Improved Computational Tools for Concept Development based on Sketches and Advanced CAD Technologies

Sketching continues to be a vital part of methods and technologies related to Concept Development, including those analyzed in this paper: "concept design with constraints", "solid from sketch", "sketching on a point cloud" and "geometric modeling of design constraints". Existing methods are analyzed and critical subproblems are identified. New solution methods are proposed for the subjects "solid from sketch" and "sketching on a point cloud". Sketching continues to be one of the most important modeling activities in Concept Design & New Product Development, since it is a powerful tool for these early stages of the Product Life-Cycle. Indeed, recent research establishes that a sketch is much more than a vague description of 2D geometry. A sketch often includes information beyond the geometric description of the product, like a functional decomposition of the product, diagrammatic analyses of nongeometric concepts, and elements related to the designer's work method. A sketch is not just an "output device" but also an "input device" for the designer's mental processes. This paper examines four subjects, related to Concept Development, all of which involve sketching. More specifically, Section 2 presents a critical view on standard "concept design with constraints" and identifies shortcomings in this methodology. Section 3 focuses on the "solid from sketch" problem and proposes a new method that is not using standard heuristics, which, according to recent research, are highly unreliable. Section 4 explores a new subject, sketching on a point cloud, in the context of "point-based CAD & Concept Development". Finally, Section 5 deals with complex design-constraints and elaborates on a new solution methodology that combines Solid Modeling with Sketching and Geometric-Constraint Solving. 2. TWO-DIMENSIONAL CONCEPTUAL DESIGN: A METHODOLOGY AND CAD SYSTEM BASED ON SKETCHES AND CONSTRAINTS