Synthesis of Planar Multi-loop Linkages Starting from Existing Parts or Mechanisms: Enumeration and Initial Sizing

MARTÍN PUCHETA; ALBERTO CARDONA

San Juan

Congreso; International Symposium on Multibody Systems and Mechatronics, MuSMe 2008; 2008

FeIbIM Commission for Mechatronics and IFToMM Technical Committee for Multibody Dynamics and Mechatronics

In this paper we present a methodology for dealing with mechanism synthesis problems in which there are initial existing parts connected arbitrarily (or even eventually disconnected). We use: (i) a Finite Element Method-like description of the initial kinematics problem; (ii) a graph representation to solve the number synthesis problem enumerating a finite number of feasible non-isomorphic topologies; (iii) a well-known analytical approach based on the Precision-Point Method to solve the initial dimensions of the linkages, (iv) a Genetic Algorithm for sweeping the design variables, if they exist in the previous step, (v) a weighted criteria for evaluating the generated alternatives. A preliminary analysis of the structural parts ? links and their types, joints and their types, and their connectivity ? in conjunction with the imposed motion constraints is considered just after the initial description. In this pre-processing stage, those parts with known dimensions are kinematically analyzed in order to obtain their displacements and rotations for a number of precision positions or pseudo-times. The proposed method allows the user to design mechanisms starting either from some parts, or from an existing mechanism, to develop additional kinematic tasks. A non standard example for function generation is illustrated throughout the paper. The method was implemented in C++ language under the object oriented environment of Oofelie.