Qualitative Rigid Body Mechanics

Abstract

We present a theory of qualitative rigid body mechanics and describe a program that uses this theory to compute qualitative dynamic simulations. 1 The program works directly from a qualitative representation of geometry (qc-space). It employs a new qualitative representation for forces that reduces ambiguity in force sums and hence reduces branching. Introduction Our work is motivated by the task of interpreting rough sketches of mechanical devices of the sort shown in Figure 1. These kinds of sketches are commonly used in mechanical engineering both to record and to communicate design information during the conceptual phase of design. By "interpreting a sketch" we mean achieving something of the understanding of the device that a human engineer would get, including the ability to simulate the device's behavior in the mind's eye (i.e., qualitatively, before knowing the quantitative details of the device's design) and the ability to understand how the geometry of the device produces ...