RFID Sensor Modeling by Using an Autonomous Mobile Robot

Radio Frequency Identification (RFID) technology has been available for more than fifty years. Nevertheless, only in the last decade, the ability of manufacturing the RFID devices and standardization in industries have given rise to a wide application of RFID technology in many areas, such as inventory management, security and access control, product labelling and tracking, supply chain management, ski lift access, and so on. An RFID device consists of a number of RFID tags or transponders deployed in the environment, one or more antennas, a receiver or reader unit, and suitable software for data processing. The reader communicates with the tags through the scanning antenna that sends out radio-frequency waves. Tags contain a microchip and a small antenna. The reader decodes the signal provided by the tag, whereas the software interprets the information stored in the tagŠs memory, usually related to its unique ID, along with some additional information. Compared to conventional identification systems, such as barcodes, RFID tags offer several advantages, since they allow for contactless identification, cheapness, reading effectiveness (no need of line of sight between tags and reader). Furthermore, passive tags work without internal power supply and have, potentially, a long life run. Owing to these advantageous properties, RFID technology has recently attracted the interest of the mobile robotics community that has started to investigate its potential application in critical navigation tasks, such as localization and mapping. For instance, in (Kubitz et al., 1997) RFID tags are employed as artificial landmarks for mobile robot navigation, based on topological maps. In (Tsukiyama, 2005), the robot follows paths using ultrasonic rangefinders until an RFID tag is found and then executes the next movement according to a topological map. In (Gueaieb & Miah, 2008), a novel navigation technique is described, but it is experimentally illustrated only through computer simulations. Tags are placed on the ceiling in unknown positions and are used to define the trajectory of the robot that navigates along the virtual line on the ground, linking the orthogonal projection points of the tags on the ground. In (Choi et al., 2011) a mobile robot localization technique is described, which bases on a sensor fusion that uses an RFID system and ultrasonic sensors. Passive RFID tags are arranged in a fixed pattern on the floor and absolute coordinate values are stored in each tag. The global position of the mobile robot is obtained by considering the tags located within the reader recognition area. Ultrasonic sensors are used to compensate for limitations and uncertainties in RFID system. 13