim robot open source simulation library; wherein, the IntelliCAM microkernel is responsible for the planning of the grinding and polishing trajectory, while the CoppeliaSim robot open source library is responsible for the robot kinematics, dynamics simulation and interference detection, and the two realize the collaborative simulation of grinding and polishing trajectory planning, robot kinematics and interference detection through Socket communication. The simulation platform can realize the simulation calculation of the non-interference configuration space of each tool contact point of the robot grinding and polishing.

5. The multi-objective planning method for robot non-interference grinding and polishing posture according to claim 1 is characterized in that: The step of converting the robot non-interference configuration space into a series of binary images comprises: The three parameters ψ, α and d that determine the polishing posture are uniformly discretized into a set S ψ ={ψ i |i=1,2,…,M}, S α ={α j |j=1,2,…,N} and S d ={d q |q=1,2,…,D}; After discretization, the three-dimensional continuous configuration space composed of parameters ψ, α and d is transformed into a space composed of D different parameters d q ∈S d The corresponding two-dimensional configuration space consists of M×N grids (ψ i ,α j ), where (ψ i ,α j )'s subscripts i and j represent their positions in the set S ψ and S α The index in ; For each grid point (ψ i ,α j ), and regard it as a pixel point with image coordinates (i, j); if the grid point (ψ i ,α j ) If there is interference in the corresponding polishing posture, the grayscale value of the pixel point (i, j) is set to 1; otherwise, it is set to 0; after each two-dimensional configuration space is converted into a binary image, the binary image is composed of M and N pixels in the horizontal and vertical directions respectively.

6. The multi-objective planning method for robot non-interference grinding and polishing posture according to claim 1 is characterized in that: The working mode of the robot non-interference configuration space fast calculation model based on image edge detection is as follows: The first knife contact point is obtained by searching the robot non-interference configuration space simulation platform. The non-interference configuration space is denoted as RCS1; Let k = 1, and the k+1th knife contact The initial value of the robot's non-interference configuration space is set to RCS k ; RCS k Convert to a series of binary images, and use the Soble edge detection operator to detect the edge pixels corresponding to each binary image; Determine the grinding and polishing posture set GPB corresponding to all edge pixels k , using the built non-interference configuration space simulation platform to analyze each boundary posture Λ∈GPB k Grinding and polishing the k+1th tool contact point Interference check and kinematic simulation are performed at the same time, and the k+1th tool contact point is updated Robot configuration space RCS k+1 The interference state in these boundary grinding and polishing postures; The search is iterated until the robot interference-free configuration space of all knife contact points is obtained.

7. The multi-objective planning method for robot non-interference grinding and polishing posture according to claim 1 is characterized in that: The multi-objective optimization model of the robot's non-interference grinding and polishing posture is based on the constraints of avoiding interference, avoiding robot singularity, ensuring high rigidity during robot processing, and the performance limit of the robot joint motor drive, and the geometric smoothness of the grinding and polishing posture and the smoothness of the robot's kinematic performance are used as optimization goals.

8. The multi-objective planning method for robot non-interference grinding and polishing posture according to claim 1 is characterized in that: The grinding and polishing posture optimization solution algorithm converts the optimization problem of the grinding and polishing posture into the problem of selecting a suitable grinding and polishing posture in the non-interference configuration space of each tool contact point to optimize the optimization target within the calculated robot non-interference configuration space. It is a typical combinatorial optimization problem and is solved by Dijkstra algorithm, particle swarm optimization algorithm or discrete differential evolution algorithm.

9. An electronic device, characterized in that: The electronic device includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement the method described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The storage medium stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement the method according to any one of claims 1 to 8.

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