Issue

• Soft wearable robots sometimes generate inaccurate postures when the tendon causes unwanted deformation of the robot's body (see the below video). 

• Since the robot body is made of soft material, preventing deformation during tendon actuation has proven to be challenging.

How the unwanted deformation of the robot body generates inaccurate postures

• The extensor not only applies extension torque but also generates torsional torque when there is a bias at the tendon routing.

Analysis on the above phenomena

• The torsional torque diverges as the tendon bias increases - Small tendon bias can cause a significant impact on generating accurate posture.

Method - How the proposed paper solves this issue

• Installation of the metal rings at the upper side of the finger stabilizes the actuation (See the below figure and video).