Singularity-consistent path planning and control of parallel robot motion through instantaneous-self-motion type singularities

Abstract

We apply our newly proposed singularity-consistent path tracking approach to nonredundant parallel-link manipulators. We analyze the singularities of such mechanisms, assuming that the output-link moves on a pre-defined and parametric path. Especially, we focus on the so-called instantaneous self-motion type singularity. We propose a closed-loop controller that guarantees asymptotic stability when tracking paths through such a singularity. As a comprehensive analytical example we use a planar five bar mechanism. A computer simulation study is also presented, using the same example, as well as the HEXA parallel robot structure.