Modified Design of a Precision Planter For a Robotic Assistant Farmer

V(V)
 
m(Kg) 
Load Cell calibration graph 

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116 
the soil. Vacuum tube was attached to the singulators and the vacuum was turned on. Mobile 
robot moved forward for a very short distance, i.e. about 50 mm, to make sure that the load cells 
are in tension before the test begined. The software started recording data and then the robot 
started moving in the soil bin, till it reached the end of its working length. Each test was 
performed twice. 
The first test was done with a 50 mm depth of disc into the soil. The depth for second test 
was set for 75 mm. The first two tests were performed to study the draft force and also the 
accuracy of the depth of disc in the soil.
A third test was performed with the shallowest depth, less than 25 mm, only to find out 
about the precision of the seeding. Because with lower depth, it was easier to recover planted 
seeds and measure the distance between them. 
Test results: The data from the load cells were converted from Volt into Newton. Figure 
5-11 shows the forces of load cells (F
c1
and F
c2
), friction in the hitch (F
h
) and the total draft force 
that is required from the mobile robot to pull the set of two planters (F
R
).The measured forces 
(summation of the two load cells F
c1
and F
c2
) are shown in figures 5-12, 5-13 for 50 mm and 75 
mm disc depths, respectively. It can be seen that the fluctuation in the measured forces are high. 
This was expected, because the soil is not a homogenous material. Although tillage and packing 
has been used to make the soil structure as homogeneous as possible, but uneven surface of the 
soil can cause the force to fluctuate. On the other hand, from the design point of view, it can be 
said that these fluctuation can give the designer a better understanding of what to expect on a 
farm field. The designer can find out how high the forces can go and how high the safety factors 
should be set. Beside the nonhomogeneous soil, the environmental noises can cause high 
frequency fluctuations in the measured results. These noises can be seen in figures 5-12 and 5-

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13. The sources of the noises can be the ventilation, the motion of the robot on the soil and other 
machinery working in the vicinity.
Figure 5- 11- Force balance between robot and set of planters 
Figure 5- 12-Measured draft force for 50 mm depth of disc in the soil 
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