Intelligent control and visual positioning error compensation system of full-automatic riveting machine

Abstract

The application belongs to the field of intelligent control systems, and particularly relates to an intelligent control and visual positioning error compensation system of a full-automatic riveting machine.The system comprises a production manufacturing execution system, a logic control unit, an industrial bus switch, a drawing recognition unit, a three-degree-of-freedom gripper, a visual positioning error compensation unit and a motion control unit.The real-time calibration of the hole position is realized by the visual positioning error compensation system, real-time feedback is given to the motion control system for dynamic error compensation, and the intelligent production scheduling and path planning algorithm is applied in combination with the intelligent control system of the full-automatic riveting machine, so that full-automatic riveting of different types of backing plates and studs can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of intelligent control systems, and particularly relates to an intelligent control and visual positioning error compensation system of a full-automatic riveting machine. BACKGROUND

[0002] At present, in the elevator industry, process requirements are made on the press riveting of different types of backing plates and studs, due to the large difference in the sizes of the backing plate products, and due to the errors of the servo transmission mechanism itself and the cumulative errors of different types of plates in the laser punching in the previous process, a large error is caused between the theoretical position and the actual position of each riveting hole. Therefore, the riveting of the backing plate and the stud is currently in the form of semi-automatic operation of the artificial press riveting machine, the riveting hole position is aligned by artificial riveting, and the press riveting work is performed by the riveting machine. Meanwhile, the traditional control mode cannot realize real-time dynamic adjustment of the deviation parameters and automatic calibration of the riveting hole position, and when the type of the backing plate changes, a large amount of manpower and material resources are wasted for adjustment of the process, assembly efficiency and quality cannot be guaranteed, and the cost of human resources is seriously consumed. SUMMARY

[0003] Based on the above deficiencies, the application is an intelligent control and visual positioning error compensation system of a full-automatic riveting machine, which realizes real-time calibration of the hole position by the visual positioning error compensation system, real-time feedback to the motion control system for dynamic error compensation, and realizes full-automatic press riveting of the backing plate and the stud by applying the intelligent production scheduling and path planning algorithm to the intelligent control system of the full-automatic riveting machine.

[0004] The technical scheme adopted by the application to achieve the above purpose is:

[0005] An intelligent control and visual positioning error compensation system of a full-automatic riveting machine, comprising:

[0006] A production manufacturing execution system for storing production manufacturing data and generating motion control instructions according to motion control data and sending the motion control instructions to a logic control unit;

[0007] A logic control unit for obtaining motion control data according to drawing data and error data and sending the motion control data to the production manufacturing execution system and receiving the motion control instructions;

[0008] An industrial bus switch for data interaction between the logic control unit and a drawing recognition unit, a three-degree-of-freedom gripper unit, a visual positioning error compensation unit and a motion control unit;

[0009] The drawing recognition unit is used for obtaining drawing data corresponding to the plate by recognizing the two-dimensional code on the plate;

[0010] A three-degree-of-freedom gripper unit is used to control the three-axis gripper to grab the plate to a set position based on the motion control instruction when the plate model changes;

[0011] A visual positioning error compensation unit is used to obtain the position of the plate in real time through a camera, map the camera coordinate system and the machine tool coordinate system through a system calibration method, calculate the error between the actual position and the reference position of the plate, and send the error data to the logic control unit;

[0012] A motion control unit is used to control the servo driver according to the motion control instruction.

[0013] The production manufacturing execution system includes an MES system and a product database for storing production manufacturing data.

[0014] The production manufacturing data includes production scheduling, opening and completion time.

[0015] The logic control unit is a PLC control system.

[0016] The drawing recognition unit includes drawing automatic recognition software, a drawing database, and a code scanning mechanism. The code scanning mechanism identifies the two-dimensional code on the plate and sends the two-dimensional code data to the drawing automatic recognition software, which matches the corresponding drawing data in the drawing database.

[0017] The visual positioning error compensation unit identifies the deviation value between the actual position and the reference position of the hole on the plate through edge fitting and distortion correction.

