Function and budget based system architecting

The paper presents the principles of a method that integrates functional modelling and requirements modelling to support the system architect in creating and comparing system architectures. Integration is achieved by a coupling matrix that connects functions to key drivers or requirements. Using the matrix, the functions found are allocated to sub-systems to create architectures. The coupling matrix is subsequently used to generate budgets for distributing requirements over the sub-systems. Architectures can be created easily. Therefore comparison is facilitated. Axiomatic design may be used to create metrics for this comparison. The elements of the coupling matrix can consist of crosses or ones early in the process to indicate what functions contribute to what requirements. By interviewing experts, the contributions of functions can be estimated more precisely, either by using values, or symmetrical triangular fuzzy numbers (STFNs). When the budgets are created and detail design starts, the specialist designers can compare their achievements with the budget.The system designer(s) can track progress on the system level. The method provides possibilities of incorporating TRIZ using the 39 parameters in combination with the contradiction matrix. This way, the method is not just an analysis tool, but a design tool: it will actually give clues to how the system to be designed can be improved. In addition to the principle of the method a possible implementation is presented together with two examples. Conclusions on the principles and directions for future elaboration, implementation and test of the method complete the paper.