Multi-step positioning machining method for three-dimensional thin-wall part

Abstract

The invention provides a multi-stage positioning machining method for a three-dimensional thin-wall part. The multi-stage positioning machining method comprises the following steps that firstly, a mechanical arm and a small three-axis combined machining workstation are established; 2, automatically identifying closed features on the workpiece to be processed, and dividing the closed features into small features and large features; 3, sorting the small features and the large features screened out in the step 2, setting corresponding sorting parameters, and executing automatic sorting to obtain a plurality of sorted line features; 4, calculating pose tracks of all the line features sequenced in the step 3; and 5, simulating and executing the pose track obtained by calculation in the step 4. According to the multi-stage positioning machining method for the three-dimensional thin-wall part based on the composite equipment composed of the mechanical arm and the small three shafts, machining tracks of various characteristics can be calculated, the high-precision and high-efficiency machining requirements of the machining characteristics are met, the method adapts to part deformation and equipment errors, and the machining efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of three-dimensional thin-walled part contour processing, and in particular relates to a multi-stage positioning processing method for batch line features of three-dimensional thin-walled parts. Background Art

[0002] CNC machine tools and multi-jointed robotic arms (robotic arms) have become the two main machining methods in recent years. CNC machine tools offer excellent rigidity and high precision, making them suitable for machining high-precision parts. However, they are expensive and have a limited machining range. Robotic arms, with their wide range of applications and high flexibility, have been widely used for laser cutting and grinding of automotive parts, as well as for machining small parts. The biggest limitation of robotic arm machining is the equipment's limited accuracy and stability, resulting in suboptimal machining results for some high-precision products.

[0003] Three-dimensional thin-walled parts, such as stamped automotive parts or handicraft parts, are widely used and easy to machine. Their characteristic features are often closed contours on the part surface, such as round, square, and irregularly shaped holes in automotive sheet metal panels. These features are numerous and require manual selection and sorting, which is complex and difficult. Robotic machining suffers from poor stability and results in low precision.

[0004] In order to solve the above-mentioned existing problems, the present invention will provide a multi-stage positioning processing method for three-dimensional thin-walled parts, based on the composite processing of a robotic arm and a small three-axis, and through the automatic selection, allocation, sorting and trajectory calculation of features, to achieve batch, efficient and high-precision processing of three-dimensional thin-walled parts. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a multi-stage positioning processing method for three-dimensional thin-walled parts. The purpose is to automatically and efficiently extract, screen and distribute line features on three-dimensional thin-walled parts in batches, and calculate the position trajectory of the robotic arm and the small three-axis when processing different features, so as to replace tedious and complex manual operations and improve the processing efficiency and precision of three-dimensional thin-walled parts.

[0006] The present invention solves the problems existing in the prior art by adopting the following technical solutions: a multi-stage positioning processing method for three-dimensional thin-walled parts, comprising the following steps: Step 1: Establish a robotic arm and a small three-axis composite machining workstation: Import the 3D model of the robotic arm into the full-chain closed-loop CAM system software HiperMOS, install a small three-axis device at the end of the robotic arm, install a machining tool at the end of the small three-axis, and install the workpiece to be machined 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 to be processed. Then, all closed line sets on the reference surfaces are automatically extracted. Each closed line set is used as a candidate line feature. Finally, the candidate line features are filtered out into small features and large features based on the processing size and feature normal consistency. Step 3: Sort the small features and large features screened out in step 2, set the corresponding sorting parameters, perform automatic sorting, and obtain several sorted line features; Step 4: Calculate the pose trajectory of all line features sorted in step 3. The pose trajectory includes: 4.1. The positioning connection trajectory of the robot arm moving to the top of each small feature; 4.2. The pose trajectory of the small three axes for each small feature after the robot arm is positioned; 4.3. The pose trajectory of the robot arm processing the large feature; Step 5: Simulate and execute the pose trajectory calculated in step 4: Use HiperMOS's existing simulation module to simulate the execution of all work steps and detect whether there are collisions, unreachable areas, singularities, or joint overruns between the robot arm, small three-axis, processing tool, and workpiece during trajectory operation. If any problems are found, adjust the trajectory and finally confirm that the trajectory is safe and send it to the actual device for online or offline execution.

[0007] The step 1 is specifically as follows: a robotic arm and small three-axis composite processing workstation is established in the full-chain closed-loop CAM system software HiperMOS, wherein the three-dimensional models to be imported include the three-dimensional models of the robotic arm, the small three-axis, the processing 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 processing 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 motion chain. The clamping posture relationship between them is obtained by calibrating the tools and workpieces in the actual scene. The tool or workpiece calibration is an existing technology.

