Grinding and polishing path planning method and simulation system of six-axis robot

Abstract

The invention relates to the technical field of robot grinding and polishing machining, in particular to a grinding and polishing path planning method and simulation system for a six-axis robot. Solving a target attitude coordinate system of each cutter location point of the robot end effector in the cutter path; obtaining a target attitude matrix from the previous cutter location point to the next cutter location point according to the target attitude coordinate systems of the two adjacent cutter location points, and obtaining all feasible solutions of the robot joint angle of the next cutter location point by using an inverse kinematics solver; all feasible solutions of the robot joint angle of each cutter location point are screened according to the solution selection fields, and an optimal solution is obtained; and outputting a grinding and polishing motion program of the robot according to the optimal solution of the robot joint angle of each cutter location point in the cutter path. According to the method, the singular solution problem caused by redundant degrees of freedom is solved, and the simulation precision and the machining efficiency of the robot can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of robot grinding and polishing processing, in particular to a grinding and polishing path planning method and simulation system of a six-axis robot. BACKGROUND

[0002] The motion planning of a robot refers to setting a series of position information of robot motion according to the business type of the robot, so that the robot moves according to the position information, that is, the tool center point (TCP) is aligned with the position point; the robot control system solves the inverse kinematics through the position information, so as to obtain the joint values of the robot, so as to meet the requirements of the target position.

[0003] The motion planning of a general robot can edit the path through a path editor, and analyze the rationality of the joint values of the robot in this process, select the combination of joint values, and set the mode of robot motion, such as PTP (Point To Point), PTP AXIS (Point-To-Point AXIS), LIN (Linear), and CIRC (Circle). PTP is to move the joint of the robot in the most efficient way, ignoring the process path of the TCP of the robot; PTP AXIS is to move the initial TCP according to the specified axis direction; LIN is to move the initial TCP in a straight line between positions; CIRC is to move the TCP of the robot along an arc, and this motion form is mainly applied to arc welding or sealing process. In addition to the basic motion path planning, path planning can also be performed according to the process type, such as spot welding, arc welding, glue coating, and spraying, and manufacturing features are used for path planning of the robot.

[0004] Since grinding and polishing is a typical five-axis numerical control machining process, and a six-axis industrial robot has six degrees of freedom in three-dimensional space, there is a problem of redundancy of degrees of freedom in actual application. In order to ensure that the TCP is accurately aligned with the target point on the workpiece surface, the robot control system needs to calculate the joint angle solution from the desired pose through the inverse kinematics algorithm, but due to the existence of redundant degrees of freedom, the same TCP position may correspond to multiple joint solutions, so that this traditional solving method has the following defects:

[0005] (1) Multiple solutions bring screening cost: the control system may obtain multiple different kinematic solutions, which need to be tried and verified one by one, reducing the processing efficiency;

[0006] (2) Error solution affects the rationality of the pose: some solutions may cause the robot to run in an unreasonable or singular pose, thereby affecting the processing quality and consistency;

[0007] (3) Operation cycle extension: to ensure the selection and execution of correct solutions, the overall operation process is lengthened, resulting in a decrease in processing efficiency.

[0008] Therefore, how to solve the singular solution problem caused by redundant degrees of freedom, improve the accuracy and posture rationality of inverse solution, and further improve the overall processing efficiency of robot grinding and polishing, is a problem to be solved in the prior art. SUMMARY

[0009] To this end, the technical problem to be solved by the present application is to overcome the problem of singular solution caused by redundant degrees of freedom in the prior art, resulting in a decrease in the processing quality and efficiency of robot grinding and polishing.

[0010] To solve the above technical problems, the present application provides a grinding and polishing path planning method for a six-axis robot, comprising:

[0011] According to the fixed direction vector input by the user or the normal vector and tangent vector of the tool position point on the surface to be ground, the target posture coordinate system of the robot end effector at each tool position point in the tool path is solved;

[0012] According to the target posture coordinate system of the adjacent two tool position points, the target posture matrix from the previous tool position point to the next tool position point is obtained, and then the inverse kinematics solver is used to obtain all feasible solutions of the robot joint angle of the next tool position point;

[0013] According to the selection field set by the user, all feasible solutions of the robot joint angle of each tool position point are screened to obtain the optimal solution of the robot joint angle of each tool position point;

[0014] According to the optimal solution of the robot joint angle of each tool position point in the tool path, the grinding and polishing motion program of the robot is output.

