Gripper force sensor/controller for robotic arm
First Claim
1. In a robotic arm, apparatus for measuring the gripping force applied by said arm upon an object grasped therein, said apparatus comprising:
- drive means having a rotating shaft;
flexible coupling means connected to said rotating shaft;
rotary displacement means positioned upon and supported by said rotating shaft and freely rotatable with respect to said rotating shaft, said rotary displacement further connected to said flexible coupling means so as to rotate in response to displacement of said rotating shaft;
gripper means coupled to said rotary displacement means and responsive to rotation thereof for engaging an object in a grasping manner; and
sensor means coupled to said rotating shaft and to said rotary displacement means for measuring the difference between their respective angular displacements for deriving the force applied by said gripper means upon said object and for measuring an increase in the gripping force when said rotating shaft is displaced in a first direction of rotation and a decrease in the gripping force when said rotating shaft is displaced in a second direction of rotation.
7 Assignments
0 Petitions
Accused Products
Abstract
A gripper assembly for a robotic arm includes two opposing elements displaced by means of a worm gear arrangement for grasping an object positioned therebetween. The worm gear is driven by a rotary drive motor with a torsion spring coupling the drive motor shaft to the worm. First and second shaft encoders are respectively mounted to the drive motor shaft and the worm shaft. First and second pairs of optical sensors respectively coupled to the first and second shaft encoders detect the angular speed and displacement of the drive motor shaft and the worm. With the torsion constant of the spring known, the force applied by the gripper assembly which is proportional to the angular displacement of the worm may be accurately determined and controlled. In addition, the size of the object grasped by the gripper assembly may be determined. By comparing these operating parameters with selected values, the gripper assembly may be precisely controlled such as by means of a microcomputer.
206 Citations
17 Claims
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1. In a robotic arm, apparatus for measuring the gripping force applied by said arm upon an object grasped therein, said apparatus comprising:
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drive means having a rotating shaft; flexible coupling means connected to said rotating shaft; rotary displacement means positioned upon and supported by said rotating shaft and freely rotatable with respect to said rotating shaft, said rotary displacement further connected to said flexible coupling means so as to rotate in response to displacement of said rotating shaft; gripper means coupled to said rotary displacement means and responsive to rotation thereof for engaging an object in a grasping manner; and sensor means coupled to said rotating shaft and to said rotary displacement means for measuring the difference between their respective angular displacements for deriving the force applied by said gripper means upon said object and for measuring an increase in the gripping force when said rotating shaft is displaced in a first direction of rotation and a decrease in the gripping force when said rotating shaft is displaced in a second direction of rotation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A controller for controlling the grasping force exerted upon an object by a gripper device, said controller comprising:
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a drive motor having a bi-directional rotary drive shaft mounted thereto; rotary displacement means coupled to said gripper device for effecting the continuous movement of said gripper device from a fully open position to a fully closed position when said rotary displacement means is rotated in a first direction and for effecting the continuous movement of said gripper device from a fully closed position to a fully open position when said rotary displacement means is rotated in a second direction, and wherein an object is grasped when said gripper device is moved in the direction of said fully closed position, said rotary displacement means positioned upon and supported by said rotary drive shaft and freely rotatable with respect thereto; flexible coupling means for connecting said rotary drive shaft to said rotary displacement means whereby said gripper device is responsive to operation of said drive motor and for permitting said rotary drive shaft and said rotary displacement means to rotate at different angular velocities in said first and second directions of rotation; sensor means coupled to said rotary drive shaft and to said rotary displacement means for measuring the difference between their respective angular displacements for determining the force applied by said gripper device upon an object positioned therein and for measuring an increase in the grasping force when said rotary drive shaft is rotationally displaced in said first direction and a decrease in the grasping force when said rotary drive shaft is rotationally displaced in said second direction; and control means coupled to said drive motor and to said sensor means for controlling the force applied by said gripper device upon said object. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification