Abstract: [Purposes]Aiming at the complex working conditions of narrow and airtight space,high occlusion and significant electromagnetic interference in tunnel construction,and to meet the practical needs of high-precision positioning and safety monitoring of construction personnel,engineering vehicles and mechanical equipment,a ultra-wide band (UWB) tunnel construction positioning system integrated with wireless AP function was designed by integrating the technical advantages of internet of things (IoT) and UWB positioning technology.[Methods]By optimizing the layout scheme of UWB base stations in tunnel scenarios,a three-layer architecture system of “positioning perception-network transmission-information application” is built to realize the functions of real-time positioning,trajectory tracing and one-key emergency alarm of monitoring targets in the tunnel.[Findings] An improved ranging algorithm based on time difference of arrival (TDOA) is adopted to effectively reduce the positioning deviation in the tunnel non-line-of-sight (NLOS) environment,and the positioning accuracy of the system was verified through field tests.The experimental results show that the positioning error of the system is stably within 0.4 m in the tunnel construction environment,which can meet the high-precision positioning and monitoring requirements of personnel and mechanical equipment in tunnel construction.At the same time,the integrated design of wireless AP simplifies the wiring process in the tunnel and improves the stability of data transmission.[Conclusions]The application of this system can provide technical support for the information management and safety emergency disposal of tunnel construction,and effectively improve the intelligent level of tunnel construction safety supervision.

Key words: tunnel construction, UWB positioning, internet of things, improved TDOA algorithm, construction safety, high-precision positioning