Design of Planar Multi-Degree-of-Freedom Morphing Mechanisms

This paper seeks to advance the design of planar shape-changing mechanisms used in a variety of applications, such as morphing extrusion dies and airfoils. The presence of defects is a limiting factor in finding suitable single-degree-of-freedom (DOF) mechanisms, particularly when the number of shapes to achieve is large and/or the changes among those shapes are significant. This paper presents a new method of designing multi-DOF mechanisms to aid in avoiding these defects. The primary method uses a building-block approach similar to the current one-DOF synthesis procedure and is compared to alternative strategies that seek to leverage the use of multiple single-DOF subchains. While more complex in terms of determining the actuation pattern, the primary method offers a larger design space in which to find solutions. In all cases a genetic algorithm is employed to search the design space. Two example problems involving four prescribed shapes demonstrate the benefits of using multi-DOF mechanisms in terms of shape matching and mechanical advantage.Copyright © 2014 by ASME