Design Of Wireless Sensor Network System For Surface Temperature Measurement Of High-speed Aircraft

Wireless sensor network technology has important research value for the cable-free measurement of ambient temperature field parameters on the outer surface of high-speed aircraft.However,subject to problems such as transmission delay and power consumption,wireless data transmission methods have not been widely used in the outer surface temperature monitoring test of high-speed aircraft.In order to solve the above problems,a synchronous and low-power wireless sensor network scheme based on a new generation of Bluetooth is proposed,and research on improving the transmission rate is carried out.The main contents of the paper are as follows:Firstly,based on the analysis of the design requirements and performance indicators of wireless sensor network of high-speed aircraft,this paper determines the overall scheme of wireless sensor network and demonstrates the two key technologies of wireless sensor network.In order to reduce the influence of time delay on multi-node communication of wireless sensor network,this paper adopts the time synchronization technology based on multi-segment compensation bidirectional clock algorithm,and predicts the clock offset of the next cycle and calibrates in advance to achieve the purpose of master and slave node clock synchronization.On this basis,the traditional polling method is improved,and a polling access method based on time synchronization is proposed,which polls multiple slave nodes by sending a synchronization frame.By reducing the time for the sensor to wake up from the node,the low-power design of the system is realized in terms of software.By reducing the redundancy of the synchronization frame signal,the average polling period is shortened,and the effective data transmission rate is improved.Secondly,the experimental system of wireless sensor network is designed,and the key circuits are discussed.The conditioning circuit of K-type thermocouple is designed to achieve the effect of cold junction compensation,reducing electromagnetic interference and improving signal gain.In the mode of dual crystal oscillators,two working conditions are designed for the n RF5340 chip for energy management,32 MHz high-speed crystal oscillator is selected during normal operation,and 32.768 KHz low-speed crystal oscillator is selected during sleep to achieve power consumption reduction;the received data is framed on the Bluetooth main node side,the access address,check digit,etc.are discarded,and the frame header and data capacity information are added to facilitate data analysis after reading;The storage and recording module is designed by file management to quickly extract effective data.In order to verify the rationality and feasibility of the above content,an experimental test platform composed of temperature sensor,conditioning circuit,Bluetooth master-slave node and storage record module was built,and the performance index test of node synchronization,power consumption,transmission rate,transmission distance and packet loss rate was carried out.The experimental results show that the difference of node synchronous sampling time is less than 10μs.When transmitting the data state,the average working power consumption of the sensor slave node is 7.4036 m W,and the power supply is supplied by a coin cell battery(550m Ah),which can be used for more than 246 h,which can meet the actual working time requirements;the data transmission rate can reach 1.375 Mbps,the effective transmission distance can reach 13 m,and the average packet loss rate is only 0.0851%,realizing the design index that the data rate is better than 1Mbps.It meets the transmission rate requirements of high-precision and synchronous acquisition of multi-sensor from nodes for surface temperature field measurement of high-speed aircraft.