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1. Project introduction
With the rapid development of urban construction in China, the demand for concrete is increasing, and concrete production enterprises are also developing in a group trend. The automatic operation and management of large enterprises has become the deciding condition for the survival and rapid development of a company.
In order to improve the efficiency of its concrete production management, radio frequency identification technology is used for vehicle transportation management, and the hardware is Siemens RFID660. As an important part of the daily production management of the concrete mixing plant, vehicle management plays a decisive role in the normal operation of the mixing plant. The quality of the vehicle arrangement can directly affect the production and operation costs of the concrete mixing plant. As the traditional management method of vehicles: the plan dispatcher shall formulate the concrete production plan of the mixing station according to the production plan of the construction site and on-site feedback information, and arrange the concrete transportation vehicles for on-site transportation; the plan dispatcher shall keep abreast of the transportation status of each vehicle, Complicated information such as transportation route, transportation time, and queuing information has a lot to do with the planner’s management experience, and is prone to errors, which is not conducive to control; if RFID radio frequency identification technology is used for vehicle management, the plan dispatcher will be removed from the complicated The information is liberated from the information, reducing the chance of error in vehicle arrangements; after each vehicle enters the mixing station, it will automatically swipe the card to queue up, and the concrete production will automatically call the vehicles according to the fleet queue. After the vehicle leaves the mixing station, swipe the card again to record the transportation site, square quantity, and departure time Wait for information; after the vehicle is transported, return to the mixing station and swipe the card again. This cycle reduces the impact of human instability in vehicle management.
2. Control system composition
The vehicle management system is configured at the entrance and exit of the mixing station. An RFID reader, 2 RFID identification antennas, and a detection indicator are installed. Each vehicle entering and leaving the mixing station is equipped with an on-board tag; transportation vehicles are entering and leaving the mixing station. When there is no need to get off the car, just slow down and drive to the RFID detection area. The identification antenna will automatically detect the stored information in the vehicle tag, transmit it to the card reader, and feed the information back to the vehicle management system through the local area network; The computer of the vehicle management dispatching center in the mixing station is connected with the RFID radio frequency identification card reader to obtain the on-board tag information, which is convenient for the concrete production and the management of the office personnel; an LED display screen is installed above the parking area of the mixing station to display the mixing station The production calls the vehicle status and the queue information of the vehicle.
Figure 1 System structure diagram
For the connection of the card reader SiemensRFID660R with the computer, two communication methods are provided: CAN bus and TCP/IP, and an RS232 and Ethernet port are provided respectively.
CAN field bus is a communication network oriented to the bottom-level control of the industry. Its data communication has outstanding reliability, real-time and flexibility; it is mainly manifested in that CAN works in a multi-master mode, and CAN bus nodes are divided into different priorities. Non-destructive arbitration technology, the message adopts a short frame structure, the data error rate is extremely low, and the node can automatically turn off the output in the case of serious errors; but its limitations are also obvious. First of all, it cannot be interconnected with the Internet and cannot realize remote information sharing. Secondly, it is not easy to directly interface with the host controller. The existing CAN interface cards are mostly expensive compared with Ethernet network cards; and the CAN field bus cannot be compared with Ethernet in terms of communication distance or communication speed.
The Ethernet based on TCP/IP is a standard and open network. The system composed of it has good compatibility and interoperability, strong resource sharing ability, and can easily realize the control of the data on the scene and the resources on the information system. Sharing, data transmission distance is long, transmission rate is high, easy to connect to the Internet, low cost, easy to network, and the interface with computers and servers is very convenient, and it has received extensive technical support.
Therefore, in the vehicle management system, the RF660R card reader and the vehicle management server adopt the TCP/IP communication method to obtain the information in the vehicle tag, which can meet the production requirements of the mixing station.
3. Functions completed by the control system
In order to meet the functional requirements of the concrete mixing plant for vehicle management, the Siemens RFID-based vehicle management system should have the following functions: automatic detection of vehicles entering and leaving the mixing plant, vehicle queuing production calls, vehicle transportation information query, and vehicle information management output.
Automatic detection of vehicles entering and leaving the mixing station
When the concrete transport vehicle enters and exits the mixing station, it drives at a reduced speed. The RF660A antenna automatically detects the information in the vehicle tag and transmits the obtained information to the vehicle management system. The information obtained in the associated system should include the vehicle number, the driver on duty, the amount of the transporter, Construction sites, etc.; the vehicle management system stores data for later recall, analysis and query;
It should be noted that the effective detection distance of the RF660A antenna is ±6m. Within this range, based on the detection principle of RF660A, it will continuously detect the information of the vehicle, so the information obtained by the card reader must be checked. Preliminary processing, the screening processing rule is that the same identification code is detected within a certain period of time for the same concrete transport vehicle to enter/exit the mixing station, which is an effective detection; at the same time, due to the installation position of the RF660A antenna and the hardware used, it is impossible to distinguish whether the vehicle is entering or leaving the mixing station. , Leaving the mixing station, but such information of vehicles is of great significance to vehicle management; when judging vehicles entering and leaving the mixing station, the judgment should be based on the vehicle loading information in the mixing building: if the vehicle is loaded with concrete, it is considered to be leaving the mixing station; On the contrary, it is entering.
The vehicle management server communicates with SiemensRF660A in real time to obtain detection information; for system stability considerations, the system should be checked in real time to see if the system communication is normal, and processing measures should be given.
Vehicles queued for production call
After the vehicle detection information is successfully obtained, it is stored in the vehicle management server. The daily detection data in this system is large and to facilitate the system’s network processing, SQLServer2000 is used as the vehicle detection data storage unit in the system; after the vehicle leaves the mixing station, The site information and loading information will be stored; when the vehicles enter the mixing station, the vehicles will be queued, the normal production of the mixing building calls the vehicles in the queue for production, and the vehicle management system interacts with the operating system of the mixing building to perform data exchange on the queued vehicles. “First-in-first-out” rule management, that is, the vehicles that enter the queue first are loaded in the mixing station. For this system, two mixing plants are used for simultaneous production. This rule is also used for the number of vehicles in the mixing plant. The first-produced mixing The station prioritizes calling the first vehicles in the queue, and sends the calling information to the LED display for display.
When two mixing towers are in production at the same time, there will be a resource grabbing problem for the call of the vehicle queue, that is, the two mixing towers call the same vehicle, so transaction processing and an interlocking mechanism should be used for the data call queue.
Vehicle transportation information query
In the vehicle management system, the vehicle detection information is classified and statistics, and reports are output to assist production management; you can check how many vehicles are currently on the same construction site, whether the construction site is normal, and judge whether to continue feeding the construction site.
On-board information management output
Interactively process the data of the mixing station, and transmit the acquired vehicle queue data to the mixing building in real time, and display the information on the LED display; after the mixing station building calls the vehicles, it will feed back the calling data to the vehicle management system in real time.
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