Abstract

Computer-aided Concurrent Engineering (CACE) of Infrared Focal Plane Arrays (IRFPAs): Emerging Directions and Future Prospects

Madni, A.M., Balcerak, R., Estrin, G., Freedy, A., and Melkanoff, A.

Abstract

Low-cost accelerated manufacturing of IRFPAs has immediate application to several major current and emerging systems for surveillance and target acquisition. Concurrent engineering (CE), i.e., the simultaneous consideration of end users, manufacturing and support requirements during the design of products and attendant processes, is critical to achieving accelerated, low-cost manufacturing objectives. The specific objectives of computer-aided concurrent engineering (CACE) are to develop a process model for selected assembly and integration processes in IRFPA manufacturing and to demonstrate a set of modular CE tools in support of these processes within a collaborative concurrent design environment. The specific concerns discussed in the paper include: the implementation of CE for focal plane array manufacturing; the development of tools for integrating materials, design, packaging, system integration and testing into a comprehensive focal plane array manufacturing line; and the integration of the standalone design tools into a single line thereby ensuring the compatibility of new system concepts with IRFPA designs.

Specifically, we present the components at the heart of computer-aided concurrent engineering (CACE) -- a hardware-software collaborative design environment, means for integrating modeling and design "tools," and process models for guiding human-machine integration -- and discuss their incremental introduction into the IRFPA manufacturing environments.

One key aspect of CE is providing the ability for members of the IRFPA production line design team to "test drive" the various simulated manufacturing processes and need to discuss the full range of concurrent engineering issues that may arise. To this end, a networked configuration of terminals, workstations and servers will be configured to support such collaboration once a software environment is created to support the sharing of data, constraints, assumptions, partial solutions, and design versions during the design process.

The X-Window System™, the UNIX™ operating system, Ethernet and TCP/IP protocols now make it possible to network terminals, workstations and servers made by different vendors and to provide high resolution graphics for user-system interaction. Multiple "executable" process models will be built to describe "AS-IS" and "TO-BE" assembly and integration processes at various levels of detail. With the help of these models, applicable facilities will be developed that support analysis at different levels of abstraction under varying sets of conditions. Members of the design team will be able to observe the state of the simulation at any time; make changes in an orderly manner, and discuss the significance of parameter changes made through the graphical interface. These interactive visualization capabilities will provide the necessary basis for exposing potential difficulties early in the design process. These process models not only form the basis of human-machine integration for various levels of automation and different task conditions, but also provide focus to the development of concurrent engineering tools. Methods to fully integrate new tools or to partially integrate existing tools are needed to support manufacturing, assembly and integration processes. Full integration is required when the output of a given tool must be an input to another tool. For some preexisting tools, partial integration may suffice in those cases where inputs to a given tool can be generated offline but the tool is used in a standalone fashion.

By and large, tools are needed to enhance the productivity of non-programmer designers, and maintaining an audit trail of initial conditions, design decisions, assumptions, and lessons learned.

Once these components are developed and put in place they will be used to integrate the focal plane array system requirements with the manufacturing constraints imposed by the infrared materials, detector processing, coupling to the read-out circuit, assembly into the dewar, and interface to the cooler and system electronics. For the first time, the system engineer and the IRFPA processing team will have the capability to determine producibility obstacles imposed by material defects, compositional non-uniformities, and detector/read-out circuit noise currents, as well as to adjust system design and production to be consistent with critical component development and manufacturing. This concurrent approach to infrared focal plane array manufacturing and IR system design is the basis of a realistic, cost effective approach for the timely integration of high technology components into major weapon systems. Taken together, the IRFPA manufacturing application and these three products fit into DARPA's Initiative in Concurrent Engineering (DICE).

From:

Madni, A.M., Balcerak, R., Estrin, G., Freedy, A., and Melkanoff, A., Invited Paper presented at the Second National Symposium on Concurrent Engineering, Morgantown, West Virginia, February 1990.