Analytical and graphical methods to synthesize three poses rigid body guidance

The kinematic synthesis of planar mechanisms for a rigid body guidance through three-poses is a common task in the industrial environment, because it is quite usual to assign the starting and final poses of the coupler link, along with one additional intermediate pose between them, in order to avoid strange movements before to reach the final pose. Moreover, the type synthesis can require different mechanisms, as four-bar linkages (4R), slidercrank/rocker mechanisms (3RP), double-sliders (2R2P), guiding mechanisms (RPRP), where R and P state for Revolute and Prismatic joints, respectively. This paper deals with the application of graphical methods by means of SolidWorks, along with the formulation of a specific algorithm, for the kinematic synthesis of three-poses rigidbody guidance mechanisms, which is mainly based on the Suh &Radcliffe method. However, a suitable use of the analytical geometry has allowed the formulation of a more general algorithm for including also the synthesis of linkages provided of prismatic joints. In particular, the proposed algorithm allows the synthesis of three-poses rigid-body guidance mechanisms of type 2R2P, as the generalized Cardan mechanism with non-orthogonal guides, along with its kinematic inversion, as the corresponding generalized Oldham coupling. Mechanisms of type RPRP, as the generalized Rapson slide and/or the Davis steering mechanism, are also considered to test the formulation. Several graphical and numerical examples are shown in this paper by validating the proposed algorithm through a careful comparison between the graphical and numerical results. © 2017 Centro Servizi d'Ateneo S.r.l. All rights reserved.