A Tendon-Driven Robot Gripper With Passively Switchable Underactuated Surface and its Physics Simulation Based Parameter Optimization

Abstract

In this paper, we propose a single-actuator gripper that can lift thin objects lying on a flat surface, in addition to the ability as a standard parallel gripper. The key is a crawler on the fingertip, which is underactuated together with other finger joints and switched with a passive and spring-loaded mechanism. While the idea of crawling finger is not a new one, this paper contributes to realize the crawling without additional motor. The gripper can passively change the mode from the parallel approach mode to the pull-in mode, then finally to the power grasp mode, according to the grasping state. To optimize the highly underactuated system, we take a combination of black-box optimization and physics simulation of the whole grasp process. We show that this simulation-based approach can effectively consider the precontact motion, in-hand manipulation, power grasp stability, and even failure mode, which is difficult for the static-equilibriumanalysis-based approaches. In the last part of the paper, we demonstrate that a prototype gripper with the proposed structure and design parameters optimized under the proposed process successfully power-grasped a thin sheet, a softcover book, and a cylinder lying on a flat surface.

Design optimization of an underactuated tendon-driven anthropomorphic hand based on grasp quality measures

“…While researchers have optimized the design of underactuated non-anthropomorphic grippers on many instances [10,11,12,13,14], this form of optimization is far less prevalent among anthropomorphic hands. Recently, there has been research on optimization of anthropomorphic hand-design for fully actuated hands based on a novel performance index for its kinematic properties referred to as "interactivity of fingers" [15].…”

“…Further, the linearization of the hand equilibrium of Eq. ( 2), yields the joint torque variation expression as δτ = J T δλ + K J,q δq + K J,u δu (14) where, K J,q δq = ∂J T λ 0 ∂q and K J,u δq = ∂J T λ 0 ∂u , that is, the derivatives of hand Jacobian matrix wrt q and u. Variation of the Lagrangian forces can be expressed as δσ = S T δτ + K S,z δz (15) where, K S,z = ∂S T τ 0 ∂z .…”

Variable-Grasping-Mode Gripper With Different Finger Structures For Grasping Small-Sized Items

“…Kakogawa et al [28] developed a gripper with an active surface that could passively switch between grasping and pull-in operations using a single actuator with a differential mechanism. Ko developed a tendon-driven gripper with an active surface that could passively switch the actuation of the surface [29]. Morino et al [30] developed a gripper with a surface that was passively driven by opening and closing operations via finger deflection.…”

F1 Hand: A Versatile Fixed-Finger Gripper for Delicate Teleoperation and Autonomous Grasping

“…For the evaluation of the resulting system, many studies evaluate the usefulness of the hand separately from the robot body [1], [4], [5], [6] or tested with a prescribed motion of the robot arm in a predefined environment [7], [8]. However, in practice, it is not always possible to set the robot hand and body at a predefined position in a real environment.…”