Object attitude estimation using passive RFID tag arrays

A technique to estimate the attitude of an object using RFID tags is presented in this paper. The approach is based on the application of MUSIC algorithm to the phase measurements of an array of RFID tags attached to the object. The cost and infrastructure of the system is minimized since a single transmitter antenna is required. The performance of this technique was validated through simulations and measurements in an anechoic chamber. Results showed that the estimated attitude accuracy is within the uncertainty margin of the RFID reader employed in wide angular range. In addition, the calibration of the array turns out to be critical in order to reduce errors mainly caused by the difference between the effective separation between RFID tags and its expected value.