Mechanical Design of a Compact Serial Variable Stiffness Actuator (SVSA) Based on Lever Mechanism

Jiantao Sun1, Yubing Zhang1, Cong Zhang1, Zhao Guo1, Xiaohui Xiao1

  • 1Wuhan University

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Regular Papers

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09:55 - 11:10 | Tue 30 May | Room 4011 | TUA1

Actuators 1

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Abstract

Compliant actuator is widely accepted for physical human-robot interaction due to its safety aspect, dynamic performance improvements and energy saving abilities. In this paper, based on the variable ratio lever mechanism, a new kind of Serial Variable Stiffness Actuator (SVSA) is proposed by using an Archimedean Spiral Relocation Mechanism (ASRM) to change the position of the pivot, implementing large range of adjustable stiffness. The ASRM introduced here makes the SVSA design has continuous stiffness adjustment ability and simply mechanical structure. Within the Variable Stiffness Mechanism (VSM), two linear springs are assembled antagonistically on a spring shaft. Their displacements are perpendicular to the output link to transmit the spring force more efficiently. Stiffness modeling and analysis of the SVSA are carried out to cover large deflection angle. The physical implementation of the SVSA shows that the output stiffness of the VSM is changed from 1.72 to 150.56 Nm/rad using a linear spring with stiffness 1882 N/m, working range covered from 0 to 360º. Control experiments also proved the wide range of stiffness adjustment ability of the SVSA.

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Summary

  • A new kind of Serial Variable Stiffness Actuator (SVSA) is proposed by using an Archimedean Spiral Relocation.
  • The ASRM makes the SVSA design has continuous stiffness adjustment ability and simply mechanical structure.
  • The output stiffness of the VSM is changed from 1.72 to 150.56 Nm/rad using a linear spring with stiffness 1882 N/m.
  • Working range covered from 0 to 360.