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Author Bertos, Georgios Andrea
Title Identification of the mechanical impedance of the human locomotor system and quantification of shock absorption characteristics: With applications in prosthetics
book jacket
Descript 570 p
Note Source: Dissertation Abstracts International, Volume: 67-03, Section: B, page: 1546
Adviser: Dudley S. Childress
Thesis (Ph.D.)--Northwestern University, 2006
Lower-limb prosthesis users who have commercially available shock absorption components in their prostheses tend to favor them; however, it is unclear why shock absorbing components should be used, how much shock absorption they provide during walking and what mechanical characteristics they should have
To determine mechanical characteristics of shock absorbers, this dissertation proposes a 2nd order vibration model to identify the mechanical impedance, based on steady-state-analysis, of the locomotor system of able-bodied persons and persons with lower-limb amputations. Based on control theory, a system/prosthesis can be proposed that compensates for differences between the shock absorption of able-bodied persons and persons using prostheses with rigid pylons. Using the proposed system/prosthesis should result in an overall person-machine system that mimics the able-bodied shock absorption system
In answer to, "How much shock absorption do shock absorbers provide?" and "Why should shock absorbers be used?" this study compared signals from accelerometers mounted on the foot, thigh, sacrum and upper back of able-bodied persons and participants with amputations in order to (1) quantify and compare shock absorption characteristics at different body levels; and (2) compare shock absorption characteristics across populations of able-bodied persons and prosthesis users walking with different configurations
Of the five methods proposed to quantify shock absorption, the walking trial-based shock factor and the associated transmitabilities provided information about which body segment attenuated high frequency accelerations across populations and configurations. The strike-based attenuation method demonstrated differentiating results of key characteristics of the attenuation transfer function between the foot and the upper back across conditions. The strike-based shock factor based on time-frequency analysis permits study of accelerations at any time and/or frequency zone. All strike-based methods can provide performance differences between the left and right sides
Based on the above-stated scientific and engineering principles, a new prosthetic component was designed and built that can improve the shock absorption ability of lower-limb amputees. This new component may improve phase shift and damping ratio. Rating the new component more favorably than the TT pylon, the prosthesis user reported less sensation of high frequency vibrations during heel strike. Further statistical studies are necessary to evaluate these results
School code: 0163
Host Item Dissertation Abstracts International 67-03B
Subject Engineering, Biomedical
Health Sciences, Rehabilitation and Therapy
Alt Author Northwestern University
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