CN101858750A - Intelligent positioning and navigation system for rescue assistance in large buildings - Google Patents

Abstract

The present invention is based on a wireless ranging sensor that combines radio frequency communication and ultrasonic ranging technology, and constructs a multifunctional sensor with precise positioning, information interaction function, information recording, path planning, video and audio integration, etc., which is used in large buildings. Rescue-assisted intelligent positioning and navigation system is used to deal with emergencies such as terrorist attacks and fires that may occur in large buildings, and rescue trapped people in the shortest possible time. The system consists of three parts: a wireless ranging sensor node array, a mobile terminal, and a remote server end, which are preset in the building. The mobile terminal receives the ranging information of the sensor node array, and as long as it obtains the ranging data between three or more positioning nodes, it can realize the precise positioning of the terminal through the triangulation method, quickly plan the optimal path for the user, and send the relevant The information is sent to the server for viewing by the monitoring center. In terms of hardware and software design, we have implemented small power consumption, accurate calculation of distance and position, and conflict avoidance algorithms.

Description

Intelligent positioning and navigation system for rescue assistance in large buildings

technical field

The technical field involves wireless communication, radio frequency communication technology and ultrasonic ranging technology, as well as Dijkstra algorithm to realize path planning and navigation and appropriate mathematical modeling ideas

Background technique

At present, in order to deal with various man-made and natural emergencies, maintain social stability and the safety of people's lives and properties, there is an urgent need for a device that can perform real-time precise positioning, navigation and information services under indoor conditions to support building interiors. search and rescue activities. The GPS system is currently the most commonly used wireless positioning system, but the GPS signal cannot cover the inside of the building. However, the wireless positioning method based on the mobile communication network has low resolution and large positioning error. Ultrasonic is a traditional ranging sensor that can be used for positioning, but the information obtained by ultrasonic is relatively simple, which is not easy to identify targets, and it is difficult to support continuous high-precision positioning in large areas. In order to solve the problem of target recognition, it is a possible solution to integrate radio frequency communication technology and ultrasonic ranging technology. This design is based on such an idea, to design an internal positioning and navigation system for intelligent buildings, to improve the security level of intelligent buildings, and to provide a better management platform for intelligent buildings, and to provide Public security, firefighting, rescue, etc. The following are only outstanding technical features and significant progress compared with the prior art.

Contents of the invention

Based on wireless sensor network, it is our solution to integrate radio frequency communication technology and ultrasonic ranging technology. This project is based on such an idea to design an internal positioning and navigation system for intelligent buildings to improve the security level of intelligent buildings. , and provide a better management platform for intelligent buildings, and can be used by public security, firefighting, and rescue under special circumstances. This design designs and implements a precise positioning system for local environment, including mobile terminals, a server that provides services for the terminals, and several sensor nodes arranged indoors.

The system can provide terminal holders with services such as precise mobile positioning, navigation and timely information interaction. The terminal can locate and navigate for the user in real time; the terminal and the server can exchange information through messages; the terminal can collect video through the camera and compress it and send it to the server through the wireless network for instructions and scheduling; the server provides information services for the terminal, user management, etc. Function. The sensor nodes are used to receive and send radio frequency ultrasonic signals to realize the positioning function. The following are the innovative technologies and technical difficulties of the project:

(1) Conflict avoidance algorithm

If the radio frequency signals RF ₁ , RF ₂ and ultrasonic signals US ₁ , US ₂ respectively represent the information received by landmarks 1 and 2 at the same detection landmark, and the RF carries landmark ID information, the detection node can identify RF ₁ and RF ₂ , and US Without carrying any information, the detection node cannot distinguish between US ₁ and US ₂ , so due to the incoordination of road signs 1 and 2, there will be conflict interference as shown in Figure 7, where US ₂ is received after RF 1 _and in front of US ₁ , because the detector Unable to identify US ₁ and US ₂ , the detection node mistakenly regards the time interval t between RF ₁ and US ₂ as the time interval between RF ₁ and US ₁ , resulting in an incorrect measurement distance.

