A multi-stage positioning machining method for three-dimensional thin-walled parts

Abstract

This invention provides a multi-stage positioning machining method for three-dimensional thin-walled parts, comprising the following steps: Step 1: Establishing a composite machining workstation consisting of a robotic arm and a small three-axis; Step 2: Automatically identifying closed features on the workpiece to be machined and classifying them into small features and large features; Step 3: Sort the small and large features selected in Step 2, setting corresponding sorting parameters, and executing automatic sorting to obtain several sorted line features; Step 4: Calculating the pose trajectories of all line features sorted in Step 3; Step 5: Simulating and executing the pose trajectories calculated in Step 4. The multi-stage positioning machining method for three-dimensional thin-walled parts proposed in this invention, based on a composite device composed of a robotic arm and a small three-axis, can calculate the machining trajectories of various features, meeting the high-precision and high-efficiency machining requirements of machining features, adapting to part deformation and equipment errors, and improving machining efficiency.

Description

Technical Field

[0001] This invention belongs to the field of three-dimensional thin-walled part contour processing technology, specifically relating to a multi-level positioning processing method for batch line features of three-dimensional thin-walled parts. Background Technology

[0002] CNC machine tools and multi-joint robots (robotic arms) are two major machining methods in recent years. CNC machine tools offer high rigidity and precision, making them suitable for machining high-precision parts, but they are expensive and have a limited processing range. Robotic arms offer a wide range of applications and high flexibility, and are widely used in laser cutting and grinding of automotive parts, as well as in the machining of small components. The biggest limitation of robotic arm machining is the relatively low precision and stability of the equipment, resulting in suboptimal machining results for some high-precision products.

[0003] Three-dimensional thin-walled parts, such as stamped automotive components or processed craft parts, are a widely used and easily machinable type of part. Their characteristics include numerous machining features, primarily closed contours on the part's surface, such as round, square, or irregularly shaped holes on automotive sheet metal panels. Currently, these features require manual selection and sorting, which is complex and difficult. Using robotic arms results in poor stability and lower machining accuracy.

[0004] To address the aforementioned problems, this invention provides a multi-stage positioning and machining method for three-dimensional thin-walled parts. This method is based on the composite machining of a robotic arm and a small three-axis system. Through the automatic selection, allocation, sorting, and trajectory calculation of features, it enables batch, efficient, and high-precision machining of three-dimensional thin-walled parts. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a multi-stage positioning and machining method for three-dimensional thin-walled parts. The purpose is to automatically and efficiently extract, filter, and allocate line features on three-dimensional thin-walled parts in batches, and calculate the pose trajectories of the robotic arm and small three-axis when machining different features. This method replaces tedious and complex manual operations and improves the machining efficiency and accuracy of three-dimensional thin-walled parts.

[0006] The technical solution adopted by the present invention to solve the problems existing in the prior art is as follows: A multi-stage positioning and machining method for three-dimensional thin-walled parts, comprising the following steps:

[0007] Step 1: Establish a robotic arm and small three-axis composite machining workstation: Import the 3D model of the robotic arm into the HiperMOS full-chain closed-loop CAM system software, install a small three-axis device at the end of the robotic arm, install machining tools at the end of the small three-axis, and install the workpiece to be processed in the workspace outside the robotic arm;

[0008] Step 2: Automatically identify closed features on the workpiece to be processed and classify them into small features and large features: First, select several reference surfaces to be processed in the workpiece model, then automatically extract all closed line sets on the reference surfaces, each closed line set as a candidate line feature, and finally filter out small features and large features based on the processing dimensions and feature normal consistency.

[0009] Step 3: Sort the small and large features selected in Step 2, set the corresponding sorting parameters, and execute automatic sorting to obtain several sorted line features;

[0010] Step 4: Calculate the pose trajectories of all line features after sorting in Step 3. The pose trajectories include: 4.1, the positioning and connection trajectory of the robotic arm moving above each small feature; 4.2, the pose trajectory of the small three axes of the robotic arm to each small feature after positioning; 4.3, the pose trajectory of the robotic arm processing the large feature.

