Abstract: A computer method is firstly proposed, which is used to do the dimension synthesis of planar 4-bar linkages for rigid-body guidance with Prescribed Timing (in short PT) by harmonic component's database of the coupler's rotation-angle function. The relationship between position function of rigid-body guidance with PT and coupler's rotation-angle function of 4-bar linkage is analyzed. The key of the method is to solve the real dimension of linkage, coupler's point position and installing dimensions of the linkage. Based on solving the problem, a harmonic component's database of the coupler's rotation-angle function including 20350 dimensional types, taking the crank-rocker linkage as an example, is established. So, it is possible to choose some linkages from the database to realize rigid-body guidance with PT by using fuzzy identification method quickly, and to approximately achieve "infinite positions" of dimensional synthesis for rigid-body guidance. An example is given to illustrate the efficiency and advantage of this method.

Key words: Coupler's rotationangle function, Dimension synthesis, Fourier theory, Prescribed timing, Rigid-body guidance