Using Rigid Body Mechanism Topologies to Design Path Generating Compliant Mechanisms

Abstract

For a path generation problem, this paper uses the base topology of a single degreeoffreedom (DOF) rigidbody mechanism solution to synthesize fully distributed compliant mechanisms that can trace the same path. Two different strategies are proposed to employ the base topology in the structural optimization so that its design space size can be intelligently reduced from an arbitrary complexity. In the first strategy, dimensional synthesis directly determines the optimal size and shape of the compliant mechanism solution while maintaining the exact base topology. In the second, the base topology establishes an initial mesh network to determine the optimal topology and dimensions simultaneously. To increase the possibility of converging to an optimal design, the objective metrics to evaluate the path generation ability are computed in a novel manner. A sectionbysection analysis with a rigidbody transformation is implemented to examine the full path of each candidate mechanism. A twoobjective genetic algorithm (GA) is employed to find a group of viable designs that tradeoff minimizing the average Euclidean distance between the desired and actual paths with minimizing the peak distance between corresponding points on those paths. Two synthesis examples generating straightline and curved paths are presented to demonstrate the procedure's utility.