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VACUUM GRIPPING APPARATUS

  • US 20100135760A1
  • Filed: 04/25/2008
  • Published: 06/03/2010
  • Est. Priority Date: 04/26/2007
  • Status: Active Grant
First Claim
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1. A vacuum gripping apparatus suited to grasp and release irregular objects, the apparatus comprising:

  • a gripper comprising;

    a unitary flexible gripping hood that includes a base formed about a first central orifice and having a circumference of a predetermined shape surrounded by a lip that extends around the circumference of the base and extends downwardly to a circumferential rim according to a generally cosine-shaped curve that produces a predetermined deformation profile, a plurality of channels being formed into the hood, each channel passing radially outwardly from the first central orifice and down the lip to a predetermined distance from the rim, the lip being sufficiently flexible that the lip and rim are adaptable to conform to an irregularly shaped work-piece when a pressure differential between the hood and the work-piece is created, each of the channels being separated from adjacent channels by a protuberance;

    a lip base mounted to the base of the hood and having a second central orifice;

    a vacuum line passing through the first and second central orifices; and

    a plurality of flexible hollow tubular vacuum channel fingers each having a proximal and a distal end, each finger being affixed to the gripping hood by mounting in a respective one of the channels;

    a robotic arm having a tool center point to which the gripper is connected, the robotic arm controllable by a real-time computerized controller incorporating tactile and visual feedback to position the gripper adjacent the work-piece to be gripped;

    at least one vacuum hose having a first and a second end, the first end in communication with the proximal ends of the fingers through the first and second orifices, the second end connected to a vacuum source and adapted to provide a suction force inside the gripping hood proximate the first central orifice and to provide a suction force through the vacuum hose to the distal ends of the fingers thereby enabling suction gripping at a plurality of points proximate the rim of the gripping hood, whereby upon initial application of a suction the majority of the vacuum force is applied through the first orifice, causing portions of the work-piece to move toward the first orifice, whereupon the vacuum force is directed through the fingers, thereby causing the hood to deform about, and conform to, a surface of the work-piece;

    an electronically operated high speed and high vacuum flow valve to control the level of suction in the vacuum hose;

    an optical system to provide robotic arm position information, the optical system comprising;

    a plurality of light emitting diodes to illuminate the work-piece;

    a plurality of segmented rings of mirrors that reflect light from the light emitting diodes to provide homogeneous illumination of the work-piece;

    a camera having an objective lens for recording predetermined image information of the work-piece;

    memory to store images captured by the camera;

    wherein the light emitting diodes illuminate the work-piece through the mirrors to permit the camera to take an image of the work-piece, following which geometric features of the irregular work-piece are extracted from the image and compared to a predefined geometrical model having similar features and a predetermined gripping offset position, whereby the robotic arm is oriented generally to align the gripper with respect to the predetermined offset position; and

    a sensor to signal to the controller that a safe holding force has been achieved by the suction force and furthermore to monitor the holding force and to respond if the holding force falls below a predetermined level.

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