A remote 5G wireless control device for shearer

In order to realize the intelligent mining mode of the shearer, this paper designs a remote 5G wireless control device to implement remote wireless control of the shearer. The device consists of two main components: upper computer system and receiving system. Among them, the upper computer system sends control commands through the 5G network and transmits them to the receiving system; The receiving system is used to receive signals from the upper computer, control the remote controller of the shearer to perform corresponding operations, and achieve the purpose of controlling the shearer. The remote wireless control device solves the problems of poor working environment and high safety risk of shearer workers in traditional control. At the same time, the introduction of 5G network, which has the characteristics of low delay and high reliability, has realized the purpose of remote wireless control of the shearer in the centralized control room.


Introduction
Nowadays, most underground mining personnel operate the shearer by using a remote controller, onboard control buttons, or wired operation console to control various operating states of the mining machine.Due to the harsh underground environment in coal mines, which is filled with a large amount of dust and fog, the visibility is very low.This control method seriously affects the driver's line of sight, increases the difficulty of operation and control, and the accident rate of equipment operation.At the same time, due to the complex geological structures, such as faults and gangue in the mining area of the shearer and the environmental characteristics of small mining spaces and low safety factors for on-board operations, the existing mining machine control methods cannot guarantee the safety of the operators [1][2][3].The communication protocol for the existing mining machine remote controller uses a 433 MHz communication protocol, and the receiver of the mining machine remote controller is installed on the body of the mining machine.Limited by the wireless transmission power underground, the actual communication distance of 433 MHz is relatively short, and workers need to operate the remote controller near the mining machine to control the mining machine.Moreover, as the mining machine is constantly moving, there are many safety issues with near-control by workers [3].
As the level of electrical automation of coal mine underground mining machines continues to increase, the demand for remote wireless control of mining machines is also increasing.However, due to the harsh underground environment of coal mines, how to improve the safety, reliability and real-time performance of wireless communication control has become the main technical problem of underground remote control devices.
5G has many advantages such as low latency, high reliability, and large bandwidth [4].In recent years, with the continuous maturity of the control technology, the application scenarios of 5G are becoming more and more widespread, and it has penetrated into the mining field.Several smart coal mines have been built using 5G technology in China, which have improved automation and informationization and achieved the goal of reducing labor while increasing efficiency [5][6][7].Therefore, applying 5G technology to the control of mining machines has strong practical significance and value, and 5G technology makes it possible for mining machines to be remotely and reliably controlled with low latency.It has greatly improved the working conditions of mining machine operators, solves the safety problems of nearby control, and realizes the automation and informationization of mining machine control.
Based on this, this paper designs a remote 5G wireless control device for mining machines, which mainly includes an upper computer system and a receiving system.Among them, the upper computer system is installed on the computer in the centralized control room of the fully mechanized mining face.The upper computer, which acts as the client, establishes a TCP connection with the 5G CPE as the server in the receiving system through TCP/IP protocol.The upper computer sends the control command and then transmits it to the receiving system through the 5G signal.The receiving system is installed on the body of the shearer in the fully mechanized mining face.After receiving the wireless control signal from the upper computer system, it connects the key I/O port of the shearer remote controller through the converter output port, so that the key I/O port of the shearer remote controller is in a low level state, and then controls the remote controller to perform the corresponding operation to achieve the purpose of controlling the shearer.

Intelligent control system of the shearer
The intelligent control system structure of the shearer is shown in Figure 1.Among them, the laser tracking and inertial navigation are used to realize the precise positioning and orientation of the shearer; Multi-sensor fusion technology is implemented to identify the coal-rock interface, so as to realize the automatic height adjustment of the shearer; According to the load sensitive adaptive technology, set the parameters such as the depth of load self-adjustment and cutting speed; Loadsensitive adaptive technology is used to set parameters for cutting depth and cutting speed.Relevant data, including cutting speed, cutting rock hardness, and cutting load, are transmitted to the central control center of the working face in real-time and reliably through wireless communication technology, allowing for remote control of the mining machine from the central control center.This achieves the functions of "one-click start, intelligent propulsion, real-time monitoring, and manual intervention [8]".As analyzed above, ensuring the accurate and rapid transmission of cutting data from the mining machine to the working face control center is the key to achieving intelligent control of the mining machine.References [9,10] used 4G communication technology to transmit the relevant data of the shearer in real time, and transmitted the control command of the upper computer to the shearer, so as to realize the remote control.Compared to the widely used 4G communication technology, 5G communication has the advantages of faster transmission rate, higher completeness, and better coverage efficiency, thus becoming a research hotspot in coal mine communication [9][10][11][12][13].Therefore, this paper develops a set of remote wireless control device for shearer based on 5G communication technology.

Design of remote 5G wireless control device for shearer
On the basis of the original mine shearer remote controller, the device adds the remote communication link and the upper computer remote control link to solve the problems of high difficulty in the mine operation control, equipment operation accident rate, narrow mining space, and low safety factor of the nearby airborne operation.The device mainly includes upper computer system and receiving system, and its structure diagram is shown in Figure 2. The upper computer system is installed on the computer in the centralized control room of the fully mechanized mining face, and the computer is connected to the 5G through the network cable connection switch.The upper computer sends the control command and then transmits it to the receiving system through the 5G signal; The receiving system is installed on the body of the shearer in the fully mechanized mining face, mainly including 5G CPE, the shearer remote controller, converter, and voltage conversion module.Its basic working principle is that the 5G CPE receives the wireless control signal sent by the upper computer system and sends the signal to the RS232 port of the connected converter through the RS232 serial port.After receiving the RS232 signal, the converter drives the corresponding output port to produce a low-level signal.The output port of the converter is connected to the button I/O port of the shearer remote controller, so that the button I/O port of the remote controller is in a low-level state, thereby controlling the remote controller to perform the corresponding operation and achieving the purpose of controlling the shearer.

