Damping Coefficients and Torque Calculations for the Joint's Stability of Lower Extremity Exoskeleton Robots

Yıl 2014, Cilt: 18 Sayı: 3, 35 - 51, 04.01.2015

Mehmet Demiray Özgür Başer Ergin Kılıç

Öz

Exoskeleton robots are wearable electromechanical structures which can work interacting with human limbs. Theserobotsareused as assistivelimbs, rehabilitationandpoweraugmentationpurposesforelderly or paralyzedpersons andhealthypersons respectively.Human body neuro-muscular system varies the stiffness and damping of the human joints regularly and thus provides flexible and stable movement capability with minimum energy consumption. Damping coefficients and torques in the joints needs to be adjusted with the change of stiffness to provide stable behavior during walking cycles. Magneto-rheological brake are the passive actuators that can adjust the damping torques in a very short response time. However, the maximum values of damping coefficients and torques are needed for the design of MR dampers to be used in the joints of exoskeleton robots. Shamaei et. al. (2013) derived a set of statistical equations to predict thejoint stiffnessin a gait cycle for the persons with different height and weights. In this paper, the maximum values of damping coefficients and torques are calculated for the design of MR dampers to provide stability in the joints of exoskeleton robots. The results can be used as initial design criteria of MR dampers which will be added to the biomimetic joints of exoskeleton robots, prostheses, ortheses and humanoid robots

Anahtar Kelimeler

Exoskeleton robot, Orthesis, Prosthesis, Variable stiffness actuator, Variable damping actuator, Magneto-rheological brake, Stability

Alt Uzuv Dış İskelet Robot Eklemlerinde Kararlılık İçin Sönümleme Katsayıları ve Momentlerinin Hesaplanması

Öz

Dış iskelet robotlar, insan uzuvları ile etkileşim halinde çalışan, giyilebilir
elektromekanik yapılardır. Bu robotlar, yürüme engeli olan ya da yaşlı kişilerde
yardımcı uzuv, felçli kişilerde rehabilitasyon ve sağlıklı insanlarda güç artırımı
amacı ile kullanılmaktadır. İnsan vücudunun sinir-kas sistemi, bağlı
bulundukları eklemlerde sertlik ve sönümlemeyi devamlı değiştirerek
minimum enerji sarfiyatı ile esnek ve kararlı bir hareket kabiliyeti
sağlamaktadır. Yürüme sırasında eklemlerin sertliğinin değişmesi ile birlikte
kararlı bir yürümenin gerçeklenebilmesi için eklemlerdeki sönümleme
katsayılarının ve sönümleme momentlerinin eş zamanlı olarak değiştirilmesi
gerekmektedir. Manyeto-reolojik (MR) frenler, bu farklı sönümleme
momentlerini en hızlı şekilde ayarlayabilen pasif eyleyicilerdir. Ancak, dış
iskelet robotların eklemlerinde kullanılacak MR fren tasarımları için istenen
maksimum sönümleme katsayısı ve sönümleme momenti değerlerinin
bilinmesi gerekmektedir. Shamaei ve arkadaşları (2013) biyomekanik bir
çalışma gerçekleştirerek farklı boy ve kilolardaki kişiler için yürüme sırasında
eklem sertlik katsayısı değişimini genel istatiksel formüller ile ifade
etmişlerdir. Bu makalede; alt uzuv dış iskelet robotların eklemlerinde kararlı
bir yürüme davranışını sağlayabilecek MR fren tasarımları için gerekli olan
sönümleme katsayısı ve momentlerinin maksimum değerleri hesaplanmıştır.
Elde edilen sonuçlar, dış iskelet robotların, ortezlerin, protezlerin ve insansı
robotların biyomimetik eklemelerine yerleştirilecek MR frenlerin başlangıç
tasarım kriteri olarak kulllanılabilecektir.

Anahtar Kelimeler

Dış iskelet robot, Ortez, Protez, Sertliği değiştirilebilir eyleyici, Sönümlemesi değiştirilebilir eyleyici, Manyeto-reolojik fren, Kararlılık

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