Aerospace Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/2206
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Item Characterization and Analysis of Extensile Fluidic Artificial Muscles(MDPI, 2021-01-30) Garbulinski, Jacek; Balasankula, Sai C.; Wereley, Norman M.Extensile fluidic artificial muscles (EFAMs) are soft actuators known for their large ranges of extension, low weight, and blocked forces comparable to those of pneumatic cylinders. EFAMs have yet to be studied in a way that thoroughly focuses on their manufacturing, experimental characterization, and modeling. A fabrication method was developed for production of two EFAMs. The quasi-static axial force response of EFAMs to varying displacement was measured by testing two specimens under isobaric conditions over a pressure range of 103.4–517.1 kPa (15–75 psi) with 103.4 kPa (15 psi) increments. The muscles were characterized by a blocked force of 280 N and a maximum stroke of 98% at 517.1 kPa (75 psi). A force-balance model was used to analyze EFAM response. Prior work employing the force-balance approach used hyper-elastic constitutive models based on polynomial expressions. In this study, these models are validated for EFAMs, and new constitutive models are proposed that better represent the measured stress values of rubber as a function of strain. These constitutive models are compared in terms of accuracy when estimating pressure-dependent stress–strain relationships of the bladder material. The analysis demonstrates that the new hyper-elastic stress models have an error 5% smaller than models previously employed for EFAMs for the same number of coefficients. Finally, the analysis suggests that the new stress functions have smaller errors than the polynomial stress model with the same number of coefficients, guarantee material stability, and are more conservative about the stress values for strains outside of the testing range.Item Extensile Fluidic Artificial Muscles in Payload-Carrying Continuum Soft Robots(2023) Garbulinski, Jacek; Wereley, Norman M.; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Intrinsically actuated continuum soft robots merge the features of hyper-redundant and soft robots. The soft structure and redundancy allow the robots to conduct tasks in confined or unstructured environments. Extensile fluidic artificial muscles (EFAMs) can be used to construct soft actuated structures that feature large deformation and enable the robots to access large reachable workspaces. However, the soft robots’ low structural stiffness limits their ability to exert force or carry payloads. This dissertation aims to improve the continuum soft robot's spatial and payload-carrying performance. The work seeks to accomplish the following: 1. Compare multi-segment continuum robots to understand how the number of segments and robot geometry affect their spatial performance.2. Experimentally characterize and model EFAMs to close existing knowledge gaps in their axial and bending behaviors. 3. Investigate the impact of radial reinforcement on the payload-carrying ability of an EFAM robot. 4. Propose a modeling approach that captures the deformation of the robot under payloads.