Cable driven exoskeleton for upper-limb rehabilitation: A design review

Abstract

One of the primary reasons for long-term disabilities in the world is strokes. The causes of these cerebrovascular diseases are various, i.e., high blood pressure, heart disease, etc. For those who survive strokes, this affectation causes loss in the mobility of extremities, requiring the intervention of long sessions with a therapeutic professional to recover the movement of the impair limb. Hence, the investment to threaten this condition is usually high, motivating researchers to implements exoskeletons in the rehabilitation process. Those devices permit the user means to conduct the therapies without the constant supervision of a professional. Furthermore, exoskeletons are capable of maintaining a detailed recording of the forces and movements developed for the patients throughout the session. However, the construction of an exoskeleton is not cheap principally for the actuation systems, especially if the exoskeleton requires the actuator to be placed at the joints of the user; in which, the actuator at a joint would have to withstand the load of the actuator of the following joint and so on.Researchers have addressed this drawback by applying cable transmission systems that allow the exoskeleton to place their actuator at a fixed base, reducing the weight of their design, and decreasing their cost. Thus, this paper reviews the principal models of cable-driven exoskeleton for stroke rehabilitation focusing on the upper-limb. The analysis departs from the study of the anatomy of the arm, including the shoulder, elbow, wrist, fingers, and thumb. Besides, it also includes the mechanical consideration to design a proper exoskeleton. Then, the article presents a compendium of the different transmission systems found in the literature, addressing their advantages, disadvantages and their requirements for the design. Lastly, the paper reviews the cable-driven exoskeleton for stroke rehabilitation of the upper limb. Again, for this analysis, it is included the design consideration of each prototype, focusing on their advantages in terms of anatomical mechanics.