The inventors have developed RF-IDraw, a novel technology to accurately trace the trajectory of an RFID. This system offers tracing capabilities accurate enough to transform any plane or surface in space into a virtual touch screen, enabling human-computer interfacing without physically touching a screen. RF-IDraw allows a user to input commands on any surface by writing, scrolling and swiping using an RFID attached to a pen or finger splint. RF-IDraw can reconstruct the RFID’s trajectory and interpret the user’s writing and gestures as input to the desired computing device.
RF-IDraw’s technology leverages multiple antennas to yield a significant improvement in both tracing and localization accuracy. The device measures the phases of the received signals at the different antennas and uses knowledge of the antenna positions to create a geometric model for estimating the RF source’s position and tracing its detailed trajectory. The beam steering capability of the antenna array is utilized to pinpoint the direction and location of the source. To obtain a high level of accuracy, RF-IDraw pairs these antennas with differing levels of separation: the pairs with larger separation have narrow beams and provide resolution in the positioning system, while the pairs with smaller separation work as filters to eliminate ambiguity in the system. This technology also offers real-time processing functionalities integrated with handwriting recognition features.