Configuration Spaces of a Kinematic System and Monster Tower of Special   Multi-Flags
  In this note we show that the configuration spaces of the kinematic system constructed in [4] and [12] gives rise to a natural tower of sphere bundles. Moreover, we prove that, each tower of projective bundles associated to special multi- flags (cf [1], [13], [2], [3]), we can associate such a tower of sphere bundles which is a two-fold covering of the previous one. In particular we give a positive answer of some conjecture proposed in [3] 
Fernand Pelletier
math.DG