Singularity robust algorithm in serial manipulators

Singularity is a fundamental problem with robotic manipulators. Various methods of singularity handling have been published in the past. In this paper, a singularity robust method is presented and its implementation issues discussed. It focuses on the discontinuity problem inherent in the singularity robust techniques with removal of degenerate components. Sources of the discontinuity are discussed and the null motion is proposed as the means of providing a continuous control of the end-effector over the boundary of the singular region. The presentation of this paper covers a complete treatment of singularities, starting from identifications of the singular configurations and the associated singular directions, the handling algorithm and the discontinuity issues. The algorithm was implemented on PUMA 560. The experimental results are presented and discussed.