Material and methods
As the hay during the growing period (early spring to mid-autumn) may have
several harvests, the mowers are particularly important to farmers. The purpose of this
study was to optimize the performance of a single circular disc mower. The output is
the stem cross section cutting quality. To evaluate the stem cutting quality of the
mower blade, an alfalfa stem was cut by a very tiny and sharp shaving blade. This
blade produces a very smooth and uniform cross section surface. An image was taken
from this cross section and the PC1 eigenvalue of this image was defined as the ideal
‘cutting quality’. The PC1 eigenvalues of the pictures taken from alfalfa stem cross
sections cut by real mower blades in the farm were compared to the ideal cutting
quality eigenvalue. The Taguchi design of experiment method was used to study the
effect of different cutting variables on the ‘cutting quality’. Mower forward speed, disc
rotational speed, number of blades on the disc and the shape of the blades were defined
as main effective variables on cutting quality. Each variable was studied at three
different levels. Three images from each test set up were taken by an sx210 canon
camera and were imported to the ENVI image processing software. This software
processes the light wavelengths which are reflected from the stem cross section
pictures and links it to the surfaces texture and smoothness.