A Modular and Self-Contained Fluidic Engine for Soft Actuators

Fluidic actuation in soft robots traditionally requires a complex assemblage of pumps, regulators, valves, and sensors, often resulting in large and bulky support systems. This added bulk can often hinder a robot's ability to be untethered, perform complex tasks, or bring challenges when it comes to maintenance or upgradeability. To address these limitations, herein, a simple and highly modular bidirectional soft robotic appendage is presented that integrates the pump, flow lines, and actuator into a compact, closed hydraulic system, which is driven by an integrated stepper motor, allowing for positional control and fast response times. The actuator can also be swapped in under five seconds, allowing for rapid reconfiguration. Each component has been thoroughly characterized to determine an overall electrical to mechanical efficiency of the system, and from these calculations, it is demonstrated that the actuator utilizes only 1/15th the required energy to achieve a specific bending angle, and is four-fold more power-efficient than similar-sized soft actuators and pumping systems reported in the literature. The integrated actuator and fluidic engine construct presented here thus represents a major departure from previous soft actuator control platforms in that everything is simplified down to a single self-contained unit, demonstrating unparalleled versatility and modularity.