Environment-Dependent Modulation of Human Ankle Stiffness and its Implication for the Design of Lower Extremity Robots

Varun Nalam, Hyunglae Lee

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

Understanding how human ankle mechanics are modulated during interaction with a wide range of environments is essential to develop reliable and robust lower extremity robots such as prosthetics and exoskeletons that mimic the behavior of the human ankle. This paper investigates the effect of mechanical environment on the modulation of human ankle stiffness and its underlying mechanisms. A novel multi-axis robotic platform, capable of actuating the ankle in both dorsiflexion-plantarflexion (DP) and inversion-eversion (IE), was used to quantify ankle stiffness in 2 degrees-of-freedom, while human subjects maintain upright posture in a range of stiffness-defined haptic environments. Ankle stiffness in DP increased with increasing compliance of haptic environment, but it was significantly lower than the stiffness measured in a rigid mechanical environment. On the other hand, ankle stiffness in IE was relatively constant in both compliant and rigid environments. Analysis of muscle activation and center of pressure of the ground reaction force provided an explanation for the underlying mechanisms of these observations. Notably, the analysis confirmed that modulation of ankle stiffness cannot be solely explained by activation of superficial ankle muscles. Implications for the design and control of lower extremity robots mimicking human ankle impedance are discussed.

Original languageEnglish (US)
Title of host publication2018 15th International Conference on Ubiquitous Robots, UR 2018
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages112-118
Number of pages7
ISBN (Print)9781538663349
DOIs
StatePublished - Aug 20 2018
Event15th International Conference on Ubiquitous Robots, UR 2018 - Honolulu, United States
Duration: Jun 27 2018Jun 30 2018

Other

Other15th International Conference on Ubiquitous Robots, UR 2018
CountryUnited States
CityHonolulu
Period6/27/186/30/18

Fingerprint

Stiffness
Modulation
Robot
Robots
Dependent
Haptics
Muscle
Activation
Inversion
Chemical activation
Degrees of freedom (mechanics)
Prosthetics
Design
Human
Compliance
Range of data
Impedance
Mechanics
Robotics
Quantify

ASJC Scopus subject areas

  • Artificial Intelligence
  • Control and Optimization
  • Mechanical Engineering

Cite this

Nalam, V., & Lee, H. (2018). Environment-Dependent Modulation of Human Ankle Stiffness and its Implication for the Design of Lower Extremity Robots. In 2018 15th International Conference on Ubiquitous Robots, UR 2018 (pp. 112-118). [8442204] Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/URAI.2018.8442204

Environment-Dependent Modulation of Human Ankle Stiffness and its Implication for the Design of Lower Extremity Robots. / Nalam, Varun; Lee, Hyunglae.

2018 15th International Conference on Ubiquitous Robots, UR 2018. Institute of Electrical and Electronics Engineers Inc., 2018. p. 112-118 8442204.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Nalam, V & Lee, H 2018, Environment-Dependent Modulation of Human Ankle Stiffness and its Implication for the Design of Lower Extremity Robots. in 2018 15th International Conference on Ubiquitous Robots, UR 2018., 8442204, Institute of Electrical and Electronics Engineers Inc., pp. 112-118, 15th International Conference on Ubiquitous Robots, UR 2018, Honolulu, United States, 6/27/18. https://doi.org/10.1109/URAI.2018.8442204
Nalam V, Lee H. Environment-Dependent Modulation of Human Ankle Stiffness and its Implication for the Design of Lower Extremity Robots. In 2018 15th International Conference on Ubiquitous Robots, UR 2018. Institute of Electrical and Electronics Engineers Inc. 2018. p. 112-118. 8442204 https://doi.org/10.1109/URAI.2018.8442204
Nalam, Varun ; Lee, Hyunglae. / Environment-Dependent Modulation of Human Ankle Stiffness and its Implication for the Design of Lower Extremity Robots. 2018 15th International Conference on Ubiquitous Robots, UR 2018. Institute of Electrical and Electronics Engineers Inc., 2018. pp. 112-118
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