Method for controlling a grasp assist system
Inventors
Rogers, Jonathan M. • Peters, Benjamin J. • Laske, Evan • McBryan, Emily R.
Assignees
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Publication Number
US-11690775-B1
Publication Date
2023-07-04
Expiration Date
2038-04-05
Abstract
A grasp assist system includes a glove having a glove palm and fingers, with the glove worn on a user's hand. A sensor measures flexion of the glove fingers, and thus a change of position and/or attitude of the fingers is determined. Finger saddles at least partially surround a phalange of a respective one of the user's fingers. The system uses one or more tendon actuators to pull on flexible tendons. Each tendon connects to a respective finger saddle. A controller is in communication with the actuators and sensor(s). The glove may use feedback from optional contact sensors to adjust tension, and may have a built-in restorative force. In executing a control method, the controller selectively applies tension to the tendons in response to finger flexion, via the tendon actuators, at a level sufficient for moving the user's fingers when the user executes a hand maneuver.
Core Innovation
A glove-based grasp assist system and related control method are disclosed, designed to selectively assist the natural hand and finger motion of a human user using a tendon drive system. The system includes a powered glove worn on the user's hand, equipped with one or more actuators that apply tension to flexible artificial tendons connected to finger saddles partially surrounding each finger phalange. This tension assists finger flexion when the user initiates a hand maneuver, which refers to any user-initiated, muscle-based motion involving finger or thumb flexing, regardless of actual grasping or contact with objects.
The grasp assist system comprises a glove having a palm and fingers to be worn, flexion sensors measuring finger flexion and determining relative position or attitude changes, tendon actuators pulling on flexible tendons connected to finger saddles, and a controller communicating with these components. The system can also include contact sensors to detect contact during hand maneuvers and provide feedback for tension adjustment. A built-in restorative force, possibly provided by a pressurizable bladder layer connected to an external pressure source, assists in returning the hand to the relaxed position when the grasp is released.
The system addresses the problem of overcoming the bending stiffness of specialized work or recreational gloves used in aerospace activities, diving, industrial work, or rehabilitation, where finger strength or dexterity is limited. The glove allows freedom of finger movement when unpowered, preserving tactile feedback for dexterous tasks, but selectively provides power assist through controlled tendon tension to help the user during hand maneuvers. Features include a multi-layer glove construction with a restraint layer, hardware layer containing actuators and the controller, and optionally protective outer and bladder layers. The glove may also have a palm bar connected to a ratchet mechanism to adjust fit.
Claims Coverage
The patent includes two independent claims focusing on methods for controlling a grasp assist system glove via flexion sensing, tendon actuation, and adjustable tension mechanisms.
Method for controlling grasp assist responsive to finger flexion and contact
Measuring finger and hand flexion using a flexion sensor, detecting contact via glove-connected contact sensors, commanding tendon actuators to apply tension sufficient to move fingers during hand maneuvers, adjusting tendon tension in response to contact, and executing two operating modes—one where closure of the whole glove is triggered by flexion of any finger, and another where closure of individual glove fingers is triggered by corresponding finger flexion.
Method involving glove fit adjustment via palm bar and ratchet mechanism
Measuring finger flexion, commanding tendon actuators to apply tension sufficient for moving the glove fingers and user fingers during hand maneuvers, mechanically coupling a palm bar to a ratchet mechanism, and adjusting glove fit by rotating the ratchet mechanism.
The independent claims cover methods for controlling glove-based grasp assist involving sensor-based measurement of finger flexion, contact detection with objects, application and adjustment of tendon tension to aid finger movement during hand maneuvers, and mechanical adjustment of glove fit using a palm bar and ratchet mechanism, including operational modes for whole-hand or finger-specific assist.
Stated Advantages
Selective assistance to overcome bending stiffness of specialized gloves improves user strength and dexterity during hand maneuvers.
Freedom of finger movement when unpowered preserves tactile feedback necessary for fine motor tasks.
Built-in restorative force assists the hand's return to a relaxed position after grasping.
Modular control architecture enables multiple real-time operational modes for intuitive and adjustable grasp assistance.
Documented Applications
Use as part of pressurized space suits for Extravehicular Activity (EVA) to assist astronaut hand movement.
Industrial work applications requiring overcoming rigid gloves' resistance.
Recreational diving gloves where finger dexterity assistance is beneficial.
Medical rehabilitation or treatment of users with limited finger strength and dexterity.
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