Design of upper computer system
The upper computer system is installed on the computer in the centralized control room of the fully mechanized mining face, and the computer is connected to the 5G network through the network cable connection switch.The upper computer system is used as the client, and the TCP connection is E1 established with the 5GCPE as the server in the receiving system through the TCP/IP protocol.The upper computer system issues the control command, and then transmits it to the receiving system through the 5G signal.The upper computer development platform is PowerBuilder.
According to the function of the remote controller, when designing the control interface of the upper computer, on the one hand, it is single-key function, and on the other hand, it is multi-key function.On the actual remote control, the operator can press two or three buttons at the same time, but on the upper computer, that is, the computer, the mouse can only press one place, that is, the control representing one button.Therefore, in this patent, the multi-button function is specially designed as an independent control representative, as shown in Figure 3.
The control used in Figure 3 is RichTextEdit control of PowerBuilder, which has the event scripts for mouse down and mouse up events and can simulate the pressing and releasing actions of a button, issuing the corresponding control command.After communication, this command is transmitted to the converter to control the high and low changes of the OUT level, thereby realizing the pressing and releasing of the buttons of the shearer.This paper provides corresponding controls for the simultaneous pressing of the two buttons on the remote controller, which also solves the problem of the mouse being able to click on only one control.The control commands are written in Tag property of RichTextEdit control's Properties, and also includes the function such as "move left and automatically close the speed," as shown in Figure 4.
Each single function command is composed of 6 bytes, and the command for combined keys is obtained by XORing the last four bytes of the single function command.The checksum is a CRC check.

Design of receiving system
The receiving system is installed on the body of the shearer in the fully mechanized mining face, mainly including 5GCPE, the original shearer remote controller, converter, and voltage conversion module.Among them, the RS232 serial port of the 5GCPE is connected to the corresponding RS232 serial port of the converter.The functions of the remote controller in the receiving system are shown in Table 1,   The main working process of the receiving system is as follows: after the 5G CPE receives the wireless control command signal sent by the upper computer system, it transparently transmits the signal to the RS232 serial port and sends the signal to the RS232 serial port of the connected converter.After receiving the RS232 signal, the converter drives the control circuit to make the corresponding output port (OUT1 to OUT19) generate a low-level signal, which causes the button I/O port (AS1 to AS19) of the remote controller for the shearer to be in a low-level state.This is equivalent to pressing the button on the remote controller for the shearer to control it to perform the corresponding operation and send out a 433MHz signal to the shearer's 433MHz receiver to achieve the purpose of controlling the shearer.
The data communication of the device adopts Winsock three-party control in the PowerBuilder development platform.The upper computer is the client, and the receiving system side of the shearer is the server.

Power supply for 5G wireless control device
The remote 5G wireless control device of the shearer supplies power to the receiving system through the cable from the shearer.The power supply voltage is 12 V, which is used to supply power to the 5G CPE and converter; The 12V to 5V module inside the device is used to power the remote controller for the shearer.The debugging network port is reserved for debugging 5G CPE.The 433M Hz antenna and 5G CPE antenna of the shearer remote controller are designed with built-in antenna to improve protection.

Effect analysis
In the experiment, a 433MHz remote control receiver was used to simulate the shearer receiving instructions.The upper computer issued instructions through the interface in Figure 4, and the receiver's indicator light would illuminate to indicate that it has correctly received the instructions.The experimental results are shown in Figure 6.
The test results show that under the 5G environment, the remote control receiver can correctly receive the action instructions sent by the upper computer.Due to the low delay characteristic of 5G, the upper computer continuously lights up the corresponding indicator light of the remote control receiver under the condition of simulating the continuous sending of instructions, indicating that the control instructions are not interrupted, which verifies the feasibility and reliability of the system.

Conclusions
Aiming at the problems of traditional control (remote control, airborne control button and wired operation), such as high operating difficulty, bad working environment of workers and high safety risk, when the shearer is in operation, this paper designs a remote wireless control device based on 5G, which has the following advantages (1) The upper computer system is installed in the control room, avoiding the problem of poor working conditions and high safety risks associated with operating the shearer in close proximity using traditional control methods.(2) The receiving system is installed on the shearer, which greatly reduce the distance between the shearer remote controller and the receiver, thereby reducing 433 wireless signal interference and latency.
(3) The introduction of 5G network has the characteristics of low delay and high reliability, which realizes the purpose of remote wireless control of coal mining machine in the centralized control room, and provides technical support for the intelligent coal mining mode of unmanned and few people in the working face.

Figure 1 .
Figure 1.Intelligent control system of the shearer.

Figure 2 .
Figure 2. Structure diagram of remote 5G wireless control device of the shearer.

Figure 3 .
Figure 3. Upper computer control interface of shearer remote control system.

Figure 4 .
Figure 4. Properties of the RichTextEdit control.

Table 1 .
Figure 5 shows the schematic diagram of the key I/O ports of the remote controller of the shearer.Each key I/O port of the remote controller for the shearer, namely AS1 to AS19, is effective at low level.When connected to the corresponding output port of the converter, namely OUT1 to OUT19, it outputs low level signals.

Figure 5 .
Figure 5. Schematic diagram of the key I/O port.

Figure 6 .
Figure 6.Effect of remote control receiving instructions from upper computer.