Lower limb response to modified ankle impedance in gait

Abstract

This project used an exoskeletal robot to increase and decrease the stiffness of the ankle joint during treadmill walking to measure the effect of ankle impedance on lower limb joint kinematics. By quantifying the effect of ankle impedance on the knee joint we sought to better understand coordination and control of the ankle and knee. Using linear regression to determine the relationship between the maximum knee flexion during stance and the imposed stiffness on the ankle, we found a measurable positive correlation in 4 out of 5 test subjects at a 95% confidence level. The knee responded to modifications in ankle stiffness as expected from a simple mechanical model. Remarkably, the response was small and variable enough to suggest the body compensates to preserve normal kinematic profiles.