We present a path determination method for an unmanned aerial vehicle (UAV) equipped with a radio frequency identification (RFID) interrogation system. UAV path design is one of the main factors influencing the cost of UAV inventory management systems. A case study for using a path-optimized UAV-RFID system is presented.

In this case study the RFID-UAV travels above the pastures of an extensive cattle ranch scanning the RFID tags attached to the cattle in order to detect their locations. Since the UAV battery limits the flight time, the UAV path must be segmented and landing locations for recharging or battery replacement must be determined.

Scanning a cattle RFID tag requires the UAV to fly within a certain distance from the animal, as opposed to approaching the animal’s exact location. The reading distance (RD) of the RFID equipment determines the allowable distance. We use an easy-to-explain method to determine the UAV path. We generate a RD-based hexagonal tiling of the pasture and minimize the UAV path such that it visits all the tile center points. Based on the current UAV system configuration and environmental conditions, the optimal UAV tour allows for the scan of each pasture segment’s animals to be completed within the battery-limited flight time.

A case study was performed at the California Polytechnic (Cal Poly) State University’s Escuela and Walters Ranches. The RFID-UAV system solution is estimated to be 62%faster than the current cattle scanning practice, which requires ranch employees to search for and scan each animal from close proximity.