Design Of Wearable Firefighter Navigation And Positioning System

Affected by toxic gas and smoke,it is difficult for firefighter to judge their current position when firefighter rescue in complex indoor environment.The monitoring and command personnels also lack an effective way to conduct real-time positioning for firefighter,and they cannot provide timely and effective rescue when firefighter is in distress.GPS cannot be used in indoor environment,and base stations need to be arranged in advance for Wi-Fi,bluetooth,RFID,UWB indoor positioning methods,which cannot meet the requirements of emergency rescue.Moreover,the disaster relief site is often accompanied by problems such as power interruption and communication paralysis,and the positioning data cannot be transmitted through the infrastructure,so an independent communication network needs to be established.However,the complex indoor environment will cause serious signal occlusion,which affects the coverage of the communication network and makes it impossible to carry out large-scale indoor positioning.In view of the above problems,this paper designs a set of wearable firefighter navigation and positioning system based on the principle of inertial navigation,which consists of four parts: a positioning node,multiple relaying nodes,a receiving node and a software in monitoring terminal.Among them,the positioning node is installed on the outside of the heel of the firefighter to collect the inertial data of the foot movement.By using the principle of inertial navigation,the three-dimensional position coordinates of the firefighter relative to the initial position are calculated in real time and the positioning data are sent out.Multiple relaying nodes are carried by firefighter and arranged indoors during the operation to establish independent wireless transmission network.The receiving node is connected with the monitoring terminal,and after receiving the positioning data,it is forwarded to the software in monitoring terminal.The software in monitoring terminal processes positioning data,displays the position coordinates of firefighter in real time,and draws the action trajectory of firefighter.The coordinate data and trajectory pictures can be saved.In this paper,the algorithm,hardware and software of the system are studied and designed in detail.The main contents are as follows:1.By studying the relevant theories of inertial navigation,analyzing the gait cycle during walking,and using the zero-velocity correction method based on kalman filter to correct the error,the navigation and positioning algorithm for firefighters that can be operated in real time in the embedded system is designed to realize the real-time estimation of the position of firefighter in three-dimensional space.2.According to the characteristics of small size and low power consumption that wearable devices should have,device type selection and circuit design were carried out for each module of system hardware,and the PCB circuit board was made to form the physical object by welding.3.The positioning program of the positioning node,the data relaying transmission program of the relaying node and the data receiving program of the receiving node are designed by analyzing the functions to be completed by each node.In the process of data transmission,the relaying transmission method based on LoRa technology is used to expand the coverage of communication network.The software in monitoring terminal is designed,and the real-time display and storage of 3D coordinates and 3D motion trajectory are realized.Finally,relative positioning error test and communication distance test are carried out for the system.The test results show that the relative positioning error of the system is within 5%.,the multi-hop transmission of data can be completed by arranging relaying nodes and the signal coverage of long-distance and multi-floor buildings can be realized,which verifies that the system has practical value.