Joint Coupling Design of Underactuated Grippers

This paper examines the nature of joint coupling in underactuated grippers for environments where object properties and location may not be well known. A grasper consisting of a pair of two-link planar fingers with compliant revolute joints was simulated as it was actuated after contact with a target object. The joint coupling configuration of the gripper was varied in order to maximize successful grasp range and minimize contact forces for a wide range of target object size and position. A normal distribution of object position was assumed in order to model sensing uncertainty and weight the results accordingly. The results show that proximal-distal joint torque ratios of around 0.6 produced the best results for cases in which sensory information available for the task was poor, and ratios of around 1.0 produced the best results for cases in which sensory information available for the task was good.