Application-Driven Design of Soft, 3-D Printed, Pneumatic Actuators With Bellows

Soft robots are flexible and adaptable allowing them to conform to objects of different shapes and sizes. However, the flexibility of soft robots leads to challenges in designing and fabricating them to satisfy application-specific requirements. In this paper, we present a class of 3-D printable three-chambered actuator modules, along with analytical models to predict actuation behavior based on a set of design parameters related to the bellows. The actuator modules are designed parametrically and fabricated on a commercial 3-D printer, which improves the speed, accessibility, and repeatability of fabrication. The approach presented here provides a framework for tailoring actuators to specific soft robotic applications. This process relates actuation characteristics (e.g., bend angle and blocked force) to a small set of design parameters with the goal of reducing the design-fabrication cycle time. The forward and inverse kinematics are defined for the three-chambered actuator. The kinematics are experimentally validated using a motion capture system. We performed a sensitivity analysis to understand which of the geometric parameters of the bellows have the greatest effect on bending and blocked force. This design framework can be tailored to realize soft actuator modules, for example applications such as fingers for a soft robotic gripper, as a robotic arm for manipulating objects, or as legs for a soft walking robot.