A new mechanical structure for adjustable stiffness devices with lightweight and small size

In this paper, we propose a new mechanical structure for adjustable stiffness devices with lightweight and small size. The proposed structure utilize a ball screw mechanism to adjust a relationship between infinitesimal displacements of joint rotation and a linear spring. Then, stiffness around the joint is adjusted. Unlike many of other adjustable stiffness structures, available elastic energy of the elastic element is maximum when the stiffness of the proposed structure is maximum. Therefore, the elastic element of this structure can be smaller and more lightweight than the other structures. Another advantage of the proposed structure is to require fewer and smaller mechanical parts, because the proposed mechanism mostly requires the ball screw mechanism and the linear spring. We developed an actual hardware to test the proposed structure.

[1]  Sadao Kawamura,et al.  Generation of energy saving motion for biped walking robot through resonance-based control method , 2009, 2009 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[2]  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.

[3]  Stefano Stramigioli,et al.  Optimization of Mass and Stiffness Distribution for Efficient Bipedal Walking , 2005 .

[4]  Antonio Bicchi,et al.  Variable Stiffness Actuators for Fast and Safe Motion Control , 2003, ISRR.

[5]  Shigeki Sugano,et al.  Development of 4-DOF manipulator using mechanical impedance adjuster , 1996, Proceedings of IEEE International Conference on Robotics and Automation.

[6]  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.

[7]  Koichi Koganezawa,et al.  Mechanical stiffness control for antagonistically driven joints , 2005, 2005 IEEE/RSJ International Conference on Intelligent Robots and Systems.

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

[9]  Sadao Kawamura,et al.  Resonance-based motion control method for multi-joint robot through combining stiffness adaptation and iterative learning control , 2009, 2009 IEEE International Conference on Robotics and Automation.

[10]  Hiroaki Kobayashi,et al.  Design of a Tendon-Driven Articulated Finger-Hand Mechanism and Its Stiffness Adjustability , 2000 .

[11]  Sadao Kawamura,et al.  Power assist system for sinusoidal motion by passive element and impedance control , 2006, Proceedings 2006 IEEE International Conference on Robotics and Automation, 2006. ICRA 2006..

[12]  Shugen Ma,et al.  Passive periodic motions of multi-joint robots by stiffness adaptation and DFC for energy saving , 2008, 2008 SICE Annual Conference.