Optoelectronic System for Counting and Sizing Fieldgrown Deciduous Trees

An optoelectronic system was developed to count and size fruit and nut trees in commercial nurseries. An opticalsensor was designed using a highpower infrared laser for illumination to allow operation with varying light conditions,including direct sunlight. The optical sensor was mounted on a threewheeled cart with pneumatic tires, and a rotary encoderwas coupled to one of the wheels for displacement measurement. Signals from the optical sensor and rotary encoder wereanalyzed with an embedded controller to determine trunk diameter, and running counts were maintained for the standardnursery size grades. A counting mode was also added to count, but not size, trees that were staked. Calibration tests showedthat the system could measure trunk diameter to .1.9 mm (3 times the standard error of prediction) with the sensor 15 to 23 cmfrom the tree line. Leaves, lowlevel suckers, weeds, and trunk stakes were observed to cause inaccurate counting and sizing.