Torque Calculation Method of a Permanent Magnet Spherical Motor

  • Lee, Hyung-Woo (Department of Vehicle Dynamics & Propulsion System Research, Korea Railroad Research Institute) ;
  • Kang, Dong-Woo (Department of Electric Engineering, Hanyang University) ;
  • Lee, Ju (Department of Electric Engineering, Hanyang University)
  • Received : 2009.07.13
  • Accepted : 2010.05.11
  • Published : 2010.09.01


This paper presents the torque calculation method of a permanent magnet spherical motor. To calculate using the finite element method (FEM), three-dimensional (3D) FEM must be used. However, since the method requires excessive time and memory, an easier torque calculation method is hereby presented. In the proposed method, it is very important to obtain the approximation function of the torque profile curve. We present the approximation method of the torque profile curve and show that the torque calculation result can approximate the torque obtained by 3-D FEM.


Supported by : National Research Laboratory (NRL)


  1. Ki-jong Kim, “The trends and prospects of the internal intelligent robot industry,” The investigation monthly report, issue 626, pp. 108-133, 2008.
  2. Sung-hong Won, “A study on the analysis and the control characteristics of a 3 D.O.F. spherical motor for robotic joints,” Ph.D. thesis, Hanyang University, Seoul, Korea, February 2007.
  3. R. A. Sosseh and K. M. Lee, “Finite element torque modeling for the design of a spherical motor,” 7th International Conference on Control Automation Robotics and Vision, Singapore, pp. 390-395, December 2002.
  4. Lee, K.-M. R. A. Sosseh & Z. Wei, “Effects of the Torque Model on the Control of a VR Spherical Motor,” IFAC J. of Contr. Eng. Practice, Vol 12/11 pp. 1437-1449, 2004.
  5. Nakamura, Shoichiro, “Numerical analysis and graphic visualization with MATLAB,” Upper Saddle River, N.J.: Prentice Hall PTR, c1996.

Cited by

  1. Analysis of Electric Machine Charateristics for Robot Eyes Using Analytical Electromagnetic Field Computation Method vol.50, pp.2, 2014,