Null-Space Grasp Control: Theory and Experiments

Platt, Robert; Fagg, Andrew H.; Grupen, Roderic A.

doi:10.1109/tro.2010.2042754

Cited by 66 publications

(46 citation statements)

References 40 publications

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“…In [29], the authors exploit tactile sensors on the fingertips to control the finger contact force under shape uncertainty. Platt's nullspace grasping control [30] uses local object geometry measurements to guide grasps and converge to unit frictional equilibrium. This involves following the negative gradient of two functions: force and moment residuals which are zero at this equilibirum.…”

Section: Grasping Under Uncertainty With Multiple Dofsmentioning

confidence: 99%

Multi-contact haptic exploration and grasping with tactile sensors

Sommer

Billard

2016

Robotics and Autonomous Systems

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Haptic exploration has received a great deal of attention of late thanks to the variety of commercially available tactile sensors. While the majority of previous works consider control of a single contact point at a time, we tackle simultaneous control of multiple contact points on several links. In addition, we use information from the existing tactile signals to increase the number of points in contact. We demonstrate the usefulness of this form of control to speed up exploration, scanning and to compliantly grasp unknown objects. Our controller requires to know only the parts of the robot on which it is desirable to make contact and does not need a model of the environment besides the robot itself. We validate the algorithm in a set of experiments using a robotic hand covered with tactile sensors and arm. In a grasping application, the active adaptation of the fingers to the shape of the object ensures that the hand encloses the object with multiple contact points. We show that this improves the robustness of the grasp compared to simple enclosing strategies. When combined with an exploration strategy, our multi-contact approach offers an efficient use of tactile sensors on the whole surface of robotic fingers, and enables the robot to perform a rapid exploration of complex, non convex shapes while maintaining low contact forces. It is robust to variation in the approach angle and to changes in the geometry and orientation of the object.

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Section: Grasping Under Uncertainty With Multiple Dofsmentioning

confidence: 99%

Multi-contact haptic exploration and grasping with tactile sensors

Sommer

Billard

2016

Robotics and Autonomous Systems

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“…Platt et al [27] devised null space grasp controllers to achieve frictionless equilibrium grasp configurations by displacing the fingers over the object surface and aiming to regulate contact force/moments error residuals to zero. Tahara et.…”

Section: Closed-loop Control Graspingmentioning

confidence: 99%

Human-inspired force compliant grasping primitives

et al. 2014

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We address the problem of grasping everyday objects that are small relative to an anthropomorphic hand, such as pens, screwdrivers, cellphones, and hammers from their natural poses on a support surface, e.g., a table top. In such conditions, state of the art grasp generation techniques fail to provide robust, achievable solutions due to either ignoring or trying to avoid contact with the support surface. In contrast, when people grasp small objects, they often make use of substantial contact with the support surface. In this paper we give results of human subjects grasping studies which show the extent and characteristics of environment contact under different task conditions. We develop a simple closed-loop hybrid grasping controller that mimics this interactive, contact-rich strategy by a position-force, pre-grasp and landing strategy for finger placement. The approach uses a compliant control of the hand during the grasp and release of objects in order to preserve safety. We conducted extensive robotic grasping experiments on a variety of small objects with similar shape and size. The results demonstrate that our approach is robust to localization uncertainties and applies to many everyday objects.

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“…in [5] a push-grasping mechanism is used to align and bring the object inside the capture envelope. Platt et al [15] devised null space grasp controllers to achieve frictionless equilibrium grasp configurations by displacing the fingers over the object surface and aiming to regulate contact force/moments error residuals to zero.…”

Section: Related Workmentioning

confidence: 99%

Robust Object Grasping using Force Compliant Motion Primitives

Kazemi¹,

Valois²,

Bagnell³

et al. 2012

Robotics: Science and Systems VIII

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Abstract-We address the problem of grasping everyday objects that are small relative to an anthropomorphic hand, such as pens, screwdrivers, cellphones, and hammers from their natural poses on a support surface, e.g., a table top. In such conditions, state of the art grasp generation techniques fail to provide robust, achievable solutions due to either ignoring or trying to avoid contact with the support surface. In contrast, we show that contact with support surfaces is critical for grasping small objects. This also conforms with our anecdotal observations of human grasping behaviors. We develop a simple closed-loop hybrid controller that mimics this interactive, contact-rich strategy by a position-force, pre-grasp and landing strategy for finger placement. The approach uses a compliant control of the hand during the grasp and release of objects in order to preserve safety. We conducted extensive grasping experiments on a variety of small objects with similar shape and size. The results demonstrate that our approach is robust to localization uncertainties and applies to many everyday objects.

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Null-Space Grasp Control: Theory and Experiments

Abstract: Abstract-A key problem in robot grasping is that of positioning the manipulator contacts so that an object can be grasped.

Cited by 66 publications

References 40 publications

Multi-contact haptic exploration and grasping with tactile sensors

Multi-contact haptic exploration and grasping with tactile sensors

Human-inspired force compliant grasping primitives

Robust Object Grasping using Force Compliant Motion Primitives

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