New Psu Software Puts More Flexibility
In Flexible Manufacturing
5-24-96
University Park, Pa. --- Penn State industrial engineers have developed and implemented new software that makes changing or adding new machines, robots, parts, or other components to an automated manufacturing system quicker, easier and more cost effective.
The new software is applicable to any "discrete part," shop- floor, control system. Such systems are used to manufacture products as single units such as individual cans of soda or cars.
The new software and the pilot implementation were described at the Industrial Engineering Engineering Research Conference in Minneapolis, Minnesota, May 19, by its developers Dr. Richard A. Wysk, who holds the Leonhard Chair in Engineering, and Dr. Sanjay Joshi, associate professor of industrial and manufacturing engineering.
Wysk notes that so-called "flexible manufacturing systems" (FMS) are usually built with very flexible machines or robots capable of a wide variety of tasks. However, writing the software to control the machines and synchronize their activities is most often a labor-intensive, costly task. Any modifications usually can only be made by the system's integration vendor. The software isn't reusable and must be custom written for each and every modification in the physical system.
"Factory managers don't fully exploit the potential of their flexible manufacturing systems because they are afraid to change the software. They're afraid that changing anything could shut the factory down," Wysk says.
The software that the Penn State team has developed and put into operation on a shop floor at the University is not only reusable but can be modified at will by the FMS operators. It can even be used to "preview" the results of a particular system change.
"The software allows a factory manager to set up an arbitrary set of conditions and play them out to determine what will happen. The director can find out 'what if' without risking shutting the factory down," says Wysk.
The new software uses a simulation, which can include an animated "cartoon" model of the factory, that is fully coordinated with the actual process on the shop floor and can be used to make real-time control decisions. The simulation is linked to a manufacturing execution system that takes the perspective of the product flowing through the manufacturing system.
Wysk says that most software written by FMS vendors takes the perspective of the machines and system rather than the product. "That's like trying to drive your car by taking the point of view of the tires or the engine instead of you, the driver, who wants to get from point A to point B," he says.
In the new software -- which uses a control structure proposed by Joshi -- scheduling, planning and execution of the individual parts of the manufacturing process are considered simultaneously at the shop level, the workstation level and at the equipment level.
Joshi notes that there is little in the engineering literature about system development and implementation of equipment level controllers in manufacturing systems that include the shop floor level, workstation level and equipment level linkages.
He notes that, at Penn State, an equipment level controller has been designed and implemented at the Computer Integrated Manufacturing Laboratory for a system that includes several robots, a lathe and a vertical milling center. The format, however, can be applied to any shop floor control system.
The new FMS control software was developed in a joint project currently underway at Penn State's Computer Integrated Manufacturing Lab, Texas A&M University and Systems Modeling Corporation. The project is funded under Phase I of ARPA's MADE Initiative.
*** Note: You can reach Dr. Wysk at (814) 863-1001 or via e-mail at rwysk@psu.edu. Dr. Joshi is at (814) 865-2108 or sbj4@psu.edu
Contacts:
Barbara Hale (814) 865-9481 (office) (814) 238-0997 (home) bah@psu.edu
Vicki Fong (814) 865-9481 (office) (814) 238-1221 (home) vyf1@psu.edu