Development of the hottest automation unit control

With the continuous expansion of industrial production scale, enterprises have increasingly urgent requirements for the degree of automation. The National Ninth Five year plan focuses on the application of advanced science and technology to transform large and medium-sized state-owned enterprises, and the theme of the National 863 plan robot man has also begun to pay attention to industrialization, promote and apply the existing robot technology to enterprises, and form large-scale automated production, Serve the national economy. China has successfully extended arc welding and spot welding robots to the automotive industry with a high degree of automation, forming products with its own characteristics. The electronic industry has higher requirements for automation and more urgent needs for robots. However, in the electronic assembly line, there are few high-tech equipment developed by our country. Our research project is based on the robot flexible assembly line of video recorder of Nanjing Panda Electronics Group, a well-known enterprise in the electronics industry. The research goal is to develop and design the horizontal screw tightening machine, the robot body for the horizontal screw tightening machine, and the automatic unit controller for the robot body control of the tape insertion/extraction machine needed in this production line

2 characteristics of automatic unit controller

the electronic assembly line has a high degree of automation and great flexibility, which can meet the production of multiple varieties and small batches. Electronic assembly does not need a large load, but the process is complex and the line body is centralized and crowded, so it requires the automatic unit controller to have the following characteristics: ① the controller volume should be small: it is only equivalent to 1/5 of the volume of the arc welding controller, which is slightly larger than the PC chassis we use. In this controller, all units of the conventional controller are included, and a built-in screw machine controller is added. ② Master slave characteristics of the controller: in the past, the relationship between the robot controller we designed and the surrounding is based on the controller as the center, and each action command of the automation unit controller must communicate with the surrounding, which is controlled by the line body, which can choose to control the execution and stop of the robot program. At the same time, it can also use its rich i/o capabilities to control the line body to operate independently and control peripheral devices. These are its master-slave functions. ③ The automation unit controller does not use our commonly used Val robot user language, but adopts tabular language. This tabular language is similar to the NC language commonly used in the factory, which is easier to be accepted by the operator

the three characteristics we summarized above are the main differences between the automation unit controller we designed and the previous robot controller. It is also the difficulty of our design: ① due to the small size of the controller, it brings a series of problems, such as crowded internal unit layout, complex wiring, difficult ventilation and cooling, electromagnetic interference and so on. ② Because the robot is controlled by the line body and the surrounding units, the control logic becomes very complex. ③ Tabular language is different from Val language. It has NC programs that express meaning through G code, SEQ programs and branch programs that express meaning through mnemonics, as well as initialization programs that describe the characteristics of control objects and set control parameters. At the same time, stacking programs determine the motion of robots through data sets. Therefore, its language compilation and interpretation system is very complex

3 functions of automatic unit controller

the automatic unit controller we designed can control four degrees of freedom at most: La and GA mass ratio, molecular weight, material shape and structure, etc. it can meet the requirements of robot control on electronic assembly line. Compared with previous robot control, it cancels the terminal keyboard. By programming the user program of the teaching box, controlling the robot movement, teaching the robot movement point, controlling the screw head movement, the user program can be executed in one step, monitoring the i/o input and controlling the i/o output. The specified user program can be controlled and executed through the front panel, which prompts the robot motion status and protects the system status when the system is abnormal. The controller has rich i/o resources, which are divided into system i/o and user i/o. Through the system i/to get the experimental results, O can complete all the control functions of the front panel and output the robot motion state signal. The user can control each step of the robot motion through the external signal and interrupt the motion planning of each step. The controller can be equipped with a screw machine controller or an external screw machine controller. The controller communicates with the external computer through the RS232 serial port, completes the uploading and downloading of the user program, stores the user application program, and can also cooperate with the NC program through this serial port to input the coordinates of the robot motion target point and guide the robot motion. It is also the input port of sensor information. The robot control adopts NC table language, which keeps the NC program, SEQ sequence program, stacking program, branch program and initialization program alive. The tabular language is simple and versatile. It takes NC program as the main program, and other programs are subroutines of G command scheduling

4 realization of controller

4.1 overall structure of controller hardware

overall structure of controller hardware is mainly composed of the following parts (see the figure below):

overall structure diagram of controller software

(1) main computer system: the main computer system includes main CPU board, multi-function board, i/o board and position servo board. It is the core of the controller. The system is based on multibus, adopts multi CPU parallel structure, and divides the upper and lower computer systems to complete the control of the robot body. This system structure is relatively popular in the design of robot controller, and it can overcome the shortcomings of too complex algorithm and structure of robot controller software system. The superior computer system mainly completes its excellent strength, toughness and processing performance functions, such as trajectory planning, kinematics calculation, user program interpretation, communication with peripheral equipment, monitoring system operation status, and controlling peripheral equipment. The lower computer completes the position closed-loop control of the robot body. The upper computer system communicates with the lower computer through the bus. The multi-function board is developed based on the isbx local bus of the CPU board. It mainly completes the control of the front panel, screw head and z-axis band brake. The design of this board can manage the control operation of the controller itself, so that users can choose the i/o board according to their needs. The i/o board is used for system i/o and user I/O

