New Bending Actuators for Soft Robots

The Problem:
Soft and continuum robots show great promise for a variety of applications. However, current actuation strategies present challenges in robotic control and performance. Tendon actuation is hampered by friction and fluidic actuation requires bulky actuation systems that are imprecise and difficult to control. In addition, these strategies require high actuation forces to reach extreme bending angles and lift heavy payloads.

The Solution:
Researchers at the University of Tennessee have developed a novel soft robot actuator based on concentric precurved bellows. Actuation is achieved by axially rotating concentrically nested precurved tubes relative to one another. Large bending angles can be safely achieved within elastic strain limits. These actuators have a wide range of scalability and can be fabricated from a variety of fabrication methods. Furthermore, this actuator has significant payload capacity relative to the robot’s weight, useful for load-bearing and gripping applications.

Benefits:

• Increased reliability, safety, and precision due to the simple mechanical nature of the actuation
• Payload capacity tailorable to application
• Can be fabricated at both large and small scales. 
• High ratio of torsional rigidity to flexural rigidity eliminates torsional lag and instability

INVENTORS

Dr. Caleb Rucker received his PhD in mechanical engineering from Vanderbilt University in 2010. His research interests include concentric tube robots, parallel continuum manipulators, tendon-driven manipulators, and needle steering.

Jake Childs is a graduate student research assistant in the Department of Mechanical, Aerospace and Biomedical Engineering at UT. His research interests include the design, fabrication and modeling of soft and continuum robots.