Evaluation of RFID power and UAV flight level in plant inventory application

Abstract

Tracking plants is an important part of growing and distributing ornamental plants. One method of inventory of these plants is to use Radio Frequency Identification (RFID) tags. The large areas of plant nurseries require an effective and efficient method of reading the RFID tags. This paper investigates the utilization of RFID with Unmanned Aerial Vehicles (UAV), specifically how the altitude and antenna power affect the accuracy of the tag counts. There were three power levels (15 dBm, 20 dBm and 27 dBm) for the RFID antenna and three flight levels (3 m, 5 m and 7 m) used in the experiment setup. Two plant types, namely 'Green Giant' arborvitae and 'Sky Pencil' holly, were also used, set on two separate plots. Four RFID tag types were utilized (L5, L6, L8 and L9) with two antenna types (dog bone and square wave) and two attachment mechanisms (loop-lock and stake). The UAV is flown to three different flight levels for each power level. For each flight level, two passes are performed. Plants were tagged randomly with 40 plants and tags for each plot. Experiments were conducted on September 9, 21-22, October 19, November 1-2, 27 and December 14, 2023 at the Dudley Nurseries in Thomson, GA. At 15 dBm power level, it yielded a tag count accuracy of 53%, 34% and 16% at flight levels of 3 m, 5 m and 7m, respectively. Increasing the power level to 20 dBm at flight level yielded a count accuracy of 90% across all tag types and plant types. At higher flight levels of 5 m and 7 m, accuracy drops to 75% and 33%, respectively, at power levels of 20 dBm and even lower at 15 dBm. The highest country accuracy was achieved at a power level of 27 dBm at a flight level of 3 m at 98%. Of the four tag types, L6 and L9 have the highest accuracy at any flight level and power setting.