[0011] Step 5: Simulate and execute the pose trajectory calculated in Step 4: Use the existing HiperMOS simulation module to simulate the execution of all steps, and detect whether there are collisions, unreachable, singularities or joint over-limit problems between the robot arm, small three-axis, machining tool and workpiece during the trajectory operation. If a problem is found, adjust the trajectory. Finally, send the confirmed safe trajectory to the actual equipment for online or offline execution.

[0012] Step 1 specifically involves: establishing a robotic arm and a small three-axis composite machining workstation in the HiperMOS full-chain closed-loop CAM system software. The three-dimensional models to be imported include the three-dimensional models of the robotic arm, the small three-axis, the machining tool, and the workpiece to be processed. The robotic arm is installed in the world coordinate system, the small three-axis is installed at the end of the robotic arm, the machining tool is installed at the end of the small three-axis, and the workpiece to be processed is installed in the workspace outside the robotic arm's kinematic chain. The clamping posture relationship between them is obtained by calibrating the tool and workpiece in the actual scene. The tool or workpiece calibration is based on existing technology.

[0013] The automatic extraction method for candidate line features in step 2 is as follows: In the 3D model of a thin-walled workpiece, the processing area where the feature to be processed is located is selected as several reference surfaces on the workpiece. These reference surfaces may be connected or discontinuous. A closed set of all boundary lines on all reference surfaces is obtained. Each closed set of lines is a candidate line feature.

[0014] The specific method for filtering small and large features in step 2 is as follows: In actual processing, not all closed contours need to be processed. This invention proposes a filtering method based on the consistency requirements of processing size and feature normal. Candidate line features are divided into three categories: small features, large features, and non-processable features. Small features are features that can be processed by a small triaxial axis. The feature size range and normal change are within the processing range of the small triaxial axis. The processing range of the small triaxial axis can be described by a cylinder. Since the small triaxial axis can only perform directional processing, the normal change angle of the small feature is required to be within the threshold range. The specific filtering method is as follows: Calculate the center normal and the maximum normal change of the feature. If it is less than the given normal change angle threshold, calculate the minimum covering cylinder of the feature with the center normal as the axis. If the radius and height of the minimum covering cylinder are both less than the user input value, then the feature is a small feature. Record the center point and axis of the minimum covering cylinder of the small feature as the input for subsequent calculation of the robot arm positioning pose.

[0015] After filtering the smaller features, the larger features can be filtered by constructing OBBs (Directed Bounding Boxes) of the remaining candidate features. The length, width, and height of the OBBs are compared with the processing dimensions to select line features that meet the processing requirements as the larger features. The specific filtering principle is as follows: assuming the three sides of the candidate feature OBB are... The user-input dimensions of the filter cube are X-axis length a, Y-axis length b, and Z-axis length c. Assume the shortest side of the OBB is... The corresponding axis corresponds to the Z-axis of the screening cube, so the basis for selecting candidate features as large features is: ,in for The minimum value, for The maximum value.

[0016] The sorting parameters in step 3 include the following three types: A. Sorting object; B. Sorting strategy; C. Connection method.

[0017] To provide a feature sorting method for workpieces with various shapes and features, the three sorting parameters provided in step 3 are as follows:

[0018] A. Sorting Objects: Supports three types of workpieces: sphere-like, cylinder-like, and plane-like. Users can determine which of the three types of workpiece is the workpiece based on its specific shape.

[0019] B. Sorting Strategies: Each type offers 8 different sorting strategies: (1) Horizontal ascending, vertical ascending; (2) Horizontal ascending, vertical descending; (3) Horizontal descending, vertical ascending; (4) Horizontal descending, vertical descending; (5) Vertical ascending, horizontal ascending; (6) Vertical ascending, horizontal descending; (7) Vertical descending, horizontal ascending; (8) Vertical descending, horizontal descending. Users can choose one of the above eight sorting strategies according to their processing needs.

