A new indoor position estimation method of RFID tags for continuous moving navigation systems

The RFID (Radio Frequency Identification) is considered as one of the most preferable ways for the position estimation in indoor environments, since GPS does not work in such situations. In RFID system, an RFID reader enables to estimate the position of RFID tags easily and inexpensively. In applications with the position estimation of RFID tags, indoor robot navigations are very important for human society. The problem is how to obtain the position estimations of RFID tags as accurately as possible. Previously S-CRR (Swift Communication Range Recognition) has been proposed for the appropriate estimation method of this kind of applications. This method is capable of the accurate position estimation of an RFID tag in very short time. The disadvantage of S-CRR is that the mobile robot must stop to search RFID tags accurately at each position. In indoor robot navigations, mobile entities like robots have to move continuously because they need to navigate smoothly and safely. In this paper, we propose a new position estimation method of RFID tags with continuous moving only using RFID technology. We call this Continuous Moving CRR (CM-CRR). CM-CRR uses two communication ranges, long and short ranges and switches them appropriately. The system estimates the position of RFID tags using their approaches and continuous moving. To show the effectiveness of CM-CRR, we evaluate the estimation error of an RFID tag by computer simulations. From the results, CM-CRR can accurately estimate the position of RFID tags with continuously moving of the mobile robot and be applied to indoor robot navigations.