Research and application of AGV and intelligent elevator interactive system

  • A+
Categories:AGV Data
Excerpt

This paper analyzes the specific application of AGV to realize the cross floor material distribution, puts forward the message security interaction system based on Ethernet LAN between AGV and intelligent elevator, and looks forward to the comprehensive intelligent manufacturing scenario of AGV to realize the interconnection of everything based on 5g industrial Internet.

With the development of intelligent elevator and the progress of Internet of things technology, the object of interaction with the elevator is not only limited to people, but also a variety of AGVs. In addition to the transportation of passengers, the transportation of drugs, food, documents, etc. has gradually become popular.

Research and application of AGV and intelligent elevator interactive system

Figure 1 AGV entering the elevator site of a biopharmaceutical factory in Shanghai


Figure 1 shows the interaction between the elevator and AGV of a biopharmaceutical factory in Shanghai. AGV transports the medicine box to the elevator entrance, interacts with the elevator through message instructions, then enters the elevator, and transports the AGV to the designated floor through the elevator. As the elevator belongs to special equipment, the equipment interacting with the elevator shall meet the relevant requirements of the special equipment safety law, and the safety, stability and reliability of the interaction system shall meet the requirements of the safe use of the elevator. Therefore, it is very important to design a safe and reliable interaction mechanism.

The interaction system between AGV and elevator needs to establish the data communication link between AGV and elevator first. Due to the mobility characteristics of AGV, the communication between AGV and AGV management server can adopt LAN Wireless communication. In this case, Wi Fi access or WAN wireless communication can be adopted, such as nb-iot and 5g. The connection between AGV server and elevator can be realized by wired network.

The overall structure of AGV access elevator system includes AGV management server, elevator, AGV, communication module moxa, wireless LAN AP, etc.

The AGV management server needs to communicate with several elevators. The elevator communicates with the AGV server through the RS485 serial port and the LAN through the Ethernet interface. A moxa communication module is added between AGV server and elevator data transmission unit to realize the mutual conversion between Ethernet interface and RS485 serial port, and establish the communication link between them, so as to realize the message interaction between one AGV management server and multiple elevators.

The communication between AGV management server and AGV is realized through wireless LAN AP.

After the AGV management server obtains the status of the elevator, it sends the relevant action instructions to the AGV through the wireless AP. After receiving the instructions, the AGV performs the actions of entering and exiting the elevator.

The overall structure of AGV and intelligent elevator system is shown in Figure 2.

Research and application of AGV and intelligent elevator interactive system

Figure 2 general structure of AGV intelligent elevator system

2、 AGV and elevator information interactive design

In order to reduce the number of messages generated in the process of direct interaction between AGV and elevator, the system uses AGV server and elevator for information interaction, analyzes the results, sends execution instructions to AGV, and AGV executes corresponding instructions.

The interaction process between AGV system and elevator is as follows: AGV applies for elevator registration → elevator feedback registration succeeds → AGV queries elevator floor → elevator feedback floor → AGV requests elevator to open the door → elevator door keeping → AGV enters / leaves the elevator → AGV stops sending door opening request → elevator door closing → elevator release succeeds. After applying for elevator registration, AGV can carry out the next step only if the elevator feedback registration is successful, and each link in the interaction process is indispensable and linked; in the communication protocol data section, make full use of each bit of data in the data section, and carry out data bit verification to avoid transmission and analysis errors, and the communication data volume can be greatly reduced.

2.1 Information interaction design of AGV entering elevator

When AGV enters the elevator, AGV system and elevator message interaction design, as shown in Figure 3.

Research and application of AGV and intelligent elevator interactive system

Figure 3 message interaction diagram of AGV entering elevator


The message interaction process of AGV entering the elevator is as follows:

① After the AGV arrives at the door of the elevator, it will send the instruction registration in car a;

② The elevator responds to the car registration instruction;

③ AGV car command registration succeeded, send the elevator status query command;

④ The elevator responds to the current status;

⑤ The floor information of the elevator is the same as that requested by AGV, and AGV sends the door opening request instruction;

⑥ Send elevator ready signal after elevator door is opened in place;

⑦ AGV starts to drive into the elevator, and continuously sends the door opening request instruction in the process;

⑧ After AGV arrives in the elevator, stop sending the door opening request instruction;

⑨ When the elevator is closed, the AGV enters the elevator message interaction is completed, and the elevator is released.

