Abstract: Using the wavelet multi-resolution analysis, the low frequency wavelet coefficients can be used to represent the coupler curve of a mechanism and stored in the database as an atlas. A corresponding closeness or measure of the error between two curves and the model redemonstrating expected curve are created. The coefficients sets have the same characteristics as the slope angles that they are independent of their directions and the scales of curves. The atlas database can be created with lager data compressing ratio and expected mechanism can be quickly retrieved from it. Comparing the closeness with the least squares of the distance between two corresponding points on expected curve and the generated coupler curve shows that the method can arrange the curves in a good indexing order when retrieving curves from the library, and it demonstrates that the wavelet analysis can be effectively used to solve the problems of path synthesis for coupler curves.

Key words: Coupler curve, Mechanism synthesis, Planar four-bar linkages, Wavelet analysis