Interference analysis and workspace optimization of 3-RRR spherical parallel mechanism

• By using Euler Quaternion, position analysis on 3-RRR SPM was investigated.
• The Least Interference Design Method (LIDeM) was proposed.
• The optimum structure of 3-RRR spherical parallel mechanism was given.
• The optimum values of link ratio β1 and β2 were found to be both equal to 0.64.
• The workspace, singularity loci and interference distribution were also visualized.

The causes of restriction on the working scope of spherical parallel mechanism (SPM) were analyzed. A systematic design methodology (Least Interference Design Methodology, LIDeM) for reducing interference among links and increasing workspace of mechanism was also developed in this study. Focusing on 3-RRR SPM, the optimal structure was given according to the LIDeM theory. The optimum values of the modified link ratio β1 and β2 were obtained through numerical simulation of its mathematical model. In addition, the total workspace mapping, singularity loci and interference regions of the optimum 3-RRR SPM were also attained in this study by computational simulation. This work improves the total workspace of 3-RRR SPM and could be applied on some other revolute-joint mechanisms.