Scheduling of parts and robot activities in a two machine robotic cell

• Published in: Computers & operations research Vol. 26; no. 4; pp. 297 - 312
• Main Authors: Aneja, Y.P., Kamoun, H.
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.04.1999; Pergamon Press Inc
• Subjects: Algorithm; Deterministic scheduling; Flexible manufacturing systems; Manufacturing; Operations research; Production scheduling; Robotic cell; Robots; Studies; Traveling salesman problem; Travelling salesman problem; Travelling salesman problem; Manufacturing; Algorithm; Deterministic scheduling; Robotic cell
• ISSN: 0305-0548; 1873-765X; 0305-0548
• DOI: 10.1016/S0305-0548(98)00063-X

We consider a scheduling problem arising in a two machine flexible robotic cell that repetitively produces parts of different types. We consider the two decisions that need to be made simultaneously: finding the robot move cycle, and finding the input part sequence. The objective is to maximize the throughput rate of the cell subject to the condition that parts are to be produced in proportion of their demand. The problem can be formulated as a special kind of traveling salesman problem. An O( n 4) time algorithm which solves this problem optimally has been provided in Hall et al. (1997). In this paper, we extend their work and provide an algorithm of complexity O(n log n) . Scope and purpose Industrial Robots play an important role in advanced manufacturing systems. A major application of these robots involves loading and unloading of production machines in cellular manufacturing. Since a robot in such a cell performs repeated sequences of pickup, move, laod, unload and drop operations, the throughput of the cell will depend upon the sequence of the different robot activities as well as on the sequence of different parts to be produced in the cell. Thus the problem of maximizing the cell’s performance belongs to a relatively new class of scheduling problems not researched well in the literature. In this paper, we look at one such problem. We consider a two machine cell with a single robot, producing a set of different parts repetitively. Each part can be produced by one of two different possible robot move cycles. The objective is to maximize the production rate of the cell. This involves two decisions that need to be made simultaneously: find the sequence in which the part set should be fed to the cell, and the robot move cycle for each part. We show that this problem can be formulated as a travelling salesman problem with a special cost structure. We improve on a knwon O( n 4) algorithm for this problem by providing one with O(n log n) complexity.