The above-mentioned conflicts can be divided into two types. One is that there is an external RF signal conflict between the transmitting RF and US of the same detection landmark, as shown in Figure 1; the other is that there is an external US signal conflict between the transmitting RF and US of the same detection landmark. as shown in picture 2.

In order to deal with the conflict shown in Figure 1, since the radio frequency and ultrasonic signals sent by the detection road signs will disappear within the Dus time, each detection road sign is first idle for a random period of time, and then turns on the radio frequency and receives external radio frequency signals. When any signal is received and the RF load is idle, it starts sending its own RF and ultrasonic signals.

In order to cope with the conflict shown in Figure 2, the detection node internally maintains the receiving time of the latest two radio frequency information. When the detection node receives the ultrasonic signal, it judges whether more than one radio frequency information is received within the Dus time. If more than one is discarded, Otherwise compute the distance.

(2) Sensor sleep mechanism

The working current of each sensor node is 20mA in full working mode, and 40uA in power-saving mode, and the normal range of working current is between 40uA and 20mA, and the normal working current is 2mA. In power-saving mode most of the time, only one serial peripheral interface SPI (Serial Peripheral Interface) is reserved for sending radio frequency signals in this mode.

(3) Accurate calculation of distance

The positioning based on TDOA (The Differential time Of Arrival) is a kind of positioning technology based on distance. The typical representatives are Active Bat and AHLos. These systems use the formula S=V*ΔT to calculate the guide node based on the arrival time difference of radio frequency signals and ultrasonic waves. The distance from the receiver, under normal room temperature and humidity, the speed V1 of sound is about 344m/s, and the speed V2 of light is about 3×10 ⁸ m/s. Since V2 is much larger than V1, there is $S\&cong;\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="DEST\_PATH\_HSB00000033168600013.png"\; state="\{\{state\}\}">V</figure-callout>}1\&Center\; Dot;T,$ Then use the least square method to fit a curve that meets the requirements according to the elements in the collected distance set. (See Figure 3)

(4) Accurate positioning of moving targets

Combining professional knowledge in the field of measurement and using the principle of triangulation, once the effective information of more than three guiding nodes (including the node's position coordinates, ID number, etc.) is received, the current position of the moving target can be calculated.

The relational formula between each guide node and receiver: ${(x-x_i)}^2+{(\mathrm{the\; y}-{\mathrm{the\; y}}_i)}^2+{(z-z_i)}^2={\mathrm{<figure-callout\; id="2"\; label="d\; i"\; filenames="DEST\_PATH\_HSB00000033168600013.png"\; state="\{\{state\}\}">d</figure-callout>}}_i^{}$

Target by: $A\stackrel{\&Right\; Arrow;}{x}=b,$ in:

$\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; =</span>\left[\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 2</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ \mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 2</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>& <span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>& <span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\\ \mathrm{<span\; class="notranslate">\; 2</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}& \mathrm{<span\; class="notranslate">\; 2</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}& \mathrm{<span\; class="notranslate">\; 2</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right]$ $\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; x</span>}\\ \mathrm{<span\; class="notranslate">\; the\; y</span>}\\ \mathrm{<span\; class="notranslate">\; z</span>}\end{array}\right]$