[0015] Preferably, according to the fixed direction vector input by the user, the target posture coordinate system of the robot end effector at each tool position point in the tool path is solved, comprising:

[0016] The fixed direction vector input by the user is taken as the x direction, the tool axis direction of the current tool position point is taken as the z direction, and then the y direction is obtained by cross multiplication according to the x direction and the z direction, to construct the target posture coordinate system of the current tool position point.

[0017] Preferably, according to the normal vector and tangent vector of the tool position point on the surface to be ground, the target posture coordinate system of the robot end effector at each tool position point in the tool path is solved, comprising:

[0018] The tool movement direction on the surface to be ground is defined as the u direction, the tool row spacing direction or the tool width direction is defined as the v direction, and the current tool position point is mapped to the surface to be ground to obtain the surface tool position point;

[0019] Calculate the tangent vectors of the surface tool point in the u direction and v direction respectively, and obtain the normal vector of the surface tool point after cross product;

[0020] The cross product of the normal vector of the surface tool point and the tangent vector of the surface tool point in the u direction is used as the x direction, the tangent vector of the surface tool point in the u direction is used as the z direction, and the y direction is obtained according to the cross product of the x direction and the z direction to construct the target posture coordinate system of the current tool point.

[0021] Preferably, the surface to be polished is a NURBS surface.

[0022] Preferably, the inverse kinematics solver adopts an inverse kinematics solver based on the Levenberg–Marquardt algorithm.

[0023] Preferably, the solution selection field includes:

[0024] Set the robot's moving shoulder to right or left;

[0025] Set the robot's elbow to be raised or lowered;

[0026] Set the robot's wrist to face up or flip up.

[0027] Preferably, after screening all feasible solutions of the robot joint angles for each tool location point according to the selected solution field set by the user, if there are still multiple solutions for the robot joint angles for any tool location point, the optimal solution for the robot joint angles for the tool location point is further selected from the multiple solutions that meet the selected solution field, including:

[0028] If the user chooses manual screening, the corresponding visualization result graph will be output for multiple solutions that meet the solution selection field for the current tool position. The user can select the optimal solution for the robot joint angle at the current tool position based on the visualization result graph;

[0029] If the user selects automatic screening, the inverse kinematics solver selects the optimal solution for the robot joint angles at the current tool location from multiple solutions that meet the solution selection field based on the nonlinear least squares optimization algorithm and the optimal solution for the robot joint angles at the previous tool location.

[0030] Preferably, before solving the target posture coordinate system of the robot end effector at each tool position in the tool path, the method further includes:

[0031] Define the robot structure and set the safety zone;

[0032] Set the robot's initial grinding and polishing position, and set multiple motion teaching points for the robot to reach the initial grinding and polishing position from the current standby position and within the safe area. Set the robot's joint angles at each motion teaching point so that all joints of the robot are within the safe area.

[0033] Let the robot pass through the motion teaching point and reach the initial grinding and polishing position.

[0034] Preferably, the method for obtaining the tool path includes: obtaining all GOTO points in the APT tool location point file and performing interpolation to obtain a continuous tool path; the interpolation method includes linear interpolation, spline interpolation and circular arc interpolation.

[0035] The present invention also provides a six-axis robot grinding and polishing path planning simulation system, comprising:

[0036] The posture solving module is used to solve the target posture coordinate system of each tool position in the tool path of the robot end effector based on the fixed direction vector or the normal vector and tangent vector of the tool position on the surface to be polished input by the user;

[0037] The joint angle solving module is used to obtain the target posture matrix from the previous tool position to the next tool position based on the target posture coordinate system of two adjacent tool positions, and then use the inverse kinematics solver to obtain all feasible solutions of the robot joint angles at the next tool position;

[0038] The screening module is used to screen all feasible solutions for each tool position according to the solution selection field set by the user, and obtain the optimal solution for the robot joint angle of each tool position;

[0039] The output module is used to output the robot's grinding and polishing motion program according to the optimal solution of the robot joint angle at each tool position in the tool path.

