A Synthesis of a Six Bar Mechanism with Nonlinear Stiffness for Prismatic Compliant Joint

A prismatic compliant joint (PCJ) composed of a linear spring and a six-bar mechanism is proposed in this paper. The operating principle of the PCJ is discussed and its mathematical model is established. The main contribution of the proposed PCJ lies in its nonlinear stiffness capability achieved thanks to only passive mechanical elements. An optimal synthesis of the six-bar mechanism with nonlinear stiffness is presented. A genetic algorithm approach (GA) is used in order to explore and identify optimal design solutions. A CAD model and a first prototype of the PCJ are presented.

[1]  Chao-Chieh Lan,et al.  Design and Analysis of a Linear Elastic Mechanism with Adjustable Stiffness , 2015 .

[2]  R. Ham,et al.  Compliant actuator designs , 2009, IEEE Robotics & Automation Magazine.

[3]  Goldberg,et al.  Genetic algorithms , 1993, Robust Control Systems with Genetic Algorithms.

[4]  Jae-Bok Song,et al.  Safe robot arm with safe joint mechanism using nonlinear spring system for collision safety , 2009, 2009 IEEE International Conference on Robotics and Automation.

[5]  Jae-Bok Song,et al.  Safe link mechanism based on nonlinear stiffness for collision safety , 2008 .

[6]  K. Koganezawa,et al.  Stiffness and Angle Control of Antagonistially driven joint , 2006, The First IEEE/RAS-EMBS International Conference on Biomedical Robotics and Biomechatronics, 2006. BioRob 2006..

[7]  Alberto Donoso,et al.  Design of an adjustable-stiffness spring: Mathematical modeling and simulation, fabrication and experimental validation , 2011 .

[8]  Chao-Chieh Lan,et al.  Linear Variable-Stiffness Mechanisms Based on Preloaded Curved Beams , 2014 .

[9]  John Kenneth Salisbury,et al.  A New Actuation Approach for Human Friendly Robot Design , 2004, Int. J. Robotics Res..

[10]  Jae-Bok Song,et al.  Safe Link Mechanism based on Passive Compliance for Safe Human-Robot Collision , 2007, Proceedings 2007 IEEE International Conference on Robotics and Automation.

[11]  Eduardo Torres-Jara,et al.  A Simple and Scalable Force Actuator , 2005 .

[12]  Donald Russell,et al.  Mechanics and stiffness limitations of a variable stiffness actuator for use in prosthetic limbs , 1999 .

[13]  Giorgio Grioli,et al.  VSA-II: a novel prototype of variable stiffness actuator for safe and performing robots interacting with humans , 2008, 2008 IEEE International Conference on Robotics and Automation.