Results on Planar Parallel Manipulators with Cylindrical Singularity Surface

In this article we give first results on Stewart Gough Platforms with planar base and platform, whose singularity set for any orientation of the platform is a cylindrical surface with rulings parallel to a given fixed direction p in the space of translations. In this case the singularity set can easily be visualized as curve by choosing p as projection direction. Moreover the computation of singularity free zones reduces to a 5-dimensional task. We prove that there do not exist non-architecturally singular Stewart Gough Platforms with planar base and platform and no four anchor points collinear which possess such a singularity surface.