[0018] An intelligent control and visual positioning error compensation method for a full-automatic riveting machine includes the following steps:

[0019] After the plate is placed, the drawing recognition unit identifies the two-dimensional code on the plate, queries the drawing database to determine the type of the plate, and determines the number and position of the holes that need to be riveted for this type of plate, and excludes the holes that cannot be riveted for this type of plate;

[0020] The logic control unit assigns riveting tasks based on the minimum beat principle to determine the number and position of the holes that need to be riveted for each full-automatic riveting machine station;

[0021] The logic control unit plans the sequence of riveting each hole through an optimal path algorithm;

[0022] The motion control unit controls the three-degree-of-freedom gripper unit to grab the plate and move it to the reference position of the hole in sequence after obtaining the position and sequence of the holes that need to be riveted;

[0023] The visual positioning error compensation unit identifies and calculates the deviation value between the actual position and the reference position of the hole through visual positioning, and feeds back the deviation XY value to the logic control unit;

[0024] The logic control unit controls the three-degree-of-freedom gripper unit to move the plate for error compensation, and prepares for riveting.

[0025] The hole positions that cannot be riveted during riveting of the plate include:

[0026] Due to the shielding of the three-degree-of-freedom gripper itself, the riveting machine has no space for riveting the holes, and according to the process requirements, the holes around each gusset plate display are set to have a space.

[0027] The present application has the following advantages and benefits:

[0028] 1. System full-process automation: the intelligent control system of the full-automatic riveting machine can realize full-automatic riveting between different types of plates and studs, identify the size of the current plate and the position and number of holes to be riveted through a drawing recognition module, and dynamically adjust the riveting sequence in real time through an intelligent scheduling module to realize full-automatic intelligent riveting between gusset plates and studs.

[0029] 2. Advanced system algorithm and high reliability: the visual positioning error compensation system of the present application can quickly identify the deviation XY value between the theoretical position and the actual position of each riveting hole position through mapping of multiple coordinate systems by calibration, and real-time feedback to the intelligent control system for rapid dynamic adjustment, alignment of the hole position, and automatic riveting, thereby improving the efficiency and quality of assembly.

[0030] 3. Good system versatility and strong expansibility: the control system of the present application adopts modular design, has open architecture, flexible configuration, can be applied to different industrial bus vision and motion control systems, and the control program and visual positioning error compensation program are expandable, portable, and can be applied to various hardware structures. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a structural diagram of an intelligent control and visual positioning error compensation system of a full-automatic riveting machine.

[0032] Figure 2 It is a structural diagram of an intelligent control and visual positioning error compensation system of a full-automatic riveting machine.

[0033] Figure 3 It is a control system flowchart of a specific implementation of an intelligent control and visual positioning error compensation system of a full-automatic riveting machine. DETAILED DESCRIPTION

[0034] The present application will be further described in detail below in combination with the drawings and examples.

[0035] In order to make the person in the art better understand the technical solutions in the present application, the technical solutions of the present application will be described clearly and completely below in combination with the drawings of the present application.

[0036] The present application relates to an intelligent control and visual positioning error compensation system of a full-automatic riveting machine, which is shown in Figure 1 which comprises a production manufacturing execution system 101, a logic control unit 102, an industrial bus switch 103, a drawing identification unit 104, a three-degree-of-freedom gripper 105, a visual positioning error compensation unit 106, and a motion control unit 107.

[0037] The production manufacturing execution system 101 comprises a MES system, a product database, a production scheduling plan, and a processing time, as described above. The logic control unit 102 can receive and send the MES system data in real time through a server.

[0038] The logic control unit 102 comprises a PLC CPU control system and controls the logic of each unit of the whole system, as described above. The logic control unit 102 supports Profinet bus control, has a motion control module, and has functions of motor parameter adaptive adjustment, beat control, and fault alarm.

[0039] The industrial bus switch 103 comprises a switch supporting multiple industrial buses and is responsible for the data exchange function of the whole system.

[0040] The drawing identification unit 104 comprises an existing automatic drawing identification software (supporting Profinet bus communication protocol), a drawing database, and a code scanning mechanism, which can determine the model of the current plate according to the two-dimensional code data fed back by the code scanning mechanism in real time, and determine the number and theoretical position of the riveting holes of the plate through the model.

[0041] The three-degree-of-freedom gripper 105 comprises a pneumatic gripper mechanism loaded with three transmission shafts, and is equipped with three absolute value encoder servo motors (supporting Profinet bus communication protocol). When the plate model changes, the three-axis gripper can be controlled by a motion control instruction to move the plate position in real time, and can ensure that each hole can be moved to the visual lens for shooting calibration.

