Issue

• Dexterous hand motion requires lots of motors but using lots of motors increases robot complexities.

• In tendon-driven soft wearable robots, the number of actuators increases because the tendon can only transmit tensile force.

Method - How the proposed paper solves this issue

• We extended the use of the under-actuation mechanism to use it between the fingers; in contrast, most tendon-driven soft wearable robots use this mechanism inside the finger. 

• Accordingly,  the robot assists in three primitive motions with four actuators; see the below figure for the tendon coupling.  

• The appropriate number of actuators was derived from the simulation and validated through the experiment as shown in the below video.