Attitude Estimation Based on Arrays of Passive RFID Tags

In this paper, a method to estimate the attitude of an object using uniform arrays of radio frequency Identification (RFID) tags is presented. This technique is based on using the multiple signal classification algorithm with the phase measurements of the signals backscattered by the RFID tags of the array. Two array topologies have been studied (uniform linear arrays and uniform circular arrays). The performance of the system has been assessed by means of simulations and measurements in a controlled environment and in an indoor scenario. Results show that, after calibration, the attitude can be estimated with an error of a few degrees for a large range of orientations as long as the signals sent by the RFID reader do not imping the tags at grazing angles.