Modeling for Phase Decoupling to Detect the Orientation and Position of Moving Objects With Simple RFID Array

Radio frequency identification (RFID) shows great potential for determining the orientation and position of objects in production line, which is critical for industrial automation and intelligence. However, the state-of-the-art schemes face challenges in decoupling the orientation- and position-induced phase from the radio frequency (RF) signal. This investigation presents a novel simple RFID array-based solution with a phase-pose model to simultaneously determine the orientation and position of moving objects with negligible mutual coupling. The main contributions include 1) a phase-orientation model to determine the orientation-induced phase differences between RFIDs in a tag array, which also extends the range of multiple signal classification (MUSIC)-based orientation measurement; 2) a novel phase-position model to decouple the position-induced phase differences between a tag and antennas from the RFID interrogation variables; and 3) fusion of the orientation and position data determined by hyperbolic positioning and MUSIC to improve the accuracy of pose estimation by reducing their mutual coupling. An experimental setup is established to verify the effectiveness of the presented techniques. The average orientation and position errors are 1.63° and 3.98 cm, which is promising compared to the peer studies.