S1
S2 		An n-unit robot move cycle is defined as the robot move cycle in which each machine is loaded and unloaded exactly once and exactly n units are produced. In a 2-machine robotic cell for which we assume that the parts must be processed on both of the machines, there are two 1-unit robot move cycles S1 and S2 namely. Follow the links to the left to watch these cycles.

S12S21 If we assume that the parts must be processed on both machines, there is only one 2-unit robot move cycle, namely S12S21. Follow the link to the left to watch this cycle.

The machines in a robotic cell are predominantly CNC machines and these machines possess an operational flexibility by definition. Operational flexibility is the ability to interchange the ordering of several operations and parocess flexibility is tha ability to perform several operations on the same machine. As a result of these, in some practical instances these machines are capable of performing all of the tasks required to process a part. These observations lead to a new cycle which can be viewed from the link to the left.

The assumption of operational flexibility is sometimes not a realistic one. The CNC machines are capable of performing different tasks by changing tools. These tools are stored in the tool magazines of these machines which have limited capacity. Thus, in some cases the required number of tools exceeds the capacity of the tool magazine. Therefore, some of the tasks of each part can only be processed in the first or second machine and the remaining ones can be processed on both machines. Let P1 (P2) denote the total task time to be processed on the first (second) machine and P denote the total task time to be allocated to the machines. Then the graph under the link to the left shows the optimal regions for an example. By clicking on the parameter names you can see how the regions optimality changes by a change on these parameters. Here alpha represents the ratio of total processing time on the second machine to the total processing time on the first machine, delta represents the robot travel time and epsilon represents the loading and unloading time of the robot.