Abstract: In this paper, the coupler curve of any mechanism is described by an designed function at first. Through specific Fourier transformation, any coupler curve can be stored as a series of coefficients independent of mechanism type. In succession, one formula designed to analyzing the coefficients is used to compare any two coupler curve’s shapes accurately. By storing the coefficients and associated dimensions of a large number of dimensional variants for one particular mechanism type, a catalogue can be created. Catalogues for wide variety of different mechanism types are combined together in a library. A method whereby this library can be created and searched to find the best “matching” mechanisms for subsequent optimization design as a path generator is discussed at last.

Key words: Dimensional synthesis, Four-bar-linkage mechanism, Fourier transformation, Geometry character