On affine motions and universal rigidity of tensegrity frameworks

Recently, Alfakih and Ye (2013) [4] proved that if an r  -dimensional bar framework (G,p)(G,p) on n⩾r+2n⩾r+2 nodes in general position in RrRr admits a positive semidefinite stress matrix with rank n−r−1n−r−1, then (G,p)(G,p) is universally rigid. In this paper, we generalize this result in two directions. First, we extend this result to tensegrity frameworks. Second, we replace the general position assumption by the weaker assumption that in configuration p, each point and its neighbors in G   affinely span RrRr.