Identification of the Mechanical Impedance at the Human Finger Tip

Hajian, Aram; Howe, Robert D.

doi:10.1115/1.2796052

Cited by 162 publications

(119 citation statements)

References 21 publications

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“…This linear approximation is accurate for a fixed point over short durations [20]. Rather than identify the impedance of individual joints, this approach represented the hand-wrist combine in terms of lumped elements to focus on the impedance strategy employed during the task [4,14,28]. Note that the wrist-hand stiffness can be modulated by stiffness of the fingers which held the handle.…”

Section: System Identification Techniquementioning

confidence: 99%

Task Performance is Prioritized Over Energy Reduction

Balasubramanian

Howe

Matsuoka

2009

IEEE Trans. Biomed. Eng.

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Abstract-The objective of this study was to characterize the temporal relationship between hand stiffness and task performance during adaptation to a brief contact task that required precision at the time of contact. The experiment required subjects to control the vertical position of a paddle on a computer display by grasping a robot's instrumented handle, with the goal of intercepting a virtual ball within 1 mm from the paddle center. A force transient was applied to the hand immediately after the ball-paddle impact to estimate the intrinsic hand impedance. There were two main results: (1) More trials were required for a brief contact task to find a low-energy strategy when compared with tasks that received feedback through the entire movement trajectory. (2) When the whole course of adaptation is long for brief contact tasks, viscoelastic forces were increased to achieve the task goal before the energy reduction initiated. Also, as the accuracy requirement was increased by changing the gain between handle and paddle motion through visual amplification, peak stiffness increased and occurred later, indicating that higher energy strategies are used for longer when the task's accuracy requirements were increased. These results indicated that task performance may be prioritized over energy reduction for a brief contact task.

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Section: System Identification Techniquementioning

confidence: 99%

Task Performance is Prioritized Over Energy Reduction

Balasubramanian

Howe

Matsuoka

2009

IEEE Trans. Biomed. Eng.

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“…More generally, vision of the object and the hand could affect the kinematics during the course of the movement . Furthermore, tactile cues available at the end of the movement can provide a powerful stimulus for the control of finger muscles (Johansson and Cole, 1992), and it is possible that subjects also take advantage of the hand's compliance in grasping an object (Hajian and Howe, 1997).…”

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confidence: 99%

Patterns of Hand Motion during Grasping and the Influence of Sensory Guidance

2002

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This study was aimed at describing temporal synergies of hand movement and determining the influence of sensory cues on the control of these synergies. Subjects were asked to reach to and grasp various objects under three experimental conditions: (1) memory-guided movements, in which the object was not in view during the movement; (2) virtual object, in which a virtual image of the object was in view but the object was not physically present; and (3) real object, in which the object was in view and physically present. Motion of the arm and of 15 degrees of freedom of the hand was recorded. A principal components analysis was developed to provide a concise description of the spatiotemporal patterns underlying the motion. Vision of the object during the reaching movement had no influence on the kinematics, and the effect of the physical presence of the object became manifest primarily after the fingers had contacted the object. Two principal components accounted for Ͼ75% of the variance. For both components, there was a strong positive correlation in the rotations of metacarpophalangeal and proximal interphalangeal joints of the fingers. The first principal component exhibited a pattern of finger extension reversing to flexion, whereas the second principal component became important only in the second half of the reaching movement.

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“…Friction constraints are derived based on general expressions for the non-planar contacts of elastic bodies, taking into account the local geometry and structure of the objects in contact. The values for the human hand skin friction coefficient and the stiffness modulus have been obtained from [29] and [30] respectively. …”

Section: Soft Contact Modelmentioning

confidence: 99%

Evaluation of Human Prehension Using Grasp Quality Measures

León

Sancho-Bru

Jarque-Bou

et al. 2012

International Journal of Advanced Robotic Systems

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One of the main features of the human hand is its grasping ability. Robot grasping has been studied for years and different quality measures have been proposed to evaluate the stability and manipulability of grasps. Although the human hand is obviously more complex than robot hands, the methods used in robotics might be adopted to study the human grasp. The purpose of this work is to propose a set of measures that allow the evaluation of different aspects of the human grasp. The most common robotic grasp quality measures have been adapted to the evaluation of the human hand and a new quality measure -the fatigue index -is proposed in order to incorporate the biomechanical aspect into the evaluation. The minimum set of indices that allows the evaluation of the different aspects of the grasp is obtained from the analysis of a human prehension experiment.

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Identification of the Mechanical Impedance at the Human Finger Tip

Cited by 162 publications

References 21 publications

Task Performance is Prioritized Over Energy Reduction

Task Performance is Prioritized Over Energy Reduction

Patterns of Hand Motion during Grasping and the Influence of Sensory Guidance

Evaluation of Human Prehension Using Grasp Quality Measures

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