[0020] The core of the automatic sorting algorithm in step 3 is to first extract the starting point of the feature as the sorting point, then map the sorting point to two-dimensional parameters according to the type of the sorting object, then perform two-dimensional sorting according to the sorting strategy, and finally map the result of the two-dimensional sorting back to the sorting point to obtain the sorted line features.

[0021] To explain strategy (1) using a spheroid as an example: First, establish a local coordinate system for the workpiece. For example, for a spheroid, establish the coordinate system at the center of the workpiece, with the positive z-axis as the North Pole axis, the horizontal axis representing the parallel of latitude parallel to the equator, and the vertical axis representing the longitude perpendicular to the equator. In strategy 1, the horizontal axis is ascending and the vertical axis is ascending, which means connecting the North Pole to the South Pole in a counterclockwise direction of latitude.

[0022] C. Connection method: Two connection methods are provided: one-way and reciprocating. Continuing with the above example, the connection method is used to determine how the first parallel of latitude is connected to the second parallel of latitude. For example, one-way means that both adjacent parallels of latitude are clockwise, and reciprocating means that the first parallel is clockwise and the second parallel is counterclockwise.

[0023] The specific process of calculating the pose trajectory in step 4 is as follows: For 4.1, the positioning connection trajectory of the robotic arm moving to each small feature: In step 2, a center point and axis (denoted as the positioning point) have been calculated for each selected small feature. First, the pose of the robotic arm when it reaches the positioning point of each small feature is calculated. The pose of the robot can be defined by the position, the direction of the main tool axis, and the direction of the secondary tool axis. The position of the robotic arm to each small feature positioning point and the direction of the main tool axis are consistent with the positioning point. The direction of the secondary tool axis can be calculated by a fixed direction specified by the user. Then, the safe connection path between the robotic arm and each positioning pose is calculated. The safe connection path can be created by constructing a safe geometric model of the workpiece. This technology is an existing function of non-machining trajectory in HiperMOS software.

[0024] Regarding 4.2, the pose trajectory of the small three-axis for each small feature after the robotic arm is positioned: For the machining of each small feature, the robotic arm first needs to reach the positioning pose of each small feature, that is, the small three-axis is positioned in a fixed pose in space. Then, with the small three-axis as the machining equipment and the small feature as the machining target, the machining trajectory of the small feature can be calculated based on parameters such as the trajectory density of the HiperMOS line machining step, the main axis and the secondary axis strategy, the trajectory compensation, and the safety connection strategy.

[0025] For 4.3, the pose trajectory of the robotic arm for machining large features: For the machining of each large feature, the machining device is the robotic arm, the small three-axis is homed and fixed, and the tool held at the end of the small three-axis is the tool to be machined. The machining trajectory of the large feature can be calculated based on parameters such as the trajectory density of the HiperMOS line machining step, the main tool axis and the secondary tool axis strategy, the trajectory compensation, and the safety connection strategy.

[0026] Step 5 specifically involves: using the existing HiperMOS simulation module to simulate the execution of all work steps. When simulating the machining trajectory of a small feature, the robotic arm moves above the small feature, and the small three-axis moves to perform machining. When simulating the safe connection trajectory of a small feature or the machining trajectory of a large feature, the small three-axis remains stationary while the robotic arm moves. During the movement of the equipment, it is detected whether there are collisions, unreachable, singularities, or joint over-limit problems between the robotic arm, the small three-axis, the machining tool, and the workpiece to be processed during the trajectory operation. If the above problems are found, the trajectory can be interactively adjusted. Finally, the confirmed safe trajectory is sent to the actual equipment for online or offline execution.

