Innovators have developed an RFID-based system for sensing the angular position of rotating systems. The RFID-Based Rotary Position Sensor can be used as a position/orientation sensor or implemented in a controller to interpolate and refine the rotation angle of a rotating system. The sensor is part of a suite of RFID-based technologies developed to monitor and manage inventory based on passive RFID sensors. NASA's RFID sensors can wirelessly track either bulk levels or discrete quantities of materials within a container without having to attach RFID tags to each item.
The RFID-Based Rotary Position Sensor was designed for use in a hand-crank dispenser with a circular disc inside the dispenser box containing RFID integrated circuits (ICs) around the disc's periphery. An antenna is coupled to the crank on the outside of the box, which allows a user to turn the disc and dispense items. An RFID interrogator, coupled to a processor, determines the orientation of the crank based on the RFID ICs, providing information about the rotation angle of the internal disc that can then be used to assess level of material remaining in the dispenser.
This sensor is useful for items that are too small to tag individually (e.g., pharmaceutical pills) but there are various potential applications for the sensor including use in limit switches, position sensors, and orientation sensors. The configuration of the RFID ICs and antenna can be tailored for specific applications; for example, the system could be used in a rack-and-pinion gear system to measure the rotational or angular displacement that arises from a linear force. Furthermore, the system could be incorporated into a rotary controller to refine the rotation angle of a rotating system like a steering system or rotor.