Robot localization by sparse and passive RFID tags

A global localization problem for a robot combining odometry data with RFID (Radio Frequency IDentification) readings is addressed in this paper. RFID tags are placed on the ceiling of the environment and the robot can detect their presence when traveling below them. The detection of the tags is the only information used in our approach (no distance or bearing to the tag is considered available), but differently from similar localization setups reported in the literature, only a small number (about one each m² or less) of tags is used. Two localization methods are proposed: the first method, computationally fast, is based on Kalman filtering and considers RFID readings as quantized measurements of the robot position; the second method is based on a Particle Filter. Both methods provide a satisfactory performance, with an average position error less than 0.1 m. This result has been achieved resorting to a suitable tag´s antenna, expressly designed to obtain regular and stable RFID detection regions. The hardware/software localization setup described in this paper may provide a satisfactory approach in several industrial and domestic scenarios.