Science China Technological Sciences

, Volume 62, Issue 1, pp 39–46 | Cite as

Design concept development of a variable magnetization motor with improved efficiency and controllable stiffness for robotic applications

  • Kun BaiEmail author
  • Lang Zhu
  • Mi Yuan
  • Kok-Meng LeeEmail author


A variable magnetization (VM) motor by incorporating magnets that can be flexibly configured with variable magnetization process is proposed to meet the emerging requirements on motor efficiency and actuator compliance in robotic applications. A generalized spin torque model is established which provides a relationship between the motor torque and two different types of motor inputs, the current inputs and the magnet magnetizations. A variable magnetization process is proposed based on the study of the hysteresis properties of the magnetic materials and the design criteria for implementing the variable magnetization process with current pulses are established. The feasibility of the variable magnetization is validated with experimental data and the motor functions and performances are numerically demonstrated and evaluated. The results show that the VM motor can maintain high efficiency by switching between two actuation modes. Controllable stiffness at different equilibria can be also achieved with the VM motor with instantaneous magnetizing current pulses.


compliant actuators direct-drive motors variable stiffness motors variable magnetization motors 


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Copyright information

© Science in China Press and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.State Key Lab of Digital Manufacturing Equipment and TechnologyHuazhong University of Science and TechnologyWuhanChina
  2. 2.Woodruff School of Mechanical EngineeringGeorgia Institute of TechnologyAtlantaUSA

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