An end effector configuration method for sheet workpiece picking and placing

Abstract

The present application relates to a kind of end effector configuration methods for plate workpiece grabbing and placing, comprising the following steps: step one, define end effector coordinate system;Step two, end effector modeling;Step three, define plate workpiece size type and end effector corresponding relationship;Step four, parse plate workpiece drawing: parse plate workpiece nesting drawing;Plate workpiece nesting filling diagram is generated, the coordinate and rotation angle of plate workpiece in nesting diagram, extract standard workpiece, generate standard workpiece filling diagram, calculate the length and width of plate workpiece, the size type and barycenter information of plate workpiece;Step five, obtain the scanning area of standard workpiece configuration end effector;Step six, calculate the best position of standard workpiece end effector gripping point;Step seven, calculate the best position of plate workpiece end effector gripping point;Step eight, calculate the rotation angle of end effector before placing plate workpiece.

Description

Technical Field

[0001] This invention relates to the field of intelligent manufacturing and to a method for configuring an end effector for gripping and placing sheet metal workpieces. Background Technology

[0002] In modern factory production lines, when it is necessary to use gantry cranes or robotic arms equipped with end effectors to pick up sheet metal workpieces from cut sheet metal, from sheet metal workpiece conveyor lines, or from material frames, in order to improve production efficiency and reduce manual intervention, it is necessary to automatically configure the optimal adsorption position of the end effector on the sheet metal workpiece, the distance between the suction cups, the on / off status of the suction column, and the rotation angle of the end effector when placing the sheet metal workpiece, based on factors such as the sheet metal workpiece posture, sheet metal workpiece size, and end effector suction cup design. Summary of the Invention

[0003] The purpose of this invention is to provide a method for configuring an end effector for gripping and placing sheet metal workpieces in the field of intelligent manufacturing, which has the advantage of high configuration efficiency. The technical solution of this invention is as follows:

[0004] A method for configuring an end effector for gripping and placing sheet metal workpieces includes the following steps:

[0005] Step 1: Define the end effector coordinate system

[0006] End effectors come in single-piece and dual-piece configurations. If the distance between the two end effectors is fixed, they are treated as a single piece. If the distance between the two end effectors is adjustable, each end effector has an independent coordinate system, which is related to the observer's position. Clockwise rotation of the end effector is a positive number, and counterclockwise rotation is a negative number.

[0007] Step 2, End effector modeling

[0008] (1) Obtain the rotatable angle range, number and size of suction cups, stretchable range between suction cups, size of suction column, spacing between suction columns, and number of suction columns from the end effector design drawings;

[0009] (2) Establish the end effector spatial model and construct the end effector table, suction cup plate table, suction column table and suction column group table;

[0010] Step 3: Define the correspondence between sheet metal workpiece size types and end effectors.

[0011] Different end effectors are used to grip sheet metal workpieces of different sizes at different workstations. The sheet metal workpiece size type is determined according to the sheet metal workpiece size, and the correspondence between the sheet metal workpiece size type and the end effector is defined.

[0012] Step 4: Analyze the sheet metal workpiece drawings

[0013] Analyze the sheet metal workpiece nesting drawing; generate the sheet metal workpiece nesting fill drawing, the coordinates and rotation angle of the sheet metal workpiece in the nesting drawing, extract the standard workpiece, generate the standard workpiece fill drawing, and calculate the length and width of the sheet metal workpiece, the size type and center of gravity information of the sheet metal workpiece;

[0014] Step 5: Obtain the scanning area of ​​the standard workpiece configuration end effector.

[0015] (1) Calculate the area of ​​the pre-scanned region 1

[0016] ① Obtain the minimum value among the four values ​​of the distance between the center of gravity of the sheet metal workpiece and the top, bottom, left, and right edges of the minimum bounding rectangle of the sheet metal workpiece;

[0017] ② The first pre-scanning area is a square, with a side length equal to the minimum value obtained in the previous step × the ratio of the end effector scanning area × 2;

[0018] ③ Calculate the area of ​​pre-scanned region one;

[0019] (2) Calculate the area of ​​the pre-scanned region 2

[0020] ① Obtain the total length and width of the end effector suction column, and use them as the length and width of the pre-scanning region two;

[0021] If there is only one suction cup, directly return the total length and total width of the end effector suction column;

[0022] If there are two suction cups, the total length of the returned end effector suction column is the side length of the scanning area one, and the total width of the returned end effector suction column is also equal to the total length of the scanning area one.

[0023] ② Calculate the area of ​​pre-scanning region two: total length of end effector suction column × total width of end effector suction column;

[0024] (3) Calculate the area of ​​pre-scanned region three.

[0025] ① Obtain the total length and width of the end effector's suction column area:

[0026] If there is only one suction cup, directly return the total length and total width of the end effector suction column;

[0027] If there are two suction cups, the total length of the returned end effector suction column area is the side length of scan area one, and the total width of the returned end effector suction column is also equal to the total length of the returned end effector suction column.

[0028] ② Take the smaller value between the center of gravity of the sheet metal workpiece and the upper and lower edges of the sheet metal workpiece, which is L1;

[0029] ③ Take the smaller value between the center of gravity of the sheet metal workpiece and the left and right edges of the sheet metal workpiece, which is L2;

[0030] ④ The length of the pre-scanning region three = 2 × (L2 - total length of the end effector suction column region / 2);

[0031] ⑤ The width of the pre-scanning area 3 = 2 × (L1 - total width of the end effector suction column area / 2);

[0032] ⑥ If the length or width of the pre-scanned region three is less than or equal to 0, then the pre-scanned region three does not exist, and the calculation of the area of ​​the pre-scanned region three ends; otherwise, the area of ​​the scanned region three is calculated as: length of the pre-scanned region three × width of the pre-scanned region three.