[0040] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0041] The grinding and polishing path planning method of a six-axis robot described in the present invention constrains the target posture coordinate system of the tool position point with a fixed direction vector input by the user or the normal vector and tangent vector of the tool position point on the surface to be ground and polished. By constructing a reasonable target posture coordinate system, the problem of redundant degrees of freedom caused by only determining the target posture with the tool axis direction without constraining the x-direction and y-direction rotational freedom in the prior art is solved. It can effectively avoid unnecessary rotation when the robot solves the joint angle and reduces the probability of singular solutions in the inverse kinematics solution. In addition, the present invention further constrains the robot's movement mode through the solution selection field set by the user, selects the optimal solution from all feasible solutions, and effectively ensures the continuity, safety and mechanical accessibility of the tool path execution. The present invention can be widely used in the grinding and polishing process tasks of six-axis robots, solves the singular solution problem caused by redundant degrees of freedom, and can not only improve the robot simulation accuracy and processing efficiency, but also ensure that the robot operates in a safe posture that meets user requirements, providing technical support for high-quality automated processing on actual production lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0043] Figure 1 This is a flow chart of a grinding and polishing path planning method for a six-axis robot according to the present invention;

[0044] Figure 2 This is a diagram of the interface for setting the robot's joint angles at the motion teaching point;

[0045] Figure 3 This is a schematic diagram of the interface for users to set a fixed direction vector;

[0046] Figure 4 It is a schematic diagram of constructing the target posture coordinate system based on the fixed direction vector and tool axis direction input by the user;

[0047] Figure 5 It is a schematic diagram of the normal vector and tangent vector of the tool position point on the surface to be ground and polished;

[0048] Figure 6 It is a schematic diagram of the target posture coordinate system under V-axis horizontal grinding;

[0049] Figure 7 It is a visualization result diagram output based on the robot joint angle. DETAILED DESCRIPTION

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0051] Reference Figure 1 As shown, the present invention provides a grinding and polishing path planning method for a six-axis robot, comprising:

[0052] S1: Define the robot structure and set the safety area.

[0053] In a simulation environment, the robot's structure is modeled, defining the types of joints (e.g., revolute joints, translatory joints), their connection methods, and their initial positions. The simulation environment used in this paper supports the rapid configuration of hinge connections based on standard motion types, allowing for the efficient creation of a complete kinematic chain model for the robot.

[0054] Once the robot structure is modeled, specific angle values ​​can be assigned to designated joints to simulate the process of a physical robot reaching the target pose. The joint values ​​obtained through inverse kinematics can be compared with the joint states uploaded from the actual robot on the shop floor to determine the accuracy and consistency of the structure definition. Any deviations are recorded in a system report to facilitate debugging and error compensation, ensuring consistency between the simulation model and the actual hardware.

[0055] S2: Set the robot's initial grinding and polishing position, and set multiple motion teaching points for the robot to reach the initial grinding and polishing position from the current standby position and be located in the safe area. Set the robot's joint angle at each motion teaching point so that all joints of the robot are located in the safe area.

[0056] To ensure the safety of the robot's state before and after simulation execution, a "motion teaching point" mechanism is introduced into the simulation process. Based on the relevant operations loaded in the visual interface, users can preview the robot's current standby position and grinding and polishing initial position and clearly specify the angles or postures of each joint to verify whether the robot is in the expected safe area at the current standby position and grinding and polishing initial position. Multiple motion teaching points are inserted between the current standby position and the grinding and polishing initial and end positions to ensure that the robot is in a safe, controllable, and known posture at the beginning and end of the simulation. These motion teaching points can be customized according to specific joint combinations or task process requirements to ensure that the robot has a safe and controllable initial state before starting the grinding and polishing task, and returns to a reasonable position to continue working or exit after completing the grinding and polishing task. Figure 2 This is a diagram of the interface for setting the robot's joint angles at the motion teaching points.

[0057] The design mechanism of motion teaching points helps to detect potential collision risks or problems of exceeding limit positions in advance, improving the robustness of overall simulation and deployment.

[0058] S3: After the robot passes the motion teaching point and reaches the initial grinding and polishing position, the tool path is obtained.

