US 4,955,653 AGranted

Spiral lead platen robotic end effector

AssigneeAdministrator of the National Aeronautics and Space Administration

InventorBeals, David C.

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Abstract

A robotic end effector is disclosed which makes use of a rotating platen (1) with spiral leads (2,3) used to impact lateral motion to gripping fingers (46,48). Actuation is provided by the contact of rolling pins (54,56) with the walls of the leads. The use of the disclosed method of actuation avoids jamming and provides excellent mechanical advantage while remaining light in weight and durable. The entire end effector is compact and easily adapted for attachment to robotic arms currently in use.

Claims1

Dependent claims

A Robotic End Effector for manipulating an object comprising:

a platen in the shape of a disc with a flat upper surface and a flat lower surface and an axis of rotation perpendicular to said upper surface, said upper surface having two spiral leads in the form of a groove formed into said upper surface,
said two spiral leads having walls perpendicular to the upper surface of the platen,
said two spiral leads being concentric about the axis of rotation, said two spiral leads originating at points on opposite sides and equidistant from said axis of rotation,
said two spiral leads diverging from said axis of rotation at substantially equal constant linear rates;
means for rotating the platen about the axis of rotation, said means comprising:
an electric motor adapted for repeated rotation to a pre-determined position, and
a gear drive mounted on the lower surface of the platen for transferring rotational force from the motor to the platen and for modifying the rate of rotation of the platen relative to that of the motor;
first and second substantially similar moveable grippers, each of having a base and grasping means and each acting against each other to grasp the object being manipulated,
each of said first and second moveable grippers being constrained to move in opposition to each other along a straight track,
said straight track being located so as to form an intersection between the axis of rotation of the platen and to extend for an equal distance on both sides of said intersection,
said straight track being parallel to the upper surface of the platen,
said straight track being formed by a pair of parallel rails to which each of the first and second moveable grippers are attached by means of precision linear bearings;
a means of engaging each of the first and second moveable grippers with a corresponding one of the two spiral leads in the platen, said means of engaging each of the first and second movable grippers comprising:
a bearing fitted to the base of each moveable gripper, and
a round pin fitted to each bearing such that the pin is free to rotate, and
the pin protrudes from the base of a moveable gripper and extends into the corresponding spiral lead,
the pin bears against one perpendicular wall of the corresponding spiral lead, and
a minimum clearance exists between the perpendicular wall of the corresponding spiral lead against which the pin does not bear, and the pin;
and
positioning means for positioning the platen, the means for rotating the platen, the first moveable gripper, the means for engaging the first moveable gripper, and a member against which the first moveable gripper acts to apply grasping force to said object being manipulated, such positioning means including a mounting surface for attaching the robotic end effector to the means for rotating the platen.

17 more elements

Dependencies are inferred from the claim text.

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Abstract

A Robotic End Effector for manipulating an object comprising:

a platen in the shape of a disc with a flat upper surface and a flat lower surface and an axis of rotation perpendicular to said upper surface, said upper surface having two spiral leads in the form of a groove formed into said upper surface,
said two spiral leads having walls perpendicular to the upper surface of the platen,
said two spiral leads being concentric about the axis of rotation, said two spiral leads originating at points on opposite sides and equidistant from said axis of rotation,
said two spiral leads diverging from said axis of rotation at substantially equal constant linear rates;
means for rotating the platen about the axis of rotation, said means comprising:
an electric motor adapted for repeated rotation to a pre-determined position, and
a gear drive mounted on the lower surface of the platen for transferring rotational force from the motor to the platen and for modifying the rate of rotation of the platen relative to that of the motor;
first and second substantially similar moveable grippers, each of having a base and grasping means and each acting against each other to grasp the object being manipulated,
each of said first and second moveable grippers being constrained to move in opposition to each other along a straight track,
said straight track being located so as to form an intersection between the axis of rotation of the platen and to extend for an equal distance on both sides of said intersection,
said straight track being parallel to the upper surface of the platen,
said straight track being formed by a pair of parallel rails to which each of the first and second moveable grippers are attached by means of precision linear bearings;
a means of engaging each of the first and second moveable grippers with a corresponding one of the two spiral leads in the platen, said means of engaging each of the first and second movable grippers comprising:
a bearing fitted to the base of each moveable gripper, and
a round pin fitted to each bearing such that the pin is free to rotate, and
the pin protrudes from the base of a moveable gripper and extends into the corresponding spiral lead,
the pin bears against one perpendicular wall of the corresponding spiral lead, and
a minimum clearance exists between the perpendicular wall of the corresponding spiral lead against which the pin does not bear, and the pin;
and
positioning means for positioning the platen, the means for rotating the platen, the first moveable gripper, the means for engaging the first moveable gripper, and a member against which the first moveable gripper acts to apply grasping force to said object being manipulated, such positioning means including a mounting surface for attaching the robotic end effector to the means for rotating the platen.

17 more elements