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Application case of synchronous correction control of large-span door crane lifting equipment based on Canopen fieldbus:
one. The particularity of door crane lifting equipment:
The safety requirements of door crane lifting equipment are becoming more and more prominent, and the concept of safety* is becoming more and more important in the control. According to regulations, large-span door cranes above 40 meters must be equipped with dual-track synchronous correction control to prevent left and right double-tracks. Accidents of gantry crane wheels gnawing or even derailing occur. Due to safety requirements, the wheels on the left and right double tracks of the gantry crane need to be controlled at multiple points. The reliable feedback of information such as speed and position directly relates to the safety and reliability of the control. The particularity of the environment of the lifting equipment determines the particularity of the selection of these signal sensors and transmissions:
1. In the complex working environment on site, frequency converters, large motors and high and low voltage power supply systems, signal cables are often arranged together with power lines, and the electrical interference on site is very serious.
2. Equipment mobility, long moving distance, difficult to ground.
3. The signal transmission distance is long, and the safety and reliability of the signal data is high.
4. Synchronous control requires high real-time and reliable signal transmission.
5. Many of them are used outdoors, with high requirements for protection level and temperature level, but low level of worker training, and high requirements for product tolerance.
two. Significance of multi-turn encoder in the application of door crane hoisting equipment:
In the use of position sensors for door cranes, there are potentiometers, proximity switches, incremental encoders, single-turn encoders, multi-turn encoders, etc. In comparison, potentiometers have low reliability and accuracy. Poor, there is a dead zone in the use angle; proximity switches, ultrasonic switches, etc. are only signals at a single point position and are not continuous; the incremental encoder signal has poor anti-interference, the signal cannot be transmitted remotely, and the power failure position is lost; the single-turn encoder can only be Working within 360 degrees, if the measurement angle is expanded by changing the speed, the accuracy will be poor. If it is used directly in a single circle to achieve multi-lap control through memory, after a power failure, the position will be lost due to wind, sliding or artificial movement. Only value multi-turn encoder can be used safely in door hoisting equipment. It is not affected by power outage jitter. It can work for long distances and multi-turns. It is fully digitalized internally, anti-interference, and the signal can also be realized remotely. Distance safe transmission. Therefore, from the perspective of the safety of the door crane equipment, a multi-turn encoder is an inevitable choice.
three. Application recommendation of Canopen value encoder in door crane lifting equipment
CAN-bus (ControllerAreaNetwork) is the controller area network, which is one of the most widely used open field buses in the world. As a remote network communication control method with advanced technology, high reliability, complete functions and reasonable cost, CAN-bus has been widely used in various automation control systems. For example, CAN-bus has incomparable advantages in various fields such as automotive electronics, automatic machinery, smart buildings, power systems, security monitoring, ships and shipping, elevator control, fire safety, medical equipment, etc., especially when it is currently in the limelight. High-speed railways, wind power generation, Can-Bus is the signal standard.
CAN-bus is developed and maintained with low cost, high bus utilization, long transmission distance (up to 10Km), high-speed transmission rate (up to 1Mbps), multi-master structure according to priority, and reliability The error detection and processing mechanism of the traditional RS-485 network fully compensates for the shortcomings of the traditional RS-485 network's low bus utilization, single-master-slave structure, and no hardware error detection, enabling users to build a stable and field bus control system, resulting in the largest The actual value. In harsher application environments such as lifting equipment, Can-bus has a reliable signal error detection and processing mechanism, and can still transmit data well in the case of strong interference and unreliable grounding, and its hardware error self-check, The multi-master station can be redundant to ensure the safety of the control equipment.
Canopen is an open protocol based on the CAN-bus bus and managed by the CiA Association. It is mainly used in the vehicle industry, industrial machinery, intelligent buildings, medical equipment, marine machinery, laboratory equipment and research fields. The Canopen specification allows the transmission of messages by broadcasting , It also supports point-to-point sending and receiving of data, and users can perform network management, data transmission and other operations through the Canopen object dictionary. In particular, Canopen has the characteristics of anti-interference and multi-master station application, which can form the actual master station redundancy backup and realize safer control.
Compared with other signal forms, Canopen's data transmission is more reliable, economical, and safer (equipment error reporting). Comparison of these characteristics with other outputs: Parallel output signal-too many power components are easily damaged, too many core wires are easily broken and the cable cost is high; SSI output signal-called synchronous serial signal, when the distance is long or interfered, the signal The delay caused the clock and data signal to be no longer synchronized, and data jump occurred; Profibus-DP bus signal-grounding and cable requirements are high, the cost is too high, the master station is not selectable, and once the bus connection gateway or master station fails, Cause the paralysis of the entire system and so on. The above use in lifting equipment may sometimes be fatal. Therefore, it can be said that the Canopen signal is more reliable, more economical and safer when used in lifting equipment.
The Canopen value encoder of Shanghai Technetium Industrial Control, due to its high-speed signal output, in the function setting, you can set the encoder value to output the angle position value together with the change speed value, for example, the first two bytes output value angle ( Multi-turn) position, the third byte outputs the speed value, and the fourth byte outputs the acceleration value (optional). This is very helpful when frequency converters are used in hoisting equipment. The speed value can be used as a frequency converter. Speed feedback, and the position value can be used as positioning and synchronization control, there can be double closed-loop control of speed and position, so as to realize positioning, synchronization control, parking anti-sway, safe area control anti-collision, speed safety protection, etc., and Canopen is unique The feature of multi-master station can realize the redundancy backup of the main station of the receiving controller. The parameters of the backup controller can be set behind the main controller. Once the main controller system fails, the backup controller can assume the latest security protection control. , So as to realize the safety control of lifting equipment.