Model-based design optimization of soft fiber-reinforced bending actuators

In this paper we present an analytical model for soft fiber-reinforced bending actuators consisting of a single air chamber made of elastomeric material and reinforced with an inextensible fiber winding. The model explicitly links the input pressure applied to the actuator to the resulting bending angle in free space and to the contact force when the actuator tip is in contact with an external rigid obstacle. The model predictions are compared to available experimental data for hemi-circular actuator with uniform wall thicknesses. The validated model is then used for design optimization of actuator's wall thicknesses which represent key geometric parameters. The model predicts that for a fixed air chamber radius, actuator with optimized wall thicknesses requires about 48 % lower input pressure to achieve a prescribed bending angle compared to non-optimized actuator with uniform wall thicknesses. In addition, the optimized actuator generates about 18 % stronger contact force between the distal tip and a rigid obstacle compared to the contact force generated by actuator with uniform wall thicknesses.