Abstract: The method of optimal dimension synthesis of planar 4-bar linkages for rigid-body guidance with prescribed timing (in short PT) by using harmonic characteristic parameters of the coupler’s rotation-angle function is developed. A harmonic component’s database of the coupler’s rotation-angle function for linkage’s dimensional types is established firstly. According to the relationship between position function of rigid-body guidance with PT and coupler’s rotation-angle function of 4-bar linkage, it is possible to choose some linkage’s dimensional types 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. For making further improvement on the precision of dimension synthesis of planer 4-bar linkages for rigid-body guidance, taking linkage’s dimension type as initial numbers from the database with fuzzy identification method, the optimal dimension types are obtained. The real dimension of linkage, coupler’s point position and installing dimensions of the linkage can be computed in the last.

Key words: Dimension synthesis, Optimization, Prescribed timing, Rigid-body guidance