# Virtual and Physical Prototyping of Reconfigurable Parallel Mechanisms with Single Actuation
## 4 Virtual and Physical Prototyping  
### Development of the Hexapod CAD Model (Virtual Prototyping)  
Based on the kinematic scheme of the 1-DOF hexapod shown in Figure 2d, we created its virtual prototype using CAD system Autodesk Inventor. Figure 3a,b show the exploded view of the hexapod assembly, considering the alignment and arrangement of all structural elements. This assembly allows for further manufacturing of these elements by 3D printing and using the standard machine elements.  
The procedure for assembling the CAD model of the hexapod is as follows. It begins with assembling circular guide 1, divided into six sectors, comprising several parts, and central ring 1a with a rolling bearing pressed into it. Then, we mount a base consisting of six columns under circular guide 1. The columns connected by metal profiles absorb the load and give additional stability to the entire system. Next, a group of links that includes shaft 2 and driving wheel 3, forming a single link, is rigidly fixed in the center of circular guide 1. After that, we connect the electric motor shaft with shaft 2 under circular guide 1.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Number of** **Kinematic Chains**} & \multicolumn{3}{c}{**Number of DOFs of the Output Link**} \\ \cline{2-4}  & **Overall** & **Controllable** & **Uncontrollable** \\ \hline
4 & 3 & 1 & 2 \\ \hline
5 & 2 & 1 & 1 \\ \hline
6 & 1 & 1 & – \\ \hline \hline \end{tabular}
\end{table}
Table 1: Summary of the mobility analysis results.  
Further, we mount a group of links including shaft 4, gear 5 and driving pulley 6 in circular guide 1 through a rolling bearing. This group also forms a single link. After that, similarly, shaft 7 connects rigidly with driven pulley 8 and crank 9 and then becomes fixed in an adjacent bearing in circular guide 1. Next, we stretch the belt between driving 6 and driven 8 pulleys and install a spacer between the bearings of their shafts. Crank 9 and slide block 10 are connected by a rolling bearing.  
The next group of links is a rigid connection of swinging arm 11 and carriage 12. Swinging arm 11 ends with fork 11a at one side for coupling with shaft 2a in the center of circular guide 1 and with lunule 11b of the spherical joint at another side. Fork 11a at each swinging arm has an individual geometry for locating them in one plane. Carriage 12 moves on the edge of circular guide 1 by a pair of rollers 12a, which are supported by shafts 12b. Lunule 11b is pressed into carriage 12, forming a single link of swimming arm 11 and carriage 12.  
Figure 3: Exploded view of the structural elements assembly (CAD model) of the proposed hexapod: (**a**) single kinematic chain with a driving part; (**b**) complete mechanism model.  
Similarly, we press balls 13a of the spherical joints into leg 13 on both sides. Platform 14, like circular guide 1, is divided into six sectors, connected by coupling plates. Further, three of these sectors connect rigidly with a pair of lunules 14a of the platform spherical joints.  
Figure 4a,b show the assembled CAD model of the hexapod with all the structural elements discussed above. This model allows 3D printing its elements and using standard mechanical parts. Table 2 presents the geometrical dimensions of the hexapod elements.