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US 4,957,320 AGranted
Methods and apparatus for mechanically intelligent grasping
AssigneeThe Trustees of the University of Pennsylvania
InventorNathan T. Ulrich
Life of this patent
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Abstract
An improved robotic end effector is disclosed. The end effector of the present invention possesses a novel breakaway clutch, which is combined with mechanically linked finger joints to significantly reduce control complexity while retaining the ability to accomplish enveloping grasps. In another embodiment, a finger using compliant tendons to accomplish enveloping grasps is disclosed. A novel palm/finger configuration which further increases the versatility of the disclosed end effector without unduly increasing complexity is also disclosed. Methods of manipulating an object are also disclosed.
Claims9
Apparatus for grasping an object, comprising:
- (a) palmar surface;
- (b) at least a first articulated member, comprising at least one rotatable joint disposed above the plane of said palmar surface, said articulated member rotatably attached to said palmar surface, said articulated member comprising:
- (i) means for actuating a first rotatable joint comprised of:
- substantially cylindrical clutch means having screw threads on a portion thereof, said clutch means further having a substantially axial bore therein;
- a first substantially cylindrical shaft, disposed within the axial bore of said clutch means;
- means for actuating said clutch means, further comprising means for creating an adjustable frictional force between said shaft and said clutch means;
- a substantially cylindrical outer body portion, having means for actuating a rotating joint on a portion thereof, comprising a worm gear train, and a second substantially cylindrical shaft affixed thereto, further having a substantially axial bore therein, the axial bore having screw threads thereon;
- and resilient means for creating a force when displaced disposed within a portion of the substantially axial bore of said substantially cylindrical outer body portion, which transfer force from said clutch means to said outer body portion when said clutch means is threaded into said outer body portion until said clutch means urges against and displaces said resilient means,
- whereby, the rotation of said means for actuation is transferred to said means for actuating a rotational joint, until said joint encounters a resistive force, causing said screw threads to unscrew said clutch means away from said resilient means, ceasing the transfer of power to a rotational joint;
- (ii) a first link, having two ends, the proximal end of said first link hingably attached to said first joint, the distal end of said link defining a second rotatable joint;
- (iii) a second link, having two ends, the proximal end of said link hingably attached to said second joint;
- and
- (iv) means for actuating said second joint affixed to said actuating means such that when said clutch mechanism ceases to transfer power to said first joint, substantially all of the actuator power is transferred to said second joint;
- and
- (c) means for rotating said first articulated member up to at least 180.degree. about an axis of rotation, whereby said articulated member moves relative to the perimeter of said palmar surface,
- whereby the relative motion of said first and second joints is compliantly coupled, such that when said first link encounters a resistive force, said means for actuating a first joint is disconnected and said second joint continues to be activated.
13 more elements
An articulated member, comprising:
- (a) means for actuating a first rotatable joint;
- (b) a first link, having two ends, the proximal end of said first link hingably attached to said first joint, the distal end of said link defining a second rotatably joint;
- (c) a second link, having two ends, the proximal end of said link hingably attached to said second joint;
- (d) means for actuating said second joint;
- whereby, when said first link encounters a resistive force, said means are actuating a first joint is disconnected to said second joint continues to be actuated thereby compliantly coupling the relative motion of said first and second joints;
- and
- wherein said means for actuating said first and said second rotatably joints is comprised of first and second tendon means and pulley means, and said compliant coupling is provided by resilient means attached to said second tendon means, said resilient means being attached to said second tendon means to provide compliance only when said articulated member is manipulated to urge against an object, said articulated member being capable of substantially resisting the urging force of said object in a substantially rigid manner,
- whereby said first tendon means actuates said second joint and said second tendon transfers the motion of said second joint to said first joint.
5 more elements
A clutch mechanism, comprised of:
- (a) substantially cylindrical clutch means having screw threads on a portion thereof, said clutch means further having a substantially axial bore therein;
- (b) a first substantially cylindrical shaft, disposed within the axial bore of said clutch means;
- (c) means for actuating said clutch means, further comprising means for creating ana adjustable frictional force between said shaft and said clutch means;
- (d) a substantially cylindrical outer body portion, having means for actuating a rotating joint on a portion thereof, comprising a worm gear train, and a second substantially cylindrical shaft affixed thereto, further having a substantially axial bore therein, the axial bore having screw threads thereon;
- and
- (e) resilient means for creating a force when displaced disposed within a portion of the substantially axial bore of said substantially cylindrical outer body portion, which transfers force from said clutch means to said outer body portion when said clutch means is threaded into said outer body portion until said clutch means urges against and displaces said resilient means,
- whereby the rotation of said means for actuation is transferred to said means actuating a rotational joint, until said joint encounters a resistive force, causing said screw threads to unscrew said clutch means away from said resilient means, ceasing the transfer of power to a rotational joint.
4 more elements
Dependencies are inferred from the claim text.