[0008] The automatic extraction method of candidate line features in step 2 is specifically as follows: selecting a processing area where the features to be processed are located in the three-dimensional model of a thin-walled workpiece as several reference surfaces on the workpiece, wherein the several reference surfaces are connected or discontinuous, and obtaining a closed line set consisting of all boundary lines on all reference surfaces, each closed line set being a candidate line feature.

[0009] The screening method for small features and large features in step 2 is specifically as follows: in actual processing, not all closed contours need to be processed. The present invention proposes a screening method based on the requirements of processing size and feature normal consistency, and divides candidate line features into three categories: small features, large features and non-processed features. Among them, small features are features that can be processed by the small three-axis, and the feature size range and normal change are within the processing range of the small three-axis. The processing range size of the small three-axis can be described by a cylinder. Since the small three-axis can only perform directional processing, the normal change angle of the small feature is required to be within the threshold range. The specific screening method is: calculate the center normal and maximum normal change of the feature. If it is less than the given normal change angle threshold, the minimum covering cylinder of the feature is calculated with the center normal as the axial direction. If the radius and height of the minimum covering cylinder are both less than the user input value, the feature is a small feature. The center point and axial direction of the minimum covering cylinder of the small feature are recorded as input for subsequent calculation of the robot arm positioning posture.

[0010] After filtering out small features, large features can be filtered by constructing OBB (oriented bounding box) of the remaining candidate features, comparing the length, width and height of OBB with the processing size, and filtering out line features that meet the processing requirements as large features. The specific screening principle is: Assume that the three sides of the candidate feature OBB are , the dimensions of the screening cube entered by the user are X-axis length a, Y-axis length b, and Z-axis length c. Assuming that the shortest side of the OBB is The corresponding axis corresponds to the Z direction of the screening cube, so the basis for the candidate feature to be a large feature is: ,in for The minimum value of for The maximum value of .

[0011] The sorting parameters in step 3 include the following three types: A. sorting object; B. sorting strategy; C. connection method.

[0012] In order to provide a feature sorting method for workpieces of various shapes and features, the three sorting parameters provided in step 3 are specifically: A. Sorting Objects: Supports three types of workpiece shapes: spherical, cylindrical, and plane-like. Users can determine which of the three types of workpieces to process based on their specific shape.

[0013] B. Sorting strategy: Each type provides 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 decide which of the above eight sorting strategies to choose according to processing needs.

[0014] 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 a two-dimensional parameter according to the type of the sorting object, then perform two-dimensional sorting according to the sorting strategy, and map the result of the two-dimensional sorting back to the sorting point to obtain the sorted line feature.

[0015] Taking a spheroid as an example, strategy (1) is explained as follows: First, a local coordinate system of the workpiece is established. For example, a spheroid establishes the coordinate system at the center of the workpiece, with the positive z-axis as the North Pole axis, the horizontal direction represents the latitude direction parallel to the equator, and the vertical direction represents the longitude direction perpendicular to the equator. In strategy 1, the horizontal ascending order and the vertical ascending order result in connecting from the South Pole to the North Pole in a counterclockwise latitude direction.

[0016] C. Connection Mode: Two connection modes are available: One-Way and Reciprocating. Continuing with the example above, the connection mode determines how the first and second wefts are connected. For example, One-Way means both adjacent wefts are connected in a clockwise direction, while Reciprocating means the first weft is connected in a clockwise direction and the second in a counterclockwise direction.

[0017] The posture trajectory calculation process of step 4 is specifically as follows: For 4.1, the positioning connection trajectory of the robot arm moving to the top of each small feature: a center point and an axial direction (recorded as a positioning point) have been calculated for each small feature screened out in step 2. First, the posture of the robot arm when it reaches each small feature positioning point is calculated. The posture 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 robot 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 robot arm and each positioning posture is calculated. The safe connection path can be created by constructing a safe geometric model of the workpiece to be processed. This technology is an existing function of non-processing trajectory in HiperMOS software.

[0018] Regarding 4.2, the position trajectory of the small three-axis for each small feature after the robot is positioned: For the processing of each small feature, the robot arm must first reach the positioning posture of each small feature, that is, position the small three-axis to a fixed posture in space, and then use the small three-axis as the processing equipment and the small feature as the processing target. Based on the parameters such as the trajectory density / main tool axis, secondary tool axis strategy / trajectory compensation / safe connection strategy of the HiperMOS line processing step, the processing trajectory of the small feature can be calculated.

