# Virtual and Physical Prototyping of Reconfigurable Parallel Mechanisms with Single Actuation
## 5 Conclusions  
This paper has presented novel variations of RPMs with similar structure and a different number of kinematic chains. The mobility analysis of the mechanisms carried out via screw theory has provided a calculation of controllable and uncontrollable DOFs. It was found that 4-DOF tripod has three uncontrollable DOFs, 3-DOF quadrupod has two uncontrollable DOFs, 2-DOF pentapod has one uncontrollable DOF and 1-DOF hexapod is fully controllable.  
The reconfigurability of the mechanisms allows for changing the output link trajectories without using additional kinematic chains or drives. The proposed mechanisms have such design advantages as a drive fixed on the base, absence of the possibility of collisions between the adjacent carriages due to correctly chosen cranks lengths and diverse reconfigurable capabilities due to having a flexible coupling in each kinematic chain.  
Based on the obtained mechanisms structures, the hexapod one (the mechanism with six kinematic chains) has been developed as an assembling CAD model, which allowed us to perform a numerical kinetostatic analysis and then fabricate an actuated physical prototype. The developed CAD model was adapted to using 3D printing technologies in prototype production.  
The conducted research confirms that virtual and physical prototyping processes relate to each other, and their cooperative execution is very effective in product development. In addition, rapid prototyping technologies, which are one of the most optimal ways to develop physical prototypes, can be often realized only with virtual prototyping.  
Figure 7: The main units of motion transmission of the proposed hexapod.  
Having the physical prototype built, we can aim our further research at its experimental study, including accuracy and repeatability tests, rigidity and load capacity analyses, tests for maximum operating speed and others. Additional research can be associated with an analysis of the presented hexapod for specific practical applications, such as rehabilitation procedures, where the hexapod platform could provide various types of cyclic motions. In this regard, the analysis would aim to calculate the initial cranks configuration and the motion laws of the driving link based on the predetermined platform displacements.  
The following are available online at: [[https://www.mdpi.com/article/10.3390/app11157158/s1](https://www.mdpi.com/article/10.3390/app11157158/s1)]([https://www.mdpi.com/article/10.3390/app11157158/s1](https://www.mdpi.com/article/10.3390/app11157158/s1)), Video S1: Movie of the CAD model operation, Video S2: Movie of the physical prototype operation.  
Conceptualization, A.F. and A.A.; methodology, A.F. and A.A.; software, A.F. and D.P.; validation, A.F. and D.P.; formal analysis, A.F. and A.A.; investigation, A.F., D.P. and A.A.; resources, A.F., D.P., A.A. and V.G.; writing--original draft preparation, A.F., A.A. and M.C.; writing--review and editing, A.F. and A.A.; visualization, A.F. and D.P.; supervision, A.F., A.-A. and V.G.; project administration, A.F.; funding acquisition, M.C. All authors have read and agreed to the published version of the manuscript.  
This research was supported by Russian Science Foundation (RSF) under grant No 21-79-10409, [[https://rscf.ru/project/21-79-10409/](https://rscf.ru/project/21-79-10409/)]([https://rscf.ru/project/21-79-10409/](https://rscf.ru/project/21-79-10409/)).  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare that they have no conflict of interest.