[0033] (4) Determine the final scanning area

[0034] The minimum area among pre-scanning region 1, pre-scanning region 2, and pre-scanning region 3 is taken as the final scan area; this scan area is the maximum range of movement of the center point of the end effector suction column area. When adjusting the position of the end effector, it is necessary to ensure that the center point of the end effector suction column area is within this area.

[0035] Step 6: Calculate the optimal gripping point of the standard workpiece end effector: Iterate through all the sheet metal workpieces that need to be configured with end effectors, obtain the end effectors that can grip the sheet metal workpiece according to the size type of the current sheet metal workpiece, draw the suction column diagram of the end effector according to the same scale as the sheet metal workpiece filling diagram, and execute different selection logic according to different numbers of suction cups to determine the optimal gripping point.

[0036] Step 7: Calculate the optimal gripping point position of the sheet metal workpiece end effector: Obtain the default rotation angle of the standard workpiece end effector and calculate the rotation angle of the end effector based on the rotation angle of the sheet metal workpiece; calculate the gripping point coordinates of the sheet metal workpiece based on the gripping point coordinates of the standard workpiece and the top left corner of the sheet metal workpiece; determine whether the coordinates of the four vertices of the end effector exceed the allowed range set for the top, bottom, left, and right of the sheet metal workpiece. If all vertices do not exceed the sheet metal workpiece, it means that the end effector configuration of the standard workpiece is suitable for the end effector configuration of the current sheet metal workpiece; otherwise, the end effector needs to be reconfigured for the sheet metal workpiece.

[0037] Step 8: Calculate the rotation angle of the front-end pick-up device for placing the workpiece.

[0038] Furthermore, in step two, the constructed table is as follows:

[0039] End effector table: Defines the end effector number, name, rotatable angle range, number of suction cups, stretchable range between suction cups, and scanning area ratio;

[0040] Suction Cup Table: Defines the end effector, suction cup number, suction cup length, and suction cup width information;

[0041] Suction Cup Table: Defines the suction cup plate, suction cup number, suction cup shape, suction cup length, suction cup width, X-coordinate of the top left corner of the suction cup, Y-coordinate of the top left corner of the suction cup, and safety distance;

[0042] Suction column group table: Defines the end effector, suction column group name, suction column group length, and suction column group width.

[0043] Furthermore, the method for step six is ​​as follows:

[0044] (1) Iterate through all the sheet metal workpieces that need to be configured with end effectors, and obtain the end effectors that can grab the sheet metal workpieces according to the size type of the current sheet metal workpiece.

[0045] (2) Draw the suction column diagram of the end effector according to the same scale as the filler diagram of the sheet metal workpiece. When drawing the suction column, add a safety distance to each suction column. For magnetic columns that are not grouped, draw all magnetic columns. For magnetic columns that are grouped, draw the selected magnetic column group.

[0046] (3) Use the suction column area to find the corresponding plate workpiece area in the plate workpiece fill map. Only white pixels are considered in the plate workpiece map. If a suction column area is completely within the plate workpiece area, it is considered that the suction column area coincides with the plate workpiece and the match is successful. Record the successfully matched suction columns. The plate workpiece overlap is equal to "the sum of the areas of all successfully matched suction columns / the area of ​​the plate workpiece area × 100%".

[0047] (4) If there is only one suction cup, execute the following logic:

[0048] ① Calculate the degree of overlap between the center of the end effector's suction column and the center of gravity of the workpiece, and record the current degree of overlap as the maximum degree of overlap, and the current position as the position of the maximum degree of overlap;

[0049] ② Under the premise of ensuring that the center of the end effector's suction column does not exceed the scanning area, scan all positions by moving a set step distance each time, first from top to bottom and then from left to right; calculate the overlap of each position. If the overlap is greater than the overlap in step ①, record the overlap as the new maximum overlap and the position as the new maximum overlap position.

[0050] (5) If there are two suction cups, execute the following logic:

[0051] ① Make the center of the end effector's suction column coincide with the center of gravity of the workpiece. Simultaneously, the suction cups on both sides retract inward from the left and right boundaries of the scanning area until the lead screw extension length on one side is equal to "minimum lead screw extension length / 2". Record the first maximum overlap and the corresponding position.

[0052] ② Under the premise of ensuring that the end effector suction column does not exceed the scanning area, scan all positions within the scanning area; move the end effector suction column in a top-down order, and calculate the overlap of each position by simultaneously contracting inward from the left and right boundaries of the scanning area. Set the step size for moving the end effector suction column from top to bottom and contracting the lead screw from outside to inside; if the overlap of the current position is greater than the maximum overlap, the current overlap is recorded as the new maximum overlap, and the current position is recorded as the new maximum overlap position.

[0053] (6) The position where the end effector's suction column and the workpiece have the maximum overlap is the optimal gripping point.

[0054] Furthermore, the method for step seven is as follows:

[0055] (1) Obtain the default rotation angle of the standard workpiece end effector; this angle defines how many degrees the end effector should be rotated clockwise to make the long side of the end effector parallel to the long side of the standard workpiece.

[0056] (2) The rotation angle of the same type of sheet metal workpiece needs to be added to the default rotation angle of the standard workpiece end effector for angle compensation; if the result exceeds 360°, then the angle needs to be subtracted by 360°.

