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Graphical System for Work-Cell Layout Evaluation

IP.com Disclosure Number: IPCOM000060540D
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 3 page(s) / 42K

Publishing Venue

IBM

Related People

Jayaraman, R: AUTHOR

Abstract

Using a computer tool to develop robot work-cell layouts by developing models, specifying robot task sequences, and specifying cost functions permits automated cost calculations for use in selecting the best work- cell layout. An industrial work-cell is a collection of equipment, controllers, and sensors, arranged spatially and operated purposefully to accomplish a specified set of operations. With the increasing use of programmable automation in industries, there is an ever increasing need for the manufacturing engineer to consider any number of layouts for the work- cell. An efficient layout is a feasible layout and is optimal with respect to some cost measure for the specified set of operations and satisfies geometric constraints and equipment constraints.

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Graphical System for Work-Cell Layout Evaluation

Using a computer tool to develop robot work-cell layouts by developing models, specifying robot task sequences, and specifying cost functions permits automated cost calculations for use in selecting the best work- cell layout. An industrial work-cell is a collection of equipment, controllers, and sensors, arranged spatially and operated purposefully to accomplish a specified set of operations. With the increasing use of programmable automation in industries, there is an ever increasing need for the manufacturing engineer to consider any number of layouts for the work- cell. An efficient layout is a feasible layout and is optimal with respect to some cost measure for the specified set of operations and satisfies geometric constraints and equipment constraints. The equipments (or objects) in the cell and the work envelope of the robot are modeled as two dimensional objects. Each object has a name and a local coordinate frame. The boundary of each object is made up of a connected string of straight line or circular arc segments. In addition, an object may have a number of named points defined with respect to its local coordinate frame. This permits the points to be addressed logically without specifying where exactly they are in the work-cell. Each named point may optionally have an orientation. There is an interactive and graphical means for defining objects. The objects are saved in a data base. The set of robot motions relevant to the layout problem is represented in the form of a directed task flow graph. The nodes of the graph are the named points in objects while the directed edges of the graph represent the necessary robot motions among the points. The task flow graph cannot have loops. It is assumed that there is an initial or root node. A cycle of operation is a sequence of motions that begins and ends at the root node. An application may have more than one cycle of operation. Each node of the task flow graph must be reachable from (i.e., connected to) the root node and the root node must be reachable from (i.e., connected to) every other node. Note that each cycle of operation is a closed walk of the task flow graph but may not be a cycle of the graph. Further, the task flow graph may have cycles that are not cycles of operation. Each edge of the task flow graph has a number of parameters associated with it, namely, speed, acceleration, type of motion, probability, and repeat factor. The first three of the parameters are used in verifying the feasibility of the motion represented by the edge and in computing the cost associated with the motion. The probability factor should be i...