Study of lower limbs string design of simple back assistive device

Abstract

The objective of this study is to minimize an influence of knee joint on an assistive moment through experiments and theoretical model as well.Tension of string was measured by a load cell. The relation between the flexion angle of knee joint and the tension of string was investigated experimentally by changing the distance along anteroposterior axis between string and knee joint. Theoretical relation between them was also investigated by using a mechanical model.Assistive moment decreased greatly due to the loosening of tension with an increment of knee angle when a string run along posterior line of knee joint. On the other hand, it became difficult to flex knee joint when the string run along anterior line of knee joint. The tension of string became almost constant when the string run along almost in the middle of anterior and posterior lines. Similar result was obtained from a theoretical model.