[0057] (3) Calculate the rotation angle of the end effector based on the rotation angle of the sheet metal workpiece;

[0058] ① Obtain the current rotatable range of the end effector;

[0059] ② If the rotation range of the end effector is -180° to 180°, then the rotation angle of the end effector is the rotation angle of the sheet metal workpiece;

[0060] ③ If the rotation range of the end effector is -90° to 90°, adjust it according to the rotation angle of the sheet metal workpiece:

[0061] If the rotation angle range of the sheet metal workpiece is 0~90°, including 90°, then the rotation angle of the end effector is determined according to the rotation angle of the sheet metal workpiece.

[0062] If the rotation angle range of the sheet metal workpiece is 270°~360° (inclusive), then the rotation angle of the end effector needs to be reduced by 360°.

[0063] If the rotation angle of the sheet metal workpiece is 90°~270° (inclusive), then the rotation angle of the end effector is the rotation angle of the sheet metal workpiece minus 180°. In this case, the center of gravity coordinates of the standard workpiece and the gripping point coordinates of the end effector need to be rotated 180° around the center of the outer rectangle of the sheet metal workpiece.

[0064] (4) Calculate the coordinates of the gripping point of the plate workpiece based on the gripping point coordinates of the standard workpiece.

[0065] ① Obtain the coordinates of the center of gravity of the standard workpiece;

[0066] ② Calculate the coordinates of the gripping point after the standard workpiece has rotated around its center of gravity by a specified angle;

[0067] ③ Obtain the centroid coordinates of the sheet metal workpiece based on the upper left corner of the sheet metal;

[0068] ④ When calculating the center of gravity of the standard workpiece to coincide with that of the sheet metal workpiece, the gripping point is based on the coordinates of the upper left corner of the sheet metal.

[0069] (5) Calculate the coordinates of the four vertices of the upper left corner of the plate after the end effector is rotated at a specified angle;

[0070] ① Calculate the coordinates of the four vertices based on the width and height of the end effector. If there is only one suction cup, the coordinates are the four vertices of that suction cup. If there are two suction cups, the coordinates are the four outermost vertices of the two suction cups after they are stretched.

[0071] ② After rotating the end effector around the center of the circumscribed rectangle by a specified angle, calculate the coordinates of the four vertices of the end effector after rotation;

[0072] ③ When the center of the outer rectangle of the rotating end effector coincides with the gripping point of the workpiece based on the upper left corner of the workpiece, calculate the coordinates of the four vertices of the end effector;

[0073] (6) Determine whether the coordinates of the four vertices of the end effector exceed the allowable range set for the top, bottom, left, and right sides of the board.

[0074] ① Traverse all 4 vertices;

[0075] If the x-coordinate of the current point is less than the allowable range for the left side of the board, it means that the left side is outside the board.

[0076] ② If the y-coordinate of the current point is less than the allowable range on the upper side of the board, it means that the upper side exceeds the board.

[0077] ③ If the x-coordinate of the current point is greater than the allowable range for the right side of the board, it means that the right side exceeds the board.

[0078] ④ If the y-coordinate of the current point is greater than the allowable range for the bottom of the board, it means that the bottom exceeds the board.

[0079] (7) If none of the points exceed the sheet metal, it means that the end effector configuration of the standard workpiece is applicable to the end effector configuration of the current sheet metal workpiece; otherwise, the end effector needs to be reconfigured for the sheet metal workpiece.

[0080] Furthermore, the method for step eight is as follows: Set the long side of the workpiece to be parallel to the long side of the frame at 0°. The current rotation angle of the workpiece and the rotation angle of the end effector are both positive. Determine the rotation angle of the end effector that grips the workpiece. If the calculated rotation angle exceeds the rotation range of the end effector, the workpiece needs to be laid flat in the reverse direction. Subtract 180° from the rotation angle of the workpiece and then calculate the angle at which the workpiece is laid flat in the reverse direction. Attached Figure Description

[0081] Figure 1 Schematic diagram of the coordinate system of the end effector;

[0082] Figure 2 Top view of the end effector;

[0083] Figure 3 Example of a nesting diagram for sheet metal workpieces;

[0084] Figure 4 Example of a filler diagram for a sheet metal workpiece;

[0085] Figure 5 Pre-scanning area one;

[0086] Figure 6 Pre-scanning region two;

[0087] Figure 7 Pre-scanning region three

[0088] Figure 8 Calculation of the optimal gripping point position for the standard workpiece end effector Figure 1

[0089] Figure 9 Calculation of the optimal gripping point position for the standard workpiece end effector Figure 2

[0090] Figure 10 Calculation of the optimal gripping point position for the standard workpiece end effector Figure 3

[0091] Figure 11 Calculation of the optimal gripping point position for the standard workpiece end effector Figure 4

[0092] Figure 12 Schematic diagram for calculating the optimal gripping point of the sheet metal workpiece end effector Detailed Implementation

[0093] The invention and its application scenarios are described below:

[0094] 1. Define the end effector coordinate system

[0095] End effectors come in single-piece and dual-piece configurations. If the distance between the two end effectors is fixed, they can be treated as a single piece. If the distance between the two end effectors can be adjusted within a certain range via a lead screw, then each end effector has an independent coordinate system. This coordinate system is independent of the production line direction but depends on the observer's position.

[0096] The angle of clockwise rotation of the end effector is positive, and the angle of counterclockwise rotation is negative.

