Regular nonadjustable four-bar linkages can only generate the desired continuous paths approximately. The whole desired continuous path can be generated precisely by an adjustable four-bar linkage with the one-degree-of-freedom adjustment of the pivot location of the driven side link. In this paper, an adjustment R joint is used to adjust the pivot location of the driven side link in the four-bar linkage. A closed-loop 5R linkage is formed by the adjustable four-bar linkage. The linkage feasibility conditions and path generation flexibilities of the adjustable four-bar linkages are analyzed. The synthesis model of the adjustable four-bar linkages is set up based on the required optimal adjustment of the pivot location when the desired continuous path is precisely generated. The global optimal solution is searched by a genetic algorithm in which the involved constraints are handled using the function penalty method. The effectiveness of the synthesis approach proposed in the paper is verified by two demonstrated examples.
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