Modified Design of a Precision Planter For a Robotic Assistant Farmer

3-2-4-Connection Assembly 
As mentioned earlier, a mechanism is needed to connect the planter to the robot, push the 
planter downward when in use, and lift it off the ground when in transportation. Connection 
assembly consists of the main spring, vertical pull bar, horizontal pull bar and lifting mechanism. 
These parts are shown in figure 3-11. The job of the main spring is to push the planter on the soil 
and provide enough down force on the planter and gauge wheel. 
Another part that had to be designed was the attachment link that connects row planters 
to the mobile robot. This mechanism also should have the ability to lift up the row planters from 
the ground for transportation and making turns.
Figure 3- 11- Connection assembly parts, 17) main spring, 18) Vertical pull bar, 19) 
horizontal pull bar 
In the existing row planters, hydraulic cylinders lift up a series of row planters off the 
ground for transportation. As mentioned in chapter 1, hydraulic power is not available for this 

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purpose from mobile robot. For the lift mechanism different ideas were examined. Using a power 
screw, worm gear or even a hand-operated wrench were among the ideas that were discussed. 
Hand-operated wrench was chosen for this system because of its simplicity, lower cost and easy 
maintenance (See Figure 3-12). 
Figure 3- 12- Parts of connection mechanism, 18) vertical pull bar, 19) horizontal pull bar 
and 20) lifting mechanism (hand wrench) 
Figure 3-13 can be used to calculate the force that is needed to lift up the planter. The 
weight of the planter and its center of mass is estimated by SolidWorks. This weight is estimated 
to be about 980 N, including the weight of the seed inside the seed hopper. Using moment 
equilibrium equation about the joint that vertical pull bar rotates (point O), the tension in cable 
can be found. 
(Eq. 3-9) 

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So, a hand wrench was chosen that can lift up to 5340 N (equals to 1200 lbf.). This gives 
a safety factor of 1.7 for the lift mechanism. 
Figure 3- 13- Forces for lifting condition of the planter