A High-Accuracy TOA-Based Localization Method Without Time Synchronization in a Three-Dimensional Space

Time-of-arrival (TOA) is a widely used localization technique in robotic localization systems. However, TOA-based methods require strict time synchronization between the source (target) and sensors (receivers), which significantly influences the localization accuracy. In this paper, we propose an iterative Time-of-arrival (iTOA) localization technique to eliminate the time synchronization error in robotic localization systems. iTOA first measures the distance between the source and sensors according to the travel time of the signal. Then, iTOA constructs the multivariate linear model based on the measured distances, position of sensors, and unknown synchronization error, and uses the least square method to calculate the synchronization error. Finally, by using the constructed model and iteratively subtracting the synchronization error, we obtain the precise source localization with the near-zero synchronization error. For the synchronization error elimination, iTOA can work well in both the two-dimensional (2-D) and 3-D space. We conduct experiments in both a simulation environment and a real sensor system to demonstrate the effectiveness of the proposed scheme. The experimental results show that the accuracy of localization is improved by more than 31% and 26% on average compared with the representative algorithms in the simulation and real environments, respectively.