Interval-analysis-based determination of the singularity-free workspace of Gough-Stewart parallel robots

This paper proposes a systematic interval-based algorithm in order to obtain the maximal singularity-free sphere of 6-DOF parallel robots and as case study the 6-UPS parallel robot is considered. To this end, the main algorithm is divided into three sub-algorithms - for obtaining the constant-orientation workspace, the singularity loci and the maximal singularity-free workspace - which eases the understanding of the main approach and leads to a more effective and robust algorithm to solve the problem. The main contribution of this work can be regarded as the combination of the maximal singularity-free sphere with the workspace analysis as additional constraint to the problem.