Research and Development of Personnel Positioning and Life Information System Based on S3C2410

1 Introduction

With the rapid development of my country's social economy and the continuous acceleration of urbanization, the hazards caused by various disasters such as earthquakes, floods, volcanoes, landslides, and mudslides are becoming more and more obvious, and the impact on society is becoming more and more serious. The country has also begun to adopt some policies and measures for earthquake resistance and disaster reduction. In April 2001, the China International Rescue Team was officially established. So far, it has participated in four international rescue activities, and each province has also organized its own rescue team. However, the construction of my country's rescue team is still in its infancy and needs to be continuously improved. This paper studies the life information system of rescue personnel, completes the extraction and transmission of life signals and positioning information, and designs the human-computer interface for data processing and display in the command center.

2. System overall design

This solution consists of two parts: hardware system and software system. The hardware system consists of two parts: extension and host, namely the equipment carried by rescuers and the central data receiving and control center platform. The extension uses Samsung's 32-bit multi-function, low-power embedded processor S3C2410 as the control chip. There are 4 sensors that can independently collect life information such as ECG, respiratory blood oxygen saturation and body temperature of rescuers, and at the same time obtain positioning information from the GPS module and transmit it to the host through wireless communication. According to the actual application site and conditions, it is composed of different numbers of extensions with one or more hosts. The extension is responsible for collecting the life status information of the rescuers and transmitting it to the host through wireless communication. The host receives the life status information data and displays the monitoring data after processing. It can receive the data sent by the extension in response or the data and distress signal automatically sent by the extension when it detects abnormal physiological parameters. The received data is stored in correspondence with the extension number and its location can be determined at the same time. The software system is mainly composed of functional modules such as electronic maps, information management, information query, action map, dynamic situation and dynamic monitoring of team members. The data processing and real-time display program of the host end of the command center. The overall system block diagram is shown in Figure 1

2.1 Hardware Design

The hardware system of the extension adopts modular design and consists of the following subsystems: 1. Life status monitoring system; 2. Gas and chemical agent detection system; GPS positioning subsystem; 4. Wireless communication system. The embedded processor controls the collection of the life status signals and GPS positioning information of the team members, and then sends them back to the control center host through the wireless data transmission radio. The physiological status signals of the team members include heart rate, respiration, body temperature, blood pressure and other signals. Drawing on the development experience at home and abroad, four physiological indicators of heart rate, respiration, body temperature and blood oxygen saturation are mainly selected as the life status signals of the team members. The GPS OEM board adopts the GARMIN series GPS25LVS OEM board. GPS25LVS is a 12-channel GPS receiver that can track 12 GPS satellites at the same time, so as to quickly locate. The embedded processor adopts Samsung's 32-bit multi-function, low-power embedded processor S3C2410 with ARM920T core and 0.18um manufacturing process. The extension design diagram is shown in Figure 2. S3C2410 is a high-end embedded microprocessor launched by Samsung in South Korea, which can be used for the development of portable products such as handheld devices and smart home appliances. The processor has: independent 16KB instruction cache and 16KB data cache, MMU, LCD controller supporting TFT, NAND flash controller, 3-way UART, 4-way DMA, 4-way Timer with PWM, I/O port, RTC, 8-way 10-bit ADC, touch screen interface, 2 USB hosts, 1 USB device, SD host and MMC interface, 2-way SPI. It can run at up to 203MHz.

2.1.1 Life Information Subsystem

The life information subsystem is mainly composed of 4 sensors and analog-to-digital conversion chips, including heart rate sensor, gas sensor, muscle oxygen saturation sensor and body temperature sensor. The gas sensor is used to detect whether there is gas and harmful chemical gas near the rescue team. After the 4 sensors collect life information, they are amplified and filtered, and then A/D converted and transmitted to the embedded processor. S3C2410 itself has 8-channel 10-bit A/D conversion function, but because A/D conversion requires strong real-time performance, although the system has transplanted a real-time operating system to automatically schedule multiple tasks, considering the stability of the system, an external A/D conversion chip is used. The A/D conversion chip uses MAX186, which is widely used in multi-channel data acquisition systems. The serial analog-to-digital converter MAX186 is a single-chip data acquisition device that uses primary and secondary approximation A/D conversion technology. It integrates multiplexer switches, reference voltage sources, clock circuits and conversion circuits in one chip, which can be easily connected to various microprocessors, and requires fewer peripheral devices and is easy to use. The A/D conversion circuit is shown in Figure 3

2.1.2 Positioning Information Subsystem

GPS positioning technology is to use navigation satellites to measure time and distance to form a global positioning system. Using GPS positioning has the advantages of simple observation and good economic benefits. After differential, the positioning accuracy can reach less than 5 meters, and after specific post-processing, the positioning accuracy can reach centimeter level. The satellites and ground support systems of the GPS system are funded and operated by relevant countries. The user receivers have also been standardized. For users, they only need to receive the signals of the user receivers. This system uses the 12-channel GARMIN series GPS25LVS OEM board. The input voltage of the GPS25LVS GPS OEM board is 3.6-6V, the positioning accuracy is less than 15 meters, the differential accuracy is less than 5 meters, the update rate is 1 second, and the positioning time: re-capture is less than 2 seconds, hot start is about 15 seconds, and cold start is about 45 seconds.

