Scheduling algorithm for flexible manufacturing cells

Abstract

The problem of scheduling the work in a Flexible Manufacturing cell is considered with the criterion of minimizing the idle time of the robot (i.e. the material handling server). This situation arises when the robot services several machines whose pro essing times are short. Static and Dynamic scheduling is presented for a work cell containing two lines having two machines in each line and no intermediate buffers for work-in-progress. The possible sequence of robot tasks and their cycle times are formulated. Then the development of a heuristic dynamic scheduler for a work cell is discussed. The heuristic algorithm is coded by using the C programming language. Four heuristic scheduling strategies are considered but only the one giving the minimum robot idle time is used. This user friendly software can be used for any cell having a finite number of n machines and n processors (assemblers) that do not have in-process buffers. It can he used even when a machine breaks down as long as the condition of each component of the cell is known at that instant. The overall strategy is evaluated by interfacing the PC-based software, and a robot controller in order to schedule a product mix in the Computer Integrated Manufacturing cell, located at the Automation Laboratory, University of Manitoba. The computations are discussed and summarized.