Session: MR-03-01 - Compliant Mechanisms (A. Midha Symposium)

Paper Number: 89825

89825 - A Novel Variable Stiffness Compliant Robotic Link Based on Discrete Variable Stiffness Units for Safe Human-Robot Interaction 

Variable stiffness manipulators balance the trade-off between manipulation performance needing high stiffness and safe human-robot interaction desiring low stiffness. Variable stiffness compliant links provide a solution to enable this flexible manipulation function in human-robot co-working scenarios. In this paper, we propose a novel variable stiffness link based on discrete variable stiffness units (DSUs). A DSU is a parallel guided beam that can adjust stiffness discretely by changing the cross-sectional area properties of the hollow beam segments. The variable stiffness link (named Tri-DSU) consists of three tandem DSUs to achieve eight stiffness modes and a maximum stiffness change raito 31. To optimize the design, stiffness analysis of the DSU and Tri-DSU under various configurations and forces was performed by a derived theoretical model compared with finite element analysis (FEA). The analytical stiffness model is derived using the approach of serially connected beams and superposition combination. It works not only for thin-walled flexure beams but also for general thick beam models. 3-D printed prototypes were built to verify the feature and performance of the Tri-DSU in comparison with the FEA and analytical model results. It’s demonstrated that our analytical model can accurately predict the stiffnesses of the DSU and Tri-DSU within a certain range of parameters. The developed variable sitffness link method and analytical model are extendable to multiple DSUs with different sizes and parameter configurations to achieve modularization and customization. The advantages of the stiffness change mechanism are rapid actuation, simple structure, and compact layout. These methods and results provide a new conceptual and theoretical basis for the development of new reconfigurable cobot manipulators, variable stiffness structures and compliant mechanisms.

Presenting Author: Jiaming Fu Purdue University

Presenting Author Biography: Jiaming Fu is a second year Ph.D. student in the School of Engineering Technology at Purdue University, West Lafayette, IN. His major advisor is Dr. Dongming Gan. He got Master’s degree in Mechanical Engineering from Columbia University in 2019 and foucus on soft robot research there. He got Bachelor’s degree in Mechanical Engineering from Florida Institute of Technology in 2017. He has published 4 international journal and conference papers so far. For now, his research interest is on discrete variable stiffness mechinnisms, including discrete variable stiffness units, actuatosr, link, and gripper.

Authors:

Jiaming Fu Purdue University
Han Lin Purdue University
Wei Xu Purdue University
Dongming Gan Purdue University