The Overview of FMS Environment

Flexible Manufacturing Systems or FMS's can produce multiple kinds of products employing various resources as like: robots, automatically guided vehicles or AGV's, multipurpose machines, etc. The basic reason of any Flexible Manufacturing Systems is to tackle either scheduling or allocation problem. The provided resource's allocation to various processes required in making each product or the scheduling and allocation problem a sequence of activities to accomplish best efficiency or the scheduling or allocation problem is accounted to be a tough job in manufacturing scenario. This type of problems has been proved to be NP hard and thus is termed for the increased computational complexities concerned to acquire an optimal solution. As a Flexible Manufacturing Systems provides a greater number of choices of resources and routings it permits greater productivity except in turn adds to the system's increased level and complexity by increasing the alternative options for a process.

Traditionally the routing of a part to finish the sequence of needed processes is considered as assignment and the planning of resources as per to the determined routing is considered as scheduling.

Usually, planning and scheduling are carried out along with almost extremely little interaction. However it was observed that these two phenomena are intrinsically concerned to each other that paved the way to the concept of Flexible Manufacturing Systems. Hence in Flexible Manufacturing Systems planning and scheduling is concurrently carried out to take full advantage of the flexibility of the system. Because a machine in Flexible Manufacturing Systems can be employed for multiple jobs along with various options of resources to be employed, scheduling operation should be taken into account while routing of a part is to be planned.

Because of the complexities concerned in the generative scheduling methods, the evaluative methods or the alternative methods as like: simulation amalgamated along with dispatch rule have found much attention in the manufacturing literature. Although, it is more expensive and difficult to enhance the comprehensive simulation models such effectively act flexible and automated manufacturing environment. Furthermore, the models and simulation results are not easy to generalize as the simulation models are exact in nature to the exact application. Furthermore, instead of systematic handling of the different constraints in a Flexible Manufacturing Systems, heuristic dispatch rules often rely upon empirical experience. Hence various simulation methods fail to simplify their approach.

Petri nets should prove to be a robust modelling method, dynamics of the flexible manufacturing systems in handling. Petri nets have a capability to concisely present the activity, constraints and resources of the system in a single coherent formulation. For a graphical tool, designers can better know, visualize and formulate the scheduling problems along with such models. The scheduling technique represented now formulates a scheduling problem employing a Petri net model and thereby provides a large scope of analysis to be carried out. The methodology followed is event driven quite than time driven, such is the schedule is given as an order of initiation of activities.