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This paper presents an approach to passively realize any specified object spatial compliance using the grasp of a robotic hand. The kinematically anthropomorphic hands considered have multiple 4-joint fingers making hard point contact with the held object, and the joints of each finger have selectable passive elastic behavior. It is shown that the space of passively realizable compliances is restricted by the kinematic structure of the anthropomorphic hand. To achieve an arbitrary compliant behavior, fingers must be able to adjust their orientation. Synthesis procedures for grasps having 3, 4, and 5 or more fingers are developed. These procedures identify the finger configurations and the individual finger joint compliances needed to passively achieve any specified spatial object compliance matrix in the 20-dimensional subspace of grasp-realizable behaviors.
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Development and Evaluation of a Passive Multiloop Wearable Hand Device for Natural Motion
Abstract This article describes the development and evaluation of our passively actuated closed-loop articulated wearable (CLAW) that uses a common slider to passively drive its exo-fingers for use in physical training of people with limited hand mobility. Our design approach utilizes physiological tasks for dimensional synthesis and yields a variety of design candidates that fulfill the desired fingertip precision grasping trajectory. Once it is ensured that the synthesized fingertip motion is close to the physiological fingertip grasping trajectories, performance assessment criteria related to user–device interference and natural joint angle movement are taken into account. After the most preferred design for each finger is chosen, minor modifications are made related to substituting the backbone chain with the wearer’s limb to provide the skeletal structure for the customized passive device. Subsequently, we evaluate it for natural joint motion based on a novel design candidate assessment method. A hand prototype is printed, and its preliminary performance regarding natural joint motion, wearability, and scalability are assessed. The pilot experimental test on a range of healthy subjects with different hand/finger sizes shows that the CLAW hand is easy to operate and guides the user’s fingers without causing any discomfort. It also ensures both precision and power grasping in a natural manner. This study establishes the importance of incorporating novel design candidate assessment techniques, based on human finger kinematic models, on a conceptual design level that can assist in finding design candidates for natural joint motion coordination.
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- Award ID(s):
- 1751770
- PAR ID:
- 10434019
- Date Published:
- Journal Name:
- Journal of Mechanisms and Robotics
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 1942-4302
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1115/1.4054168