[0059] Since grinding and polishing have strict requirements on the end path and high requirements on posture control accuracy, that is, the polishing tool direction must always be vertical or fit the surface at a specific angle, the present invention obtains the tool path according to the APT tool location file in Cartesian space, including:

[0060] All GOTO points in the APT tool location file are obtained and interpolated to obtain a continuous tool path; the interpolation methods include linear interpolation, spline interpolation and circular interpolation.

[0061] The GOTO points in an APT tool location file define the trajectory of the tool in space. Interpolation methods determine the motion between GOTO points, interpolating a series of points with positions and directions in space to form a continuous tool path.

[0062] S4: Based on the fixed direction vector or the normal vector and tangent vector of the tool position point on the surface to be polished input by the user, the target posture coordinate system of the robot end effector at each tool position point in the tool path is solved.

[0063] The robot's end-effector pose consists of (X, Y, Z, RX, RY, RZ), where X, Y, and Z are the three-dimensional position coordinates of the end-effector, and RX, RY, and RZ are the rotation angles around the x-axis, y-axis, and z-axis, respectively. Therefore, the key to the post-processing of the robot's path planning algorithm is to convert the tool position of the tool path into the target pose coordinate system on the surface to be polished, ultimately converting it into a pose point in the form of (X, Y, Z, RX, RY, RZ).

[0064] Because the end effector of a six-axis robot in three-dimensional space typically has six degrees of freedom (3 translations + 3 rotations), existing techniques only determine the calculated pose based on the tool axis direction (the z-direction in the attitude coordinate system). When other rotational freedoms (such as rotation around the z-axis, i.e., rotation) are unconstrained, there is a problem of redundant degrees of freedom. Therefore, it is necessary to clearly define the target attitude coordinate system for each tool position point to avoid unnecessary rotation of the robot, thereby reducing the probability of singular solutions in the inverse solution.

[0065] In order to ensure the stability and accuracy of the target posture coordinate system solution, especially when dealing with grinding / polishing tasks that are highly posture-sensitive, the present invention improves the design of the target posture coordinate system construction method in the end effector.

[0066] The first method for constructing the target pose coordinate system uses a fixed direction vector entered by the user as the x-direction, the tool axis direction of the current tool position as the z-direction, and then cross-products the x- and z-directions to obtain the y-direction. This method is suitable for working conditions where the tool path direction is constant.

[0067] Figure 3 This is a schematic diagram of the interface for users to set a fixed direction vector. Figure 4 It is a schematic diagram of constructing the target posture coordinate system based on the fixed direction vector and tool axis direction input by the user.

[0068] The second method to construct the target attitude coordinate system is:

[0069] Define the tool movement direction on the surface to be polished as u, the tool spacing direction or tool width direction as v, and map the current tool position point to the surface to be polished to obtain the surface tool position point P(u,v);

[0070] Calculate the tangent vector S of the surface tool point in the u direction and v direction respectively u and S v , after cross product, we get the normal vector N(u,v) of the surface tool point;

[0071] The cross product of the normal vector of the surface tool point and the tangent vector of the surface tool point in the u direction is used as the x direction, the tangent vector of the surface tool point in the u direction is used as the z direction, and the y direction is obtained according to the cross product of the x direction and the z direction to construct the target posture coordinate system of the current tool point.

[0072] This embodiment takes V-direction transverse grinding during blade grinding and polishing as an example. V-direction transverse grinding generally controls the grinding and polishing posture along the tool normal direction, which produces the best processing effect. Therefore, the tool exit point is required to be at the normal vector of the surface to be ground and polished.

[0073] The surface to be polished is defined as a NURBS surface with p degrees in the u direction and q degrees in the v direction. Its expression is:

[0074]

[0075] Among them, P i,j is the characteristic grid control point sequence on the rectangular domain, w i,j is the weight factor of the corresponding control point, N i,p (u) and N j,q (v) are the B-spline basis functions of order p and order q, respectively.

[0076] Reference Figure 5 As shown, according to the processing characteristics and NURBS surface properties, the u direction of the surface is set as the tool movement direction, then S u is the tangent vector of the surface tool position point P(u,v) in the tool movement direction; the v direction of the surface should be orthogonal to u, so it can be set to the tool width direction or the spacing direction, then S v It is the tangent vector of the surface tool point P(u,v) in the v direction. u and S v They are orthogonal, and the cross product of the two is the normal vector N(u,v) on the surface of the tool point, that is, N(u,v)=S u ×S v .

