UWB/INS Integrated Positioning Method Considering Time Latency and NLOS Errors

Ultra-wideband (UWB) positioning technology has currently become a research hotspot for local small-scale positioning and navigation due to its advantages of high accuracy and wide bandwidth. The UWB positioning accuracy based on time of arrival (TOA) can theoretically reach centimeter level accuracy. However, due to the susceptibility of UWB signals to system time latency and non line of sight (NLOS) errors during propagation, it is difficult to achieve the expected positioning accuracy. Based on the method of broadcasting clock differencing approach in GNSS positioning, a UWB time synchronization station is established. Time differencing observation information is used to calibrate the time latency of the base station relative to the main base station. The unknown parameters include tag position information and equivalent time delay latency. The UWB/INS tightly coupled model combines Kalman filtering with ranging innovation vector to reduce the impact of UWB NLOS errors on positioning accuracy by multi-factor adaptive adjustment of the weight of UWB ranging information containing NLOS errors. The impact of time latency is also considered. The experimental results show that the static UWB positioning plane accuracy can reach centimeter level by considering the time latency. The tightly coupled UWB/INS positioning, considering both time latency and NLOS errors, can effectively reduce the influence of system time latency and NLOS errors on positioning accuracy. The positioning accuracy and stability are further improved compared with the conventional UWB/INS combination.