Automobile windshield assembly workstation based on ABB industrial robot

. Traditional automotive companies’ manual assembly line operation with higher labor intensity, lower efficiency, and product quality is difficult to ensure and other shortcomings have been unable to meet the growing demand for industry development and quality assurance. This project with the IRB-1410 model robot as the core robot, combined with an industrial vision system and gluing system, completed a vehicle windshield assembly workstation based on ABB industrial robots, to improve the degree of automation while greatly improving the efficiency and degree of operational safety, and can both improve the visibility of companies while establishing a good image of the enterprise.


Introduction
With the rapid development of the automobile manufacturing industry, the manufacturer's requirements for efficiency and precision of automobile manufacturing are increasing as the market demand increases.Not only to reduce the workforce's labor intensity, and ensure production accuracy, but also to carry out process innovation and equipment upgrading, constantly improve the coupling parameters to optimize the degree of automation, and meet the flexibility requirements.In this regard, this project is based on practical applications, with actual production operations as the blueprint for the design of the system, integrated with the ABB robot's high-precision, multi-degree-of-freedom control technology, and gluing equipment, industrial vision technology.Finally, online programming to set the gluing speed, turning radius, offset height, and other parameters to meet the needs of the actual production process, improve the adaptability and robustness of the gluing process, effectively improve production efficiency, and contribute to achieving the production intelligence of enterprises [1][2][3][4][5][6][7][8][9].

Overall design scheme
The functional requirements of this project lie in the assembly of windshields of automobiles in actual automobile manufacturing operations, so the windshield installation system based on IRB-1400 industrial robots is designed according to actual needs, and the overall design scheme is shown in Figure 1.

System function design
(1) The absolute elbow joint motion instruction MoveAbsJ by six axes angle defined coordinates to make the robot back to the starting point, place detection, suction cup, gluing signals.
(2) Components to generate random signals, corresponding to the random appearance of glass shapes, industrial cameras to identify the shape of the glass.(3) After the recognition is completed, the robot searches for the corresponding type of glass in the glass incoming material library according to the received signal.(4) After finding the corresponding type of glass, the suction cup tGripper picks up the glass and enters the gluing process to glue the glass edges.(5) The robot installs the glued glass into the cab glass slot.The program flow is shown in Figure 2:

Layout design
The system contains four fences, a car frame, a glass placement rack, three glasses, an IRB-1410 robot, a demonstrator, a control terminal PC, a control cabinet, a base, a gluing device, and a gluing supply device, and the specific layout is shown in Figure 3.

Board Hardware Setup
The robot provides various forms of communication, including master kinetic, slave functions, and data communication.The ABB IRB1410 industrial robot workstation uses standard communication methods.There is a DSQC652 board in the control cabinet.The DSQC652 board has 16 inputs and 16 outputs.The way the board address is set up is shown in Figure 4.

I/O Settings
The I/O signals used in this workstation are assigned as shown in Table 1 and Table 2 below.

Control program
The connection of this design is shown in Fig. 5, which shows that the ABB robot controller, robot, industrial camera, and glue supply system are connected.

Determination of quality standards for gluing
To prevent excessive glue overflow after pressing, it is necessary to carry out a technical inspection of the gluing area at the same time in the product design stage.The location of the glue application is generally at the edge of the object to be bonded about 5mm from the edge of both sides of the bonding surface, as shown in Figure 6, to ensure that the bonding surface is not contaminated, it should be fixed with a special glue.Flange edge bonding requires the width of the flange edge to be greater than 14mm, to ensure the effect of the width of the adhesive layer after bonding, to avoid overflow of glue (as shown in Figure 7).The quality of the glue application must meet the above standards.
4 Software design

Logical arrangement of the robot program for each process
To program a good understanding of the random detection of the three pieces of glass were named r1, r2, and r3.robot by six axes angle definition coordinates of the absolute elbow joint motion instruction.MoveAbsJ to make the robot back to the starting point, set the detection, suction cups, and gluing signals.
In the rchushuhua program for the initialization of the workstation, the component generates a random signal, corresponding to the random appearance of the glass shape, a reliance program for industrial cameras to identify the shape of the glass.After the recognition is completed, according to the accepted signals in the glass material library find the corresponding type of glass.After finding the corresponding type of glass, the r_pick_tujiao_put program picks up the glass with the suction cup tGripper, enters the gluing process, glues the glass edges, and then installs it into the card slot.

Robot Routine Program Arrangement
The control programs for ABB robots are written in the RAPID language, and each robot usually has one task containing several program modules in which routines are written to control the robot's actions.In general, one program module is often sufficient for small workstations, but for large workstations, several program modules can be created to hold the entire program, and the programs and data from each module call each other.Only one program module is needed for the robot of this design because the program is of medium complexity.However, to make the program logic smooth and clear, more readable, and easier to change, the program module creates nine new routines, whose main program settings are shown in Table 3.