$\stackrel{\&Right\; Arrow;}{b}=\left[\begin{array}{c}{x}_1^2-x_0^2+{\mathrm{the\; <figure-callout\; id="1"\; label="y"\; filenames="DEST\_PATH\_HSB00000033168600013.png"\; state="\{\{state\}\}">y</figure-callout>}}_1^2-{\mathrm{the\; y}}_0^2+{\mathrm{<figure-callout\; id="1"\; label="z"\; filenames="DEST\_PATH\_HSB00000033168600013.png"\; state="\{\{state\}\}">z</figure-callout>}}_1^2-z_0^2-({\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="DEST\_PATH\_HSB00000033168600013.png"\; state="\{\{state\}\}">d</figure-callout>}}_1^2-d_0^2)\\ x_2^2-x_0^2+{\mathrm{the\; <figure-callout\; id="2"\; label="y"\; filenames="DEST\_PATH\_HSB00000033168600013.png"\; state="\{\{state\}\}">y</figure-callout>}}_2^2-{\mathrm{the\; y}}_0^2+{\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="DEST\_PATH\_HSB00000033168600013.png"\; state="\{\{state\}\}">z</figure-callout>}}_2^2-z_0^2-({\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="DEST\_PATH\_HSB00000033168600013.png"\; state="\{\{state\}\}">d</figure-callout>}}_2^2-d_0^2)\\ ...\\ x_{m-1}^2-x_0^2+{\mathrm{the\; y}}_{m-1}^2-{\mathrm{the\; y}}_0^2+z_{m-1}^2-z_0^2-(d_{m-1}^2-d_0^2)\end{array}\right]$ m≥4

Triangulation positioning calculation formula:

$\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; b</span>}}$

(5) Path planning and navigation

The mobile terminal determines the best path from the current location to the target location with the aid of positioning information. Combined with the data structure of the designed map, the improved Dijistra algorithm is applied to search for the shortest path to each location, and the shortest path is obtained according to the path recorded by the search. (The effect is shown in Figure 4)

(6) map design;

The electronic map of the mobile terminal should provide the holder with a friendly interface to assist positioning and navigation. The existing electronic map is not suitable for indoor three-dimensional applications in terms of display style and storage format. Therefore, it is planned to customize the electronic map in XML format. The map is stored in a file in XML format. Users can select different files to apply to different maps, read them into memory through an XML reader (custom class), and display the map on the mobile terminal.

(7) Video collection and transmission

The camera collects the data around the mobile terminal, then displays it on the mobile terminal, compresses it, and transmits it to the remote server through 802.11 wireless, and the server decompresses the data and reproduces the video. The compression algorithm uses h263 to compress the data from RGB format to YUV format. The actual before and after transmission effects are shown in Figure 5 and Figure 6.

Description of drawings

Figure 1 An external RF signal conflict occurs between the transmitting RF of the same detection road sign and the US

Figure 2 There is an external US signal conflict in the middle of transmitting RF and US on the same detection road sign

Figure 3 Comparison chart of ranging scatter curves

Figure 4 Path planning result map

Figure 5 video screenshot before compression

Figure 6 video screenshot after compression

Figure 7 Actual Effect Diagram of Mobile Terminal

Figure 8 Schematic diagram of system positioning

Figure 9 Schematic diagram of information transfer between guidance nodes and receivers

Figure 10 Mobile Terminal Software Flowchart

Figure 11 Server-side software flow chart

Figure 12 sensor node layout model

Detailed ways

(1) Realization principle of real-time high-precision indoor positioning

As shown in Figure 8, several wireless sensor nodes are arranged according to certain rules in the indoor environment as guides (Beacon). Each guide node has the function of radio frequency communication and the function of sending and receiving ultrasonic signals, and has a unique ID number. , the corresponding location information and its ID number are stored inside the node.

As shown in Figure 9, after the moving target enters the area, the receiver (Listener) carried by itself can obtain the ID number and location information of the adjacent guidance node through radio frequency communication, and can obtain the received information through ultrasonic ranging. Once the information of more than 3 adjacent guidance nodes is obtained, according to the position of each guidance node and the distance between each guidance node and the receiver, it can be calculated by using the principle of triangulation Out of the receiver is the current position of the moving object. The receiver is responsible for identifying the guidance node and measuring the distance, and then transmits the information to the mobile terminal equipment connected to it, and the mobile terminal with strong computing ability completes the more complex positioning calculation.