[0027] The present invention has the following advantages:

[0028] 1. The multi-stage composite machining method of the composite equipment composed of a robotic arm and a small three-axis proposed in this invention can calculate the machining trajectory of various features, meet the high precision and high efficiency machining requirements of machining features, adapt to part deformation and equipment errors, and improve machining efficiency;

[0029] 2. The automatic line feature extraction and sorting method involved in this invention can be widely applied in the actual high-efficiency processing of rotary parts and planar parts, and can improve the processing efficiency of process scenarios represented by laser cutting and quenching. Attached Figure Description

[0030] Figure 1 This is a flowchart of the multi-stage positioning machining method of the present invention;

[0031] Figure 2 This is a schematic diagram of the device clamping in an embodiment of the present invention, wherein: 1-multi-joint serial robotic arm model, 2-small three-axis, 3-machining tool, 4-small feature, 5-large feature;

[0032] Figure 3This is a schematic diagram of the feature sorting of a planar thin-walled component in an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram showing the feature sorting of a spherical thin-walled component in an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram showing the feature sorting of a cylindrical thin-walled component in an embodiment of the present invention. Detailed Implementation

[0035] The technical solution of the present invention will be further described in detail below through embodiments and with reference to the accompanying drawings. This embodiment provides a method and specific implementation for multi-stage positioning machining of three-dimensional thin-walled parts, wherein... Figure 1 The flowchart below shows the multi-stage positioning machining method in this embodiment of the invention, corresponding to the following 5 steps:

[0036] Step 1: Establish a robotic arm and a small three-axis composite machining workstation. Import the 3D model of the robotic arm into the HiperMOS full-chain closed-loop CAM system software, and install a small three-axis device at the end of the robotic arm. Install machining tools at the end of the small three-axis device, and install the workpiece in the workspace outside the robotic arm. Figure 2 As shown, component 1 is a multi-joint serial robotic arm, component 2 is a small three-axis mounted at the end of the robotic arm, which can move linearly in the XYZ directions, and component 3 is a machining tool mounted at the end of the small three-axis.

[0037] Step 2: Automatically identify closed features on the workpiece and classify them into small features and large features. Figure 2 On the workpiece being machined, solid line contours, as shown in component 4, are small features, while dashed line contours, as shown in component 5, are large features. Several reference surfaces are selected on the workpiece to be machined. Based on the line-surface relationship and continuity, all closed line sets on all reference surfaces can be automatically extracted. Each closed line set is considered a candidate line feature. Then, based on the machining dimensions and the consistency of the feature normal, the candidate line features are filtered to identify small and large features.

[0038] Small features are those that can be machined by a small triaxial machining center, requiring that the feature size range and normal variation be within the machining range of the small triaxial machining center. The machining range of the small triaxial machining center can be described by a cylinder (the cylinder diameter is the travel in the XY direction, the cylinder height is the travel in the Z direction, and the zero position of the small triaxial machining center is located at the center point of the cylinder axis). Since the small triaxial machining center can only perform directional machining, the normal variation angle of the small feature must be within a threshold range. The specific selection method is as follows: 2.1 Discretize the feature into several discrete points, calculate the normal of each discrete point on the reference plane, then calculate the central normal, and calculate the angle between the normal of each discrete point and the central normal. Take the maximum value of the angle and compare it with the normal variation angle threshold given by the user. If it is less than the threshold, it means that the feature can be directionally machined; 2.2 Calculate the minimum covering cylinder of the feature with the central normal as the axis. If the radius and height of the minimum covering cylinder are both less than the user input values, then the feature is a small feature. Record the center point and axis of the minimum covering cylinder of the small feature as input for subsequent calculation of the robot arm positioning pose. The method for calculating the minimum covering cylinder is as follows: First, project the feature onto a plane with the axis as the normal direction, find its minimum covering circle (existing technology) to obtain the center and radius of the circle, and then calculate the projection points of all discrete points on the axis. The maximum distance between the projection points is the height of the cylinder.

