Kinematic Analysis and Singularity Avoidance for a Seven-Joint Manipulator

This paper focuses on kinematic analysis and singularity avoidance for a seven-joint manipulator derived from the PUMA geometry. Mechanical singularities are found and the motion of the structure in such configurations is analyzed. An inverse kinematics algorithm which exploits redundancy in an augmented task space framework is adopted. A suitable constraint task is introduced which is aimed at preventing the occurrence of singularities and possibly recovering the original PUMA design. Artificial singularities that originate from conflicting task situations are avoided using a task priority strategy. The algorithm has been implemented in two case studies, and numerical results are reported.