[0097] The coordinate system of the observer looking down at the end effector is as follows: Figure 1 As shown:

[0098] 2. End effector modeling

[0099] (1) Based on the CAD drawings of the end effector provided by the customer, obtain information such as the range of rotation angle of the end effector (e.g., ±180°), the number and size of the suction cups, the stretchable range between the suction cups (the shortest and maximum distance between the centers of the two suction cups), the size of the suction column, the spacing between the suction columns, and the number of the suction columns.

[0100] Example of a top view of an end effector planar top view: Figure 2 :

[0101] Figure 2 The end effector has two suction cups, each consisting of two rows of circular suction columns and one row of square suction columns. The circular suction columns are numbered from 1 to 36, and the square suction columns are numbered from 37 to 41. During installation, the suction column numbers must correspond one-to-one with the diagram. The diameter of the circular suction columns is 65mm, and the spacing between them is 0mm. The side length of the square suction columns is 110mm, and the spacing between them is 138.75mm ((1105mm - 110mm × 5) / 4). The distance between the square and circular suction columns is 30mm (117.5mm - 65mm / 2 - 110mm / 2). The shortest extension distance between the two suction cups is 150mm (345mm - 65mm × 3), and the maximum extension distance is 1710mm (1905mm - 65mm × 3). Each suction cup plate is 270mm long (117.5mm + 65mm + 65mm / 2 + 110mm / 2) and 1170mm wide (1105mm + 65mm).

[0102] (2) Establish the end effector spatial model. The end effector modeling mainly involves 4 tables: end effector table, suction cup plate table, suction column table, and suction column group table.

[0103] ① End effector table: Defines the end effector number, name, rotatable angle range, number of suction cups, suction cup stretching range, scanning area ratio, etc.

[0104] ② Suction Cup Table: Defines information such as the end effector, suction cup number, suction cup length, and suction cup width.

[0105] ③ Suction Cup Table: Defines the suction cup plate, suction cup number, suction cup shape (circular, square, etc.), suction cup length (the length of the outer rectangle of the prototype suction cup), suction cup width (the width of the outer rectangle of the prototype suction cup), X coordinate of the upper left corner of the suction cup, Y coordinate of the upper left corner of the suction cup, safety distance, etc.

[0106] ④ Suction Column Group Table: Defines the end effector, suction column group name, suction column group length, suction column group width, etc.

[0107] 3. Define the correspondence between sheet metal workpiece size types and end effectors.

[0108] On the production line, sheet metal workpieces of different sizes are typically gripped at different workstations using different end effectors. The correspondence between sheet metal workpiece size types and end effectors is shown in the table below:

[0109]

[0110] 4. Analyzing sheet metal workpiece drawings

[0111] Depending on project requirements, sheet metal workpiece drawings can be either nesting diagrams or individual sheet metal workpiece drawings. Analyzing these drawings is crucial for configuring end effectors for sheet metal workpieces. The analysis results can generate sheet metal workpiece nesting diagrams, the coordinates and rotation angles of the sheet metal workpiece on the sheet (if a nesting diagram is analyzed), extract standard workpieces, generate standard workpiece filling diagrams, and calculate the length and width of the sheet metal workpiece, its size type, and center of gravity, among other information.

[0112] Both the sheet metal workpiece nesting and filling diagrams have black backgrounds, and the surface of the sheet metal workpiece is filled with white.

[0113] The drawing parsing algorithm is quite complex and will not be described in this document. Please refer to patent CN202310276738.X, which provides a method for parsing nesting drawings for sheet metal workpieces.

[0114] 5. Obtain the scanning area of ​​the standard workpiece configuration end effector.

[0115] (1) Calculate the area of ​​the pre-scanned region 1.

[0116] ① Obtain the minimum value among the four values ​​of the distance between the center of gravity of the sheet metal workpiece and the top, bottom, left, and right edges of the minimum bounding rectangle of the sheet metal workpiece.

[0117] ② The pre-scanning area is a square with a side length of 2”, which is the minimum value obtained in the previous step × the ratio of the end effector scanning area (e.g., 0.8).

[0118] ③ Calculate the area of ​​pre-scan region one. Pre-scan region one is as follows: Figure 5 The area shown in the white box is:

[0119] (2) Calculate the area of ​​the pre-scanned region 2.

[0120] ① Obtain the total length and width of the end effector suction column, and use them as the length and width of the pre-scanning region two.

[0121] If there is only one suction cup, directly return the total length and total width of the end effector suction column.

[0122] If there are two suction cups, the total length of the returned end effector suction column is the side length of the scanning area one, and the total width of the returned end effector suction column is also calculated.

[0123] ② Calculate the area of ​​pre-scanning region two: "Total length of end-effector suction column × Total width of end-effector suction column". Pre-scanning region two is as follows: Figure 6 The area shown in the white box is:

[0124] (3) Calculate the area of ​​pre-scanned region three.

[0125] ① Obtain the total length and total width of the end effector's suction column area.

[0126] If there is only one suction cup, directly return the total length and total width of the end effector suction column.

[0127] If there are two suction cups, the total length of the returned end effector suction column area is the side length of scan area one, and the total width of the returned end effector suction column is returned.

[0128] ② Take the smaller value between the center of gravity of the workpiece and the upper and lower edges of the workpiece, which is L1.

[0129] ③ Take the smaller value between the center of gravity of the sheet metal workpiece and the left and right edges of the sheet metal workpiece, which is L2.

[0130] ④ The length of the pre-scanning region 3 = 2 × (L2 - the total length of the end effector suction column region / 2).

[0131] ⑤ The width of the pre-scanning area 3 = 2 × (L1 - total width of the end effector suction column area / 2).