Connected to the embedded processor via RS-232 serial port, the serial port outputs NMEA-0183 version 2.0 ASCII sentences. NMEA-0183 format starts with "$" and ends with " ". The main sentences are: GPGGA, GPGLL, GPVTG, GPRMC, GPZDA, PKODA, PDODG1, PKODG7, GPGSA, GPGSV, etc. Among them, GPGGA is a positioning output sentence, including time and positioning data, which is widely used. Its specific format is as follows (DGPS is not used):

$GPGGA, hhmmss (Coordinated Universal Time UTC), 111111111 (latitude), N/S (North/South), yyyy1yyyy (longitude), E/W (East/West), x(positioning status), xx (number of satellites used), xxx (HDOP value), 0/-xxxx (antenna height), M (meter), 0/-xxx (geographic altitude), M (meter), 3 hh (checksum) ．[page]

2.1.3 Wireless Transmission Subsystem

Taking into account the various situations at the disaster relief site, this system can realize multiple transmission methods, such as GPRS, data radio and Ethernet. It can also expand the GSM module to transmit data to the command center in the form of short messages. However, communication at the disaster relief site is generally difficult, so the system mainly considers using spread spectrum communication to send life information and positioning information.

The system initially considered using the spread spectrum baseband processing chip W9310 to realize the spread spectrum and despread processing of life information and positioning information, and then formed a complete wireless spread spectrum system through the RF module WHT9261 to transmit life information and positioning signals to the command center. As shown in Figure 1

3. Software part: Command center data processing and display system

The software system consists of electronic maps, information management, information query, action maps, dynamic situation and team dynamic monitoring modules. Each module is integrated under the same interface. They are interconnected and relatively independent. It uses a variety of digital information technologies to achieve the best allocation of resources within the entire rescue site and can monitor all rescue operations in real time.

With rescue team members, together with the hardware system, the rescue team's command, control, communication, and logistics support functions are integrated, completing the design of the rescue team's life information system

The main functions are as follows

1. Team member location tracking function: Receive GPS data sent back by team members' portable devices, and display the team members' real-time location in a frame-by-frame list, including team member number, latitude and longitude, speed, direction, time and date data.

2. Team member life information tracking: Receive the life signal data collected by the team member's portable device, compare it with the standard life data, and display it in a list. Abnormal signals will issue a warning.

3. Electronic map marking: The location information of the designated team members is marked on the two-dimensional electronic map of the rescue area. The electronic map can be arbitrarily reduced, enlarged, restored and switched. It can be polled and marked arbitrarily.

The expandable functions include auxiliary command and decision-making functions, and can also be combined with GIS to realize three-dimensional electronic map display, further completing and facilitating the efficient deployment of rescue work. The overall block diagram of the software system is shown in Figure 4.

4 Conclusion

The rescue team member life information system integrates advanced technologies such as GPS positioning technology, spread spectrum communication technology and embedded processors to complete the life information monitoring of the rescue team members. When encountering emergencies or unexpected situations at the rescue site, the rescue team members can receive alarms in a very short time, take emergency measures in time or evacuate the scene quickly, ensuring the life safety of the rescue team members, minimizing casualties and ensuring the efficient implementation of the rescue operation. At the same time, the command personnel can monitor the location of the team members through the system, conveniently understand the situation of the rescue, and reasonably realize the automation and digitization of personnel dispatch and command management. To a certain extent, it plays a positive role in promoting the modernization of the rescue team. In summary, this system can complete the predetermined goal of collecting the life signals and location data of the rescue team members and display them through the human-computer interaction interface in the center. It is an advanced and feasible rescue system.

The author's innovation points:

1. For the first time, advanced technologies such as GPS differential positioning, embedded processors, and spread spectrum communication are applied to rescue equipment, and various functional modules are integrated to achieve system integrated design.

2. The information collected can be transmitted back to the command center and teammates. The information communication with teammates and the command center can be maintained, and the collaborative rescue capability will be significantly improved. It can enhance the ability to implement mobile rescue according to the command of the superior command center or the request of the rescue team members of the same level, and improve the response speed.

3. The location and status information of each team member is displayed in the command center list to facilitate the commander's overall scheduling and macro command.

References

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