Vacuum-Powered Soft Robots

Vacuum-powered robotic systems empower diverse capabilities

We have developed a Vacuum-powered Soft Pneumatic Actuator (V-SPA) which leverages a single, shared vacuum power supply and enables complex soft robotic systems with multiple-DoF and diverse functions. In addition to actuation, other utilities enabled by vacuum pressure include gripping and stiffening through granular media jamming, as well as direct suction adhesion to smooth surfaces, for manipulation or vertical fixation. We investigated the performance of the new actuator through direct characterization of a 3-DoF, plug-and-play V-SPA Module built from multiple V-SPAs, and demonstrate the integration of different vacuum-enabled capabilities with a continuum-style robot platform outfitted with modular peripheral mechanisms.  We show these different vacuum-powered modules can be combined to achieve a variety of tasks, including multi-modal locomotion, object manipulation, and stiffness tuning to illustrate the utility and viability of vacuum as a singular alternative power source for soft pneumatic robots, and not just a peripheral feature in itself. Our results highlight the effectiveness of V-SPAs in providing core soft robot capabilities and facilitating the consolidation of previously disparate subsystems for actuation and various specialized tasks, conducive to improving the compact design efficiency of larger, more complex multi-functional soft robotic systems.

Continuous workspace joystick control of single V-SPA module

Continuous angle control of a single V-SPA module was achieved using pulse width modulation (PWM) of the onboard solenoid valve. Empirical testing was performed to obtain the relationship between the duty cycle and corresponding angular position for a single actuator direction in the module. A heuristic mapping strategy was then employed to estimate the duty cycle commands for driving multiple adjacent actuators in the module to achieve continuous spherical control. A joystick was used to provide angular and directional command inputs to a single module. This example demonstrates a useful method for controlling soft robotic actuator modules based on estimated control distribution between multiple actuators, providing a simplified control strategy for complex, multi-DoF soft robotic systems.

Low inertia Coil V-SPAs

We produced a new type of vacuum-powered SPA known as the Coil V-SPA with extreme bending range of motion, and high speed actuation. This type of actuator is fabricated from the same materials used in 3-DoF V-SPA modules, including a soft foam core and silicone rubber skin, with the addition of a flexible constraint layer resistant to buckling or stretching. The actuators have been used to characterize the relative relationship of simple chamber geometries to actuator performance, toward optimizing V-SPA designs at different customized scales. Coil V-SPAs are envisioned to have great utility in applications which benefit from their light weight, and rapid motion capabilities, or extreme range-of-motion coiling behavior which might allow efficient underactuated grasping of slender objects.

References