[0019] Regarding 4.3, the posture trajectory of the robot arm for processing large features: For the processing of each large feature, the processing equipment is the robot arm, the small three-axis returns to zero and remains stationary, and the tool clamped at the end of the small three-axis is the tool to be processed. The processing trajectory of the large feature can be calculated based on the parameters such as the trajectory density / main tool axis, secondary tool axis strategy / trajectory compensation / safe connection strategy of the HiperMOS line processing step.

[0020] The step 5 is specifically as follows: using the existing simulation module of HiperMOS to simulate the execution of all work steps; when simulating the processing trajectory of small features, the robot arm moves above the small feature, and the small three-axis moves for processing; when simulating the safe connection trajectory of small features or the processing trajectory of large features, the small three-axis does not move the robot arm and moves; during the movement of the equipment, it is detected whether there is a collision, unreachable, singular, or joint over-limit problem between the robot arm, the small three-axis, the processing tool and the workpiece to be processed during the trajectory operation; if the above problems are found, the trajectory can be interactively adjusted, and finally the safe trajectory is confirmed and sent to the actual equipment for online or offline execution.

[0021] The present invention has the following advantages: 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 trajectories of various features, meet the high-precision and high-efficiency machining requirements of the machining features, adapt to part deformation and equipment errors, and improve machining efficiency; 2. The automatic line feature extraction and sorting method involved in the present invention can be widely used in the actual efficient processing of rotating parts and planar parts, and can improve the processing efficiency of process scenarios represented by laser cutting and quenching. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of the multi-stage positioning processing method of the present invention; Figure 2 Schematic diagram of equipment clamping in an embodiment of the present invention, where: 1-multi-joint serial robot arm model, 2-small three-axis, 3-processing tool, 4-small feature, 5-large feature; Figure 3 Schematic diagram of feature sorting of quasi-planar thin-walled parts in an embodiment of the present invention; Figure 4Schematic diagram of feature sorting of spherical thin-walled parts in an embodiment of the present invention; Figure 5 Schematic diagram of feature sorting for cylindrical thin-walled parts in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following examples and accompanying drawings further illustrate the technical solution of the present invention. This embodiment provides a method and specific implementation for multi-stage positioning processing of three-dimensional thin-walled parts. Figure 1 Flowchart of the multi-stage positioning processing method according to an embodiment of the present invention, corresponding to the following five steps: Step 1: Establish a robotic arm and a small three-axis composite processing workstation, import the 3D model of the robotic arm into the full-chain closed-loop CAM system software HiperMOS, install a small three-axis device at the end of the robotic arm, install the processing tool at the end of the small three-axis, and install the processed workpiece in the workspace outside the robotic arm. Figure 2 As shown, component 1 is a multi-joint serial robot arm, component 2 is a small three-axis installed at the end of the robot arm, which can move linearly in the three directions of XYZ, and component 3 is a processing tool installed at the end of the small three-axis.

[0024] Step 2: Automatically identify closed features on the workpiece and divide them into small features and large features. Figure 2 On the workpiece being machined, the solid outline shown in Part 4 is a small feature, and the dashed outline shown in Part 5 is a large feature. By selecting several reference surfaces on the workpiece to be machined, all closed line sets on all reference surfaces are automatically extracted based on line-surface relationships and continuity. Each closed line set is considered a candidate line feature. The candidate line features are then screened for small and large features based on the machining size and feature normal consistency.

[0025] Small features are those that can be machined by the small three-axis machining system. Their size range and normal variation must fall within the machining range of the small three-axis machining system. The machining range of the small three-axis machining system can be described by a cylinder (the cylinder diameter is the XY travel, the cylinder height is the Z travel, and the small three-axis zero position is located at the center of the cylinder axis). Since the small three-axis machining system can only perform directional machining, the normal variation angle of small features must fall within a threshold. The specific screening method is as follows: 2.1. Discretize the feature into a number of discrete points. Calculate the normal of each discrete point on the reference surface, then the center normal. Calculate the angle between the normal of each discrete point and the center normal. Compare the maximum value of the angle to the user-specified normal variation angle threshold. If it is less than the threshold, the feature is considered directional. 2.2. Calculate the minimum covering cylinder of the feature, with the center normal as the axis. If both the radius and height of the minimum covering cylinder are less than the user-entered values, the feature is considered small. Record the center point and axis of the minimum covering cylinder for this small feature as input for subsequent calculation of the robot's positioning pose. The calculation method of the minimum covering cylinder is to first project the feature into a plane with the axial direction as the normal, find its minimum covering circle (existing technology) to obtain the center and radius, and then calculate the projection points of all discrete points on the axial direction. The maximum distance between the projection points is the height of the cylinder.

[0026] After filtering out small features, large features can be filtered by constructing OBB (oriented bounding box) of candidate features, comparing the length, width and height of OBB with the processing size, and filtering out line features that meet the processing requirements as large features. The screening method is: calculate the OBB of each feature according to the existing technology, assuming that the three sides of the calculated OBB are , the dimensions of the screening cube entered by the user are X-axis length a, Y-axis length b, and Z-axis length c. Assuming that the shortest side of the OBB The corresponding axial direction corresponds to the Z direction of the screening cube, so the basis for the candidate features as the features to be processed is: ,in for The minimum value of for The maximum value of .

[0027] After filtering the large and small features, the large features and small features are divided into two sets for separate sorting in the next step.

[0028] Step 3: Get the starting point of each small feature and select appropriate sorting parameters for sorting. The sorting method for large features is similar. Figure 3 、 Figure 4 、 Figure 5 The feature sorting method is introduced using the three thin-walled parts shown in the figure as examples.

[0029] First, no matter it is a sphere-like, cylinder-like, or plane-like object, the general feature sorting steps are: calculate the two-dimensional parameters corresponding to the feature starting point, sort the two-dimensional parameters, and map the sorted features.

[0030] The following describes the two-dimensional parameter calculation methods for three sorting objects: The plane-like coordinate system is [ ] coordinates as two-dimensional parameters; The spherical body is inversely solved using the spherical coordinate system to obtain the two-dimensional parameter selection [ ], is the angle between the vector formed by a point on the sphere and the origin and the z-axis, It is the angle between the projection vector of the vector formed by a point on the sphere and the origin on the XOY plane and the X axis. is the radius of the sphere: (1); The two-dimensional parameters of the cylindrical body are obtained by inverse solution of the cylindrical coordinate system. ], is the angle between the vector formed by a point on the cylinder and the origin and the z-axis, The z coordinate value of the point.

[0031] The specific method of sorting based on two-dimensional points is as follows: first sort the first dimension parameters, then cluster them, and then sort the second dimension parameters in each category. Based on the two-dimensional parameters, priority order, and positive and negative order of sorting, the present invention proposes eight 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.

[0032] by Figure 3 Take the example to explain the sorting result of the plane-like model using the sorting strategy (1) reciprocating connection: 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 [ ], horizontal ascending means that the feature sorting results are parallel to the X-axis, and x is from small to large, and vertical ascending means that y is also sorted from small to large. To achieve this goal, first calculate the xy values ​​of all feature starting points, then cluster all y values. As shown in the figure, the y values ​​are divided into 6 groups from small to large, and then x is sorted in each group. For example, the first group is from small to large. Due to the reciprocating connection, the x of the second group is arranged from large to small, and they are connected in sequence to form the feature sorting connection line shown as the dotted line in the figure.

[0033] by Figure 4Take the example of the spheroid using the sorting strategy (1) unidirectional connection sorting result, where the dotted arrows represent the feature direction after sorting: in the spheroid, the horizontal direction represents the latitude direction parallel to the equator, and the vertical direction represents the meridian direction perpendicular to the equator. In strategy 1, the horizontal ascending order means that the sorting is from bottom to top in the latitude direction, and the vertical descending order means that on each latitude line, the features are arranged counterclockwise. The unidirectional connection means that after the first circle of latitude lines, the second circle of latitude lines is still counterclockwise.

[0034] by Figure 5 Take the example of spheroids to explain the sorting results of the one-way connection using the sorting strategy (5): in the cylinder-like object, the horizontal direction represents the direction perpendicular to the cylinder axis, and the vertical direction represents the direction parallel to the cylinder axis. In the sorting strategy (5), the vertical ascending order means that the sorting is the first dimension of the feature sorting in the counterclockwise direction parallel to the cylinder axis, and the horizontal descending order means that the second dimension parameter (z value) is arranged from large to small. One-way connection is achieved by one-way connection between every two vertical arrangements.

