In a curved surface design, the overall shape features that emerge from combinations of shape elements are important. However, controlling the features of the overall shape in curved profiles is difficult using conventional microscopic shape information such as dimension. Herein two types of macroscopic shape information, curvature entropy and quadrature curvature entropy, quantitatively represent the features of the overall shape. The curvature entropy is calculated by the curvature distribution, and represents the complexity of a shape (one of the overall shape features). The quadrature curvature entropy is an improvement of the curvature entropy by introducing a Markov process to evaluate the continuity of a curvature and to approximate human cognition of the shape. Additionally, a shape generation method using a genetic algorithm as a calculator and the entropy as a shape generation index is presented. Finally, the applicability of the proposed method is demonstrated using the side view of an automobile as a design example.

In the early design process called conceptual design and basic design, diverse ideas of design must be obtained from global solution search under the constraint of unclear design conditions. It is difficult to apply the conventional engineering design method from the necessity of the setting of the objective function in the early design process. Therefore, in a previous study, the emergent design system, which is applicable from the early design process, has been proposed. In this study, the degree of freedom in an emergent design solution was extended, to form a method with two types of form elements: existing form elements (matrix element) and fiber form elements. To help construct the system, a differentiation phenomenon, which is seen in the morphogenesis of organisms with diverse forms, was introduced into the form generation algorithm in this system, and the relationship between the input parameters and the newly defined evaluation indexes was analyzed.