(2) the front panel mainly includes two parts: the front panel operation board and the front panel control board. The front panel operation board is equipped with control buttons (keys), status display part and LED light status part. The front panel control board mainly completes the functions of operation logic control, display drive, signal isolation, system protection, etc

(3) electric screwdriver drive controller: used to complete the control of screw head and hopper. Screw machine includes: screw hopper and screw machine head. The hopper feeding motor drives the feeding wheel to rotate and applies screws to the screw groove. There is a photoelectric detection device above the screw slot. When the photoelectric signal of the detection screw is on, the feeding motor starts. Normally, when the screw is full, the photoelectric signal of the detection screw is off, and the feeding motor stops. If there is no screw in the hopper or the screw slot is not full within a certain time due to other reasons, the feeding motor stops and alarms. The screw head part includes: screw head upper switch. Before the robot body moves, the controller equipped with screw machine must check whether the screw head is on, that is, whether the upper switch is on. If it is not on, the robot body cannot move. The screw head moves up and down by the push of the cylinder. When the cylinder solenoid valve is on, the screw head moves down, and when it is off, the screw head moves up. The screw head moves to the lower limit switch, and the travel of the screw head can be controlled by adjusting the stop. When the screw head reaches the limit switch, it stops moving and outputs the signal that the screw is screwed in place. The screw driver motor starts to rotate after receiving the start signal. Under normal circumstances, when the screw tightening torque reaches the set value, and the limit switch is on, it stops rotating and outputs the screw tightening end signal. When the set screw tightening time expires, the set torque is not met, or when the torque reaches the set value, and the limit switch is off, the motor stops rotating and outputs the screw tightening end signal and bad signal. The screw machine controller uses 8031 as the CPU to control the action and timing of the screw machine. The setting of screw tightening torque and the control of the action timing of the screw machine are determined by the communication between the main CPU board and the screw machine controller 8031 through 8255 on the multi-function board. The torque section of 100 can be set

(4) power drive unit: used to complete the motor drive of each joint. MSD series 200W full digital AC servo motor and driver of Panasonic company in Japan are selected. It has the characteristics of small volume and full digitalization, which can meet the requirements of small volume of the controller

(5) programming teaching box: it is the main man-machine interface for programming, monitoring, teaching points, trajectory, operation control, speed setting, screw machine operation, test operation, etc. it is a key component that directly affects the performance of the controller. The programming teaching box is self-developed and designed by us. The programming teaching box of all robots on the body is common. In this way, the programming teaching box can be used as an attachment of the robot controller. It is not necessary for each robot to be equipped with a programming teaching box. The programming teaching box can be inserted only when the above work needs to be done. At ordinary times, the execution of the program is completely realized by the front panel switch or system i/o

(6) offline programming computer: a user interface developed on a portable PC based on the windows system. For user programs, upload and download, store user programs, and all controllers on the line are common

4.2 controller computer software system structure

in the production of automotive interior trim, the controller is divided into upper computer and lower computer in computer structure

the upper computer system mainly has the functions of trajectory planning, kinematics calculation, user program interpretation, communication with external computers and peripheral devices, monitoring system operation status, controlling peripheral devices and so on. The upper computer software system is a special operating system for robot control, which combines the core part of irmxiii real-time multitasking operating system with the application program written in C language. Users can complete all functions of the above controller through this system

irmxiii is a real-time multitasking operating system. According to the function of the system, it is tailored by the program developer according to the needs, and combined with the application program to form a real-time control system of multi task running robot. The system is managed by a real-time multitasking operating system. The controller software system includes: startup, initialization, clock interrupt, monitoring, program execution, memory management, programming teaching box control and other modules. We define each module as a task, and each task is assigned a certain priority according to its importance. The tasks are scheduled by the priority of external events and tasks, and only one task occupies CPU at each time, In each planning cycle of the controller, multiple tasks can run at the same time. Each task is converted between running, ready, suspended and sleep. The operation of the robot control system is the conversion process of each task in these four states. The system is an open and modular software system, which is easy to further expand and supplement. The system provides users with a tabular NC language, which is consistent with the NC equipment programming language commonly used in factories, and is simple, intuitive and easy to learn. Due to the real-time characteristics of the system, it can carry out high-speed kinematic operations, timely output system state signals and input external control signals