(2) Sensor node layout model

Arrange the wireless ranging sensor node array in advance in the building according to L=H tanθ (L is the distance between two adjacent guidance nodes, H is the height of the room, θ is the beam angle of ultrasonic waves), and the wireless sensor network is to be deployed. After finishing, turn on the server side and the whole system can work normally. As shown in Figure 12.

(3) Mobile terminal software process

When the mobile terminal software is running, the basic initialization is performed first, especially the initialization and parameter setting of the relevant hardware modules. Then enter the main program loop. Next start the corresponding module. The main flowchart of the mobile terminal software is shown in Figure 10, and the description is as follows:

System initialization: Initialize the basic display information and the display model of the basic controls of the program.

Main program entry: After the program is initialized, it waits for the user to operate.

Main interface module: import and store map file information in a custom structure and display it; wait for user input commands.

Navigation module: responsible for receiving the location information from the surrounding Beacon, and then read the Listener serial port data and convert it into map coordinates.

Video module: responsible for collecting on-site images, compressing them, and transmitting them to the network module.

Network module: responsible for sending compressed video images to the server, and exchanging information between the server and the mobile terminal.

(4) Server-side software process

Map import, user management, map management, and information service are performed according to the administrator's command. After completing the corresponding service, judge whether to exit, if it is confirmed to exit, then exit, otherwise return to the state after initialization. Figure 11

Start the server. After the user opens the mobile terminal, he needs to send a message request to the server. After the verification is successful, provide relevant services for him, otherwise give the reason for the error.

User management: verify users, manage application users, etc.

Information service: receive messages and send messages, reply.

Locate User: Display the location of the specified user. Position according to the location information sent by the user, and mark it on the server-side interface. Supports zooming of the map display.

Map management: download maps, import maps, and support the import of specified maps.

Claims (8)

1. An intelligent positioning and navigation system for rescue assistance in large buildings, the system includes three components: a wireless ranging sensor node array, a mobile terminal, and a remote server end arranged in advance in the building, and is characterized in that the positioning The navigation process consists of the following steps: Step 1: The receiver carried by itself obtains the ID number and location information of the adjacent guide node through radio frequency communication, and combines the ultrasonic ranging method to obtain the distance between the receiver and the guide node; Step 2: As long as the distance measurement data between three or more positioning nodes (the position coordinates of each positioning node are recorded in the node in advance), the accuracy of the location of the terminal holder can be calculated by the triangulation method position; Step 3: It can quickly plan the optimal path for the user from the current location to the set destination, use the camera to collect the scene information around the mobile terminal, compress it and send it to the server for viewing by the monitoring center; the server side provides the terminal with user management, Guidance and other functions. 2. by the described system of claim 1, it is characterized in that according to L=H tan (L is the distance between adjacent two guide nodes, H is the height of room, is the beam angle of ultrasonic wave) in advance in building interior Arrange the wireless ranging sensor node array. 3. The system according to claim 1, characterized in that the ID number and location information of the adjacent guiding nodes are obtained through radio frequency communication, and the distance between the receiver and the guiding nodes is obtained in combination with ultrasonic ranging. 4. The system according to claim 1, characterized in that the electronic map in XML format can be customized to mark elements such as floors, rooms, inflection points, and the user can choose to load and display different maps. 5. The system according to claim 1, characterized in that it is based on the distance positioning technology, and according to the element in the collected distance collection, the least squares method is used to fit a curve that meets the requirements, and the distance accuracy can reach centimeter level. 6. The system according to claim 1, characterized in that 802.11 wireless network is used to realize wireless communication and video transmission. In the process of video transmission, the frame is used to compress, and after reaching the server, the video is decompressed and reproduced. 7. The system according to claim 1, characterized in that an optimal route from the current position to the specified position can be determined through route planning. 8. The system according to claim 1, characterized in that one or more relay stations are used to transmit data between the base station and the user in a wireless manner.

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