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Method for computer-aided layout of manufacturing cells

  • US 6,847,922 B1
  • Filed: 01/06/2000
  • Issued: 01/25/2005
  • Est. Priority Date: 01/06/2000
  • Status: Expired due to Term
First Claim
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1. A method of arranging at least one workpiece and one or more workpiece processing devices in a manufacturing cell using a programmable computer with a database, each said device either consisting of a rigid body or comprising two or more rigid bodies connected by kinematic joints, one of which bodies is declared to be the base link of said device, and each said workpiece and said rigid bodies having one or more virtual embedded coordinate systems, said method comprisingentering a geometric description of said manufacturing cell in said database;

  • entering a geometric description for each said workpiece and workpiece processing device including kinematic and limit of motion data for each said joint of said devices into said database;

    entering in said database an initial position and orientation of each workpiece and each base link, in which location each is either attached to ground in the cell or to another rigid body;

    entering in said database a tree structure of program steps, the root node of said tree containing a value for each joint of each device in said manufacturing cell at some initial time, and each child node of a particular node in said tree representing an alternative motion in terms of a list of devices which will move should that alternative be chosen, and containing for each joint of each such moving device a value to be attained at the completion of the motion;

    entering in said database identification of attracting pairs of coordinate systems, each member of the attracting pair being one of the embedded coordinate systems of said workpiece or said rigid bodies of said devices at a specified program step;

    entering in said database identification of repelling pairs, each member of which is a workpiece or device in said manufacturing cell;

    identifying in said database those workpieces and base links whose locations are to be moved from their initial positions and orientations and those joints whose values are to be adjusted, such movements and adjustments being optimized with respect to said attracting pairs and repelling pairs;

    formulating a total potential function as a weighted sum over all program steps of the contributions from all attracting pairs at a step, all repelling pairs at a step, and the limits of those joints whose values are to be adjusted at the step; and

    subjecting the total potential function to a mathematical optimization analysis to find the prospective locations of workpieces and base links and the joint values to minimize the total potential function, thereby achieving an arrangement of each said workpiece and device in said cell in which said attracting pairs of coordinate systems are coincident, said repelling pairs are separated, and said joint values all lie within said limits of motion.

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