[0039] After filtering the smaller features, the larger features can be filtered by constructing OBBs (Directed Bounding Boxes) for candidate features. The length, width, and height of the OBBs are compared with the processing dimensions to select line features that meet the processing requirements as the larger features. The filtering method is as follows: calculate the OBB for each feature based on existing technology. Assume the calculated OBB has three sides of length... The user-input dimensions of the filter cube are X-axis length a, Y-axis length b, and Z-axis length c. Assume the shortest side of the OBB is... The corresponding axis corresponds to the Z-axis of the screening cube, so the basis for using candidate features as features to be processed is: ,in for The minimum value, for The maximum value.

[0040] After filtering by size features, the large features and small features are divided into two sets for sorting in the next step.

[0041] Step 3: Obtain the starting point of each small feature, select appropriate sorting parameters, and sort them. The sorting method for large features is similar. The following will use... Figure 3 , Figure 4 , Figure 5 The feature sorting method is illustrated using the three types of thin-walled components shown as examples.

[0042] First, regardless of whether it is a sphere-like, cylinder-like, or plane-like feature sorting method, the general feature sorting steps are as follows: calculate the two-dimensional parameters corresponding to the feature starting point, sort the two-dimensional parameters, and map them to obtain the sorted features.

[0043] The following describes three methods for calculating the two-dimensional parameters of sorting objects:

[0044] The plane-like structure uses a coordinate system relative to the local coordinate system. Coordinates are used as two-dimensional parameters;

[0045] The spherical-like objects are obtained by inverse solving in spherical coordinates, and the two-dimensional parameters are selected []. ], Let be the angle between the vector formed by a point on the sphere and the origin, and the z-axis. Let X be the angle between the projection of the vector formed by a point on the sphere and the origin onto the XOY plane and the X-axis. Let the radius of the sphere be:

[0046] (1);

[0047] The cylindrical-like object is obtained by inverse kinematics in cylindrical coordinates, and the two-dimensional parameters are selected. ], Let be the angle between the vector formed by a point on the cylinder and the origin, and the z-axis. This is the z-coordinate of the point.

[0048] The two-dimensional point-based sorting method is as follows: first, sort the first dimension parameter, then cluster, and then sort the second dimension parameter in each category. Based on the two-dimensional parameters, priority order, and sorting order, this invention proposes eight different sorting strategies: (1) horizontal ascending order, vertical ascending order; (2) horizontal ascending order, vertical descending order; (3) horizontal descending order, vertical ascending order; (4) horizontal descending order, vertical descending order; (5) vertical ascending order, horizontal ascending order; (6) vertical ascending order, horizontal descending order; (7) vertical descending order, horizontal ascending order; (8) vertical descending order, horizontal descending order.

[0049] by Figure 3 To explain the sorting result of the reciprocal connection using the sorting strategy (1) in the plane-like model: In the plane-like model, a local coordinate system is established so that the model is approximately parallel to the XOY plane, and the two-dimensional parameters are [ The horizontal ascending order means that the feature ranking results are parallel to the X-axis, with x increasing from smallest to largest. The vertical ascending order means that the y-axis is also ranked from smallest to largest. To achieve this, the xy values ​​of all feature origins are first calculated. Then, all y values ​​are clustered, as shown in the figure, with the y values ​​divided into 6 groups from smallest to largest. Then, the x values ​​in each group are ranked. For example, the first group is ranked from smallest to largest, and since a back-and-forth connection is used, the x values ​​in the second group are arranged from largest to smallest. These are then connected to form the feature ranking connection line shown by the dashed line in the figure.

