Architecture singularities of platform manipulators

The architecture singularity of platform manipulators is considered with reference to a class of six-DOF (degree-of-freedom) parallel manipulators. It is pointed out that an architecture singularity usually spans the whole workspace or a significant part thereof, which makes it very difficult to implement control or singularity-avoidance strategies. Several groups of singular architectures are reported, with comprehensive theoretical proofs. This work can serve as a guide for the optimum design of parallel manipulators in the sense of achieving optimum kinematic and force-transmission performances