[0077] According to the processing requirements, the target posture of the tool position point needs to meet the geometric fitting. In the tangential processing of the blade polishing, the normal vector of the curved surface tool position point determines the contact angle, because the normal vector is the only vertical direction of the curved surface at the point, and directly determines the contact state of the tool and the curved surface. There is an angle between the tool axis direction and the normal vector N(u, v), and in special cases, the two are close to perpendicular, for example, the rotating shaft of the belt sander needs to be parallel to the tangent plane to maximize the effective grinding area (such as blade chord polishing). Tangential vector S u and S v defines the processing path while meeting the characteristics of the NURBS curved surface, because S u directly relates to the tool motion direction, affects the cutting force, heat distribution and surface texture, and S v is orthogonal to S u , the row spacing can be accurately controlled to avoid excessive residual height.

[0078] Therefore, the cross product of the normal vector of the curved surface tool position point and the tangential vector of the curved surface tool position point in the u direction can be taken as the x direction x L , the tangential vector of the curved surface tool position point in the u direction is taken as the z direction z L , and the cross product of the x direction and the z direction is taken as the y direction y L , to construct the target posture coordinate system of the current tool position point, and the formula is:

[0079]

[0080] Referring to Figure 6 , the XYZ three directions form the target posture coordinate system of the robot at the current tool position. Through the above steps, the tool path planned is analyzed, and the target posture coordinate system corresponding to each tool position point is within the set angle threshold α, β and γ relative to the next tool position point, which ensures the smooth transition of the robot polishing process posture.

[0081] The target posture coordinate system construction method proposed by the application can ensure that the polishing direction is along the tool path advancing direction, not only makes the end posture definition of each tool position point more complete, significantly reduces the singularity problem in the inverse solution process, but also effectively avoids the local optimal solution into the problem caused by the unclear target posture, and effectively improves the convergence stability and overall trajectory quality of the LMA algorithm.

[0082] S5: obtaining the target posture matrix from the previous tool position point to the next tool position point according to the target posture coordinate systems of the two adjacent tool position points, and then using the inverse kinematics solver to obtain all feasible solutions of the robot joint angle of the next tool position point.

[0083] Specifically, the target pose coordinate system of the previous tool location is used as the reference coordinate system. The target pose coordinate system of the next tool location can be converted into a 4×4 homogeneous transformation matrix or a 3×3 rotation matrix plus a translation vector. The rotation angles are extracted sequentially in Euler angle order (X, Y, Z), and the translation component is extracted. This ultimately forms the pose point of the robot end effector. An inverse kinematics solver can then be used to obtain all feasible solutions for the robot's joint angles at the next tool location.

[0084] Preferably, the inverse kinematics solver adopts the inverse kinematics solver based on the Levenberg–Marquardt algorithm (LMA) in KDL (Kinematics Dynamics Library).

[0085] S6: According to the solution selection field set by the user, all feasible solutions of the robot joint angle of each tool position are screened to obtain the optimal solution of the robot joint angle of each tool position.

[0086] For the same achievable poses of the end effector in Cartesian space, a six-axis robot typically has multiple feasible inverse kinematic solutions (i.e., different robot posture combinations). These solutions are mathematically equivalent, but in practice they result in different robot motions, potentially involving elbow elevation or descent, shoulder adduction or abduction, wrist rotation, and other differences.

[0087] Therefore, the present invention defines a set of common solution flags based on different models of six-axis robots and their controllers to specify the specific posture constraints used by the controller when calculating the inverse solution. The solution flags include:

[0088] Set the robot's kinematic shoulder to right (righty) or left (lefty);

[0089] Set the robot's elbow to be raised (epositive) or lowered (enegative);

[0090] Sets the robot's wrist to be upward (wpositive) or flipped (wnegative).

[0091] By combining the above solution selection fields, the optimal solution that best meets the process requirements can be selected from multiple mathematically feasible solutions to avoid singular / collision postures.

