Hand Synergies: Mapping from human hand to robotic hand

Many robotic researcher propose a novel mapping approach to map a human grasp to a robotic grasp based on human grasp motion trajectories rather than grasp poses, because  human grasp motions usually contain complex and nonlinear patterns in a high-dimensional space.

In recent advnces in neuroscience research, the control of the human hand during grasping is dominated by movement in a configuration space of highly reduced dimensionality.

Especilly, static hand posture was measured by recording the angular position of 15 joint angles of the fingers and of the thumb. Although subjects adopted distinct hand shapes for the various objects,

the joint angles of the digits did not vary independently.

Principal components analysis showed that the first two components could account for .80% of the variance, implying a substantial reduction from the 15 degrees of freedom that were recorded.

These results suggest that the control of hand posture involves a few postural synergies, regulating the general shape of the hand, coupled with a finer control mechanism providing for small, subtle adjustments.

Because the postural synergies did not coincide with grip taxonomies, the results suggest that hand posture may be regulated independently from the control of the contact forces that are used to grasp an object.

 

Reference :

1. Postural hand Synergies for Tool use (1998, journal of neuroscience)

2. synergy_based_hand_pose_sensing(2013, IJRR).pdf

3. Hand synergies during reach to grasp(2001, Journal of neurophysiology).pdf

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