[0035] Step 4: Calculate the pose trajectory of all processing features. All pose trajectories include: 4.1. The positioning connection trajectory of the robot arm moving to the top of each small feature, 4.2. The pose trajectory of the small three axes for each small feature after the robot arm is positioned, and 4.3. The pose trajectory of the robot arm processing large features.

[0036] For 4.1, the robot moves to the positioning connection trajectory above each small feature: In the above step 2, each small feature selected has a center point and an axis (recorded as a positioning point) calculated. ) First, calculate the position of the robot arm when it reaches each small feature positioning point. The position of the robot can be obtained by the position , main tool axis direction , secondary tool axis direction Definition, where the position of each small feature positioning point guided by the robot arm and the direction of the main tool axis are consistent with the positioning point, and the direction of the secondary tool axis can be calculated by the fixed direction specified by the user. Suppose the fixed direction input by the user is , then the direction of the secondary tool axis at each trajectory point is The safe connection path between each positioning pose of the robot arm is then 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.

[0037] Regarding 4.2, the posture trajectory of the small three-axis for each small feature after the robot arm is positioned: For the processing of each small feature, the small three-axis is used as the processing equipment and the small feature is used as the processing target. Based on the trajectory calculation of the HiperMOS line processing step, the trajectory density / main tool axis, secondary tool axis strategy / trajectory compensation / safe connection strategy and other parameters are set to calculate the processing trajectory of the small feature.

[0038] Regarding 4.3, the posture trajectory of the robot arm for processing large features: For the processing of each large feature, the processing equipment is the robot arm, the small three-axis returns to zero and remains stationary, and the tool clamped at the end of the small three-axis is the processing tool. The processing trajectory of the large feature can be calculated based on the parameters such as the trajectory density / main tool axis, secondary tool axis strategy / trajectory compensation / safe connection strategy of the HiperMOS line processing step.

[0039] Step 5: Trajectory Simulation and Execution: HiperMOS's existing simulation modules are used to simulate the execution of all process steps. When simulating the machining trajectory of small features, the robot moves over the small feature and the small three-axis motion performs machining. When simulating the safe connection trajectory of small features or the machining trajectory of large features, the robot moves without the small three-axis motion. During the equipment movement, the trajectory is checked for collisions, unreachable areas, singularities, or joint overruns between the robot, small three-axis, machining tool, and workpiece. If any of these issues are found, the trajectory can be interactively adjusted. Finally, a safe trajectory is confirmed and sent to the actual equipment for online or offline execution.

[0040] The scope of protection of the present invention is not limited to the above-described embodiments. Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the scope and spirit of the present invention. If such modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A multi-stage positioning processing method for three-dimensional thin-walled parts, characterized in that: The following steps are involved: Step 1: Establish a robotic arm and a small three-axis composite processing workstation: import the 3D model of the robotic arm into the full-chain closed-loop CAM system software HiperMOS, install a small three-axis device at the end of the robotic arm, install a processing tool 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 divide them into small features and large features: First, select several reference surfaces to be processed in the workpiece model to be processed, then automatically extract all closed line sets on the reference surfaces, each closed line set as a candidate line feature, and finally filter the candidate line features into small features and large features according to the processing size and feature normal consistency; Step 3: Sort the small features and large features selected in step 2 respectively, set the corresponding sorting parameters, perform automatic sorting, and obtain several sorted line features; Step 4: Calculate the pose trajectory of all line features sorted in step 3, the pose trajectory includes: 4.1, the positioning connection trajectory of the robot arm moving to the top of each small feature; 4.2, the pose trajectory of the small three axes for each small feature after the robot arm is positioned; 4.3, the pose trajectory of the robot arm processing large features; Step 5: Simulate and execute the pose trajectory calculated in step 4: Use the existing simulation module of HiperMOS to simulate the execution of all work steps, and detect whether there are collisions, unreachable, singular or joint overrun problems between the robot arm, small three-axis, processing tools and the workpiece to be processed during the trajectory operation. If problems are found, adjust the trajectory, and finally confirm that the safe trajectory is sent to the actual device for online or offline execution.

2. A multi-stage positioning processing method for three-dimensional thin-walled parts according to claim 1, characterized in that: The step 1 is specifically to establish a robotic arm and small three-axis composite processing workstation in the HiperMOS software, wherein the 3D models to be imported include the 3D models of the robotic arm, the small three-axis, the processing 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 processing 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 motion chain, and the clamping posture relationship between them is obtained by calibrating the tools and workpieces in the actual scene.

