Vision-based human grasp reconstruction inspired by hand postural synergies

Abstract This paper presents a soft, tendon-driven, robotic glove designed to augment grasp capability and provide rehabilitation assistance for postspinal cord injury patients. The basis of the design is an underactuation approach utilizing postural synergies of the hand to support a large variety of grasps with a single actuator. The glove is lightweight, easy to don, and generates sufficient hand closing force to assist with activities of daily living. Device efficiency was examined through a characterization of the power transmission elements, and output force production was observed to be linear in both cylindrical and pinch grasp configurations. We further show that, as a result of the synergy-inspired actuation strategy, the glove only slightly alters the distribution of forces across the fingers, compared to a natural, unassisted grasping pattern. Finally, a preliminary case study was conducted using a participant suffering from an incomplete spinal cord injury (C7). It was found that through the use of the glove, the participant was able to achieve a 50% performance improvement (from four to six blocks) in a standard Box and Block test.

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The Motor Control of Hand Movements in the Human Brain: Toward the Definition of a Cortical Representation of Postural Synergies

Springer Series on Touch and Haptic Systems - Human and Robot Hands ◽

10.1007/978-3-319-26706-7_4 ◽

2016 ◽

pp. 41-60

Author(s):

Andrea Leo ◽

Giacomo Handjaras ◽

Hamal Marino ◽

Matteo Bianchi ◽

Pietro Pietrini ◽

...

Keyword(s):

Motor Control ◽

Human Brain ◽

Hand Movements ◽

Cortical Representation ◽

Definition Of ◽

Postural Synergies

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Postural Synergies

Encyclopedia of Neuroscience ◽

10.1007/978-3-540-29678-2_4716 ◽

2008 ◽

pp. 3228-3233

Author(s):

Lena H. Ting

Keyword(s):

Postural Synergies

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Motor equivalence and structure of variance: multi-muscle postural synergies in Parkinson’s disease

Experimental Brain Research ◽

10.1007/s00221-017-4971-y ◽

2017 ◽

Vol 235 (7) ◽

pp. 2243-2258 ◽

Cited By ~ 15

Author(s):

Ali Falaki ◽

Xuemei Huang ◽

Mechelle M. Lewis ◽

Mark L. Latash

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Motor Equivalence ◽

Postural Synergies

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A Comparative Study for Postural Synergy Synthesis Using Linear and Nonlinear Methods

International Journal of Humanoid Robotics ◽

10.1142/s0219843616500092 ◽

2016 ◽

Vol 13 (03) ◽

pp. 1650009 ◽

Cited By ~ 2

Author(s):

Kai Xu ◽

Huan Liu ◽

Yuheng Du ◽

Xiangyang Zhu

Keyword(s):

Comparative Study ◽

Latent Variable ◽

Robotic Hand ◽

Nonlinear Method ◽

Variable Model ◽

Nonlinear Methods ◽

Nonlinear Dimension Reduction ◽

Linear And Nonlinear ◽

Nonlinear Dimension ◽

Postural Synergies

Human controls dozens of muscles for different hand postures in a coordinated manner. Such coordination is referred to as a postural synergy. Postural synergy has enabled an anthropomorphic robotic hand with many actuators to be applied as a prosthetic hand and controlled by two to three channels of biological signals. Principle component analysis (PCA) of the hand postures has become a popular way to extract the postural synergies. However, relatively big errors are often produced while the hand postures are reconstructed using these PCA-synthesized synergies due to the linearity nature of this method. This paper presents a comparative study in which the postural synergies are synthesized using both linear and nonlinear methods. Specifically, the Gaussian process latent variable model (GPLVM), as a nonlinear dimension reduction method, is implemented to produce nonlinear postural synergies and the hand postures can then be reconstructed from the two-dimensional synergy plane. Computational and experimental verifications show that the posture reconstruction errors are greatly reduced using this nonlinear method. The results suggest that the use of nonlinear postural synergies should be considered while applying a dexterous robotic hand as prosthesis. Versatile hand postures could be formed via only two channels of bio-signals.

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Postural Synergies and Their Development

Neural Plasticity ◽

10.1155/np.2005.119 ◽

2005 ◽

Vol 12 (2-3) ◽

pp. 119-130 ◽

Cited By ~ 19

Author(s):

Mark L. Latash ◽

Vijaya Krishnamoorthy ◽

John P. Scholz ◽

Vladimir M. Zatsiorsky

Keyword(s):

Uncontrolled Manifold ◽

Motor Tasks ◽

Performance Variables ◽

Motor Synergies ◽

Motor Abundance ◽

Motor Practice ◽

Recent Developments ◽

The Central Nervous System ◽

Postural Perturbations ◽

Postural Synergies

The recent developments of a particular approach to analyzing motor synergies based on the principle of motor abundance has allowed a quantitative assessment of multieffector coordination in motor tasks involving anticipatory adjustments to self-triggered postural perturbations and in voluntary posturalsway. This approach, the uncontrolled manifold (UCM) hypothesis, is based on an assumption that the central nervous system organizes covariation of elemental variables to stabilize important performance variables in a task-specific manner. In particular, this approach has been used to demonstrate and to assess the emergence of synergies and their modification with motor practice in typical persons and persons with Down syndrome. The framework of the UCM hypothesis allows the formulation of testable hypotheses with respect to developing postural synergies in typically and atypically developing persons.

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