Preliminary design of a revolute to prismatic morphing compliant joint

Abstract

The reduction of weight and size of mechanisms are important and difficult challenges considering portability, energy efficiency, and simplicity of fabrication. One of the solutions to address these issues consists of mechanisms with variable topology for which the mobility of the output is a succession of several simpler elementary motions. This change of mobility allows for achieving complex motions without necessitating a complicated design where many actuators or types of mechanical transmissions are required. Indeed, these variable topology mechanisms, also referred to as morphing mechanisms, have the ability to change their output motion throughout their workspace. Hand tools, medical devices, and aerospace robotic end-effectors are potential applications of this technology. In this paper, conceptual designs of such a revolute to prismatic morphing joint and its implementation using compliant hinges are proposed. Additionally, performance indexes pertaining to the desired output motion are proposed. First, a pseudo-rigid body model of a design candidate is presented, and simulations of this model are compared with finite element analyses to ensure accuracy. Then, several design features are quantitatively evaluated to propose improvements for future versions of the design. Finally, an early prototype illustrates the potential and feasibility of the proposed design as well as a possible application. Video