Direct Drive Hands: Force-Motion Transparency in Gripper Design

Abstract

The Direct Drive Hand (DDHand) project is exploring an alternative design philosophy for grippers. The conventional approach is to prioritize clamping force, leading to high gear ratios, slow motion, and poor transmission of force/motion signals. Instead, the DDHand prioritizes transparency: we view the gripper as a signal transmission channel, and seek high-bandwidth, highfidelity transmission of force and motion signals in both directions. The resulting design has no gears and no springs, occupying a new quadrant in the servo gripper design space. This paper presents the direct drive gripper design philosophy, compares the performance of different design choices, describes our current design and implementation, and demonstrates a fly-by “smack and snatch” grasping motion to show the gripper’s ability to safely detect and respond quickly to variations in the task environment.