Assessing Grasp Quality using Local Sensitivity Analysis

We propose a new approach to investigate and quantify dynamic grasp performance. Oftentimes, existing approaches to grasp analysis assess a grasp's quality in a static situation. We build upon such considerations to also account for the dynamic nature of most grasp operations. In particular, these typically do not, in practice, occur in a static setting. Robotic grasping is indeed commonly involved in, for instance, pick-and-place operations which involve movement and thus a dynamic aspect. We investigate grasp quality over such movements, affording consideration not only to the gripper's and grasp configuration, but also to their trajectory. More specifically, we explore the relationship from the gripper's base acceleration to the stability of the grasped object (assessed using the relative acceleration of the object with respect to that of the gripper), using linear approximations of the corresponding dynamics. From such relations, we construct a grasp's robustness metric, which accounts for the movements involved in the considered scenario. Numerical simulations are used to compare achieved results with those obtained using alternate existing methods. We illustrate merit of the proposed metric by exploring robustness of a given grasp under different trajectories.