A new architecture and expert system for aircraft design synthesis

Aircraft designers have recognized for many years the importance of preliminary design tools that accommodate unprecedented extensibility--in both the set of variables used to describe the design and the set of analysis routines. This requirement is especially important if the program is to be used to assess new technology. Much of the development of a new aircraft concept involves, not the design of the configuration itself, but the design of methods by which the concept can be analyzed and evaluated. This thesis describes a new program architecture which satisfies this requirement, and illustrates its application to the problem of aircraft design. In this architecture, a set of procedural modules are compiled separately and linked with the main executive program. Unlike conventional programs, the subroutines and order of execution are selected by the system during the computation, based on the desired output and on the currently available results in the database. Furthermore, this quasi-procedural method decides which variables need to be recomputed in response to the change of a design parameter, permitting the variables to be recalculated efficiently. The method can greatly improve the efficiency of aircraft design optimization by generating the computational path for a given objective function, and avoiding redundant calculations made by conventional methods with rigid program structures. The quasi-procedural architecture is enhanced by a rule-based expert system. The expert system warns of problems with the current design and suggests solutions to make the design feasible. For design optimization, the expert system can identify the active constraints and suggest a set of design variables to satisfy the constraints while best retaining the objective value.