Estimation of Knee Joint Impedance During Walking and Its Implications for Robotic Control and Beyond

Abstract

The mechanical impedance of the human lower-limb joints during locomotion encodes our understanding of how the human feedback system stabilizes the body and is a key component of several strategies for translating this behavior to robots, to powered prosthetic limbs, and to people empowered by exoskeletons. Knowledge of how this property varies in lower limb joint is sparse, with the amount of information available decreasing as you move up the kinematic chain from the ankle to the hip. This work looks to broaden the knowledge base of how knee impedance is modulated, particularly during the process of ambulation. This work first provides an overview of the lower limb joint impedance literature, and from this overview, produces three aims to address current gaps in the knowledge base. The first aim validates the use of methods for impedance estimation. The second aim characterizes a device that can be used to estimate impedance, and utilizes that device to estimate knee impedance in a pilot study. The third aim produces estimates of knee impedance during walking for a group of abled bodied participants. Finally, this work discusses the implications of the work produced on the fields of human system identification, wearable robotics, and rehabilitation, concluding with recommendations for future work.