Optimal design of a variable stiffness joint in a robot manipulator using the response surface method

Jeonghoon Yoo Dr., Myung Wook Hyun, Jun Ho Choi, Sungchul Kang, Seung Jong Kim

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


The response surface method combined with the design of experiment-based design optimization of a variable stiffness joint (VSJ) is presented in this article. A VSJ used in a manipulator of a robot arm to support 1 kg payload at the end is designed by considering the minimization of the total weight as the objective function. Owing to the requirement of large rotational stiffness of the VSJ, over 10 N · m, ring-type permanent magnets are adopted. First, a model composed of two permanent magnets was initially manufactured and tested for comparison with the analysis results. Then, a three-ring-type permanent magnet-based model is suggested and optimized to increase the torque of VSJ. The finite element method is used as a magnetic field analysis method to substitute for the expensive experimental process. Optimization results decrease the weight from 0.899 kg to 0.538 kg, still satisfying the requirement for the rotational stiffness.

Original languageEnglish
Pages (from-to)2236-2243
Number of pages8
JournalJournal of Mechanical Science and Technology
Issue number8
Publication statusPublished - 2009 Aug
Externally publishedYes

Bibliographical note

Funding Information:
This work is supported by the Intelligent Robot Research Center (IRRC) in the Korea Institute of Science and Technology (KIST).


  • Design of experiments
  • Finite element method
  • Permanent magnet
  • Response surface method
  • Robot manipulator
  • Variable stiffness joint

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering


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