[0042] The visual positioning error compensation unit 106 as described above comprises an industrial intelligent camera, a lens, a visual controller (supporting a Profinet bus communication protocol), a light source, mapping of multiple coordinate systems is realized through system calibration, advanced algorithms such as edge fitting and distortion correction are used, the deviation value between the actual position of the hole and the reference position can be quickly identified, the motion control system is guided to move quickly, and the requirements of accurate automatic riveting are met. The XY axis deviation value of the actual position of each hole and the theoretical position can be fed back in real time, distortion correction, feature recognition and other algorithms are used in the visual positioning error compensation process, and the visual accuracy can reach ±0.01mm.

[0043] The motion control unit 107 as described above comprises a servo driver supporting an industrial bus (supporting a Profinet bus communication protocol), each driver controls the corresponding motor to perform position control, speed control and other control modes, and the encoder can feed back the current speed and position in real time, and the motion control module is written in the logic control unit for programming control.

[0044] The complete full-automatic riveting production line disclosed by the application comprises three full-automatic riveting stations to complete riveting of all holes on each backing plate, and the distribution of riveting holes required by each station can realize balanced production capacity, consistent rhythm, efficient flexible production scheduling, balanced production resources and improved production delivery capacity.

[0045] Referring to Figure 2 ,

[0046] The full-automatic riveting station mechanical structure disclosed by the application comprises a gripper 201, a machine vision 202, a three-degree-of-freedom sliding table 203, a transfer platform 204 and a riveter 205.

[0047] The specific implementation steps are described in Figure 3 ,

[0048] Step 1, when the system is ready, the backing plate is fed, after the plate is scanned by the automatic scanning mechanism in the previous process, the PLC controls the manipulator to be transferred to the transfer platform 204 according to the two-dimensional code information, there are secondary positioning mechanisms in the length direction and the width direction according to different plate models and plate placement positions, after the plate is placed, the manipulator informs the logic control unit that the backing plate feeding is completed, and the PLC sends the two-dimensional code information to the drawing recognition unit.

[0049] Step 2, after the drawing recognition unit receives the two-dimensional code information of the plate, the database is queried to determine the type of the plate, and the number and position of the holes that need to be riveted are determined, and the holes that cannot be riveted during riveting of the plate are excluded: 1, the holes without riveting space for the riveter due to the shielding of the gripper 201 are not riveted and are riveted by the next station. 2, according to the process requirements, the holes in a specific space around the display of each backing plate are not riveted. The number and position of the remaining holes need to be riveted.

[0050] Step 3, the logic control unit assigns tasks based on the minimum tact principle, realizes balanced production capacity, consistent tact, efficient flexible production scheduling, balanced production resources, and further determines the absolute coordinate XY value corresponding to the movement of each hole of the three-degree-of-freedom sliding table 204 to the vision lens, and the coordinate value is sent to the PLC logic control unit 102 through Profinet.

[0051] The minimum tact principle is specifically:

[0052] (1) input the circular hole coordinate set;

[0053] (2) determine whether the circular hole interferes, if it interferes, proceed to step (3); if it does not interfere, proceed to step (4);

[0054] (3) determine the interference station label of the interfering circular hole, if all stations are interference stations, the circular hole will not be able to be automatically riveted; if there is a non-interference station for the circular hole, the circular hole is added to the nearest station set;

[0055] (4) determine whether the station of the circular hole set reaches the maximum capacity N, if not, add the circular hole to the station set, if the capacity is reached, proceed to (5);

[0056] (5) add the circular hole to the nearest station set from the original station, and execute (4) again;

[0057] Step 4, path planning system, when confirming the number and position of the holes needed to be riveted for each full-automatic riveter station, the optimal path algorithm is used to plan the riveting sequence of each hole according to the tact requirement, and the data is sent to the PLC logic control unit 102 through Profinet.

[0058] The optimal path algorithm is specifically:

[0059] (1) determine the number of riveted circular holes M in a single station, and the distance between two circular holes is L CiCi+1 , then the loss function of a single station can be represented as:

[0060]

[0061] In the formula, v represents the moving speed, and t represents the riveting time.

[0062] (2) calculate the loss function of each station, and the final loss function is represented as:

[0063] L=MAX(L i )

[0064] (3) Traverse N, recalculate the minimum beat principle, take the loss function when the minimum calculation results as the final riveting path.

[0065] Step 5, motion control system, after getting the position and order of the holes that need to be riveted, the three-degree-of-freedom slide table 203 moves to the theoretical position of the hole in turn, so that the vision camera can take pictures of the current hole that needs to be riveted, and after the vision positioning error compensation system gives the deviation XY value of the actual value and the theoretical value, it can move and calibrate in real time, preparing for the next automatic riveting work.

