We introduce 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 investigate 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. Summary We introduce a foam-based vacuum powered actuator and exemplary complex, multifunctional soft robotic system which it enables.

This work presents a comprehensive open-source simulation and design tool for Soft pneumatic actuators (SPAs) using finite element method, compatible and extensible to a diverse range of soft materials and design parameters. Thorough characterization of the hyperelastic and viscoelastic behavior is illustrated using a sample soft material (Ecoflex 00_30), and an appropriate material constitutive law. SPA performance (displacement and blocked-force) are simulated for two types of SPA and validated with experimental testing. Real-world case studies are presented in which SPA designs are iteratively optimized through simulation to meet specified performance criteria and geometric constraints.

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Soft actuators made from elastomeric active materials can find widespread potential implementation in a variety of applications ranging from assistive wearable technologies targeted at biomedical rehabilitation or assistance with activities of daily living, bioinspired and biomimetic systems, to gripping and manipulating fragile objects, and adaptable locomotion. In this manuscript, we propose a novel two-component soft actuator design and design tool that produces actuators targeted towards these applications with enhanced mechanical performance and manufacturability. Our numerical models developed using the finite element method can predict the actuator behavior at large mechanical strains to allow efficient design iterations for system optimization. Based on two distinctive actuator prototypes’ (linear and bending actuators) experimental results that include free displacement and blocked-forces, we have validated the efficacy of the numerical models. The presented extensive investigation of mechanical performance for soft actuators with varying geometric parameters demonstrates the practical application of the design tool, and the robustness of the actuator hardware design, towards diverse soft robotic systems for a wide set of assistive wearable technologies, including replicating the motion of several parts of the human body.

Soft pneumatic actuators (SPAs) are versatile robotic components enabling diverse and complex soft robot hardware design. However, due to inherent material characteristics exhibited by their primary constitutive material, silicone rubber, they often lack robustness and repeatability in performance. In this article, we present a novel SPA-based bending module design with shell reinforcement. The bidirectional soft actuator presented here is enveloped in a Yoshimura patterned origami shell, which acts as an additional protection layer covering the SPA while providing specific bending resilience throughout the actuator's range of motion. Mechanical tests are performed to characterize several shell folding patterns and their effect on the actuator performance. Details on design decisions and experimental results using the SPA with origami shell modules and performance analysis are presented; the performance of the bending module is significantly enhanced when reinforcement is provided by the shell. With the aid of the shell, the bending module is capable of sustaining higher inflation pressures, delivering larger blocked torques, and generating the targeted motion trajectory.

This paper presents low-profile torsional actuators applicable for mesoscale and microscale robots. The primary actuator material is thermally activated Ni-Ti shape memory alloy (SMA), which exhibits remarkably high torque density. Despite the advantages of SMAs for actuator applications-high strain, silent operation, and mechanical simplicity-the response time and energy efficiency limit overall performance. As an alternative to SMA wires, thin SMA sheets are used to fabricate effective yet compact torsional actuators. Also, instead of using conventional Joule heating, an external Ni-Cr heating element is utilized to focus heat on the regions of highest required strain. Various design parameters and fabrication variants are described and experimentally explored in actuator prototypes. Controlled current profiles and discrete heating produces a 20% faster response time with 40% less power consumption as compared to Joule heating in a low-profile (sub-millimeter) torsional actuator capable of 180 • motion.

Abstract-We present a fully edible pneumatic actuator based on gelatin-glycerol material. The actuator is monolithic, fabricated via a molding process, and measures 90 mm in length, 20 mm in width, and 17 mm in thickness. Thanks to the material mechanical characteristics similar to those of silicone elastomers, the actuator exhibits a bending angle of 170.3• and a blocked force of 0.34 N at the applied pressure of 25 kPa. These values are comparable to elastomer based pneumatic actuators. As a validation example, two actuators are integrated to form a gripper capable of handling various objects, highlighting the high performance and applicability of the edible actuator. These edible actuators, combined with other recent edible materials and electronics, could lay the foundation for a new type of edible robots.

Soft pneumatic actuators (SPAs) are found in mobile robots, assistive wearable devices, and rehabilitative technologies. While soft actuators have been one of the most crucial elements of technology leading the development of the soft robotics field, they fall short of force output and bandwidth requirements for many tasks. In addition, other general problems remain open, including robustness, controllability, and repeatability. The SPA-pack architecture presented here aims to satisfy these standards of reliability crucial to the field of soft robotics, while also improving the basic performance capabilities of SPAs by borrowing advantages leveraged ubiquitously in biology; namely, the structured parallel arrangement of lower power actuators to form the basis of a larger and more powerful actuator module. An SPA-pack module consisting of a number of smaller SPAs will be studied using an analytical model and physical prototype. Experimental measurements show an SPA pack to generate over 112 N linear force, while the model indicates the benefit of parallel actuator grouping over a geometrically equivalent single SPA scale as an increasing function of the number of individual actuators in the group. For a module of four actuators, a 23% increase in force production over a volumetrically equivalent single SPA is predicted and validated, while further gains appear possible up to 50%. These findings affirm the advantage of utilizing a fascicle structure for high-performance soft robotic applications over existing monolithic SPA designs. An example of high-performance soft robotic platform will be presented to demonstrate the capability of SPA-pack modules in a complete and functional system.