[0092] Furthermore, when the present invention finds the optimal solution for the robot joint angle at each tool position, it can also provide all feasible postures that meet the solution selection field for users to choose according to user needs, or automatically screen the optimal solution through the rules of the inverse kinematics solver to ensure the continuity, safety and mechanical accessibility of trajectory execution.

[0093] Specifically, after screening all feasible solutions for the robot joint angles at each tool location according to the solution selection field set by the user, if there are still multiple solutions for the robot joint angles at any tool location, the optimal solution for the robot joint angles at that tool location is further selected from the multiple solutions that meet the solution selection field, including:

[0094] If the user chooses manual screening, the corresponding visualization result graph will be output for multiple solutions that meet the solution selection field for the current tool position. The user can select the optimal solution for the robot joint angle at the current tool position based on the visualization result graph; Figure 7 It is a visualization result diagram output based on the robot joint angle;

[0095] If the user selects automatic screening, the inverse kinematics solver selects the optimal solution for the robot joint angles at the current tool location from multiple solutions that meet the solution selection field based on the nonlinear least squares optimization algorithm and the optimal solution for the robot joint angles at the previous tool location.

[0096] The solution selection field provided in the present invention can guide the robot to select a solution with stable posture and meeting the processing requirements from multiple feasible solutions, thereby ensuring that the simulation results can be used for actual processing deployment.

[0097] S7: Output the robot's grinding and polishing motion program based on the optimal solution of the robot joint angle at each tool position in the tool path.

[0098] In summary, the grinding and polishing path planning method of a six-axis robot described in the present invention constrains the target posture coordinate system of the tool position point with a fixed direction vector input by the user or the normal vector and tangent vector of the tool position point on the surface to be ground and polished. By constructing a reasonable target posture coordinate system, the problem of redundant degrees of freedom caused by only determining the target posture with the tool axis direction without constraining the rotational freedom in the x-direction and y-direction in the prior art is solved. It can effectively avoid unnecessary rotation when the robot solves the joint angle and reduces the probability of singular solutions in the inverse kinematics solution. In addition, the present invention further constrains the robot's movement mode through the solution selection field set by the user, selects the optimal solution from all feasible solutions, and effectively ensures the continuity, safety and mechanical accessibility of the tool path execution. The present invention can be widely used in the grinding and polishing process tasks of six-axis robots, solves the singular solution problem caused by redundant degrees of freedom, and can not only improve the robot simulation accuracy and processing efficiency, but also ensure that the robot operates in a safe posture that meets user requirements, providing technical support for high-quality automated processing on actual production lines.

[0099] Based on the above-mentioned grinding and polishing path planning method of a six-axis robot, the present invention also provides a grinding and polishing path planning simulation system of a six-axis robot, comprising:

[0100] The posture solving module is used to solve the target posture coordinate system of each tool position in the tool path of the robot end effector based on the fixed direction vector or the normal vector and tangent vector of the tool position on the surface to be polished input by the user;

[0101] The joint angle solving module is used to obtain the target posture matrix from the previous tool position to the next tool position based on the target posture coordinate system of two adjacent tool positions, and then use the inverse kinematics solver to obtain all feasible solutions of the robot joint angles at the next tool position;

[0102] The screening module is used to screen all feasible solutions of the robot joint angle at each tool position according to the solution selection field set by the user, and obtain the optimal solution of the robot joint angle at each tool position;

[0103] The output module is used to output the robot's grinding and polishing motion program according to the optimal solution of the robot joint angle at each tool position in the tool path.

[0104] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0105] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0106] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0107] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0108] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A grinding and polishing path planning method for a six-axis robot, characterized in that: include: According to the fixed direction vector or the normal vector and tangent vector of the tool position point on the surface to be polished input by the user, the target posture coordinate system of the robot end effector at each tool position point in the tool path is solved; The target pose matrix from the previous tool position to the next tool position is obtained based on the target pose coordinate system of the two adjacent tool positions, and then the inverse kinematics solver is used to obtain all feasible solutions for the robot joint angles of the next tool position. According to the solution selection field set by the user, all feasible solutions of the robot joint angle at each tool position are screened to obtain the optimal solution of the robot joint angle at each tool position; The robot's grinding and polishing motion program is output based on the optimal solution of the robot joint angle at each tool position in the tool path.

