Grip-force control of an elastic object by vision-based slip-margin feedback during the incipient slip

In this paper, a grip-force control of an elastic object is proposed based on a visual slip-margin feedback. When an elastic object is pressed and slid slightly on a rigid plate, a partial slip, called "incipient slip," occurs on the contact surface. The slip margin between an elastic object and a rigid plate is estimated based on the analytic solution of a Hertzian contact model. A one-degree-of-freedom gripper consisting of a camera and a force sensor is developed. The slip margin can be estimated from the tangential force measured by a force sensor, the deformation of the elastic object and the radius on the contact area both measured by a camera. In the proposed method, the friction coefficient is not explicitly needed. The "eccentricity" is used to estimate the displacement of the elastic object at the contact area with high accuracy. The grip force is controlled by a direct feedback of the estimated slip margin. The proof of the contact stability by the proposed control is analytically given. As a result, the slip margin is maintained at a desired value, without occurring the gross slip against a disturbance traction force to the object. The validity of the proposed method is confirmed by experiments.

[1]  H. Maekawa,et al.  A finger-shaped tactile sensor using an optical waveguide , 1993, Proceedings of IEEE Systems Man and Cybernetics Conference - SMC.

[2]  Y. Tatara.  On Compression of Rubber Elastic Sphere Over a Large Range of Displacements—Part 1: Theoretical Study , 1991 .

[3]  Gaston H. Gonnet,et al.  On the LambertW function , 1996, Adv. Comput. Math..

[4]  R. S. Johansson,et al.  Roles of glabrous skin receptors and sensorimotor memory in automatic control of precision grip when lifting rougher or more slippery objects , 2004, Experimental Brain Research.

[5]  Claudio Melchiorri,et al.  Slip detection and control using tactile and force sensors , 2000 .

[6]  Imin Kao,et al.  Modeling of Contact Mechanics and Friction Limit Surfaces for Soft Fingers in Robotics, with Experimental Results , 1999, Int. J. Robotics Res..

[7]  Imin Kao,et al.  Stiffness and contact mechanics for soft fingers in grasping and manipulation , 2004, IEEE Transactions on Robotics and Automation.

[8]  Mark R. Cutkosky,et al.  Sensing skin acceleration for slip and texture perception , 1989, Proceedings, 1989 International Conference on Robotics and Automation.

[9]  Mark R. Cutkosky,et al.  Estimating friction using incipient slip sensing during a manipulation task , 1993, [1993] Proceedings IEEE International Conference on Robotics and Automation.

[10]  Takashi Maeno,et al.  Analysis and design of a tactile sensor detecting strain distribution inside an elastic finger , 1998, Proceedings. 1998 IEEE/RSJ International Conference on Intelligent Robots and Systems. Innovations in Theory, Practice and Applications (Cat. No.98CH36190).

[11]  K. Johnson.  Contact Mechanics: Frontmatter , 1985 .

[12]  Raymond D. Mindlin,et al.  Compliance of elastic bodies in contact , 1949 .

[13]  M. Tada,et al.  Investigation of the touch processing model in human grasping based on the stick ratio within a fingertip contact interface , 2002, IEEE International Conference on Systems, Man and Cybernetics.

[14]  Tsukasa Ogasawara,et al.  A novel pointing device utilizing the deformation of the fingertip , 2003, Proceedings 2003 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2003) (Cat. No.03CH37453).

[15]  Hiroyuki Shinoda,et al.  Ultrasonic emission tactile sensor for contact localization and characterization , 1994, Proceedings of the 1994 IEEE International Conference on Robotics and Automation.

[16]  J. Barbera,et al.  Contact mechanics , 1999 .

[17]  Takashi Maeno,et al.  Control of grasping force by detecting stick/slip distribution at the curved surface of an elastic finger , 2000, Proceedings 2000 ICRA. Millennium Conference. IEEE International Conference on Robotics and Automation. Symposia Proceedings (Cat. No.00CH37065).

[18]  Roger W. Brockett,et al.  Reconstructing the Shape of a Deformable Membrane from Image Data , 2000, Int. J. Robotics Res..

[19]  J. Lucero,et al.  On Compression of Rubber Elastic Sphere Over a Large Range of Displacements—Part 2: Comparison of Theory and Experiment , 1991 .