Roadheader is one of the important mechanical equipment of short wall mining in coal mine. The driving quality and working efficiency of roadheader are related to the production efficiency of the whole short wall mining face. In the actual production process, the roadheader driver needs to operate the roadheader manually. Due to the existence of blind area, over excavation and under excavation often occur, which affects the quality and speed of the roadheader. The roadheader driver is in the goaf for a long time, the production environment is bad, and the life safety is seriously threatened. Due to the continuous development of computer technology, intelligent control technology and network technology, the mechanization, intelligent and network level of underground mining equipment is also higher and higher. In order to improve the working environment of TBM driver, ensure their life safety and improve the production efficiency of TBM, this paper designs and realizes the remote control system of TBM. The remote control system can make the roadheader driver operate the roadheader in the safe area behind the roadheader, and in the process of operation, the field of vision is wide, there is no blind area [1-2], which can improve the tunneling quality of the roadheader and ensure the production efficiency. Based on rc-21 flameproof and intrinsically safe remote control system, the typical application in roadheader is given based on the analysis of remote control receiving device and remote control transmitting device.
Remote Control System of Roadheader
The remote control transmitter is a portable small power short distance wireless transmitter with stainless steel and reinforced plastic shell. It is composed of battery pack, safety current limiting module, operation button, power management circuit, low-power micro controller, special RF chip and transmitting antenna, as shown in Figure 1 [3-4]. The transmitter is based on single chip microcomputer and adopts direct frequency modulation technology of quartz crystal frequency stabilization. It has advanced functions such as intelligent power saving, which are not possessed by general analog remote controller.
Fig.1 Structure of Remote Control Launcher
The main technical parameters of the remote control transmitter are shown in Table 1. The remote control transmitter is compact in size and solid in structure, which is in line with the dust and wet environment characteristics of industrial and mining, and has good sealing performance, so it is suitable for use in the dust, wet coal mine and other harsh environment. The remote control device has different operating distance in different environments, so it must be tested before use to ensure its effective range.
When the remote control transmitter is on, operate any single button, and the operation command light is on, indicating that the operation command is being sent until the button is released. If the power supply voltage of the battery is lower than 2.7 V and the remote control operation is carried out after the power on, the under voltage lamp of the battery will flash, indicating that the battery power is insufficient. The remote control transmitter is equipped with automatic shutdown function. If there is no key operation for more than 15 minutes, the transmitter will shut down automatically.
Remote Control Receiver
The remote control receiving device is composed of explosion-proof shell, intrinsically safe circuit board combined movement, external lead-in antenna, remote communication interface and control cable. It has compact structure, convenient combination, and all internal connections are connected by sockets, so it is convenient to connect. Its control output can be divided into communication output and relay contact output. The main technical parameters of RC-21 remote control receiver are shown in Table 2.
There are two kinds of transmission signals of remote control receiving device: one is can bus signal, the other is RS485 signal. The transmission rate of CAN bus signal is 250 kb/s, the signal transmission distance is about 20 m, and the signal output level is 1.0 ~ 5.0 pp. The RS485 signal transmission rate is 9600 b / s, the transmission distance is 20 m, and the signal output level is 1.0 ~ 5.0 pp. The remote control receiving device can also output switch signals, which are 15 passive node switch signals.
How to Use Remote Control Device
RC-21 flameproof and intrinsically safe remote control system can only have one master station and one to seven data stations in a network. Each site can transmit 1-16 bytes to any other site in the network. The network management station is responsible for the token transfer management, and the site that obtains the token can send its own node data to all other sites in the network. Each site stores the received node data of the site in the network, and stores I5 in the order of the site address from small to large. The communication device is connected with the host computer through RS-485 and adopts Modbus protocol. Otherwise, the sending device and the remote control device must be paired one by one.
The typical design of roadheader remote control system is shown in Figure 2, which is divided into two parts: remote control system and roadheader electric control system. The remote control system is divided into remote transmitter unit and remote receiver unit. Taking a "cutting motor start" command of roadheader as an example, the operation process of roadheader remote control system is explained. First, press the "cutting motor start" command on the remote transmitter. The command is sent wirelessly to the remote control receiver. After receiving the command, the remote control receiver carries out internal logic processing and sends it to the electric control system of roadheader by RS-485 communication. After the roadheader electric control system receives the command, the PLC controller, the core component of the electric control system, makes logical judgment. If it meets the starting conditions of the cutting motor, the "cutting motor start" button will be triggered and the cutting motor will be started, otherwise no operation will be carried out. Therefore, in the actual system design and implementation, only when there is a logical relationship between the remote control receiver and the electric control system of the roadheader, it is necessary to associate and match each button function in the remote control transmitter with the input and output points of the PLC controller in the electric control system of the roadheader, and finally the PLC controller sends out instructions and executes them.
Fig.2 Typical Design of Remote Control System
According to the special action of the roadheader, the buttons set in the remote transmitter include "oil pump motor start / stop", "cutting motor start / stop", "cutting high speed", "cutting low speed", "dust removal motor start / stop", "left emergency stop", "right emergency stop", "system reset", "front lighting", "rear lighting", "transfer motor start / stop", "left walking", "right walking" and other buttons to control the roadheader. These buttons correspond to the input / output points of the PLC controller in the electric control system of the roadheader one by one, and the PLC controller finally completes the control command.
When the roadheader is operated by remote control, faults may occur. When the fault occurs, it needs to analyze and solve the fault. The common faults, cause analysis and treatment methods of remote receiver and remote transmitter are shown in Table 3.
The use of remote control system device in the roadheader greatly reduces the labor intensity of the roadheader driver, increases the labor safety, improves the labor environment, and enhances the automatic control level of the roadheader. The roadheader remote control system has completed the industrial test, the results show that the system runs stably and safely, and achieves the expected design goal. However, in the industrial test, it is found that the battery power consumption of the remote controller is particularly large when the production team is in the remote control operation of the roadheader, and a production office needs at least two batteries to complete the remote control operation of the roadheader. Therefore, in the follow-up work, it is necessary to study the power consumption of the remote control system of the roadheader to reduce its power consumption and ensure the safe, reliable and stable operation of the roadheader.
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