2. The method for planning a grinding and polishing path for a six-axis robot according to claim 1, wherein: Based on the fixed direction vector input by the user, the target pose coordinate system of the robot end effector at each tool position in the tool path is solved, including: The fixed direction vector input by the user is used as the x direction, the tool axis direction of the current tool position point is used as the z direction, and the y direction is obtained by cross-producting the x direction and the z direction to construct the target posture coordinate system of the current tool position point.

3. The grinding and polishing path planning method of a six-axis robot according to claim 1, characterized in that: According to the normal vector and tangent vector of the tool position point on the surface to be ground and polished, the target posture coordinate system of each tool position point in the tool path of the robot end effector is solved, including: Define the tool movement direction on the surface to be ground and polished as u direction, the tool spacing direction or tool width direction as v direction, and map the current tool position point to the surface to be ground and polished to obtain the surface tool position point; Calculate the tangent vectors of the surface tool point in the u direction and v direction respectively, and obtain the normal vector of the surface tool point after cross product; The cross product of the normal vector of the surface tool point and the tangent vector of the surface tool point in the u direction is used as the x direction. The tangent vector of the surface tool position point in the u direction is used as the z direction, and the y direction is obtained by cross-producting the x direction and the z direction to construct the target posture coordinate system of the current tool position point.

4. The method for planning a grinding and polishing path for a six-axis robot according to claim 1, wherein: The surface to be polished is a NURBS surface.

5. The method for planning a grinding and polishing path for a six-axis robot according to claim 1, wherein: The inverse kinematics solver adopts an inverse kinematics solver based on the Levenberg–Marquardt algorithm.

6. The method for planning a grinding and polishing path for a six-axis robot according to claim 1, wherein: The solution selection field includes: Set the robot's moving shoulder to right or left; Set the robot's elbow to be raised or lowered; Set the robot's wrist to face up or flip up.

7. The method for planning a grinding and polishing path for a six-axis robot according to claim 6, wherein: After filtering all feasible solutions for the robot joint angles at each tool location according to the solution selection field set by the user, if multiple solutions still exist for the robot joint angles at any tool location, the optimal solution for the robot joint angles at that tool location is further selected from the multiple solutions that meet the solution selection field, including: If the user chooses manual screening, the corresponding visualization result graph will be output for multiple solutions that meet the solution selection field for the current tool position. The user can select the optimal solution for the robot joint angle at the current tool position based on the visualization result graph; If the user selects automatic screening, the inverse kinematics solver selects the optimal solution for the robot joint angles at the current tool location from multiple solutions that meet the solution selection field based on the nonlinear least squares optimization algorithm and the optimal solution for the robot joint angles at the previous tool location.

8. The method for planning a grinding and polishing path for a six-axis robot according to claim 1, wherein: Before solving the target pose coordinate system of the robot end effector at each tool position in the tool path, it also includes: Define the robot structure and set the safety zone; Set the robot's initial grinding and polishing position, and set multiple motion teaching points for the robot to reach the initial grinding and polishing position from the current standby position and within the safe area. Set the robot's joint angles at each motion teaching point so that all joints of the robot are within the safe area. Let the robot pass through the motion teaching point and reach the initial grinding and polishing position.

9. The method for planning a grinding and polishing path for a six-axis robot according to claim 1, wherein: The method of obtaining the tool path includes: obtaining all GOTO points in the APT tool location file and interpolating them to obtain a continuous tool path; the interpolation methods include linear interpolation, spline interpolation and circular arc interpolation.

10. A six-axis robot grinding and polishing path planning simulation system, characterized in that: include: The posture solving module is used to solve the target posture coordinate system of each tool position in the tool path of the robot end effector based on the fixed direction vector or the normal vector and tangent vector of the tool position on the surface to be polished input by the user; The joint angle solving module is used to obtain the target posture matrix from the previous tool position to the next tool position based on the target posture coordinate system of two adjacent tool positions, and then use the inverse kinematics solver to obtain all feasible solutions of the robot joint angles at the next tool position; The screening module is used to screen all feasible solutions of the robot joint angle at each tool position according to the solution selection field set by the user, and obtain the optimal solution of the robot joint angle at each tool position; The output module is used to output the robot's grinding and polishing motion program according to the optimal solution of the robot joint angle at each tool position in the tool path.

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