[0132] ⑥ If the length or width of pre-scanned region three has a value less than or equal to 0, then the calculation of the area of ​​pre-scanned region three ends. Otherwise, calculate the area of ​​scanned region three: length of pre-scanned region three × width of pre-scanned region three. Pre-scanned region three is as follows... Figure 7 The area shown in the white box is:

[0133] (4) Determine the final scanning area

[0134] The minimum area among pre-scan region one, pre-scan region two, and pre-scan region three (when pre-scan region three exists) is taken as the final scan region. This scan region is the maximum range of movement of the center point of the end effector's suction column area. When adjusting the end effector position, it is necessary to ensure that the center point of the end effector's suction column area is within this region.

[0135] 6. Calculate the optimal gripping point of the standard workpiece end effector.

[0136] (1) Iterate through all the sheet metal workpieces that need to be configured with end effectors, and obtain the end effector that can grab the sheet metal workpiece according to the size type of the current sheet metal workpiece.

[0137] (2) Draw the suction column diagram of the end effector according to the same scale as the fill diagram of the sheet metal workpiece. When drawing the suction columns, a safety distance needs to be added to each suction column to avoid the end effector sucking up areas outside the outline of the sheet metal workpiece due to gripping errors. For magnetic columns that are not grouped, all magnetic columns are drawn; for magnetic columns that are grouped, the selected magnetic column group is drawn.

[0138] (3) Use the suction column area to find the corresponding plate workpiece area in the plate workpiece fill map. Only white pixels are considered in the plate workpiece map to exclude interference from other elements such as the plate edge lines. If a suction column area is completely within the plate workpiece area, it is considered to coincide with the plate workpiece, and the match is successful. Record the successfully matched suction columns. The plate workpiece overlap degree is equal to "the sum of the areas of all successfully matched suction columns / the area of ​​the plate workpiece area × 100%".

[0139] (4) If there is only one suction cup, execute the following logic:

[0140] ① Calculate the degree of overlap between the center of the end effector's suction column and the center of gravity of the workpiece, and record the current degree of overlap as the maximum degree of overlap, and the current position as the position of maximum degree of overlap. For example... Figure 8 As shown.

[0141] ② While ensuring the center of the end effector's suction column does not exceed the scanning area, scan all positions by moving a set step size (set in the configuration parameters) each time, starting from top to bottom and then from left to right. Positions from step ① do not need to be scanned again. Calculate the overlap at each position. If the overlap is greater than that in step ①, record this overlap as the new maximum overlap, and record this position as the new maximum overlap position. For example... Figure 9 As shown.

[0142] (5) If there are two suction cups, execute the following logic:

[0143] ① Align the center of the end effector's suction column with the center of gravity of the workpiece. Then, simultaneously retract the suction cups on both sides from the left and right boundaries of the scanning area until the lead screw extension length on one side equals "minimum lead screw extension length / 2". Record the first occurrence of maximum overlap and its corresponding position. For example... Figure 10 As shown.

[0144] ② Ensuring the end effector's suction column does not exceed the scanning area, scan all positions within the scanning area. Positions from step ① do not need to be scanned again. Move the end effector's suction column from top to bottom, calculating the overlap at each position by simultaneously contracting inwards from the left and right boundaries of the scanning area. Set the step size (configured in the settings) for moving the end effector's suction column from top to bottom and contracting the lead screw from outside to inside. If the overlap at the current position is greater than the maximum overlap, record the current overlap as the new maximum overlap, and the current position as the new maximum overlap position. For example... Figure 11 As shown.

[0145] (6) The position where the end effector's suction column and the workpiece have the maximum overlap is the optimal gripping point.

[0146] 7. Calculate the optimal gripping point of the sheet metal workpiece end effector.

[0147] (1) Obtain the default rotation angle of the standard workpiece end effector. This angle defines how many degrees the end effector should be rotated clockwise to make the long side of the end effector parallel to the long side of the standard workpiece.

[0148] (2) The rotation angle of the same type of sheet metal workpiece needs to be added to the default rotation angle of the standard workpiece end effector for angle compensation. If the result exceeds 360°, then the angle needs to be subtracted by 360°.

[0149] (3) Calculate the rotation angle of the end effector based on the rotation angle of the sheet metal workpiece.

[0150] ④ Obtain the rotatable range of the current end effector.

[0151] ⑤ If the rotation range of the end effector is -180° to 180°, then the rotation angle of the end effector is the rotation angle of the sheet metal workpiece.

[0152] ⑥ If the rotation range of the end effector is -90° to 90°, it needs to be adjusted according to the rotation angle of the workpiece. The specific logic is as follows:

[0153] Explanation of the rotation angle of sheet metal workpieces: The rotation angle range is 0°-360°, with no negative numbers. It represents how many degrees a standard workpiece rotates clockwise to achieve the desired position for the sheet metal workpiece. For example... Figure 12 As shown:

[0154] If the rotation angle range of the sheet metal workpiece is 0~90° (inclusive), the rotation angle of the end effector can be determined according to the rotation angle of the sheet metal workpiece.

[0155] If the rotation angle range of the sheet metal workpiece is 270°~360° (inclusive), then the rotation angle of the end effector needs to be reduced by 360°.

