Improvement of position estimation of the ultrasonic 3D tag system

This paper presents an improvement of position estimation of the ultrasonic 3D tag system developed by the authors. We are involved in a joint project of developing an omnidirectional autonomous mobile robot system and our ultrasonic 3D tag system was employed as an indoor GPS system to the robot. However, the position estimation error of current system is not enough to support the mobile robot, that is, position estimation error of the system is about 50 mm by using the currently implemented robust estimation methods. By employing a new estimator based on a nonparametric filter, the estimation error was reduced to less than 20 mm on average. Moreover, the new method is much robuster than the previous methods. This paper introduces an overview of the system and experimental results of simulations.