Design Platform for Planar Mechanisms based on a Qualitative Kinematics

Our long term aim is to address the open problem of combined structural/dimensional synthesis for planar mechanisms . For that purpose, we have developed a design platform for linkages with lower pairs which is based on a qualitative kinematics . Our qualitative kinematics is based on the notion of Instantaneous Centers of Velocity, on considerations of curvature and on a modular decomposition of the mechanism in Assur groups . A qualitative kinematic simulation directly generates qualitative trajectories in the form of a list of circular arcs and line segments . A qualitative simulation amounts to a propagation of circular arcs along the mechanism from the motor-crank to an effector point. A general understanding of the mechanism, independent of any particular dimensions, is extracted . This is essential to tackle synthesis problems . Moreover, we show that a dimensional optimization of the mechanism based on our qualitative kinematics successfully competes, for the path generation problem, with an optimization based on a conventional simulation.