A computational approach for human-like motion generation in upper limb exoskeletons supporting scapulohumeral rhythms

This paper proposes a computational approach for generation of reference path in upper-limb exoskeletons for Activities of Daily Living (ADL) involving upper limb and the scapulohumeral rhythms of the shoulder. The proposed method can be used in exoskeletons with 3 Degrees of Freedom (DoF) in shoulder and 1 DoF in elbow, which are capable of supporting shoulder girdle. Existing computational reference generation methods are based on the assumption of fixed shoulder center during motions. However, most upper limb motions such as ADL include large scale reaching motions, during which the center of shoulder joint moves significantly. The proposed method generates the user specific reference motion in the human arm joint space and through a transformation the developed motion can be mapped into exoskeleton joint space. Comparison of the computational model outputs with experimental results of healthy subjects performing ADL, show that the proposed model is able to reproduce human-like motions.