A New Method for the Singularity Analysis of Simple Six-link Manipulators

This paper presents a new method for identifying conditions governing all singular configurations of simple six-link ma nipulators whose inverse kinematic position problems have closed-form solutions. The method is developed based on the concepts of service sphere, free service region, and dextrous wrist. For a simple six-link manipulator, we identify its singular state with finite internal degrees of freedom by using the conditions that cause the manipulator's inverse solutions to be indeterminate. Meanwhile its singular state with infini tesimal internal degrees of freedom can be identified by examining the determinant of the Jacobion of the first three links. This simple and straightforward method is illustrated by three examples.