## 6 Conclusions  
The study proves that tensegrity systems can be regarded as smart structures. They have some unique features that they owe to the infinitesimal mechanisms balanced with self-stress states.  
According to the authors' opinion, neither the external devices installed on the structure, nor the applied intelligent technologies make the structure smart. The structure itself should have some special properties, referred to by the authors as \"inherent\", which allow controlling it without any operation  
Figure 15: Influence of self-stress in single modules on the displacement of Node A.  
from the outside. To the inherent properties of smart structures belong: self-control, self-diagnosis, self-repair and self-adjustment (active control).  
The analyses presented in this paper prove that tensegrity structures have all of the defined inherent properties. Self-control is realized by self-stiffening of tensegrities under the applied external load that causes displacements consistent with the infinitesimal mechanism mode. Self-diagnosis relates to the possibility of damage detection and identification by measuring internal forces in active members. Self-repair of tensegrity structures is possible through an adjustment of self-stress forces: a proper change of pre-stressing level can compensate the damaged element and restore the values of structural displacements from before damage. Active control, on the other hand, is realized by adjusting the level of self-stress in only one selected part of the structure, hence affecting the properties of the whole system.  
Another very significant conclusion that may be drawn from this study is that it is extremely important to choose a proper approach to the analysis of tensegrity systems. Analysis according to the second order theory, which includes self-stress, but neglects geometrical non-linearities, allows identifying infinitesimal mechanisms and determining self-stress states of the structure, but does not take into account self-stiffening of the structure. Therefore, in some cases, a geometrically non-linear theory must be applied.  
According to the best knowledge of the authors, it is necessary to brake barriers in engineering design to allow the tensegrity structures to be introduced into common projects. The results presented in the paper should encourage engineers to design structures with non-standard inherent properties for potential technical/engineering applications with smart features. It is believed that smart structures will be more common in the near future, not only in aerospace engineering, but also in mechanical and civil engineering. Reliable results can be theoretically obtained with the use of fully-geometrically non-linear theory (third order) with a previous analysis of the properties of tensegrity structures (infinitesimal modes and self-equilibrated forces) within the second order theory. Experimental support is strongly recommended.  
In future research, the authors plan to focus on two of the described properties of tensegrity structures: self-diagnosis and self-repair, as they seem to be particularly interesting from the point of view of engineering applications. Different tensegrity systems will be analyzed and various damage scenarios considered.  
Introduction was written by [PERSON] and [PERSON]. Numerical results were obtained by [PERSON]. The analysis of the results and conclusions were written by [PERSON] and [PERSON].  
The authors declare no conflict of interest.