Industrial robots may create a new era of PLC

Since the birth of the robot, people have been trying to explain what robots are. However, with the rapid development of robotics and the arrival of the information age, the content covered by robots is becoming more and more abundant, and the definition of robots is constantly enriched and innovated. As one of the great inventions of mankind in the 20th century, robotics has made great progress since its inception in the early 1960s. With the continuous development of manufacturing industry in recent years, industrial robots have become the key technology and important products of intelligent manufacturing and industrial automation, and also an important part of the higher stage of automation of CNC machine tools.


With the continuous development of electronic control technology, PLC is developing in the direction of high-speed, large-capacity Internet of Things and intelligent communication. Through the Internet of Things, PLC, inverter, remote I/O, etc. can be connected with the host computer. To construct a multi-stage distribution system.


for example:


An open field-oriented bus network system built by CC-Link in Mitsubishi Industrial Motors, DIN is a German industrial standard. The use of guide rails is an installation method for industrial electrical components, and electrical components supporting this standard are installed. It can be easily stuck on the guide rail without fixing with screws, and the maintenance is also very convenient. Generally speaking, the commonly used guide rail width is 3.5CM. Nowadays, many electrical components have adopted such standards, such as PLCs, circuit breakers, switches, contactors, and the like.


Industrial robots do not work in isolation. A robotic workstation often requires the cooperation of peripheral equipment, such as fixtures, conveyor belts, welding positioners, moving rails, etc. These roles need to be coordinated with each other. Such as AGV cars, automated warehouses, spraying equipment, assembly equipment and so on.


Industrial robot automatic control system


1, the underlying controller


The bottom controller is the core of the control system. The choice of whether it is suitable or not is very important to the whole system. Its performance directly affects the reliability of the control system, data processing speed, and real-time data collection. The mobile robot has a harsh operating environment and many interference sources. It requires high real-time and reliability of the motion controller. Therefore, it is important to choose a stable and reliable motion controller, which must meet the system requirements and have good performance. Scalability and compatibility.


In order to realize the effective control of the robot to the external device, the underlying controller provides the corresponding underlying control functions of the device. These control functions can directly access the hardware registers of the robot to control the operation of the robot, and these control functions can make the device driver no longer depend on For specific hardware, effective control of the robot can be achieved by calling the control function interface.


2, electrical system


After selecting the hardware of the wheeled omnidirectional mobile robot control system, the electrical system design is performed according to the hardware composition of the mobile robot. The mobile robot's electrical system mainly consists of three parts: the main circuit, the servo drive system circuit and the PLC control system circuit.


The main circuit of the mobile robot control system is controlled by PLC and relay. That is, the relay consists of two parts: a coil and an auxiliary contact. When the coil is energized, its corresponding normally open contact closes and the normally closed contact opens.


3, I / O configuration section


The I/O configuration section includes an I/O refresh cycle (typically 4ms) and I/O data map area size information, which is visually configured through the engineering configuration module of the soft PLC programming system to accommodate different robot applications to I/O devices. Different needs. The main reason is that the robot uses other signals as the end effector I/O, and the end effector I/O is linked to the connector at the end of the robot arm to ensure its function.


4, PLC program


In the underlying controller, use the PTO motion control command of the programming software STEP 7 PROFESSIONAL V12, use the position control mode to control the four steering servo motors to control the steering angle of the four wheels; in addition, use the extended analog output module output voltage Value, control 4 wheel motor, drive robot movement. In addition to the hardware factors, the quality of the program directly determines the high performance of the sport. Therefore, the preparation of the program is one of the most important aspects of the entire design.


PLC needs to meet the high performance requirements of industrial robots to be improved


The robot controller can be understood as the structural realization of the robot control function. Therefore, the robot controller is the core "heart" of the robot. It affects the development of the robot to some extent. The high-performance industrial robot not only needs PTP control, but also Also implement CP control. Although the use of PC-based motion controllers and DSP-based motion controllers can realize the motion control of robots, it can not meet the requirements of high-performance industrial robots, and the circuit design and programming are quite complicated. Therefore, PLC control Wiring and technical innovation are a major challenge.


The PLC control wiring is simple, as long as the motion control of the robot can be realized by the motion control command. Therefore, it takes a certain time for the PLC to obtain an advantage in the robot multi-axis motion coordinated control and network communication. Because the high-performance industrial robot is mainly the driving motion of each joint, it not only realizes the control of PTP and CP, but also meets the requirements of multi-axis coordinated control, speed, acceleration and motion precision.


At present, in PLC, PLC of Japan Lishi Company and PLC of ABB Company are powerful in micro-miniature control; although Siemens PLC has the function of motion control, it is far less than MITSUBISHI PLC, because MITSUBISHI PLC combines Internet of Things and high-tech The technology enables complete motion control. Through the high-speed backplane, the processor can communicate with the servo interface module for highly integrated operation and closed-loop control of the position loop and speed loop. From simple point-to-point motion to complex gearing to meet the requirements of high-performance industrial robots.