[0156] If the rotation angle range of the sheet metal workpiece is 90°~270° (inclusive), then the rotation angle of the end effector is the rotation angle of the sheet metal workpiece minus 180°. In this case, both the center of gravity coordinates of the standard workpiece and the coordinates of the end effector's gripping point need to be rotated 180° around the center of the circumscribed rectangle of the sheet metal workpiece. If there is only one suction cup, the energization status of the standard workpiece's suction column is as follows: Figure 12 As shown, the suction cups need to be reversed symmetrically along the diagonal (i.e., the upper left suction cup corresponds to the lower right suction cup, and the lower left corresponds to the upper right). If there are two suction cups, the energization status of the suction cups on the two suction cups needs to be swapped first, and then the energization status of the suction cups on each suction cup needs to be reversed symmetrically along the diagonal.

[0157] (4) Calculate the coordinates of the gripping point of the plate workpiece based on the coordinates of the gripping point of the standard workpiece. The coordinates of the gripping point of the plate workpiece based on the upper left corner of the plate workpiece are: "taking the upper left corner of the plate workpiece as the origin, the horizontal direction to the right is the positive direction of the X-axis, and the vertical direction downward is the positive direction of the Y-axis".

[0158] ① Obtain the coordinates of the center of gravity of the standard workpiece.

[0159] ② Calculate the coordinates of the gripping point after the standard workpiece is rotated around its center of gravity by the specified angle.

[0160] ③ Obtain the centroid coordinates of the sheet metal workpiece based on the upper left corner of the sheet metal.

[0161] ④ When calculating the center of gravity of the standard workpiece to coincide with the center of gravity of the sheet metal workpiece, the gripping point is based on the coordinates of the upper left corner of the sheet metal.

[0162] (5) Calculate the coordinates of the four vertices of the upper left corner of the plate after the end effector is rotated at a specified angle.

[0163] ④ Calculate the coordinates of the four vertices based on the width and height of the end effector, using the four vertices at the top left corner. If there is only one suction cup, the coordinates are the four vertices of that suction cup. If there are two suction cups, the coordinates are the four outermost vertices of the two suction cups after they have been stretched.

[0164] ⑤ After rotating the end effector around the center of the circumscribed rectangle by a specified angle, calculate the coordinates of the four vertices of the rotated end effector.

[0165] ⑥ When the center of the outer rectangle of the rotating end effector coincides with the gripping point of the workpiece based on the upper left corner of the workpiece, calculate the coordinates of the four vertices of the end effector.

[0166] (6) Determine whether the coordinates of the four vertices of the end effector exceed the allowable range set for the top, bottom, left, and right sides of the board.

[0167] ① Traverse the 4 vertices.

[0168] If the x-coordinate of the current point is less than the allowable range on the left side of the board, it means that the left side is outside the board.

[0169] ② If the y-coordinate of the current point is less than the allowable range on the upper side of the board, it means that the upper side exceeds the board.

[0170] ③ If the x-coordinate of the current point is greater than the allowable range on the right side of the board, it means that the right side is outside the board.

[0171] ④ If the y-coordinate of the current point is greater than the allowable range for the bottom of the board, it means that the bottom is outside the board.

[0172] (7) If none of the points exceed the sheet metal, it means that the end effector configuration of the standard workpiece is applicable to the end effector configuration of the current sheet metal workpiece; otherwise, the end effector needs to be reconfigured for the sheet metal workpiece.

[0173] 8. Calculate the rotation angle of the front-end pick-up device for placing the sheet metal workpiece.

[0174] After being picked up, the sheet metal workpiece generally needs to be placed in a material frame or on a sheet metal workpiece conveyor line. The specific steps for calculating the rotation angle of the front-end gripper when placing the sheet metal workpiece are as follows:

[0175] (1) The long side of the plate workpiece is parallel to the long side of the material frame at 0°. The current rotation angle of the plate workpiece and the rotation angle of the end effector are both positive.

[0176] (2) Assuming the rotation angle of the workpiece on the board is 70° clockwise and the rotation angle of the gripper at the front end of the workpiece is 50° clockwise, then the rotation angle of the gripper at the front end of the workpiece = 50° - 70° = -20°.

[0177] (3) If the calculated rotation angle exceeds the rotation range of the end effector, the workpiece needs to be laid flat in the reverse direction. First, subtract 180° from the rotation angle of the workpiece, and then apply the above formula to obtain the angle at which the workpiece is laid flat in the reverse direction.

