Title: Understanding How Exoskeletons Affect Muscle-tendon Mechanics During Walking
Speaker: Rachel W. Jackson, Carnegie Mellon University and Stanford University
Time: Tuesday, September 19, 2017 at 10:00 a.m. Pacific Daylight Time
Ankle exoskeletons have the potential to improve mobility in able-bodied individuals and restore mobility to those with gait impairments. In order to achieve the desired improvements in locomotor performance, however, these exoskeletons must interact effectively with the highly complex human musculoskeletal system. Understanding the impact different exoskeleton behaviors have on muscle-tendon mechanics could help guide the development of more effective exoskeleton assistance strategies in the future, but directly measuring muscle-tendon mechanics during human walking is quite challenging. Musculoskeletal simulations provide a unique opportunity for studying how muscle-level mechanics and energetics change when operating in parallel with an assistive device.
In this webinar, we will discuss how we used OpenSim to perform electromyography-driven simulations of a musculoskeletal model to obtain estimates of lower-limb muscle-tendon mechanics during walking with exoskeleton-applied torque. We will then discuss how we fed the results from these simulations into a model of individual muscle energy expenditure to obtain estimates of muscle-level energetics.
Throughout the webinar, we will highlight important strategies we used to improve confidence in our simulation results. By performing these simulations, we found that exoskeletons can affect the functioning of the muscles and tendons acting about the assisted joint. Specifically, when ankle exoskeleton torque was applied passively, without providing any net work input, the ankle plantarflexor muscles did more positive mechanical work, which is costly. These findings stress the importance of considering how muscle-tendon interactions might be affected by exoskeleton-applied torque when designing new devices.
The OpenSim Project and the National Center for Simulation in Rehabilitation Research (NCSRR) at Stanford.
Tuesday, September 19, 2017 - 10:00am
Rachel W. Jackson, Carnegie Mellon University and Stanford University
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