DEVELOPMENT OF TRACTOR OPERATED AUTOMATED INTER AND INTRA ROW WEEDER 2938
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Date
2019-07
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JAU, JUNAGADH
Abstract
Weed management is a tedious task especially in organic crop production since
synthetic herbicides are prohibited, and manual weeding is relatively costly and time
consuming. However, mechanical weed control is one of the options that can be
implemented by growers to control weeds but the main challenge to both practical
farmers and researchers is the selective control of the intra-row weeds. Based on this
challenge the objective of the study was to develop a tractor operated inter and intra
row weeder. In this research work static structural analysis of inter row weeder was
carried out using Creo and ANSYS software. If a inter row weeder is unable to handle
with high magnitude reaction forces from the soil during weeding operation, they
become useless due to plastic deformation or parts breaking. Therefore, proper design
of inter row weeder is necessary in order to increase their working life time and reduce
the farming costs. 3D models of inter row weeder was made using Creo software and
static structural analysis was carried out using ANSYS software. Main components of
the automated weeder was ultrasonic sensor, D.C. motor, microcontroller, battery,
frame, tine, inter and intra row blade. Ultrasonic sensor was used to differentiate crop
plant from weed. When the ultrasonic sensor detect a crop plant then intra row blades
rotate in anti-clockwise direction and when there are no plants then intra row blades
rotate in clockwise direction and come into the working position to remove the
particular weed. The performance of automated weeder was evaluated in the field for
determining weeding efficiency, percentage of plant damage and field efficiency. These
parameters are mainly affected by the forward speed of the tractor and the rake angle
of the blade. Different forward speeds of the tractor were 1.5, 2.0 and 2.5 km/h where,
three different rake angles 18º, 20º and 22º were selected for evaluating it in laboratory
as well as in field.
Results of simulation of inter row weeder showed that maximum deformation
was observed as 0.65 mm at the given boundary conditions while maximum equivalent
(von-mises) stresses of 42.39 MPa was observed. Maximum equivalent stresses was
found to be very low as compared to yield strength of material so inter row weeder
satisfy the safety conditions. Weeding efficiency, plant damage percentage and field
efficiency were found 93.65%, 11.48% and 94.04%, respectively. The optimum forward speed and best rake angle were found as 1.5 km/h and 22º respectively, looking
to minimum plant damage and maximum field efficiency.
From the experimental results, the depth and with of cut of automated inter and
intra row weeder was found as 30 mm and 600 mm, respectively. The draft requirement
was 49.13 kgf at 1.50 km/h speed of operation. The power required for weeding
operation was 0.93 hp with fuel consumption of 1.21 l/h and 9.57% wheel slip at
12.07% moisture content (d.b.). The theoretical field capacity of weeder was found as
0.09 ha/h while effective field capacity was 0.084 ha/h with the field efficiency of
94.03%.
By adapting this automated weeder, problems of the labor crises can be reduced
in terms of time reduction 88.44% and cost reduction 35.73% as compared to manually
weeding. The payback period and B-C ratio of developed weeder was found as 4.93
years and 2.02, respectively. The results indicate that the tractor operated automated
inter and intra row weeder is viable proposition and usful in reducing time as well as
cost of operation.