3. A multi-stage positioning processing method for three-dimensional thin-walled parts according to claim 1, characterized in that: The automatic extraction method of candidate line features in step 2 is specifically as follows: selecting a processing area where the features to be processed are located in the three-dimensional model of a thin-walled workpiece as several reference surfaces on the workpiece, wherein the several reference surfaces are connected or discontinuous, and obtaining a closed line set composed of all boundary lines on all reference surfaces, each of which is a candidate line feature.

4. A multi-stage positioning processing method for three-dimensional thin-walled parts as claimed in claim 1, characterized in that: The method for screening small features in step 2 is specifically as follows: calculate the center normal and maximum normal change of the candidate line feature. If it is less than a 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, 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 positioning posture of the robotic arm.

5. A multi-stage positioning processing method for three-dimensional thin-walled parts as claimed in claim 1, characterized in that: The method for selecting large features in step 2 is as follows: after selecting small features, large features are selected by constructing a directed bounding box (OBB) of the remaining candidate line features, comparing the length, width and height of the OBB with the processing size, and selecting line features that meet the processing requirements as large features. Assuming that the three sides of the candidate feature OBB are , the dimensions of the screening cube entered by the user are x-axis length a, y-axis length b, z-axis length c, assuming that the shortest edge in the OBB The corresponding axis corresponds to the Z direction of the screening cube, so the basis for the candidate feature to be a large feature is: ,in for The minimum value of for The maximum value of .

6. A multi-stage positioning processing method for three-dimensional thin-walled parts according to 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. A multi-stage positioning processing method for three-dimensional thin-walled parts according to claim 6, characterized in that: The sorting objects include workpieces of three shapes: spherical, cylindrical, and plane-like; The sorting strategy includes 8 different order sorting strategies 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 modes include one-way connection and reciprocating connection.

8. A multi-stage positioning processing method for a three-dimensional thin-walled part as claimed 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 a two-dimensional parameter according to the type of the sorting object, then perform two-dimensional sorting according to the sorting strategy, and map the result of the two-dimensional sorting back to the sorting point to obtain the sorted line feature.

9. A multi-stage positioning processing method for three-dimensional thin-walled parts as claimed in claim 1, characterized in that: The posture trajectory calculation process of step 4 is specifically as follows: for 4.1, the positioning connection trajectory of the robot arm moving to the top of each small feature: for each small feature screened out in step 2, a center point and an axial direction are calculated, recorded as a positioning point, firstly, the posture of the robot arm when it reaches each small feature positioning point is calculated, and the posture of the robot is defined by the position, the direction of the main tool axis, and the direction of the secondary tool axis, wherein the position of the robot arm to each small feature positioning point and the direction of the main tool axis are consistent with the positioning point, and the direction of the secondary tool axis is calculated by a fixed direction specified by the user, and then the safe connection path between the robot arm and each positioning posture is calculated, and the safe connection path is created by constructing a safe geometric model of the workpiece to be processed; For 4.2, the position trajectory of the small three-axis for each small feature after the robot is positioned: For the processing of each small feature, the robot arm must first reach the positioning posture of each small feature, that is, the small three-axis is positioned to a fixed posture in space, and then the small three-axis is used as the processing equipment and the small feature is used as the processing target. Based on the trajectory density of the HiperMOS line processing step, the main tool axis and the auxiliary tool axis strategy, the trajectory compensation and the safety connection strategy parameters, the processing trajectory of the small feature is calculated; Regarding 4.3, the position trajectory of the robot arm for processing large features: For the processing of each large feature, the processing equipment is the robot arm, the small three-axis returns to zero and remains stationary, and the tool clamped at the end of the small three-axis is the processing tool. The processing trajectory of the large feature is calculated based on the trajectory density of the HiperMOS line processing step, the main tool axis and secondary tool axis strategy, trajectory compensation and safety connection strategy parameters.

10. The multi-stage positioning processing method of a three-dimensional thin-walled part according to claim 1, characterized in that: The step 5 specifically uses the existing simulation module of HiperMOS to simulate all work steps. When simulating the processing trajectory of small features, the robot arm moves above the small feature, and the small three-axis moves for processing. When simulating the safe connection trajectory of small features or the processing trajectory of large features, the small three-axis does not move the robot arm and moves. During the movement of the equipment, it is detected whether there is a collision, unreachable, singularity, or joint over-limit problem between the robot arm, the small three-axis, the processing tool and the workpiece to be processed during the trajectory operation. If the above problems are found, the trajectory is interactively adjusted, and finally the safe trajectory is confirmed and sent to the actual device for online or offline execution.

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