A Soft Ring-Shaped Actuator for Radial Contracting Deformation: Design and Modeling

Area of Science:

• Soft robotics
• Bioinspired engineering
• Mechanical actuation

Background:

• Radial contraction is a common natural deformation (e.g., esophagus, bladder) but is understudied in soft robotics.
• Existing soft actuators primarily focus on elongation, shortening, and bending movements.

Purpose of the Study:

• To present a novel soft ring-shaped actuator designed for radial contraction.
• To investigate the quasi-static performance of this actuator under pressurization.
• To validate theoretical and computational models against experimental data.

Main Methods:

• Fabrication of a soft ring actuator with a concentric air chamber using the lost-wax method.
• Formulation of a theoretical model based on the minimum total potential energy principle.
• Development of a finite-element method (FEM) model for simulation.
• Experimental testing to determine maximum input pressure and measure deformation.

Main Results:

• The soft ring actuator achieved axisymmetric radial contraction at 20.0 kPa.
• Theoretical and FEM models showed good agreement with experimental results (3.4% and 5.4% mean relative differences at peak points).
• Pilot tests indicated the actuator's capability for gripping and holding tasks.

Conclusions:

• The developed soft ring actuator effectively generates radial contraction.
• The theoretical and FEM models provide reliable predictions of the actuator's behavior.
• This novel actuator shows promise for applications in soft robotics, particularly in manipulation.