[0066] Step 6, vision positioning error compensation system, after the three-degree-of-freedom slide table moves to the theoretical position of each hole, trigger the vision camera to take pictures, the vision positioning error compensation system uses advanced algorithms such as edge fitting and distortion correction to quickly identify the deviation value between the actual position of the hole and the reference position, and quickly feedback the deviation XY value to guide the three-degree-of-freedom slide table to move and pin the hole, preparing for the next automatic riveting.

[0067] Step 7, after the three-degree-of-freedom grabber pins the hole, the control system controls the riveter to blow the rivet and lower the riveting head to complete the riveting, and enters the next automatic riveting cycle until all the holes that need to be riveted at this station are riveted.

Claims

1. A method for intelligent control and visual positioning error compensation of a fully automatic riveting machine, characterized in that, Includes the following steps: After the boards are placed, the drawing recognition unit identifies the QR code on the board, queries the drawing database to determine the model of the board, and then determines the number and location of the rivet holes required for this type of board, and excludes the holes that cannot be riveted when riveting this type of board. The logic control unit allocates riveting tasks based on the minimum cycle time principle to determine the number and location of the holes to be riveted at each fully automatic riveting machine station; The logic control unit plans the riveting sequence for each hole using an optimal path algorithm; After obtaining the position and sequence of the holes to be riveted, the motion control unit controls the three-degree-of-freedom gripper unit to grip the sheet metal and move it sequentially to the reference position of the hole. The visual positioning error compensation unit identifies and calculates the deviation between the actual position of the hole and the reference position through visual positioning, and feeds back the deviation XY value to the logic control unit. The logic control unit controls the three-degree-of-freedom gripper unit to move the plate to compensate for errors, in preparation for riveting.

2. The intelligent control and visual positioning error compensation method for a fully automatic riveting machine according to claim 1, characterized in that, The holes that cannot be riveted when riveting the plates include: Because the three-degree-of-freedom gripper itself is obstructed, the riveting machine lacks holes for riveting space and holes for calculating the space around each liner display according to process requirements.

3. An intelligent control and visual positioning error compensation system for a fully automatic riveting machine, used to implement the intelligent control and visual positioning error compensation method for a fully automatic riveting machine as described in claim 1, characterized in that, include: The manufacturing execution system is used to store manufacturing data and generate motion control commands based on motion control data, which are then sent to the logic control unit. The logic control unit is used to obtain motion control data based on drawing data and error data, send it to the manufacturing execution system, and receive motion control commands. The industrial bus switch is used for the logic control unit to interact with the drawing recognition unit, the three-degree-of-freedom gripper unit, the vision positioning error compensation unit, and the motion control unit, respectively. The drawing recognition unit is used to obtain the drawing data corresponding to the board by recognizing the QR code on the board. The three-degree-of-freedom gripper unit is used to control the three-axis gripper to grip the plate to a set position based on motion control commands when the plate material type changes. The visual positioning error compensation unit is used to acquire the position of the board in real time through the camera and map the camera coordinate system to the machine tool coordinate system through the system calibration method, calculate the error between the actual position of the board and the reference position, and send the error data to the logic control unit. The motion control unit is used to control the servo drive according to motion control commands.

4. The intelligent control and visual positioning error compensation system for a fully automatic riveting machine according to claim 3, characterized in that, The Manufacturing Execution System includes a MES system and a product database for storing manufacturing data.

5. The intelligent control and visual positioning error compensation system for a fully automatic riveting machine according to claim 4, characterized in that, The production data includes production schedules and start and completion times.

6. The intelligent control and visual positioning error compensation system for a fully automatic riveting machine according to claim 3, characterized in that, The logic control unit is a PLC control system.

7. The intelligent control and visual positioning error compensation system for a fully automatic riveting machine according to claim 3, characterized in that, The drawing recognition unit includes automatic drawing recognition software, a drawing database, and a barcode scanning mechanism. The barcode scanning mechanism recognizes the QR code on the board and sends the QR code data to the automatic drawing recognition software, which then matches the corresponding drawing data in the drawing database.

8. The intelligent control and visual positioning error compensation system for a fully automatic riveting machine according to claim 3, characterized in that, The visual positioning error compensation unit identifies the deviation between the actual position of the hole on the plate and the reference position through edge fitting and distortion correction methods.

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