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.

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.

Abstract-In robotics, controlling the stiffness of the joints that contribute to the robots' degree of freedom dictates the adaptability, versatility, and safety of the whole system. We can achieve variable stiffness or impedance in a robotic system purely by the control or by introducing new material or mechanisms to address cases that require innate safety through system compliancy. This paper presents JammJoint, a compliant and flexible wearable robot, which uses jamming of granular media to vary its stiffness. It consists of a silicone sleeve with hollow sections that are filled with cubic rubber granules and subjected to different levels of vacuum pressure. Unlike contemporary vacuum-based actuators or systems, JammJoint is wearable, portable, and autonomous: It uses a powerful miniature vacuum pump, a small battery, and bluetoothenabled electronics. Experiments revolving around bending and torsional stiffness show that the system is able to achieve up to a fourfold increase in spring stiffness. Further measurements of individual variable stiffness structures indicate that for other modes of deformation, including simply supported bending or compression for alternative linear applications, higher changes in stiffness over a factor of seven are possible. These aspects make mobile jammingbased stiffness variation as wearable joint assistance promising for future applications such as rehabilitation after injuries and joint support in challenging working conditions. Index Terms-Wearable robots, soft material robotics, variable stiffness joint, vacuum jamming, hydraulic/pneumatic actuators.

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Autotrophic respiration involves the use of fixed carbon by plants for their own metabolism, resulting in the release of carbon dioxide as a by-product. Little is known of how autotrophic respiration components vary across environmental gradients, particularly in tropical ecosystems. Here, we present stem CO 2 efflux data measured across an elevation transect spanning ca. 2800 m in the Peruvian Amazon and Andes. Forest plots from five elevations were studied: 194, 210, 1000, 1500, and 3025 m asl Stem CO 2 efflux (R s ) values from each plot were extrapolated to the 1-ha plot level. Mean R s per unit stem surface area declined significantly with elevation, from 1.14 AE 0.12 at 210 m elevation to 0.62 AE 0.09 mmol C m À2 s À1 at 3025 m elevation. When adjusted for changing forest structure with elevation, this is equivalent to 6.45 AE 1.12 Mg C ha À1 yr À1 at 210 m elevation to 2.94 AE 0.19 Mg C ha À1 yr À1 at 3025 m elevation. We attempted to partition stem respiration into growth and maintenance respiration components for each site. Both growth and maintenance respiration rates per unit stem showed similar, moderately significant absolute declines with elevation, but the proportional decline in growth respiration rates was much greater. Stem area index (SAI) showed little trend along the transect, with declining tree stature at higher elevations being offset by an increased number of small trees. This trend in SAI is sensitive to changes in forest stature or size structure. In the context of rapid regional warming over the 21st century, such indirect, ecosystem-level temperature responses are likely to be as important as the direct effects of temperature on maintenance respiration rates.

Wearable soft robotic systems are enabling safer human-robot interaction and are proving to be instrumental for biomedical rehabilitation. In this manuscript, we propose a novel, modular, wearable robotic device for human (lumbar) spine assistance that is developed using vacuum driven, soft pneumatic actuators (V-SPA). The actuators can handle large, repetitive loads efficiently under compression. Computational models to capture the complex non-linear mechanical behavior of individual actuator modules and the integrated assistive device are developed using the finite element method (FEM). The models presented can predict system behavior at large values of mechanical deformations and allow for rapid design iterations. It is shown that a single actuator module can be used to obtain a variety of different motion and force profiles and yield multiple degrees of freedom (DOF) depending on the module loading conditions, resulting in high system versatility and adaptability, and efficient replication of the targeted motion range for the human spinal cord. The efficacy of the finite element model is first validated for a single module using experimental results that include free displacement and blocked-forces. These results are then extended to encompass an extensive investigation of bio-mechanical performance requirements from the module assembly for the human spine-assistive device proposed.

Underwater swimming robots permit remote access to over 70% of the Earth's surface that is covered in water for a variety of scientific, environmental, tactical, or industrial purposes. Many practical applications for robots in this setting include sensing, monitoring, exploration, reconnaissance, or inspection tasks. In the interest of expanding this activity and opportunity within aquatic environments, this letter describes the development of a swimming robot characterized by simple, robust, and scalable design. The robot, named RoboScallop, is inspired by the locomotion of bivalve scallops, utilizing two articulating rigid shell components and a soft elastic membrane to produce water jet propulsion. A single-DoF, reciprocating crank mechanism enclosed within the shell housing of the robot is used to generate pulsating thrust, and the performance of this novel swimming method is evaluated by characterization of the robot jet force and swimming speed. This is the first time jet propulsion is demonstrated for a robot swimming in normal, Newtonian fluid using a bivalve morphology. We found the metrics of the robot to be comparable to its biological counterpart, but free from metabolic limitations which prevent sustained free swimming in living species. Leveraging this locomotion principle may provide unique benefits over other existing underwater propulsion techniques, including robustness, scalability, resistance to entanglement, and possible implicit water treatment capabilities, to drive the further development of a new class of self-contained, hybrid-stiffness underwater robots.

This article presents a new modular robotic platform for enabling reconfigurable, actively controlled, high-degree-of-freedom (high-DoF) systems with compact form factor. The robotic modules exploit the advantages of origami-inspired construction methods and materials, and soft pneumatic actuators (SPAs) to achieve an actuator embedded, parallel kinematic mechanism with three independently controlled “waterbomb” base legs. The multi-material, layer-fabricated body of the modules features selectively compliant flexure hinge elements between rigid panels that define the module as a kinematic 6R spherical joint. The precision layer-fabrication technique is also used to form embedded distribution channels within the module base to connect actuators to onboard control hardware. A decentralized control architecture is applied by integrating each module with small-scale solenoid valves, communication electronics, and sensors. This design approach enables a single pneumatic supply line to be shared between modules, while still allowing independent control of each leg joint, driven by soft, inflatable pouch actuators. A passive pneumatic relay is also designed and incorporated in each module to leverage the coupled, inverted inflation, and exhaust states between antagonistic actuator pairs allowing both to be controlled by a single solenoid valve. A prototype module is presented as the first demonstration of integrated modular origami and SPA design, or pneumagami, which allows predefined kinematic structural mechanisms to locally prescribe specific motions by active effect, not just through passive compliance, to dictate task space and motion. The design strategy facilitates the composition of lightweight, high-strength robotic structures with many DoFs that will benefit various fields such as wearable robotics.