Design, development, and testing of a lightweight hybrid robotic knee prosthesis

Tommaso Lenzi*, Marco Cempini, Levi J Hargrove, Todd A Kuiken

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

100 Scopus citations


We present a lightweight robotic knee prosthesis with a novel hybrid actuation system that enables passive and active operation modes. The proposed hybrid knee uses a spring-damper system in combination with an electric motor and transmission system, which can be engaged to provide a stair ambulation capability. In comparison to fully powered prostheses that power all ambulation activities, a hybrid knee prosthesis can achieve significant weight reduction by focusing the design of the actuator on a subset of activities without losing the ability to produce equivalent torque and mechanical power in the active mode. The hybrid knee prototype weighs 1.7 kg, including battery and control, and can provide up to 125 Nm of repetitive torque. Experiments with two transfemoral amputee subjects show that the proposed hybrid knee prosthesis can support walking on level ground in the passive mode, as well as stair ambulation with a reciprocal gait pattern in the active mode.

Original languageEnglish (US)
Pages (from-to)953-976
Number of pages24
JournalInternational Journal of Robotics Research
Issue number8
StatePublished - Jul 1 2018


  • Rehabilitation robotics
  • and control
  • and virtual reality
  • design
  • human-centered and life-like robotics
  • interfaces
  • kinematics
  • mechanics
  • mechanism design
  • physical human–robot interaction
  • simulation

ASJC Scopus subject areas

  • Software
  • Modeling and Simulation
  • Mechanical Engineering
  • Artificial Intelligence
  • Electrical and Electronic Engineering
  • Applied Mathematics


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