Tensegrity Rings for Deployable Space Antennas: Concept, Design, Analysis, and Prototype Testing
In this paper, an extended version of Zolesi et al. (Proceedings of the 42nd ICES (AIAA 2012 3601) San Diego, CA, 2012) we describe a tensegrity ring of innovative conception for deployable space antennas. Large deployable space structures are mission critical technologies for which deployment failure cannot be an option. The difficulty to fully reproduce and test on ground the deployment of large systems dictates the need for extremely reliable architectural concepts. In 2010, ESA promoted a study focused on the pre development of breakthrough architectural concepts offering superior reliability. This study, which was performed as an initiative of ESA Small Medium Enterprises Office by Kayser Italia at its premises in Livorno (Italy) with Universita di Roma TorVergata (Rome, Italy) as sub contractor and consultancy from KTH (Stockholm, Sweden) led to the identification of an innovative large deployable structure of tensegrity type, which achieves the required reliability because of a drastic reduction in the number of articulated joints in comparison with non tensegrity architectures. The identified target application was in the field of large space antenna reflectors. The project focused on the overall architecture of a deployable system and the related design implications. With a view toward verifying experimentally the performance of the deployable structure, a reduced scale breadboard model was designed and manufactured. A gravity off loading system was designed and implemented, so as to check deployment functionality in a 1 g environment. Finally, a test campaign was conducted, to validate the main design assumptions as well as to ensure the concept's suitability for the selected target application. The test activities demonstrated satisfactory stiffness, deployment repeatability, and geometric precision in the fully deployed configuration. The test data were also used to validate a finite element model, which predicts a good static and dynamic behavior of the full scale deployable structure.