[0050] by Figure 4 To explain the sorting results of the sphere-like object using the sorting strategy (1) unidirectional connection, the dashed arrow indicates the direction of the features after sorting: In the sphere-like object, the horizontal direction represents the latitude direction parallel to the equator, and the vertical direction is the longitude direction perpendicular to the equator. In strategy 1, the horizontal ascending order means that the sorting is from bottom to top along the latitude direction, and the vertical descending order means that the features are arranged counterclockwise on each latitude line. Unidirectional connection means that after the first circle of latitude lines is completed, the second circle of latitude lines is still counterclockwise.

[0051] by Figure 5 To explain the sorting result of the sphere-like sorting strategy (5) with unidirectional connection, in the cylindrical-like structure, the horizontal direction represents the direction perpendicular to the cylinder axis, and the vertical direction is the direction parallel to the cylinder axis. In the sorting strategy (5), the first vertical ascending order means that the sorting is the first dimension of the feature sorting in the counterclockwise direction parallel to the cylinder axis. The horizontal descending order means that the second dimension parameter (z value) is arranged from large to small. The unidirectional connection is between every two vertical arrangements.

[0052] Step 4: Calculate the pose trajectory of all machining features. All pose trajectories include: 4.1, the positioning connection trajectory of the robot arm moving to each small feature; 4.2, the pose trajectory of the small three axes of the robot arm to each small feature after positioning; and 4.3, the pose trajectory of the robot arm machining the large feature.

[0053] For 4.1, the positioning connection trajectory of the robotic arm moving above each small feature: In step 2 above, a center point and axis (denoted as the positioning point) have been calculated for each selected small feature. First, calculate the pose of the robotic arm when it reaches each small feature localization point. The robot's pose can be determined by its position. Main tool axis direction Secondary tool axis direction Defined as follows: the position of the robotic arm at each small feature positioning point and the direction of the main tool axis are consistent with the positioning point; the direction of the secondary tool axis can be calculated from a fixed direction specified by the user. Let the fixed direction input by the user be... Then the direction of the secondary tool axis at each trajectory point is Then, the safe connection path between the robotic arm reaching each positioning pose is calculated. The safe connection path can be created by constructing a safe geometric model of the workpiece, a technique that is an existing function of non-machining trajectories in the HiperMOS software.

[0054] For 4.2, the pose trajectory of the small three-axis for each small feature after the robotic arm is positioned: For the machining of each small feature, the small three-axis is used as the machining equipment and the small feature is used as the machining target. Based on the trajectory calculation of the HiperMOS line machining step, parameters such as trajectory density / main tool axis, sub-tool axis strategy / trajectory compensation / safety connection strategy can be set to calculate the machining trajectory of the small feature.

[0055] For 4.3, the pose trajectory of the robotic arm for machining large features: For the machining of each large feature, the machining equipment is the robotic arm, the small three-axis is homed and fixed, and the tool held at the end of the small three-axis is the machining tool. The machining trajectory of the large feature can be calculated based on parameters such as the trajectory density of the HiperMOS line machining step, the main tool axis and the secondary tool axis strategy, the trajectory compensation, and the safety connection strategy.

[0056] Step 5: Trajectory Simulation and Execution: The existing HiperMOS simulation module is used to simulate the execution of all steps. When simulating the machining trajectory of small features, the robotic arm moves above the small feature, and the small three-axis moves to perform the machining. When simulating the safe connection trajectory of small features or the machining trajectory of large features, the small three-axis remains stationary while the robotic arm moves. During the equipment's movement, the system detects whether there are collisions, unreachable points, singularities, or joint over-limit issues between the robotic arm / small three-axis / machining tool and the workpiece. If any of these issues are found, the trajectory can be interactively adjusted. Finally, a safe trajectory is sent to the actual equipment for online or offline execution.

[0057] The scope of protection of this invention is not limited to the embodiments described above. Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its scope and spirit. If these modifications and variations fall within the scope of the claims of this invention and their equivalents, then the intent of this invention also includes these modifications and variations.

