Three common cross-sectional shapes seen in soft actuators are rectangular, circular, and semi-circular. Assuming identical wall thicknesses and cross-sectional areas, we have found the following:
a) Increasing the radius of the actuator's semi-circular cross-section decreases the pressures required for the actuator to achieve a given amount of bending (in degrees). In addition, actuators with a larger radius (all other parameters being equal) achieve higher tip forces at a given pressure. b) Longer actuators require lower pressures to achieve the same amount of bending as their shorter counterparts. However, length did not greatly affect the force exerted at the actuator tip for a given pressure. c) Increasing wall thickness increases the pressures required for the actuator to achieve a certain amount of bending |
As the spacing of the fiber wrapping gets closer together (increasing turn number n), lower pressures are needed to achieve the same amount of bending. At low turn numbers with fibers spaced far apart, significant bulging and radial expansion is observed in the area between threads.