Claims

1. A method for configuring an end effector for gripping and placing sheet metal workpieces, comprising the following steps: Step 1: Define the end effector coordinate system End effectors come in single-piece and dual-piece configurations. If the distance between the two end effectors is fixed, they are treated as a single piece. If the distance between the two end effectors is adjustable, each end effector has an independent coordinate system, which is related to the observer's position. Clockwise rotation of the end effector is a positive number, and counterclockwise rotation is a negative number. Step 2, End effector modeling (1) Obtain the rotatable angle range, number and size of suction cups, stretchable range between suction cups, suction column size, suction column spacing and suction column numbering information of the end effector design drawings; (2) Establish the end effector spatial model and construct the end effector table, suction cup plate table, suction column table and suction column group table; Step 3: Define the correspondence between sheet metal workpiece size types and end effectors. Different end effectors are used to grip sheet metal workpieces of different sizes at different workstations. The sheet metal workpiece size type is determined according to the sheet metal workpiece size, and the correspondence between the sheet metal workpiece size type and the end effector is defined. Step 4: Analyze the sheet metal workpiece drawings Analyze the sheet metal workpiece nesting drawing; generate the sheet metal workpiece nesting fill drawing, the coordinates and rotation angle of the sheet metal workpiece in the nesting drawing, extract the standard workpiece, generate the standard workpiece fill drawing, and calculate the length and width of the sheet metal workpiece, the size type and center of gravity information of the sheet metal workpiece; Step 5: Obtain the scanning area of ​​the standard workpiece configuration end effector. (1) Calculate the area of ​​the pre-scanned region 1 ① Obtain the minimum value among the four values ​​of the distance between the center of gravity of the sheet metal workpiece and the top, bottom, left, and right edges of the minimum bounding rectangle of the sheet metal workpiece; ② The pre-scanning area is a square with a side length equal to the minimum value obtained in the previous step × the ratio of the end effector scanning area × 2; ③ Calculate the area of ​​pre-scanned region one; (2) Calculate the area of ​​the pre-scanned region 2 ① Obtain the total length and width of the end effector suction column, and use them as the length and width of the pre-scanning region two; If there is only one suction cup, directly return the total length and total width of the end effector suction column; If there are two suction cups, the total length of the returned end effector suction column is equal to the side length of the pre-scanned area one, and the total width of the returned end effector suction column is equal to the total width of the returned end effector suction column. ② Calculate the area of ​​pre-scanning region two: total length of end effector suction column × total width of end effector suction column; (3) Calculate the area of ​​pre-scanned region three. ① Obtain the total length and width of the end effector's suction column area: If there is only one suction cup, directly return the total length and total width of the end effector suction column; If there are two suction cups, the total length of the returned end effector suction column area is the side length of the pre-scan area one, and the total width of the returned end effector suction column is also equal to the total width of the returned end effector suction column. ② Take the smaller value between the center of gravity of the sheet metal workpiece and the upper and lower edges of the sheet metal workpiece, which is L1; ③ Take the smaller value between the center of gravity of the sheet metal workpiece and the left and right edges of the sheet metal workpiece, which is L2; ④ The length of the pre-scanning region 3 = 2 × (L2 - total length of the end effector suction column region / 2); ⑤ The width of the pre-scanning area 3 = 2 × (L1 - total width of the end effector suction column area / 2); ⑥ If the length or width of the pre-scanned region three has a number less than or equal to 0, then the pre-scanned region three does not exist, and the calculation of the area of ​​the pre-scanned region three ends; otherwise, the area of ​​the pre-scanned region three is calculated as: length of the pre-scanned region three × width of the pre-scanned region three. (4) Determine the final scanning area The pre-scanning area with the smallest area among pre-scanning area one, pre-scanning area two, and pre-scanning area three is taken as the final scan area; this scan area is the maximum range of movement of the center point of the end effector suction column area. When adjusting the position of the end effector, it is necessary to ensure that the center point of the end effector suction column area is within this area. Step 6: Calculate the optimal gripping point of the standard workpiece end effector: Iterate through all the sheet metal workpieces that need to be configured with end effectors, obtain the end effectors that can grip the sheet metal workpiece according to the size type of the current sheet metal workpiece, draw the suction column diagram of the end effector according to the same scale as the sheet metal workpiece filling diagram, and execute different selection logic according to different numbers of suction cups to determine the optimal gripping point. Step 7: Calculate the optimal gripping point position of the sheet metal workpiece end effector: Obtain the default rotation angle of the standard workpiece end effector and calculate the rotation angle of the end effector based on the rotation angle of the sheet metal workpiece; calculate the gripping point coordinates of the sheet metal workpiece based on the gripping point coordinates of the standard workpiece and the top left corner of the sheet metal workpiece; determine whether the coordinates of the four vertices of the end effector exceed the allowed range set for the top, bottom, left, and right of the sheet metal workpiece. If all vertices do not exceed the sheet metal workpiece, it means that the end effector configuration of the standard workpiece is suitable for the end effector configuration of the current sheet metal workpiece; otherwise, the end effector needs to be reconfigured for the sheet metal workpiece. Step 8: Calculate the rotation angle of the front-end pick-up device for placing the workpiece.

2. The end effector configuration method for gripping and placing sheet metal workpieces according to claim 1, characterized in that, The table constructed in step two is as follows: End effector table: Defines the end effector number, name, rotatable angle range, number of suction cups, stretchable range between suction cups, and scanning area ratio; Suction Cup Table: Defines the end effector, suction cup number, suction cup length, and suction cup width information; Suction Cup Table: Defines the suction cup plate, suction cup number, suction cup shape, suction cup length, suction cup width, X-coordinate of the top left corner of the suction cup, Y-coordinate of the top left corner of the suction cup, and safety distance; Suction column group table: Defines the end effector, suction column group name, suction column group length, and suction column group width.

