Modeling and Parameter Study of Bistable Spherical Compliant Mechanisms

Abstract

The Bistable Spherical Compliant Mechanisms (BSCM) is a novel device capable of large, repeatable, out-of-plane motion, characteristics that are somewhat difficult to achieve with surface micro-machined MEMS. An improved pseudo-rigid-body model to predict the behavior of the BSCM is presented. The new model was used to analyze seven different versions of the device, each with a different compliant joint length. The new model, which adds torsion, is compared with a Finite-Element beam model. The new model more closely approximates the results yielded by FEA than previous models used to analyze the BSCM. Future work is needed to quantify stress-stiffening interactions between bending and torsion. Both FEA and the current model show that increasing the length of the compliant segment decreases the amount of force required to actuate the device.

Waterbomb base: a symmetric single-vertex bistable origami mechanism

“…By definition, a spherical mechanism is one in which all axes of rotation intersect at a common point, as illustrated in figure 3. Bistable spherical compliant mechanisms have been considered previously [27,28], but these mechanisms had fewer links than are found in a waterbomb base. Nevertheless, some of the concepts used in these investigations are applicable to the current study.…”

Design and Stiffness Evaluation of a Compliant Joint with Parallel Architecture Realizing an Approximately Spherical Motion

“…In the present work, attention is focused on a particular class of beam-based CM, namely the so-called spherical CMs [33], in which all the points of an end-link are ideally constrained to move on concentric spherical surfaces that are fixed with respect to a ground link, with the spheres' centroid being defined as the center of spherical motion. As for previous attempts to provide this type of motion via compliant structures, a bistable spherical CM has been presented in [34], where a pseudo-rigid body model has been used to analyze seven versions of the device, each comprising joints of different length. In a similar direction, a spherical lamina-emergent CM has been proposed in [35], the main purpose being to obtain a compliant mechanical device fabricated from planar materials, although providing motions out of the fabrication plane.…”