Exo-Glove Shell

This website is a supplementary site of the paper "Exo-Glove Shell: A Hybrid Rigid-Soft Hand-Wearable Robot for Thumb Opposition, with an Under-Actuated Tendon-Driven System" submitted at Soft Robotics. 

Main Figure: Two main design features of the Exo-Glove Shell: (a) - (d) show the proposed hybrid design that uses a soft garment and rigid metal rings; (e) - (g) show the under-actuated robot design, to assist three primitive motions with only four tendon-driven actuators

(a) shows the fabrication process of the robot. The robot is fabricated by attaching metal routers, components to route the tendon, to the router hanger at the glove; (b) and (c) show possible problems that can occur when the robot is not fixed well to the user body; (d) shows the wearing part of the Exo-Glove Shell that was fabricated with both a soft garment and rigid metal ring; (e) shows the specifically designed actuator that enables the use of the under-actuation mechanism without complicating the robot wearing part;(f) shows how the tendons are routed along the glove to enable the desired motions; (g) shows how the tendons are pulled with fewer actuators.

Abstract

Usability and functionality are important when designing hand-wearable robots; however, while researchers have made important progress in some areas, satisfying both indicators remains a challenging issue. To work to address this issue, we present in this paper a tendon-driven, hybrid, hand-wearable robot, named Exo-Glove Shell. The proposed robot assists in three motions (thumb opposition motion, which is known as the most important hand function, and flexion/extension of the index/middle fingers) while employing only four actuators by using an under-actuation mechanism. The Exo-Glove Shell was designed by combining a soft robotic body with rigid tendon router modules. The use of soft garments enables the robot to be fitted well to users without customization or adjustment of the mechanisms; the metal routers facilitate accurate force transmission. 

Contributions

The Exo-Glove Shell has three contributions (Please click the title of each contribution for the detailed content): 

• Hybrid design with a soft glove and metal rings for functional decoupling
  The soft glove ensures easy wearing and a comfortable fit for the user. The tendon router, which fixes the tendon path, with a metal structure enables to route the tendon firmly and improves the accuracy of force transmission. The metal rings, which are strong enough even with the thin structure, also enable to develop the robot to have a thin profile.

• Three-step fabrication for ease of manufacturing and enabling design changes
  The glove used in the proposed robot can be easily manufactured due to their design similarity to general-use gloves. This is because the tendon router (the metal ring component that fixes the tendon path) can be attached after the glove's fabrication. Further, the riveting used to attach the metal routers to the glove is an easier method, as compared to other bonding methods (e.g., sewing or silicone adhesion) employed in other SWR fabrication. The decoupled functions of the two robot components also facilitate design modifications easily, such as changing the tendon routing by simply replacing the metal routers. In the previous design, since sewing and molding are almost irreversible, any change required the fabrication of another new robot. 

• Assistance with three primitive motions, with only four actuators
  To reduce the required number of actuators, we extended the use of the under-actuation mechanism to use it between the fingers; in contrast, most SWRs use this mechanism inside the finger. With this extension, it is possible to enable the robot to assist in three primitive motions with four actuators. The motions to be assisted were chosen according to biomechanic studies that demonstrate the importance of thumb opposition. The appropriate number of actuators was derived from our simulation of the proposed wearable robot and validated through the experiment.

The user interview video can be found in the below:

The overall explanation of the entire paper can be found in the below video.