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-12208597-B1
Publication Date
2025-01-28
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 grasp assist system is disclosed that comprises a glove with multiple glove fingers, finger saddles attached to the posterior surface of respective glove fingers, one or more tendon actuators, and artificial tendons connected via a triple Brummel loop connection. The finger saddles have a rectangular body partially circumscribing the glove fingers, each having a pair of end lobes at opposite distal ends. The tendons form a triple Brummel loop at one end, with two anchor loops disposed around the end lobes of the finger saddles, creating a soft anchor with two tendon anchor points when under tension.
The invention addresses problems in existing grasp assist devices, such as uneven load distribution and discomfort caused by single circumferential tendon loops on arcuate finger saddles or cylindrical phalange rings. The triple Brummel loop soft anchor arrangement is designed to evenly distribute tensile loads from the tendons on the finger saddles, reducing cinching or pinching that can damage the glove material or cause user discomfort. Additionally, the soft anchor configuration allows maintenance or replacement of tendons without removing the glove, improving operational efficiency.
The system selectively assists natural grasping motions initiated by the user. Tendon actuators apply power assist during user-initiated grasp maneuvers involving flexion of fingers and/or thumb. The system supports various applications, including work-based and recreational uses, and rehabilitation for users with limited finger movement or dexterity. The finger saddles are anisotropic, constructed of thermoplastic polyurethane-coated nylon, and configured with specific shapes (rounded double-headed arrow) and thickness ratios to support different bending strengths along orthogonal axes. Sensors and controllers can modulate tendon tension based on detected finger flexion and contact with objects.
Claims Coverage
The independent claims define inventive features covering the grasp assist system with finger saddles having end lobes, tendon actuators, triple Brummel loop tendons forming a soft anchor, and methods for connecting tendons to glove fingers.
Grasp assist system with finger saddles featuring end lobes
The system includes a glove having multiple glove fingers and finger saddles attached to the posterior surface of respective glove fingers. Each finger saddle includes a rectangular body partially circumscribing a glove finger and a pair of end lobes disposed at opposite distal ends of the body.
Triple Brummel loop tendon connection forming a soft anchor
Each tendon has a first portion connected to a tendon actuator and at least one end defining a triple Brummel loop. The triple Brummel loop includes a pair of Brummel loops disposed around respective end lobes of the finger saddle, forming a soft anchor that provides two tendon anchor points when the tendon is placed under tension.
Finger saddle structural features
Finger saddles have an outer perimeter shaped as a rounded, double-headed arrow with end lobes at least double the thickness of the rectangular body. They are anisotropic with bending strengths differing along orthogonal axes. They are constructed of thermoplastic polyurethane-coated nylon and may be sewn to the glove through through-holes defined by the end lobes.
Sensor and controller integration for selective tension application
The system may include sensors such as flexion and contact sensors and a controller in communication with the actuators. The controller is configured to receive feedback signals and selectively command tension application to the tendons.
Method of connecting flexible tendons using triple Brummel loop
The method includes attaching a finger saddle to a glove finger, forming a triple Brummel loop defining a main loop and a pair of anchor loops at a first tendon end, attaching the second tendon end to a tendon actuator, inserting the finger saddle end lobes into the anchor loops to form a soft anchor with two tendon anchor points, and applying tension via the controller and actuator to tighten the loops around the saddle.
The claims cover a grasp assist system employing finger saddles with end lobes secured by a novel triple Brummel loop tendon soft anchor providing two tendon anchor points, finger saddle structural features optimizing bending strengths, integration with sensors and controllers for selective actuation, and a specific method for connecting the tendons that facilitates maintenance and efficient operation.
Stated Advantages
Improved load distribution on finger saddles reducing cinching or pinching and enhancing user comfort.
Facilitates maintenance and tendon replacement without removing the glove, improving operational efficiency.
Selective assistance of user-initiated grasp maneuvers, enhancing work efficiency, recreation, and rehabilitation applications.
Documented Applications
Use as part of a pressurized space suit glove in aerospace operations.
Non-aerospace applications including manufacturing, construction, medical rehabilitation, and recreational applications such as scuba diving.
Assistive glove for users with limited finger movement, strength, and dexterity.
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