Soft actuators are typically designed to be inherently stress‐free and stable. Relaxing such a design constraint allows exploration of harnessing mechanical prestress and elastic instability to achieve potential high‐performance soft robots. Here, the strategy of prestrain relaxation is leveraged to design pre‐curved soft actuators in 2D and 3D with tunable monostability and bistability that can be implemented for multifunctional soft robotics. By bonding stress‐free active layer with embedded pneumatic channels to a uniaxially or biaxially pre‐stretched elastomeric strip or disk, pre‐curved 2D beam‐like bending actuators and 3D doming actuators are generated after prestrain release, respectively. Such pre‐curved soft actuators exhibit tunable monostable and bistable behavior under actuation by simply manipulating the prestrain and the biased bilayer thickness ratio. Their implications in multifunctional soft robotics are demonstrated in achieving high performance in manipulation and locomotion, including energy‐efficient soft gripper to holding objects through prestress, fast‐speed larva‐like jumping soft crawler with average locomotion speed of 0.65 body‐length s−1 (51.4 mm s−1), and fast swimming bistable jellyfish‐like soft robot with an average speed of 53.3 mm s−1.
This content will become publicly available on April 4, 2023
Design, Characterization, and Dynamic Modeling of BEAST: a Bistable Elastomeric Actuator for Swift Tasks
Recent work in fluid-driven soft robots has demonstrated the potential to achieve high power-to-weight ratios, low fabrication costs, and improved safety, making them well suited for interactive tasks. However, the low speed of pneumatic actuation prevents use of these robots in more dynamic tasks. This paper aims to design, characterize, and model a bistable elastomeric actuator for swift tasks (BEAST). This actuator enables both fast actuation and mechanical compliance, and is designed by integrating silicone and polyethylene terephthalate (PET) in a bendy straw structure. The BEAST contains three states - compressed, natural, and stretched states. Two operation modes - compressed and stretched modes, are defined to model the continuous elongation dynamics before and after the quickly switching around the natural state. A set of design rules and a novel fabrication method are presented to develop the BEAST. The actuator characterization shows that the maximum extension ratio, snapping speed, and output force of the BEAST to be 0.58, 1.5m/s, and 48N, respectively. A hybrid linear parameter varying (HLPV) model is developed to describe the pressure-dependent dynamics of the actuator. The actuators are evaluated in an object sorting task where both fast and gentle behaviors are demonstrated.
- Award ID(s):
- 1828010
- Publication Date:
- NSF-PAR ID:
- 10345492
- Journal Name:
- 2022 IEEE 5th International Conference on Soft Robotics (RoboSoft)
- Page Range or eLocation-ID:
- 390 to 395
- Sponsoring Org:
- National Science Foundation
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