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A Foldable Antagonistic Actuator

  • Authors: Shintake, Jun; Rosset, Samuel; Schubert, Bryan Edward; Floreano, Dario; Shea, Herbert

We report on an actuator based on dielectric elastomers that is capable of antagonistic actuation and passive folding. This actuator enables foldability in robots with simple structures. Unlike other antagonistic dielectric elastomer devices, our concept uses elastic hinges to allow the folding of the structure, which also provides an additional design parameter. To validate the actuator concept through a specific application test, a foldable elevon actuator with outline size of 70 mm × 130 mm is developed with angular displacement range and torque specifications matched to a 400-mm wingspan micro-air vehicle (MAV) of mass 130 g. A closed-form analytical model of the actuator is constructed, which was used to guide the actuator design. The actuator consists of 125-μm-thick silicone membranes as the dielectric elastomers, 0.2mm-thick fiberglass plate as the frame structure, and 50-μm-thick polyimide as the elastic hinge. We measured voltage-controllable angular displacement up to ±26° and torque of 2720 mN · mm at 5 kV, with good agreement between the model and the measured data. Two elevon actuators are integrated into the MAV, which was successfully flown, with the foldable actuators providing stable and well-controlled flight. The controllability was quantitatively evaluated by calculating the correlation between the control signal and the MAV motion, with a correlation in roll axis of over 0.7 measured during the flights, illustrating the high performance of this foldable actuator.

Posted on: September 16, 2014

Dielectric Elastomer Actuators for soft-grasping

  • Authors: Shintake, Jun; Rosset, Samuel; Schubert, Bryan Edward; Floreano, Dario; Shea, Herbert

We demonstrate here a configuration of soft actuator which has several features such as, being completely soft, simple, thin, foldable, and stretchable while having uni/bidirectional bending actuation. Theoretically the actuation can be extended to multidirectional. We used Dielectric Elastomer Actuators (DEA) as a base actuation mechanism, and molded PDMS was used as a substrate of the device.

Posted on: September 5, 2014

Soft Pneumatic Actuator Fascicles for High Force and Reliability

  • Authors: Robertson, Matthew Aaron; Sadeghi, Hamed; Florez, Juan Manuel; Paik, Jamie

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. Additionally, 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, 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 scales 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 high-performance soft robotic platform will be presented to demonstrate the capability of SPA-pack modules in a complete and functional system.

Posted on: September 20, 2016