Grasp assist system with triple Brummel soft anchor
Inventors
McBryan, Emily R. • Rogers, Jonathan M. • Peters, Benjamin J. • Laske, Evan
Assignees
National Aeronautics and Space Administration NASA
Publication Number
US-11019862-B1
Publication Date
2021-06-01
Expiration Date
2038-04-05
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Abstract
A grasp assist system includes a glove, finger saddles attached to a respective glove finger, one or more tendon actuators, and artificial tendons. The saddles have a rectangular body partially circumscribing a respective glove finger. Each saddle includes end lobes at opposite distal ends of the body. A first end of each tendon is secured to one of the tendon actuators. A second end forms a triple Brummel loop defining a main loop and two anchor loops. The anchor loops are disposed around the lobes. The saddles may form a rounded, double-headed arrow shape that is at least double the thickness of the body. The finger saddles are anisotropic, with different bending strengths depending on the axis, and may be constructed of thermoplastic polyurethane-coated nylon. Flexion and/or contact sensors and a controller, may be used. A method of connecting the tendon actuator to the finger is also disclosed.
Core Innovation
A glove-based grasp assist system is disclosed which includes a glove with finger saddles attached to respective glove fingers, tendon actuators, and artificial tendons. The finger saddles have a rectangular body partially circumscribing each glove finger and include end lobes at opposite distal ends. The artificial tendons connect to the tendon actuators at one end and form a triple Brummel loop at the other end that creates a soft anchor around the end lobes of the finger saddles. This arrangement provides two anchor points for the tendons.
The problem addressed by the invention is related to improving the performance of existing arcuate finger saddles or cylindrical phalange rings engaged by a single circumferentially-extending tendon loop, which can lead to issues such as cinching, pinching, glove damage, and user discomfort. Existing designs also complicate tendon maintenance since tendons need to be replaced or repaired only after removing the glove.
This invention solves these problems by employing finger saddles with a triple Brummel loop soft anchor that evenly distributes tensile loads on the finger segments and prevents cinching or pinching. The finger saddles are anisotropic with different bending strengths depending on the axis, constructed of thermoplastic polyurethane-coated nylon. The soft anchor allows in-place maintenance of the tendons without removing the glove, improving operational efficiency. The system assists natural grasping forces by selectively activating tendon actuators in response to user-initiated hand motion.
Claims Coverage
The patent includes one independent claim focusing on the structure and configuration of a triple Brummel soft anchor for a grasp assist system. The inventive features involve the finger saddle design and tendon anchoring method.
Triple Brummel soft anchor finger saddle configuration
A finger saddle with a rectangular body partially circumscribing a glove finger and having a pair of end lobes at opposite distal ends, configured to attach to the posterior surface of a glove finger.
Flexible artificial tendon with triple Brummel loop
An artificial tendon having a first portion forming a loop for connecting to a tendon actuator, and a second end defining a triple Brummel loop comprising a pair of Brummel loops disposed around the end lobes of the finger saddle, forming a soft anchor with two anchor points to distribute pulling forces along the lateral sides of the glove finger.
Specific shape and thickness of finger saddle
The finger saddle has an outer perimeter shaped as a rounded, double-headed arrow, with the end lobes having thickness at least double that of the rectangular body for load distribution.
Anisotropic bending strength of finger saddle
The finger saddle is anisotropic with bending strength of end lobes exceeding that of the rectangular body in one axial direction and vice versa in the orthogonal axial direction.
Construction material of finger saddle
The finger saddle is constructed of thermoplastic polyurethane-coated nylon.
The claims collectively cover a grasp assist system featuring a finger saddle designed with lobed ends and anisotropic properties, combined with a flexible artificial tendon secured by a triple Brummel loop forming a soft anchor that provides two anchor points for effective distribution of pulling forces along a glove finger.
Stated Advantages
Minimizes cinching or pinching during operation, preventing damage to the glove material and user discomfort.
Allows in-place maintenance of tendons without removing the glove, improving operating efficiency.
Evenly distributes tensile load along the lateral sides of the fingers, reducing stress concentrations.
Improves efficiency in work-based, recreational, and rehabilitation applications by selectively assisting natural grasping forces.
Documented Applications
Use as part of a pressurized space suit glove for aerospace operations.
Manufacturing and construction applications.
Medical rehabilitation to assist users with limited finger movement strength and dexterity.
Recreational applications such as scuba diving.
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