According to relevant statistics, the number of casualties caused by safety accidents in coal mines is at the forefront of safety accidents in the country.

The tunnels under the mine are complex and there are many difficulties in carrying out rescue work. At the same time, the management of personnel underground in coal mines is different from the management on the ground. On the one hand, the positioning of personnel underground is limited by the tunnel, so many personnel positioning technologies cannot be realized; on the other hand, the personnel positioning technology underground requires higher anti-interference. . When an accident occurs underground in a coal mine, the most commonly used search and rescue method is infrared detectors. The principle of using infrared detectors is to detect the infrared radiation emitted by the human body to achieve the purpose of positioning and rescue. However, due to the lack of safety measures in coal mines, The presence of gas will cause the infrared propagation to weaken, and it is also susceptible to interference from other infrared heat sources underground, making it less efficient in actual use. In addition to infrared detectors, life detectors are also commonly used. They mainly detect the ultra-low frequency waves emitted by the human heart to locate people. Microwaves have strong penetrability, but they can also detect some people with weak heart beats. some problems. Under this situation, a device capable of real-time positioning has been developed for underground coal mine personnel. It can be used to solve the daily management of personnel and improve labor efficiency during normal work; when an accident occurs, this device can be used to promptly locate Trapped personnel are located. This article proposes a locating device for underground personnel based on RFID technology, hereafter referred to as the RFID rescue locating device. This device can be worn and is small in size, and can be used as a necessary component of underground rescue work.

1

Overall system design

1.1

Design requirements analysis

Before designing the RFID rescue positioning device, it is necessary to analyze the positioning needs and technical characteristics of underground coal mine personnel.

Finally, a detailed system design can be made. After detailed analysis, 3 requirements must be met:

(1) Comes with its own power supply and has long working hours

Considering the underground

The length of time personnel work in normal work and the timeliness of rescue operations

performance, so the system must be able to work for more than 48 hours;

Abstract: Due to the complex underground environment and the application of infrared detection and life detection instruments, safety rescue in coal mines is subject to many problems.

Limitation, the development of an underground personnel positioning device for coal mine rescue plays a very important role. proposed a method based on RFID technology

Based on the analysis of the needs of coal mine underground positioning systems, the system’s sending module and receiving module were

The design was proposed, a low-power system design method was proposed, the RSSI positioning algorithm and KWWN algorithm in RFID personnel positioning technology were expounded, and a hybrid algorithm was proposed to locate underground personnel. A simulation environment was built and simulated, and the K value was changed. When K=4, the error value for personnel positioning is the smallest, and the system can meet the needs of underground rescue positioning in coal mines.

(2) High reliability and anti-interference. Due to the harsh underground environment, high humidity and many sources of interference during and after the accident, the

The RFID rescue positioning device needs to have a high degree of reliability and anti-interference;

(3) Store user information and support multi-user management. There are generally more than 100 underground workers in large coal mines. Considering the design

There is a margin left, so the RFID rescue positioning device must be able to store user information and support user management functions for 150 people.

1.2

Overall system design

RFID technology is a relatively mature wireless radio frequency communication technology, which is mainly realized through the coupling phenomenon of radio frequency signals in space.

Transmission of information. RFID technology is widely used in fields such as product tag identification and electronic anti-theft. In the positioning system, animals and cars can be marked. Typical applications include pet marking, medical waste management, etc.

The overall design of the rescue positioning device based on RFID technology is divided into two parts. One part is a transmitter worn on the body of underground personnel.

The other part of the unit module is the receiving module for receiving signals.

(1) Launch unit module

The overall block diagram of the transmitter unit module design is shown in Figure 1. Figure 1 Module diagram of transmitting unit based on RFID

The RFID transmitting unit module design includes STC microcontroller, buttons, tag information pre-storage, SPI interface, radio frequency information sending module and power module, etc.

①STC microcontroller The microcontroller is the core control unit. It implements

The detection of reset button and function button input is now implemented, and it also realizes

Pre-storage of tag information. Select MSP430F413 microcontroller, core

The supply voltage is 3.3 V;

②Button

The button is an important factor in realizing the rescue positioning function.

Elements, including reset button and function button, reset button help system in

The initial state can be restored when working abnormally, and the function button can be

Sends a distress signal when pressed;

③Pre-storage of label information. This function uses underground statistics in advance.

Employee related information, age, gender, height, and whether there are underlying diseases

etc., convert this information into binary information and store it in FLASH

, select K9F1G08U0 with a capacity of 128 MB. in need

When sending information, the STC microcontroller first reads the phase in FLASH.

information, and finally the information is sent out through the radio frequency information sending module;

④SPI interface

The SPI interface is a microcontroller and radio frequency information transmission

Send communication interface between modules;

⑤RF information sending module

Since STC microcontroller SPI

The communication signal voltage does not match the final transmitted signal, so

It is necessary to realize the frequency required for synthesis and modulate and demodulate the signal,

Finally, the signal is amplified and sent;

⑥Power module The indicator of the power module is to ensure underground rescue

The key factors, in addition to the signal transmitting unit module in the software

In addition to power management, the power module also needs to be designed independently so that

The overall power supply voltage is stable and the continuous working time exceeds 48 hours.

(2) Receiving module design

The receiving module still uses STC microcontroller as the core control

unit, the tag information is sent through RS232 communication after modulation and demodulation.

Send it to the STC microcontroller. The STC microcontroller stores the RFID tag information.

Store to FLASH, wait for external button command to use LCD to pass

The user tag information processed by the microcontroller is displayed, and the power module

The block is responsible for the power supply of the entire receiving module. RFID based receipt

The meta-module is shown in Figure 2.

Figure 2 RFID-based receiving unit module diagram

2

Low power consumption design and implementation of personnel positioning

2.1

System low power consumption design

Power supply module in RFID-based transmitter unit module

is certain, so in order to ensure that the system can work stably for a long time

To operate, the system must be designed for low power consumption. System low power consumption

Design includes hardware design and software design, specifically including 2

aspect:

(1) Selection of core controller

The core chosen in this design

The controller is MSP430F413, which has multiple low-power modes that can

Meet the system's long-term work. With a 2.2 V supply,

MSP430F413 current 0.5 μA in standby mode, shutdown mode

(RAM retention) current is 0.1 μA, ultra-low power run mode current

The flow is 230 μA. Therefore, in practical applications, the transmitting unit module is

The power is very low during normal operation;

(2) Software design In order to realize that the system can achieve long-term

continuous operation for a period of time, so the system begins to enter ultra-low

Power consumption operating mode, based on its own clock system in software design

To time, enter without external button entry interrupt

Standby mode, and the designed active wake-up button can help underground

Personnel can immediately put the system from standby state to low power when using it.

consumption working mode. This not only meets the needs of underground rescue, but also

It also creates conditions for the system to continue to perform standby work.