2.2 Message interaction design of AGV driving out of elevator

When AGV drives out of the elevator, AGV and elevator message interaction design, as shown in Figure 4.

Research and application of AGV and intelligent elevator interactive system

Figure 4 message interaction diagram of AGV driving out of elevator


The message interaction process of AGV leaving the elevator is as follows:

① After the AGV enters the elevator, it sends the instruction registration in car a;

② The elevator responds to the car registration instruction;

③ AGV car command registration succeeded, send the elevator status query command;

④ The elevator responds to the current status;

⑤ The floor information of the elevator is the same as that requested by AGV, and AGV sends the door opening request instruction;

⑥ Send elevator ready signal after elevator door is opened in place;

⑦ AGV starts to drive out of the elevator, and continuously sends the door opening request instruction in the process;

⑧ When AGV reaches the outside of elevator, it stops sending door opening request instruction;

⑨ When the elevator is closed, the AGV enters the elevator message interaction is completed, and the elevator is released.

2.3 AGV and elevator heartbeat process design

AGV sends heartbeat message to elevator every 3 seconds to check the link connectivity between AGV and elevator. The heartbeat flow design between AGV and elevator is shown in Figure 5.

Research and application of AGV and intelligent elevator interactive system

Figure 5 AGV elevator heartbeat flow chart

3、 AGV and elevator interactive message design

AGV and elevator interactive message design, as shown in Figure 6.

Research and application of AGV and intelligent elevator interactive system

Figure 6 AGV elevator interactive message format

See Table 1 for specific contents of interactive message.

Research and application of AGV and intelligent elevator interactive system

Table 1 Contents of interaction message

The data content contains the request instructions of AGV and the feedback information of elevator. The instructions defined in this case are shown in Table 2.

Research and application of AGV and intelligent elevator interactive system

Table 2 instruction content of interactive message

4、 Interactive reliability design of AGV and elevator

AGV and elevator need frequent data interaction. During the actual use, it is found that due to the unreliable delivery of services provided by Ethernet, that is to say, the best efforts will be made to deliver, and there will be packet loss, wrong packet, uneven data and other situations in the transmission, especially in the case of data blocking. If the transmission is still sent according to the data transmission frequency before blocking, it will only further aggravate the occurrence of data abnormalities.

In software implementation, the received data is stored in the receiving queue by setting up a data queue at both ends of the receiving and sending, so as to prevent the failure of verification due to packet breakage and the loss of data due to improper processing when the data arrives at the same time due to blocking. In actual receiving processing, the legitimate data packet is extracted from the receiving queue for processing; in sending, the data is stored in the receiving queue The sending queue is placed uniformly, and the sending unit periodically extracts legal packets from the sending queue for sending. The flow chart of AGV and elevator buffer is shown in Figure 7.

Research and application of AGV and intelligent elevator interactive system

Figure 7 AGV elevator buffer design


In addition, it can also adjust the sending frequency of the legal packets of the sending unit to avoid the data content of the buffer being filled too fast when it is blocked

5、 Conclusion

With the development of industrial automation, there will be more and more interactive application scenarios between AGV and elevators, ranging from shopping malls to residences, where there are elevators, there may be AGV applications. The integration of 5g network and industrial Internet will gradually make the industry of AGV application more and more, with a larger span. AGV has become an integral part of the factory logistics distribution system. In order to achieve a higher degree of automation and a higher efficiency of the distribution system, it is necessary to realize the automatic up and down elevator of AGV, and to realize the automatic up and down elevator of AGV, it is necessary to realize the communication between AGV and elevator system. How to design stable and reliable interaction mechanism is very important, which is the key research topic of intelligent manufacturing technology.

This paper proposes a secure interaction system based on Ethernet LAN, which ensures the success rate of message interaction by designing message buffer and retransmission mechanism, and ensures the safety and reliability of AGV and elevator interaction to the greatest extent, which has certain reference value.

Comment

You must beto post a comment.