Going for walks is just placing one foot in front of the other, but there are sophisticated biomechanical aspects using put all over every single action — primarily in the ankle.
Hyunglae Lee, an assistant professor of mechanical and aerospace engineering in the Ira A. Fulton Schools of Engineering at Arizona Point out College, took a special approach to studying the ankle’s dynamic motion through going for walks. 

Arizona Point out University Assistant Professor Hyunglae Lee (appropriate) combines expertise in robot-aided neurorehabilitation and neuromuscular control of human ankles, shoulders and other joints to create revolutionary platforms for knowledge and aiding human health and fitness. Image by Erika Gronek/ASU
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The results of this do the job — developed in collaboration with Elliott Rouse, an assistant professor of mechanical engineering at the University of Michigan, Ann Arbor, and Hermano Igo Krebs, a principal research scientist at Massachusetts Institute of Technologies, and originally posted in 2016 in the IEEE Journal of Translational Engineering in Wellbeing and Drugs — is helping enhance rehabilitation and human-robot conversation applications.
“Outcomes of this and relevant studies will not only contribute to the scientific development of our understanding of typical and pathological ankle habits for the duration of various serious-lifestyle process ailments, but also the growth of assistive or rehabilitation equipment able of giving optimal aid with no hindering natural lower extremity perform,” mentioned Lee, who has developed upon this analysis about the past various years.
As the next-highest cited work around the earlier five decades in the IEEE Journal of Translational Engineering in Wellbeing and Medication, this calendar year Lee’s 2016 paper attained the second prize in the IEEE Engineering Medication and Biology Culture Prize Paper Awards.
Analyzing ankles
The system of walking, or gait, is designed up of two major areas. The stance section will involve the foot that stays on the ground even though the swing period involves the other leg that swings ahead to choose the following move.
Ankle joint impedance — the connection among the joint placement and the drive of rotation in motion — is a basic section of the human neuromuscular technique that clarifies the electrical power exchanges that occur when going for walks.
“Quantification of this property is crucial in knowledge the stability of the human physique as effectively as the top quality of strolling purpose,” Lee mentioned. “Until we printed this do the job, almost all beforehand reported function on the quantification of ankle impedance was strictly restricted to static posture circumstances, these as seated and quiet standing positions, and there was no systemic way to quantify ankle impedance in the course of dynamic strolling.”
In people scientific tests, scientists used motion assessment, 3D motion capture and drive-plate sensing devices to comprehensively have an understanding of ankle biomechanics, but these techniques do not make it possible for for the review of impedance. So, Lee and his collaborators developed a distinct strategy.
Their program, explained in the award-successful 2016 paper, involved two robotic platforms: one particular recessed into the floor on which a exploration issue could wander, and another that is worn on the ankle and introduces perturbations to the ankle throughout the stance and swing phases of strolling.
Then the group utilised procedure identification to quantify ankle impedance by way of the analysis of enter perturbations and the corresponding output responses.
“This built-in approach permitted us to reliably characterize ankle impedance throughout the whole gait cycle for the duration of strolling, which is not achievable in the conventional movement investigation configurations,” Lee reported.
When when compared to static poster research, the trustworthiness of Lee and his collaborators’ strategy was just as powerful and trustworthy in quantifying impedance. They also found that ankle impedance could be approximated properly by way of a few factors: the stiffness of the ankle joint, the capability to absorb perturbations (damping) and the inclination to stay in movement or at rest (inertia). The details showed ankle stiffness underwent the most changes for the duration of the gait cycle.
“Joint stiffness is one particular of the principal focuses in controlling human-interactive robots and administering neurorehabilitation for practical advancement,” Lee explained.