SEQUENCING OF ROBOT ACTIVITIES AND PARTS IN 2-MACHINE ROBOTIC CELLS

This paper deals with the development of analytical methods for determ ining an optimal sequence of parts and robot activities to minimize cy cle time in robotic cells with two machines. A robot is used to feed p arts to the two machines or in the absence of machines two robots perf orm processing operations on parts. Three different types of robotic c ellular layouts, namely the robot-centered cell, the mobile robot cell , and the in-line robot cell have been considered in an automated flow line manufacturing system with no storage buffers. Optimal sequences have been established for both single and multiple part types when par t production is performed in a repetitive fashion. In order to keep ab reast with the current trend toward just-in-time manufacturing, produc tion of a quantity known as the minimum part set (MPS) is considered f or multiple part types. The analysis for a single MPS has further been extended to include the cyclic production of multiple MPSs. The probl em of determining the optimal sequence of multiple part types has been shown equivalent to a two machines no-wait flow shop problem, and has been solved by Gilmore and Gomory's (1964) algorithm.