Add to ORKGnone2In 1978, Hunt found a set of vector subspaces of screws that guarantee 'full-cycle mobility' of mechanisms. They are subalgebras of the Lie algebra se(3) of the Euclidean group and they are at the basis of most families of mechanisms with special motion capabilities. Recently, a more general concept was presented. Persistent screw systems (PSSs) are not subalgebras of se(3), but they still exhibit relevant properties for full-cycle motions, namely the invariance of both the space dimension and the pitch of the principal screws. For this reason, they are believed to play an important role in both mobility analysis and mechanism synthesis. This paper provides the detailed derivation and the comprehensive classification of PSSs of dimensi...