Despite the huge amount of methods available in literature, the practical use of multiobjective optimization tools in industry is still an open issue. A strategy to reduce objective function evaluations is essential, at a fixed degree of Pareto optimal front (F P ) approximation accuracy. To this aim, an extension of single objective Generalized response surface (GRS) methods to F P approximation is proposed. Such an extension is not at all straightforward due to the usually complex shape of the Pareto optimal set (S P ) as well as the non-linear relation between the F P and the S P . As a consequence of such complexity, it is extremely difficult to identify a multiobjective analogue of single objective current optimum region. Consequently, the design domain search space zooming strategy around the current optimum region, which is the core of a GRS method, has to be carefully reconsidered when F P approximation is concerned. In this paper, a GRS strategy for multiobjective optimization is proposed. This strategy links the optimization (based on evolutionary computation) to the interpolation (based on Neural Networks). The strategy is explained in detail and tested on various test cases. Moreover, a detailed analysis of approximation errors and computational cost is given together with a description of real-life applications.Keywords Evolutionary multiobjective optimization, Neural networks interpolation, Response surface methods
IntroductionEvolutionary multiobjective optimization has now come to full maturity, both in terms of methodologies [1, 2] and algorithm development [3][4][5][6][7][8][9].Nevertheless, the application of the wide variety of available methods to problems arising from industrial design (in particular electromagnetic devices shape design [10-15] and optimal controllers design), is still not completely straightforward, due to the computational cost needed to evaluate the objective function. In fact, it is often either a (non-linear or coupled) Finite Element Method, or a long time-domain full-system simulation.Two alternative (to available MOEAs) approaches have been considered by the authors and colleagues in previous papers, being specifically devoted to the reduction of objective function calls. They are useful and meaningful when the following constraint and requirement hold.-On one hand (the constraint), the number of objective function calls that can be afforded from the point of view of an industrially practical computational cost is much smaller than the threshold number required for convergence of available powerful MOEAs. -On the other hand (the requirement) the few affordable solutions should converge towards the F P and be diverse each other. In other words this means that solutions are to be few (due to the computational cost) but distributed all along the F P (in order to me meaningful).The two approaches can be summarized as follows:-Build specific MOEAs for tiny populations.-Reconsider a particular preference function method with hybrid global-evolutionary and local-determinist...