Engineering Costs and Production Economics, 17 ( 1989) 29-34 29 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands ROBOT LOCATION FOR MINIMUM CYCLE TIME* Layek L. Abdel-Malek zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPON Divisio n of Industrial and Management Engineering, New Jersey Institute of Technology, Newark, NJ 07 102 (U.S. A.) and Zhiming Li Department of Industrial Mechanics, Wuhan institute of Technology (P.R. China) ABSTRACT Increasing the productivity qf automated manufacturing cells is one of today’s manage- ment ‘s top priorities. The large amounts of cap- ital invested in these ventures have lead many researchers to investigate methods to increase the utilization of such systems. In this paper, we address the problem offinding the robot loca- tion in a manuj&turing cell that minimizes the execution time of its assigned tasks. Minimiz- ing the robot cycle time leads to increased pro- ductivity in several industrial applications. In our approach, the robot geometric structure and specifications are considered in developing models using Inverse Kinematics to determine the traveling times betlveen the different tasks of a particular manufacturing cell. Then, an op- timization scheme is introduced to.find the ro- bot base location that minimizes its cycle time. INTRODUCTION The number of fully automated manufactur- ing systems in existence in this day and age is rapidly increasing. However, there are con- cerns over the large amount of capital needed to build such systems. To justify the imple- mentation of these automated systems, their productivity measures have to be well investi- gated. Researchers, in general, have spared no effort in addressing several issues of concern to enhancing these systems’ productivity. This paper addresses one of the issues which we believe is important. Nevertheless, thus far it has not been sufficiently studied. This issue is the location of the robot base in a produc- tion cell. The location of the robot base affects *Presented at the 5th International Working Seminar on Pro- duction Economics, Igls, Austria, February 22-26, 1988. its traveling time among the different tasks. Consequently, reducing this travel time results in an improved cell productivity. This is espe- cially important in cases where the robot cycle time is the governing factor in the determina- tion of the cell cycle time. That occurs in situ- ations where the cycle time of the robot is the longest among the cell’s components. An ex- ample of this situation is robotic spot welding cells which is widely used in today’s auto in- dustry. The car arrives at the robot work sta- tion and waits until the robot visits the differ- ent joints to be welded. Other examples are: robotic assembly cells and drilling processes (where the robot gripper holds the drill and visits predetermined points). Thus, a faster execution time for these assigned tasks de- creases the cell cycle time improving its productivity. The problem of minimizing the cell cycle 0167-188X/89/$03.50 0 1989 Elsevier Science Publishers B.V.