Defect-free synthesis of Stephenson-III motion generators

The main purpose of this article is to present a method for the dimensional synthesis of Stephenson-III motion generators without order, circuit, and branch defects. Using the concepts of the coupler curve of a four-bar linkage, the accessible region of a dyad, and the geometric feature of dead-centre configurations, a procedure is proposed for identifying the different circuits and branches of a Stephenson-III mechanism. Using the characteristics of order, circuit, and branch defects, the constraint equations to avoid them are presented. An optimization approach is proposed for the dimensional synthesis of defect-free Stephenson-III motion generators. An example is given to demonstrate the feasibility of the proposed method.