Translating Analytical Descriptions of Cities into Planning and Simulation Models

Abstract

The paper focuses on representing and evaluating planar mechanisms designed using graph grammars. Graph grammars have been used to represent planar mechanisms but there are disadvantages in the methods presently available. This is due to the lack of information in understanding the details of a mechanism represented by the graph since the graphs do not include information about the type of joints and components such as revolute links, prismatic blocks, gears and cams. In order to overcome the drawbacks in the existing methods, a novel representation scheme has been developed. In this method, the authors represent a variety of mechanism types by the use of labels and x, y position information in the nodes. A set of sixteen grammar rules that construct different mechanisms from the basic seed is developed, which implicitly represents a tree of candidate solutions. The scheme is tested to determine its capability in capturing the entire set of feasible planar mechanisms of one degree of freedom. In addition to the representation, another important consideration is the need for an accurate and generalized evaluator for kinematic analysis of the mechanism which, given the lack of information, may not be possible with current design automation schemes. The graph grammar based analysis module is implemented in an existing object-oriented grammar framework and the results have found this to be superior to existing commercial packages.