Modified Design of a Precision Planter For a Robotic Assistant Farmer

 

---

93 
4-2-5- Press wheel link 
There are two press wheel links that attach the press wheel to the chassis and also transfer 
the spring force to the press wheel. Figure 4-15 shows the forces on this part. These forces are 
applied to the press wheel link form the spring connection part. The link is hinged at one end, 
point A, and on the other end is fixed only in vertical direction to model the end that is attached 
to the wheel. 
Meshing: Since the stress concentration is happening at one of the holes, finer mesh is 
used to create the elements in that area. Also to find out about the effect of stress concentration 
and real value for stress at that point, different meshing sizes and refinements are used and 
compared. Figure 4-14 shows the mesh used for this part, which has 10 mm element size for the 
whole part and 3 mm element size for the area with high stresses. 
External loads and boundary condition: As mentioned earlier, at point B in figure 4-
15, the part is hinged. So, support B is a cylindrical support which is free in tangential direction. 
Point A is the hole that supports the press wheel shaft. support A is must be fixed only in Z 
direction (vertical direction). Thus, a zero displacement in Z direction is defined for support A. 
Forces and moments are applied to this part, form the spring connection. These forces and 
moments are the reaction force and moments results of the previous analysis, and they are 
transformed form the coordinate system of the spring connection to the coordinate system of 
press wheel link. 

---

94 
Figure 4- 14- Meshing for press wheel link 

---

95 
Figure 4- 15- Geometry, external loads and supports for press wheel link