Research On Orientation Sensing Via RFID Tag Array

With the rapid development of the Internet of Things,Radio Frequency IDentifi-cation(RFID)has been widely used in several applications due to its property of the marked battery-free sensing,i.e.the warehouse management,the logistics tracking and the access control.Compared with other battery-free sensing technologies like Radar or WiFi,RFID is capable of identifying sensing signal sources,which makes RFID suitable for the applications with multiple sensing objects.However,the main drawback of RFID technology is that its signal is very sensitive to surrounding environ-ments.Especially for the single-tag sensing,such interference constraints the sensing ability of RFID-based systems to a large extent.Considering the above limitations,this paper concentrates on the research on how to expand the sensing ability of RFID-based systems via the tag array,so as to improve the accuracy and robustness of RFID-based sensing systems and provide RFID technologies with the more opportunities of sup-porting more sensing scenarios.Overall,in this paper,we focus on the orientation sensing and explore two aspects of the orientation sensing as follows.First,study the indirect orientation sensing mechanism via localizing RFID tag arrays.For the problem of the 3-dimensional(3D)orientation sensing,we propose an angle-of-arrival-profile-based orientation sensing method in a static way.With the 3D orientation sensing method,we research the problem of the 3D reconstruction on pack-aged objects via RFID tag arrays,and evaluate its performance in the real environmen-t.By exploring the relationship between the phase variations and the angle-of-arrival variations,we build an angle-of-arrival-profile-based model to derive the relative lo-calization among tags.Finally,We perform a 2-dimensional(2D)mobile scanning to reconstruct the tagged package placement in the 3D space.The experiments show that our solution achieved the average identification accuracy of the bottom face is about 92.5%,and the average estimation error of the rotation angle is about 4.08°.Second,study the direct orientation sensing mechanism via tracking RFID tag ar-rays.For the problem of the complex orientation tracking,we propose a rigid-motion-based orientation tracking method in a dynamic way.With the 2D orientation sensing method,we research the problem of the novel human-computer interaction via RFID tag arrays,and evaluate its performance in the real environment.By exploring the re-lationship between phase variations of the tag array and the rigid body motion of the tagged object,we build a geometric model to decompose the rigid body motion to track the rigid transformation of the tagged object,including the translation and the rotation.The experiments show that our solution achieved an average accuracy of 0.6cm in the translation tracking,and an average accuracy of 1.9° in the rotation tracking.