Research On Range-free Sound Source Localization Method In A Wireless Sensor Network

The maturity of wireless sensor networks(WSNs)technology provides a huge development space and a wide range of application scenarios for sound source localization methods based on WSNs,such as security warning,environmental monitoring,and smart city.In some specific application scenarios,the robustness of the sound source localization method is more concerned than the localization accuracy.Therefore,this paper proposes a highly robust sound source localization method based on range-free: Sequence-Based Localization with Linear Programming(LPSBL)algorithm.In addition,this paper also designs and implements a sound source localization system based on existing mobile devices to verify the performance of the LPSBL localization algorithm in real environment.The LPSBL localization algorithm constructs constraints by using the order of the sound source signals reach each node,and converts them into a linear programming form to estimate the position of the sound source.To enhance the robustness,the LPSBL algorithm also uses the relaxation amount idea in convex optimization to solve the problem of localization failure caused by the Time of Arrival(TOA)measurement error.The sound source localization system based on the existing mobile device utilizes the Precise Time Protocol(PTP)under WLAN to perform coarse-grained time synchronization on the mobile device,and a statistical method is introduced to ensure the stability of time synchronization.The mobile devices detect the first arriving signal sampling point from the sound source by a moving variance method and obtain the TOA of sound source signal reach the mobile device through the linear interpolation method.Finally,this system estimates the sound source position by inputting the TOA of each node into the LPSBL localization algorithm.In this paper,the localization performance of the LPSBL algorithm is verified by simulation and experiments,and the SBL algorithm is introduced for comparison.The experimental results show that the LPSBL localization algorithm can effectively locate the sound source in the presence of node position error and node TOA measurement error.This shows that the LPSBL algorithm maintains extremely high robustness while providing satisfactory localization accuracy.