DESIGN SHEET(tm): An Engineer's Spreadsheet"

Ken Fertig and Sudhakar Reddy
Rockwell Science Center

Abstract:

Design Sheet is a toolset for flexible analysis in support of design, including tradeoff studies in complex engineering systems on the scale of reusable space launch vehicles.

Design Sheet is a constraint management system with an interface that is specially designed for performing conceptual design cost and performance tradeoff studies. The tool integrates algebraic constraint management, symbolic mathematics and robust numerical methods to effectively deal with large systems of equations present in practical design models. Equations and variables are represented in a bipartite graph, and graph search algorithms are used to efficiently decompose the system into subsets of more manageable size that are solved individually before being combined to obtain the overall solution.

The flexibility provided by its constraint management methods has contributed to the success of Design Sheet on a wide range of applications, with some of the models involving thousands of constraints and design variables from multiple disciplines. An important feature allows the user to switch which variables are input and which are output at run time, and the procedures needed to solve the system of equations in the new state are automatically re-computed. This capability is especially useful in facilitating design to cost. Design Sheet has been demonstrated on applications ranging from the design of infrared detector systems to the fatigue life analysis of automotive drive trains.

This talk describes the constraint management techniques in Design Sheet that are exploited to solve the typically thousands of coupled non-linear equations that make up the parametric models used in the early design of spacecraft and aircraft. An example is given involving the integrated design of a UAV with FLIR detection capability. We conclude with an outline of current research directions for this project.

Related material can be found at http://www.rpal.rockwell.com/design-sheet/ and http://www.rpal.rockwell.com/made.