Debugging results
The robot demonstrator switch was turned to automatic operation in the illustrated workstation, then the robot was run to the initial position in preparation for specific actions, and then the operation mode was adjusted to continuous in the simulation settings (as shown in Figure 8).When the program starts, the industrial camera starts to identify the glass model to be installed: shoot the glass and compare it with the shape of the glass in the database, as shown in Figure 9(a), after identifying the glass model, the identified content is sent to the robot, which drives the robot to find the corresponding model of glass after receiving the signal, as shown in Figure 9(b), and then picks up the glass and enters into gluing: the gluing equipment calls the track of the corresponding model to complete the gluing of the glass according to the received glass model, as shown in Figure 9(c) after the gluing procedure is completed, the robot installs the glass into the slot, as shown in Figure 9(c), and the robot then installs the glass into the slot.model calls the corresponding model trajectory to complete the glass gluing, as in Figure 9(c), after the gluing program is completed, the robot installs the glass into the card slot, as in Figure 9(d).
According to the actual situation and the requirements of the production beat, it is necessary to carry out comprehensive adjustments and optimization of the robot's motion pickup, installation, and glue application.Robot motion speed directly affects the quality of the product and the production cycle, so in the assembly of an automotive cab windshield project adjusting the robot motion speed to the appropriate range is one of the effective ways to solve this problem, but also an important means of eliminating potential safety hazards.

Conclusion and prospect analysis
This project is mainly used for vehicle cab windshield automatic glue application and automatic bonding.This design greatly reduces the unit operating time, and at the same time improves the robustness of this system in the industrial operation site, This design's flexibilization aspects are also related to the configuration, providing great flexibility and product scalability.This project adopts several new technologies, such as a vision system application, to realize the automated installation of windshield glass, with the robot as the main body of the operation, to provide uniform, consistent, and accurate installation, and adhesive to ensure the quality of construction.However, in the design and application of the whole system, there are still the following problems to be solved.
(1) Precision problem of alignment and positioning When aligning, the positioning needs to be confirmed accurately.Currently, there are three types of glass, mainly with different length and width specifications, so the alignment method designed in this project not only compares the effect of the glass size error on the adhesive but also compares the reading signal and the preset standard value.After the model of the glass is determined, the robot calls the corresponding glass gluing program.
(2) Gripper design requirements Due to the different sizes and curvatures of the glass, it is necessary to carefully consider the installation position and number of suction cups in the end picker so that each size of glass can be sucked by the suction cups.Simulation and experimental results show that: the use of vacuum suction cups as end pickups enables the suction cups to accurately suck the glass and lift the glass; in addition, to avoid deviation when the manipulator grips the glass, it needs to be equipped with a deviation correction device to prevent the glass from deviating from the set direction.A manual correction mechanism is also needed to ensure that the suction cup can accurately adsorb the glass.
Thanks to other authors who participated in the design research with me and helped to complete this article.

Fig. 1 .
Fig. 1.Block diagram of the system scheme This workstation mainly accomplishes three tasks: (1) Visual inspection: applying an industrial camera to inspect the randomly appearing glass models that need to be installed; (2) Automatic gluing: Pick up the corresponding model of glass for the gluing process, at the same time, depending on the setup of different glass models, corresponding to different gluing programs.(3) Glass assembly: The robot grabs the glass and installs it in the windshield mounting slot of the driver's cab, meanwhile, it should correspond to different installation plans according to the different settings of the glass models.After the detection of the vision unit, the detected model of the windshield glass on the glass placement rack in the form of digital signals, through the communication unit sent to the control unit.The control unit outputs a signal to control the gluing unit to apply the glue, and then the assembly unit assembles the windshield into place.

3 Analysis of some main programs A
complete set of robot programs is written in this project, the most important programs are main program main, initialization program rchushihua, detection program rjiance, gluing p rogram r1/r2/r3,picking up glass and gluing assembly program rpick_tj_put1/rpick_tj_put2/ rpick_tj_put3.The industrial robot control program starts from the main program, which is mainly responsible for controlling the running sequence of the industrial robot and calling various routine programs.mainprogram is as follows.PROC main() rchushihua;!The system enters the initialization (set speed, signal, and other parameters) PulseDO\PLength:=1,do_copy; pulse output instruction, run do_copy MoveJ pjiance,v1000,fine,tool0\WObj:=wobj0;Excess point ENDIF (IF judgment instruction, if di1=1 to run the first glass of the program, di2=1 to run the second glass of the program, di3=1 to run the third glass of the program) rchushihua; program initialization stop ENDPROC