title: Running With an Elastic Lower Limb Exoskeleton.
abstract: Although there have been many lower limb robotic exoskeletons that have been tested for human walking, few devices have been tested for assisting running. It is possible that a pseudo-passive elastic exoskeleton could benefit human running without the addition of electrical motors due to the spring-like behavior of the human leg. We developed an elastic lower limb exoskeleton that added stiffness in parallel with the entire lower limb. Six healthy, young subjects ran on a treadmill at 2.3 m/s with and without the exoskeleton. Although the exoskeleton was designed to provide ~50% of normal leg stiffness during running, it only provided 24% of leg stiffness during testing. The difference in added leg stiffness was primarily due to soft tissue compression and harness compliance decreasing exoskeleton displacement during stance. As a result, the exoskeleton only supported about 7% of the peak vertical ground reaction force. There was a significant increase in metabolic cost when running with the exoskeleton compared with running without the exoskeleton (ANOVA, P < .01). We conclude that 2 major roadblocks to designing successful lower limb robotic exoskeletons for human running are human-machine interface compliance and the extra lower limb inertia from the exoskeleton.
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Cherry
authors.forename: Sridhar
authors.initials: S
authors.lastname: Kota
authors.forename: Aaron
authors.initials: A
authors.lastname: Young
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Ferris
mesh_terms: D001696:Biomechanical Phenomena; D004548:Elasticity; D004576:Electromyography; D004867:Equipment Design; D005080:Exercise Test; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D009989:Orthotic Devices; D010101:Oxygen Consumption / Q000502:physiology; D012371:Robotics / Q000295:instrumentation*; D012420:Running / Q000502:physiology*; D012984:Software; D055815:Young Adult