Morphological Design Optimization of Kinematically Redundant Manipulators Using Weighted Isotropy Measures

Kinematically redundant manipulators are coveted for their ability to perform more complex and a greater variety of tasks than their non-redundant counterparts. This increased utility demands that manipulator designs be carefully optimized to achieve the kinematic dexterity required to perform their numerous intended tasks. The optimization of redundant manipulator designs to improve isotropy has been studied at great length, but a vast majority of the work done focuses on planar manipulation tasks and workspaces that, unlike many modern manufacturing environments, offer few or no physical impediments to motion. In this paper we investigate the incorporation of secondary manipulation goals, in particular obstacle avoidance, into the calculation of kinematic isotropy measures. We will use these weighted isotropy measures as a performance metric for redundant manipulators working in obstacle-laden workspaces, and employ the metric as part of an objective function for a global search design optimization problem. The effectiveness of the weighted isotropy design optimization will be demonstrated by increasing the global dexterity of a sub-optimal seven degree-of-freedom manipulator design used for pick-and-place tasks within a small, enclosed workspace.