Claims

1. A multi-stage positioning and machining method for three-dimensional thin-walled parts, characterized in that, Includes the following steps: Step 1: Establish a robotic arm and small three-axis composite machining workstation: Import the 3D model of the robotic arm into the HiperMOS full-chain closed-loop CAM system software, install a small three-axis device at the end of the robotic arm, install machining tools at the end of the small three-axis, and install the workpiece to be processed in the workspace outside the robotic arm; Step 2: Automatically identify closed features on the workpiece to be processed and classify them into small features and large features: First, select several reference surfaces to be processed in the workpiece model, then automatically extract all closed line sets on the reference surfaces, each closed line set as a candidate line feature, and finally filter out small features and large features based on the processing dimensions and feature normal consistency. Step 3: Sort the small and large features selected in Step 2 separately, set the corresponding sorting parameters, and execute automatic sorting to obtain several sorted line features; Step 4: Calculate the pose trajectories of all line features after sorting in Step 3. The pose trajectories include: 4.1, the positioning and connection trajectory of the robotic arm moving above each small feature; 4.2, the pose trajectory of the robotic arm machining each small feature on the small three axes after positioning; 4.3, the pose trajectory of the robotic arm machining the large feature. Step 5: Simulate and execute the pose trajectory calculated in Step 4: Use the existing HiperMOS simulation module to simulate all steps, detect whether there are collisions, unreachable, singularities or joint over-limit problems between the robot arm, small three-axis, machining tool and workpiece during the trajectory operation. If a problem is found, adjust the trajectory. Finally, send the confirmed safe trajectory to the actual equipment for online or offline execution.

2. The multi-stage positioning and machining method for a three-dimensional thin-walled part as described in claim 1, characterized in that: Step 1 specifically involves establishing a robotic arm and a small three-axis composite machining workstation in HiperMOS software. The imported 3D models include the robotic arm, the small three-axis, the machining tool, and the workpiece to be processed. The robotic arm is installed in the world coordinate system, the small three-axis is installed at the end of the robotic arm, the machining tool is installed at the end of the small three-axis, and the workpiece to be processed is installed in the workspace outside the robotic arm's kinematic chain. The clamping and orientation relationships between them are obtained by calibrating the machining tool and the workpiece in the actual scene.

3. The multi-stage positioning and machining method for a three-dimensional thin-walled part as described in claim 1, characterized in that: The specific method for automatically identifying closed features on the workpiece in step 2 is as follows: Select the processing area where the feature to be processed is located in the three-dimensional model of the workpiece to be processed, and use it as several reference surfaces on the workpiece to be processed. These reference surfaces may be connected or discontinuous. Obtain a set of closed lines composed of all boundary lines on all reference surfaces. Each set of closed lines is a candidate line feature.

4. The multi-stage positioning and machining method for a three-dimensional thin-walled part as described in claim 1, characterized in that: The specific method for filtering small features in step 2 is as follows: calculate the center normal and maximum normal change of the candidate line feature. If they are less than a given threshold for the angle between the normal changes, calculate the minimum covering cylinder of the feature with the center normal as the axis. If the radius and height of the minimum covering cylinder are both less than the user input value, then the feature is a small feature. Record the center point and axis of the minimum covering cylinder of the small feature as input for subsequent calculation of the pose of the robotic arm when it reaches the positioning point of each small feature.

5. The multi-stage positioning and machining method for a three-dimensional thin-walled part as described in claim 1, characterized in that: The specific method for filtering large features in step 2 is as follows: After filtering small features, large features are filtered by constructing directed bounding boxes (OBBs) of the remaining candidate line features. The length, width, and height of the OBBs are compared with the processing dimensions to filter out line features that meet the processing requirements as large features. Assume the three side lengths of the candidate feature OBB are... The user-input dimensions of the filter cube are X-axis length a, Y-axis length b, and Z-axis length c. Assume the shortest side of the OBB is... The corresponding axis corresponds to the Z-axis of the screening cube, so the basis for selecting candidate features as large features is: ,in for The minimum value, for The maximum value.

