The motivation for this research is to model the impedance of the human ankle during walking in variable environments. In order to characterize ankle impedance, subjects walk over a robotic platform in a rigid or compliant state. The platform perturbs the ankle throughout the stance phase of walking while platform torque, ankle angle, and muscle activity are recorded in order to calculate the modulation of ankle impedance. This research allows for modeling of actively controlled healthy human ankles in order to aid in the controller design of lower extremity wearable robotics, which currently struggle to adapt to changing environments.
In this project, researchers investigated how surface roughness affects the force needed to shear ice off of steel after it has been sprayed onto a cold surface. Steel specimens were prepared with various levels of surface roughness in which a bridging ice layer was formed from a spray. The force required to fracture the ice from the specimens was then measured to determine the relationship between surface roughness and interfacial strength. The findings of this research will be useful for optimizing naval vessel designs and operating procedures in cold regions where ice build-up is prevalent.