Typical control system and structure of industrial robot
Abstract: Industrial robot is composed of three basic parts: main body, drive system and control system. The main body is the base and the actuator, including the arm, wrist, and hand, and some robots also have a walking mechanism. Most industrial robots have 3 to 6 degrees of freedom of movement, of which the wrist usually has 1 to 3 degrees of freedom of movement; the drive system includes a power unit and a transmission mechanism to cause the actuator to generate corresponding actions; the control system is based on input The program sends command signals to the drive system and the actuator and controls them.
Keywords: industrial robot control system structure system
(I) Functions to be achieved by the industrial robot control system
The robot control system is an important part of the robot. It is used to control the manipulator to complete specific tasks. Its basic functions are as follows:
(1) Memory function: It stores the operation sequence, movement path, movement mode, movement speed and information related to the production process.
(2) Teaching function: offline programming, online teaching, indirect teaching. Online teaching includes teaching box and guided teaching.
(3) Contact function with peripheral equipment: input and output interface, communication interface, network interface, synchronization interface.
(4) Coordinate setting function: There are four coordinate systems: joint, absolute, tool, and user-defined. (5) Human-machine interface: teaching box, operation panel, display screen.
(6) Sensor interface: position detection, vision, touch, force, etc.
(7) Position servo function: robot multi-axis linkage, motion control, speed and acceleration control, dynamic compensation, etc.
(8) Fault diagnosis safety protection function: system status monitoring during operation, safety protection under fault state and self-diagnosis of fault.
(II) Composition of industrial robot control system (Figure 1)
(1) Control computer: the dispatching command mechanism of the control system. Generally, there are 32-bit and 64-bit microcomputers and microprocessors, such as Pentium series CPUs and other types of CPUs.
(2) Teaching box: The working trajectory and parameter settings of the teaching robot, as well as the interactive operation of all human-computers, has its own independent CPU and storage unit, and realizes information exchange with the host computer through serial communication.
(3) Operation panel: It consists of various operation keys and status indicators, which only complete basic function operations. (4) Hard disk and floppy disk storage: Peripheral memory for storing robot working programs.
(5) Digital and analog input and output: input or output of various states and control commands.
(6) Printer interface: record various information to be output.
(7) Sensor interface: It is used for automatic detection of information and realizes the compliance control of the robot. Generally, it is a force sensor, a tactile sensor and a visual sensor.
(8) Axis controller: complete the joint position, speed and acceleration control of the robot.
(9) Auxiliary equipment control: It is used to cooperate with robots for auxiliary equipment control, such as hand positioner. (10) Communication interface: It realizes the information exchange between robot and other equipment. Generally, there are serial interface and parallel interface.
(11) Network interface
1) Ethernet interface: Direct PC communication of several or single robots can be realized through Ethernet. The data transmission rate is up to 10Mbit / s. After the application program is programmed on the PC with windows library functions, it supports TCP / IP communication protocol. , Load data and program into each robot controller through Ethernet interface.
2) Fieldbus interface: supports a variety of popular fieldbus specifications, such as Device net, AB Remote I / O, Interbus-s, profibus-DP, M-NET, etc.
(3) Classification of Industrial Robot Control System
(1) Program control system: by applying a certain regular control to each degree of freedom, the robot can achieve the required space trajectory.
(2) Adaptive control system: When external conditions change, in order to ensure the required quality or to improve the control quality by itself as experience accumulates, the process is based on the observation of the state of the operating machine and servo error, and then adjust the non- The parameters of the linear model until the error disappears. The structure and parameters of such a system can change automatically over time and conditions.
(3) Artificial intelligence system: It is impossible to prepare a motion program in advance, but it is required to determine the control function in real time based on the obtained surrounding state information during the exercise. Drive mode: see industrial robot drive system. Movement method:
(4) Point type: The robot is required to accurately control the posture of the end effector, regardless of the path; (5) Trajectory type: The robot is required to move according to the taught trajectory and speed.
(6) Control bus: International standard bus control system. The international standard bus is used as the control bus of the control system, such as VME, MULTI-bus, STD-bus, PC-bus.
(7) Custom bus control system: The bus defined by the manufacturer is used as the control system bus.
(8) Programming mode: Physical setting programming system. The operator sets a fixed limit switch to realize the program operation of starting and stopping, which can only be used for simple picking and placing operations.
(9) On-line programming: The programming method of memorizing the operation information is completed by human teaching, including direct teaching (that is, hand-to-hand teaching) simulation teaching and teaching box teaching.
(10) Off-line programming: instead of teaching the actual robot directly, you can create a teaching program separately from the actual working environment, and use advanced robots, programming languages, and remotely generate robot operation trajectories offline.
(IV) Structure of Robot Control System Robot control systems can be divided into three types according to their control methods.
(1) Centralized Control System (Centralized Control System): a computer to achieve all control functions, simple structure, low cost, but poor real-time, difficult to expand, this structure is often used in early robots, and its block diagram, as shown in the figure 2 shown. In the PC-based centralized control system, the characteristics of the openness of PC resources are fully used to achieve good openness: a variety of control cards, sensor devices, etc. can be integrated into the control through standard PCI slots or through standard serial ports and parallel ports. System. The advantages of the centralized control system are: low hardware cost, convenient information collection and analysis, easy to achieve optimal control of the system, good integrity and coordination, and PC-based system hardware expansion is more convenient. Its shortcomings are also obvious: the system control lacks flexibility, and the control danger is easy to focus. Once a failure occurs, the impact is wide and the consequences are serious; due to the high real-time requirements of industrial robots,