6. The multi-stage positioning and machining method for a three-dimensional thin-walled part as described in claim 1, characterized in that: The sorting parameters in step 3 include the following three types: A. Sorting object; B. Sorting strategy; C. Connection method.

7. The multi-stage positioning and machining method for a three-dimensional thin-walled part as described in claim 6, characterized in that: The sorting objects include workpieces of three shapes: sphere-like, cylinder-like, and plane-like. The sorting strategy includes eight different sorting orders for each type of workpiece: (1) horizontal ascending order, vertical ascending order; (2) horizontal ascending order, vertical descending order; (3) horizontal descending order, vertical ascending order; (4) horizontal descending order, vertical descending order; (5) vertical ascending order, horizontal ascending order; (6) vertical ascending order, horizontal descending order; (7) vertical descending order, horizontal ascending order; (8) vertical descending order, horizontal descending order. The connection methods include both unidirectional and reciprocating connection methods.

8. The multi-stage positioning and machining method for a three-dimensional thin-walled part as described in claim 1, characterized in that: The core of the automatic sorting algorithm in step 3 is to first extract the starting point of the feature as the sorting point, then map the sorting point to two-dimensional parameters according to the type of the sorting object, then perform two-dimensional sorting according to the sorting strategy, and finally map the result of the two-dimensional sorting back to the sorting point to obtain the sorted line features.

9. The multi-stage positioning and machining method for a three-dimensional thin-walled part as described in claim 4, characterized in that: The specific process of calculating the pose trajectory in step 4 is as follows: For 4.1, the positioning connection trajectory of the robotic arm moving to each small feature: calculate a center point and axis for each small feature selected in step 2, and record it as the positioning point. First, calculate the pose of the robotic arm when it reaches each small feature positioning point, and record it as the positioning pose. The pose of the robot is defined by the position, the main tool axis direction, and the secondary tool axis direction. The position of the robotic arm to each small feature positioning point and the main tool axis direction are consistent with the positioning point. The secondary tool axis direction is calculated by the fixed direction specified by the user. Then, calculate the safe connection path between the robotic arm and each positioning pose. The safe connection path is created by constructing a safe geometric model of the workpiece to be processed. For 4.2, the pose trajectory of the small three-axis machining each small feature after the robotic arm is positioned: For the machining of each small feature, the robotic arm first needs to reach the positioning pose of each small feature, that is, the small three-axis is positioned in a fixed pose in space. Then, with the small three-axis as the machining equipment and the small feature as the machining target, the machining trajectory of the small feature is calculated based on the trajectory density of the HiperMOS line machining step, the main tool axis and the secondary tool axis strategy, the trajectory compensation and the safety connection strategy parameters. For 4.3, the pose trajectory of the robotic arm for machining large features: For the machining of each large feature, the machining device is the robotic arm, the small three-axis is homed and fixed, and the tool held at the end of the small three-axis is the machining tool. The machining trajectory of the large feature is calculated based on the trajectory density of the HiperMOS line machining step, the main tool axis and the secondary tool axis strategy, the trajectory compensation and the safety connection strategy parameters.

10. The multi-stage positioning and machining method for a three-dimensional thin-walled part as described in claim 1, characterized in that: Step 5 specifically involves using the existing HiperMOS simulation module to simulate all work steps. When simulating the machining trajectory of a small feature, the robotic arm moves above the small feature, and the small three-axis moves to perform machining. When simulating the positioning and connection trajectory of a small feature or the machining trajectory of a large feature, the small three-axis remains stationary while the robotic arm moves. During the movement of the equipment, it is detected whether there are collisions, unreachable, singularities, or joint over-limit problems between the robotic arm, the small three-axis, the machining tool, and the workpiece to be processed during the trajectory operation. If the above problems are found, the trajectory is interactively adjusted. Finally, the safe trajectory is sent to the actual equipment for online or offline execution.

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