3. The end effector configuration method for gripping and placing sheet metal workpieces according to claim 1, characterized in that, The method for step six is ​​as follows: (1) Iterate through all the sheet metal workpieces that need to be configured with end effectors, and obtain the end effectors that can grab the sheet metal workpieces according to the size type of the current sheet metal workpiece. (2) Draw the suction column diagram of the end effector according to the same scale as the filler diagram of the sheet metal workpiece. When drawing the suction column, add a safety distance to each suction column. For magnetic columns that are not grouped, draw all magnetic columns. For magnetic columns that are grouped, draw the selected magnetic column group. (3) Use the suction column area to find the corresponding plate workpiece area in the plate workpiece fill map. Only white pixels are considered in the plate workpiece map. If a suction column area is completely within the plate workpiece area, it is considered that the suction column area coincides with the plate workpiece and the match is successful. Record the successfully matched suction columns. The plate workpiece overlap is equal to "the sum of the areas of all successfully matched suction columns / the area of ​​the plate workpiece area × 100%". (4) If there is only one suction cup, execute the following logic: ① Calculate the degree of overlap between the center of the end effector's suction column and the center of gravity of the workpiece, and record the current degree of overlap as the maximum degree of overlap, and the current position as the position of the maximum degree of overlap; ② Under the premise of ensuring that the center of the end effector's suction column does not exceed the scanning area, scan all positions by moving a set step distance each time, first from top to bottom and then from left to right; calculate the overlap of each position. If the overlap is greater than the overlap in step ①, record the overlap as the new maximum overlap and the position as the new maximum overlap position. (5) If there are two suction cups, execute the following logic: ① Align the center of the end effector's suction column with the center of gravity of the workpiece. Simultaneously retract the suction cups on both sides from the left and right boundaries of the scanning area until the lead screw extension length on one side is equal to "minimum lead screw extension length / 2". Record the first maximum overlap and the corresponding position. ② Under the premise of ensuring that the end effector suction column does not exceed the scanning area, scan all positions within the scanning area; move the end effector suction column in a top-down order, and calculate the overlap of each position by simultaneously contracting inward from the left and right boundaries of the scanning area. Set the step size by moving the end effector suction column from top to bottom and contracting the lead screw from outside to inside; if the overlap of the current position is greater than the maximum overlap, the current overlap is recorded as the new maximum overlap, and the current position is recorded as the new maximum overlap position. (6) The position where the end effector's suction column and the workpiece have the maximum overlap is the optimal gripping point.

4. The end effector configuration method for gripping and placing sheet metal workpieces according to claim 1, characterized in that, The method for step seven is as follows: (1) Obtain the default rotation angle of the standard workpiece end effector; this angle defines how many degrees the end effector should be rotated clockwise to make the long side of the end effector parallel to the long side of the standard workpiece. (2) The rotation angle of the same type of sheet metal workpiece needs to be added to the default rotation angle of the standard workpiece end effector for angle compensation; if the result exceeds 360°, then the angle needs to be subtracted by 360°. (3) Calculate the rotation angle of the end effector based on the rotation angle of the sheet metal workpiece; ① Obtain the current rotatable range of the end effector; ② If the rotation range of the end effector is -180° to 180°, then the rotation angle of the end effector is the rotation angle of the sheet metal workpiece; ③ If the rotation range of the end effector is -90° to 90°, adjust it according to the rotation angle of the sheet metal workpiece: If the rotation angle range of the sheet metal workpiece is 0~90°, including 90°, then the rotation angle of the end effector is determined according to the rotation angle of the sheet metal workpiece. If the rotation angle range of the sheet metal workpiece is 270°~360° (inclusive), then the rotation angle of the end effector needs to be reduced by 360°. If the rotation angle of the sheet metal workpiece is 90°~270° (inclusive), then the rotation angle of the end effector is the rotation angle of the sheet metal workpiece minus 180°. In this case, the center of gravity coordinates of the standard workpiece and the gripping point coordinates of the end effector need to be rotated 180° around the center of the outer rectangle of the sheet metal workpiece. (4) Calculate the coordinates of the gripping point of the plate workpiece based on the gripping point coordinates of the standard workpiece. ① Obtain the coordinates of the center of gravity of the standard workpiece; ② Calculate the coordinates of the gripping point after the standard workpiece has rotated around its center of gravity by a specified angle; ③ Obtain the centroid coordinates of the sheet metal workpiece based on the upper left corner of the sheet metal; ④ When calculating the center of gravity of the standard workpiece to coincide with that of the sheet metal workpiece, the gripping point is based on the coordinates of the upper left corner of the sheet metal. (5) Calculate the coordinates of the four vertices of the upper left corner of the plate after the end effector is rotated at a specified angle; ① Calculate the coordinates of the four vertices based on the width and height of the end effector. If there is only one suction cup, the coordinates are the four vertices of that suction cup. If there are two suction cups, the coordinates are the four outermost vertices of the two suction cups after they are stretched. ② After rotating the end effector around the center of the circumscribed rectangle by a specified angle, calculate the coordinates of the four vertices of the end effector after rotation; ③ When the center of the outer rectangle of the rotating end effector coincides with the gripping point of the workpiece based on the upper left corner of the workpiece, calculate the coordinates of the four vertices of the end effector; (6) Determine whether the coordinates of the four vertices of the end effector exceed the allowable range set for the top, bottom, left, and right sides of the board. ① Traverse all 4 vertices; If the x-coordinate of the current point is less than the allowable range for the left side of the board, it means that the left side is outside the board. ② If the y-coordinate of the current point is less than the allowable range on the upper side of the board, it means that the upper side exceeds the board. ③ If the x-coordinate of the current point is greater than the allowable range for the right side of the board, it means that the right side exceeds the board. ④ If the y-coordinate of the current point is greater than the allowable range for the bottom of the board, it means that the bottom exceeds the board. (7) If none of the points exceed the sheet metal, it means that the end effector configuration of the standard workpiece is applicable to the end effector configuration of the current sheet metal workpiece; otherwise, the end effector needs to be reconfigured for the sheet metal workpiece.

5. The end effector configuration method for gripping and placing sheet metal workpieces according to claim 1, characterized in that, Step eight is as follows: Set the long side of the workpiece to be parallel to the long side of the frame at 0°. The current rotation angle of the workpiece and the rotation angle of the end effector are both positive. Determine the rotation angle of the end effector that grips the workpiece. If the calculated rotation angle exceeds the rotation range of the end effector, the workpiece needs to be laid flat in the reverse direction. Subtract 180° from the rotation angle of the workpiece and then calculate the angle at which the workpiece is laid flat in the reverse direction.

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