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 Bending Properties of an Extensile Fluidic Artificial Muscle(Frontiers, 2022-04-13) Garbulinski, Jacek; Wereley, Norman M.Low stiffness, large stroke, and axial force capabilities make Extensile Fluidic Artificial Muscles (EFAMs) a feasible soft actuator for continuum soft robots. EFAMs can be used to construct soft actuated structures that feature large deformation and enable soft robots to access large effective workspaces. Although FAM axial properties have been well studied, their bending behavior is not well characterized in the literature. Static and dynamic bending properties of a cantilevered EFAM specimen were investigated over a pressure range of 5–100 psi. The static properties were then estimated using an Euler-Bernoulli beam model and discrete elastic rod models. The experiments provided data for the determination of bending stiffness, damping ratio, and natural frequency of the tested specimen. The bending stiffness and the damping ratio were found to change fourfold over the pressure range. Experimentally validated bending properties of the EFAM presented insights into structural and control considerations of soft robots. Future work will utilize the data and models obtained in this study to predict the behavior of an EFAM-actuated continuum robot carrying payloads.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.