A new variable stiffness actuator (CompAct-VSA): Design and modelling

This paper describes the design and modelling of a new variable stiffness actuator (CompAct-VSA). The principle of operation of CompAct-VSA is based on a lever arm mechanism with a continuously regulated pivot point. The proposed concept allows for the development of an actuation unit with a wide range of stiffness and a fast stiffness regulation response. The implementation of the actuator makes use of a cam shaped lever arm with a variable pivot axis actuated by a rack and pinion transmission system. This realization results in a highly integrated and modular assembly. Size and weight are indeed an open issue in the VSAs design, which ultimately limit their implementation in multi-dof robotic systems. The paper introduces the mechanics, the principle of operation and the model of the actuator. Preliminary results are presented to demonstrate the fast stiffness regulation response and the wide range of stiffness achieved by the proposed CompAct-VSA design.

[1]  Jae-Bok Song,et al.  Hybrid dual actuator unit: A design of a variable stiffness actuator based on an adjustable moment arm mechanism , 2010, 2010 IEEE International Conference on Robotics and Automation.

[2]  G. Hirzinger,et al.  A new variable stiffness design: Matching requirements of the next robot generation , 2008, 2008 IEEE International Conference on Robotics and Automation.

[3]  Nikolaos G. Tsagarakis,et al.  A novel actuator with adjustable stiffness (AwAS) , 2010, 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[4]  Bram Vanderborght,et al.  MACCEPA, the mechanically adjustable compliance and controllable equilibrium position actuator: Design and implementation in a biped robot , 2007, Robotics Auton. Syst..

[5]  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.

[6]  Antonio Bicchi,et al.  Fast and "soft-arm" tactics [robot arm design] , 2004, IEEE Robotics & Automation Magazine.

[7]  Stephen P. DeWeerth,et al.  Biologically Inspired Joint Stiffness Control , 2005, Proceedings of the 2005 IEEE International Conference on Robotics and Automation.

[8]  Antonio Bicchi,et al.  Design and Control of a Variable Stiffness Actuator for Safe and Fast Physical Human/Robot Interaction , 2005, Proceedings of the 2005 IEEE International Conference on Robotics and Automation.

[9]  Matthew M. Williamson,et al.  Series elastic actuators , 1995, Proceedings 1995 IEEE/RSJ International Conference on Intelligent Robots and Systems. Human Robot Interaction and Cooperative Robots.

[10]  Nikolaos G. Tsagarakis,et al.  VSA-CubeBot: A modular variable stiffness platform for multiple degrees of freedom robots , 2011, 2011 IEEE International Conference on Robotics and Automation.

[11]  Joel E. Chestnutt,et al.  An actuator with physically variable stiffness for highly dynamic legged locomotion , 2004, IEEE International Conference on Robotics and Automation, 2004. Proceedings. ICRA '04. 2004.

[12]  Alin Albu-Schäffer,et al.  On joint design with intrinsic variable compliance: derivation of the DLR QA-Joint , 2010, 2010 IEEE International Conference on Robotics and Automation.

[13]  Nikolaos G. Tsagarakis,et al.  MACCEPA 2.0: Adjustable compliant actuator with stiffening characteristic for energy efficient hopping , 2009, 2009 IEEE International Conference on Robotics and Automation.

[14]  Nikolaos G. Tsagarakis,et al.  Exploiting natural dynamics for energy minimization using an Actuator with Adjustable Stiffness (AwAS) , 2011, 2011 IEEE International Conference on Robotics and Automation.

[15]  Manuel G. Catalano,et al.  VSA-HD: From the enumeration analysis to the prototypical implementation , 2010, 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems.