Two-phase gripper to reorient and grasp

Patent metadata

Field	Value
Publication number	US-9808936-B2
Application number	US-201615200110-A
Country	US
Kind code	B2
Filing date	Jul 1, 2016
Priority date	Aug 3, 2015
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

Two-phase gripper. The gripper reorients and grasps an object while being picked up. The gripper includes a parallel jaw gripper including a pair of opposed, two-phase fingers, each finger including a cavity covered by an elastic strip wherein the elastic strip includes a point contact. Closure of the jaws of the gripper on an object at a first relatively lower force results in contact with lower friction between the point contact on the elastic strip on the fingers and the object allowing the object to rotate under gravity as the gripper is raised. Thereafter, closure of the jaws of the gripper on the object at a second relatively higher force causes the elastic strip to receded into the cavity resulting in multi-point contact with higher friction between the fingers and the object to securely grasp the object. In a preferred embodiment, the cavity is a Y-shaped groove and the object is cylindrical or prismatic.

First claim

What is claimed is:

1. Two-phase gripper to reorient and grasp an object while being picked up comprising:
a parallel jaw gripper including a pair of opposed, two-phase fingers, each finger including a cavity covered by an elastic strip, the elastic strip including a point contact providing minimal frictional resistance to rotation of the object and wherein the elastic strip has a stiffness, K, such that F pivot /2δ pivot ≦K≦F grasp /2δ grasp wherein δ pivot is maximum allowable deflection for a first relatively lower force F pivot suitable for pivoting; and wherein δ grasp is minimum extension of the elastic strip to recede into the cavity for a second relatively higher force;
whereby closure of the jaws of the gripper on the object at the first relatively lower force results in contact with lower friction between the point contact on the elastic strip and on the fingers and the object allowing the object to rotate under gravity as the gripper is raised; and
whereby closure of the jaws of the gripper on the object at the second relatively higher force causes the elastic strip to recede into the cavity resulting in multi-point contact with higher friction between the fingers and the object to securely grasp the object.

2. The gripper of claim 1 wherein the cavity is a V-shaped groove.

3. The gripper of claim 1 wherein the object is a cylinder or prismatic object.

4. The gripper of claim 1 wherein the point contact on the elastic strip is cured rubber.

Assignees

• Massachusetts Inst Technology
• Univ Carnegie Mellon

Inventors

• Chavan Dafle Nikhil Narsingh
• Rodriguez Garcia Alberto
• Mason Matthew T

Classifications

• B25J15/0042

  V-shaped gripping surfaces · CPC title

• B25J15/0253

  comprising parallel grippers · CPC title

• B25J15/0004 Primary

  with provision for adjusting the gripped object in the hand · CPC title

• Y10S294/902

  Gripping element · CPC title

• B25J15/12

  with flexible finger members · CPC title