Humans have a remarkable ability to walk on a variety of surfaces. Compliant, uneven, or even slippery surfaces present little challenge to most people, yet are hazardous to individuals with locomotor impairments and even to bipedal robotic systems designed to mimic what we understand about human locomotion. Our ability to navigate seamlessly across different terrains stems in part from how we can adapt the mechanical properties of our legs to the unique requirements of each surface. The objective of this dissertation was to study this ability, using locomotion on slippery surfaces as a paradigm for examining the neural and mechanical adaptations that allow us to traverse a multitude of terrains. We demonstrated a significant adaptation for walking on slippery surfaces is to reduce ankle muscle activity, which directly contributes to a reduction in shear forces and ankle joint stiffness, minimizing slip potential. We further investigated how individual changes in joint torque and joint position, which change simultaneously during walking, affect ankle joint mechanics to gain a better understanding of the link between neural and mechanical adaptations during walking. We found that isolated changes in joint position and joint torque reduced ankle joint stiffness, and simultaneous changes resulted in a dependence on the direction of these changes. Our work demonstrates the neural and mechanical adaptations employed on unique terrains, such as on a slippery surface, are critical for successfully negotiating the terrain and reducing the likelihood of a fall. This has significant implications for people who have impaired neural control and for whom the mechanical properties of the leg have been altered through injury or disease.

Last modified

• 01/09/2019

Creator

• Mariah Weaver Whitmore

DOI

• https://doi.org/10.21985/N21N1R

Subject

• Biomedical Engineering

Keyword

• slippery surfaces
• ankle impedance
• electromyography
• prosthetic limbs
• gait

Date created

• 2017-01-01

Resource type

• Dissertation

Rights statement

• In Copyright