A COMPUTER-AIDED-DESIGN TECHNIQUE FOR SEMIAUTOMATED INFINITE POINT COUPLER CURVE SYNTHESIS OF 4-BAR LINKAGES

At the present time, there are no satisfactory computer-aided solution schemes for solving the infinite point coupler curve synthesis proble m (i.e., the problem of synthesizing a four-bar linkage whose coupler curve best approximates a fully specified closed trajectory). In order to develop a programmable solution process for this class of problems , it is necessary to devise a way of storing a catalog of coupler curv es in a computer database. In addition, comparison procedures must be developed for detecting geometric similarities between curves; these p rocedures must be capable of observing similarities in the shapes of c urves which may be scaled or oriented differently. In this paper, a da ta representation scheme based on uniform periodic B-splines is propos ed as a viable means of storing coupler curves in a database. Automate d procedures for fitting B-splines to coupler cures or other closed cu rves are also developed. The paper also presents a set of algorithms f or comparing the shapes of curves based on the control polygons of the ir B-spline approximations. These algorithms are implemented in a comp uter program that is an effective tool for semi-automated computer-aid ed solution of the infinite point coupler curve synthesis problem. Exa mple problems solved using this program are discussed, along with some suggestions for further work on this topic.