The Synthesis of Stable Force-Closure Grasps
This thesis addresses the problem of synthesizing grasps that are force-closure and stable. The synthesis of force-closure grasps constructs independent regions of contact for the fingertips, such that the motion of the grasped object is totally constrained. The synthesis of stable grasps cons...
| Main Authors: | , |
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| Language: | en_US |
| Published: |
2004
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| Online Access: | http://hdl.handle.net/1721.1/6849 |
| _version_ | 1826197915430813696 |
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| author | Nguyen Van-Duc |
| author_facet | Nguyen Van-Duc |
| author_sort | Nguyen |
| collection | MIT |
| description | This thesis addresses the problem of synthesizing grasps that are force-closure and stable. The synthesis of force-closure grasps constructs independent regions of contact for the fingertips, such that the motion of the grasped object is totally constrained. The synthesis of stable grasps constructs virtual springs at the contacts, such that the grasped object is stable, and has a desired stiffness matrix about its stable equilibrium. A grasp on an object is force-closure if and only if we can exert, through the set of contacts, arbitrary forces and moments on the object. So force-closure implies equilibrium exists because zero forces and moment is spanned. In the reverse direction, we prove that a non-marginal equilibrium grasp is also a force-closure grasp, if it has at least two point contacts with friction in 2D, or two soft-finger contacts or three hard-finger contacts in 3D. Next, we prove that all force-closure grasps can be made stable, by using either active or passive springs at the contacts. The thesis develops a simple relation between the stability and stiffness of the grasp and the spatial configuration of the virtual springs at the contacts. The stiffness of the grasp depends also on whether the points of contact stick, or slide without friction on straight or curved surfaces of the object. The thesis presents fast and simple algorithms for directly constructing stable fore-closure grasps based on the shape of the grasped object. The formal framework of force-closure and stable grasps provides a partial explanation to why we stably grasp objects to easily, and to why our fingers are better soft than hard. |
| first_indexed | 2024-09-23T10:56:04Z |
| id | mit-1721.1/6849 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T10:56:04Z |
| publishDate | 2004 |
| record_format | dspace |
| spelling | mit-1721.1/68492019-04-12T08:32:30Z The Synthesis of Stable Force-Closure Grasps Nguyen Van-Duc This thesis addresses the problem of synthesizing grasps that are force-closure and stable. The synthesis of force-closure grasps constructs independent regions of contact for the fingertips, such that the motion of the grasped object is totally constrained. The synthesis of stable grasps constructs virtual springs at the contacts, such that the grasped object is stable, and has a desired stiffness matrix about its stable equilibrium. A grasp on an object is force-closure if and only if we can exert, through the set of contacts, arbitrary forces and moments on the object. So force-closure implies equilibrium exists because zero forces and moment is spanned. In the reverse direction, we prove that a non-marginal equilibrium grasp is also a force-closure grasp, if it has at least two point contacts with friction in 2D, or two soft-finger contacts or three hard-finger contacts in 3D. Next, we prove that all force-closure grasps can be made stable, by using either active or passive springs at the contacts. The thesis develops a simple relation between the stability and stiffness of the grasp and the spatial configuration of the virtual springs at the contacts. The stiffness of the grasp depends also on whether the points of contact stick, or slide without friction on straight or curved surfaces of the object. The thesis presents fast and simple algorithms for directly constructing stable fore-closure grasps based on the shape of the grasped object. The formal framework of force-closure and stable grasps provides a partial explanation to why we stably grasp objects to easily, and to why our fingers are better soft than hard. 2004-10-20T20:02:20Z 2004-10-20T20:02:20Z 1986-07-01 AITR-905 http://hdl.handle.net/1721.1/6849 en_US AITR-905 134 p. 14521192 bytes 5533792 bytes application/postscript application/pdf application/postscript application/pdf |
| spellingShingle | Nguyen Van-Duc The Synthesis of Stable Force-Closure Grasps |
| title | The Synthesis of Stable Force-Closure Grasps |
| title_full | The Synthesis of Stable Force-Closure Grasps |
| title_fullStr | The Synthesis of Stable Force-Closure Grasps |
| title_full_unstemmed | The Synthesis of Stable Force-Closure Grasps |
| title_short | The Synthesis of Stable Force-Closure Grasps |
| title_sort | synthesis of stable force closure grasps |
| url | http://hdl.handle.net/1721.1/6849 |
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