Modeling, design, and optimization of Mindwalker series elastic joint

Shiqian Wang, Cor Meijneke, Herman van der Kooij

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

52 Citations (Scopus)
18 Downloads (Pure)


Weight and power autonomy are limiting the daily use of wearable exoskeleton. Lightweight, efficient and powerful actuation system are not easy to achieve. Choosing the right combinations of existing technologies, such as battery, gear and motor is not a trivial task. In this paper, we propose an optimization framework by setting up a power-based quasi-static model of the exoskeleton joint drivetrain. The goal is to find the most efficient and lightweight combinations. This framework can be generalized for other similar applications by extending or accommodating the model to their own needs. We also present the Mindwalker exoskeleton joint, for which a novel series elastic actuator, consisting of a ballscrew-driven linear actuator and a double spiral spring, was developed and tested. This linear actuator is capable of outputting 960W power and the exoskeleton joint can output 100Nm peak torque continuously. The double spiral spring can sense torque between 0.08Nm and 100Nm and it exhibits linearity of 99.99%, with no backlash or hysteresis. The series elastic joint can track a chirp torque profile with amplitude of 100Nm over 6Hz (large torque bandwidth) and for small torque (2Nm peak-to-peak), it has a bandwidth over 38Hz. The integrated exoskeleton joint, including the ballscrew-driven linear actuator, the series spring, electronics and the metal housing which hosts these components, weighs 2.9kg.
Original languageEnglish
Title of host publication2013 IEEE 13th International Conference on Rehabilitation Robotics, ICORR 2013, Seattle, U.S.A., 24-26 June 2013
Place of PublicationPiscataway, NJ
Number of pages8
ISBN (Electronic)978-1-4673-6024-1
ISBN (Print)978-146736024-1
Publication statusPublished - 24 Jun 2013
EventIEEE 13th International Conference on Rehabilitation Robotics, ICORR 2013: Design and Control of Robotic Exoskeletons with Compliant Joints and Actuation Systems - University of Washington , Seattle, United States
Duration: 24 Jun 201326 Jun 2013
Conference number: 13

Publication series

NameIEEE International Conference on Rehabilitation Robotics
ISSN (Print)1945-7898


ConferenceIEEE 13th International Conference on Rehabilitation Robotics, ICORR 2013
Abbreviated titleICORR
Country/TerritoryUnited States
Internet address


  • Wearable
  • Exoskeleton
  • Series elastic actuation
  • SEA
  • Spiral spring
  • Power based quasi-static modeling


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