The system is an important part of the industrial robot, its role is equivalent to the human brain. Having a well-functioning, sensitive and reliable control system is the key to the coordinated action of industrial robots and equipment, and the common completion of operational tasks. The control system of industrial robots is generally composed of two parts: the control of its own movement and the coordinated control of industrial robots and peripheral equipment.
1. The characteristics of the industrial robot control system, robot structurally speaking belongs to a space open chain mechanism, in which the movement of each joint is independent, in order to achieve the end point of the movement trajectory, the need for multi-joint motion coordination, its control system than the ordinary control system is much more complex.
The characteristics of the robot control system are as follows: the control of the robot is closely related to the kinematics and dynamics of the mechanism. The state of the robot hand and foot can be described in various coordinates, and the reference coordinate system should be selected according to the specific needs and appropriate coordinate transformations should be made. Solutions for both forward and inverse kinematics are often required, in addition to the effects of inertial forces, external forces (including gravity), and centripetal forces.
Even a simple robot requires at least 3 to 5 degrees of freedom, and more complex robots require dozens or even tens of degrees of freedom. Each degree of freedom typically contains a servo mechanism that must be coordinated to form a multivariable control system. By the computer to realize the coordinated control of multiple independent servo systems and robots in accordance with the will of the human action, and even give the robot a certain "intelligence" of the task. Therefore, the robot control system must be a computer control system. At the same time, the computer software has a difficult task.
As the description of the robot state and movement is a nonlinear mathematical model, with the change of state and external force changes, its parameters also change, and there is also coupling between the variables. Therefore, it is not sufficient to use only position closure, but velocity and even acceleration closure must also be employed. Gravity compensation, feed-forward, decoupling or adaptive control are often used in the system.
Since the robot's movements can often be accomplished in different ways and paths, there is an "optimization" problem. For more advanced robots, artificial intelligence can be used, using computers to build a huge information base, with the help of the information base for control, decision-making, management and operation.
According to the sensor and pattern recognition methods to obtain the object and the environment of the working conditions, according to the requirements of the given indicators, automatically select the best control law. In summary, the control system of the robot is a coupled, nonlinear multivariable control system closely related to the principles of kinematics and dynamics. Because of its special characteristics, neither classical control theory nor modern control theory can be copied and used. So far, the robot control theory is not complete and systematic enough.
2. The main functions of the industrial robot control system, the motion position, attitude and trajectory of the industrial robot in the workspace, the sequence of operation and the timing of the action and other items The control of the industrial robot in the workspace, attitude and trajectory, the sequence of operation and the timing of the action and other items is the main task of the industrial robot control system, and the control of some of these items is very complex.
What does the controller of the robot consist of and how does it realize the control
Demonstration reproduction function. Teaching reproduction function means that the control system can be taught by the teaching box or by hand to teach the sequence of movements, speed of movement, position and other information in a certain way in advance to the industrial robot, and the memory device of the industrial robot will automatically record the process of the operation taught in the memory, and when it is necessary to reproduce the operation, replaying the contents stored in the memory can be done. If you need to change the operation content, you only need to teach it again. Motion control function. The motion control function refers to the control of the position, speed, acceleration and other items of the industrial robot end manipulator.
3. The composition of the control system, industrial robot control system consists of the corresponding hardware and software. The hardware mainly includes the following parts: the sensing device can be divided into internal sensors and external sensors. The former is used to sense its own state, its role is to detect the position, speed and acceleration of the joints of the industrial robot; the latter is used to sense the working environment and the state of the working object, the external sensors include visual, force, tactile, auditory, slippery senses and other sensors.
Control device generally consists of a micro or small computer and the corresponding interface. Its role is used to process a variety of sensory information, the implementation of control software, and produce control instructions. Joint servo drive part. The main role of this part is based on the instructions of the control device, according to the requirements of the task to drive the joint movement. The control software consists of motion trajectory planning algorithms and joint servo control algorithms and corresponding action programs. It can use all the programming language preparation, but the mainstream of industrial robot control software is formed by the modularization of the general-purpose language and the preparation of a special industrial language.
4. The name and role of each component of the industrial robot control system, the control computer is the control system of the scheduling command organization, generally using a microcomputer or microprocessor. The role of the teaching box is to complete the teaching robot trajectory, parameter setting and all human-machine interaction, it has an independent CPU and storage unit, serial communication with the main computer to achieve information interaction. The operation panel consists of various operation buttons and status indicator lights, and its function is to complete the basic function operation.
The hard disk and floppy disk memory is equal to the memory for storing the working program of the robot. Digital and analog input/output. The function of this part is to realize the input or output function of various status and control commands. The printer interface serves to record various information that needs to be output. The sensor interface is used for the automatic detection of information to realize the robot supple control, generally for force, touch and vision sensors.
The role of the axis controller is to complete the robot joints position, speed and acceleration control. Auxiliary equipment control is used to control the auxiliary equipment that cooperates with the robot, such as hand claw variators. Communication interface is used to realize the information exchange between the robot and other devices, generally serial interface, parallel interface and so on. Network interface includes Ethernet interface and Fieldbus interface.
Through the Ethernet interface can realize multiple or single robot direct PC communication, data transfer rate can reach 10Mb / s, and can be directly on the PC with Windows95 or Windows nt library functions for application programming, support for TCP / P communication protocols, but also through the Ethernet interface will be loaded into the data and programs of each robot controller. The Fieldbus interface supports a variety of popular fieldbus specifications, such as Device net, ABRemote I/O, Interbus-s, profibus-DP, M-NET and so on.