Kinematic model for mechanical apple blossom thinning

Abstract

The international apple trade requires apples with diameters of over 70 mm. Left untouched, apple trees tend to produce many apples of small diameter. To increase apple size, the number of blossoms can be reduced in their early growth stage, leaving fewer apples which will grow larger because of access to a greater portion of nutrients. Over the past few decades this has been mainly accomplished through chemical means, but recent demand for sustainable fruit production with fewer chemicals requires means of blossom thinning using e.g. mechanical methods, i.e. a machine with rotors and brushes. The goal of this project was to perform kinematic analysis on such a mechanical thinning machine to model the motion and behavior, both mathematically and graphically, as well as offer recommendations of operating parameters to maximize the machine’s efficiency. The project involved creating and assembling a three dimensional model of the machine in Pro/ENGINEER, performing kinematic analysis on the model, using the output to produce a mathematical formula, and using that formula to both analyze and predict the operation of the machine. The mathematical model was verified successfully against field test data. It was then used to provide tractor and rotor speeds for a range of desired percentage of blossoms removed. It also accomplished the reverse, predicting the percentage of blossoms removed for a series of chosen tractor and rotor speeds.