University of Illinois Urbana-Champaign

On the design, modeling, fabrication, and application of fiber-reinforced soft pneumatic actuators

Thompson, Nicholas A.

Content Files
THOMPSON-DISSERTATION-2022.pdf

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https://hdl.handle.net/2142/115815

Description

Title
On the design, modeling, fabrication, and application of fiber-reinforced soft pneumatic actuators
Author(s)
Thompson, Nicholas A.
Issue Date
2022-04-21
Director of Research (if dissertation) or Advisor (if thesis)
  • Hsiao-Wecksler, Elizabeth T
  • Krishnan, Girish
Doctoral Committee Chair(s)
Hsiao-Wecksler, Elizabeth T
Committee Member(s)
  • Ewoldt, Randy H
  • Kesavadas, Thenkurussi
Department of Study
Mechanical Sci & Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • soft robotics
  • soft robots
  • pneumatic artificial muscles
  • fiber-reinforced elastomeric enclosures
  • actuators
  • soft actuators
  • pneumatics
  • exoskeletons
  • transseptal puncture
  • cardiac catheterization
  • simulator
  • right atrium
  • Brockenbrough needle
  • design
  • finite-element analysis
  • FEA
  • additive manufacturing
  • 3D printing
  • silicone
  • casting
Abstract
Fiber reinforced elastomeric enclosures (FREEs) are soft pneumatic actuators with performance characteristics that can be customized during fabrication. In the decades since their initial conception, FREEs and their predecessors have been applied in a multitude of linear force generation applications. A variety of theoretical models have been developed to predict their force and displacement output. However, existing research has predominantly focused on FREEs as singular actuators in near-linear configurations. There is a vast and relatively unexplored design space accessible when one deviates from this paradigm. The work in this dissertation expands the FREE design space by using them as building blocks in unique architectures and applying them in wrapped and curved configurations. Two exoskeleton applications served as platforms for exploration of new FREE architectures designed to actuate revolute joints. A nested linear architecture and a helical wrapped architecture were combined for effective joint actuation and stiffening in a soft elbow sleeve exoskeleton. A cable-driven variation of the nested linear architecture was compared to a bioinspired pennate architecture for a shoulder exoskeleton application. These two investigations served to demonstrate the ability of FREE architectures to deliver tailored solutions to unique mechanical challenges. The centerpiece of this research is a medical training simulator uniquely enabled by novel curved FREEs. Transseptal puncture (TP) is the technique used to access the left atrium of the heart from the right atrium via the interatrial septum in increasingly common cardiac catheterization procedures. There is a need for a realistic TP task trainer to help cardiology fellows learn to recognize key haptic cues felt through the catheter as they navigate to the correct puncture site on the fossa ovalis. To create low-risk training opportunities for new TP operators, we developed a Soft Active Transseptal Puncture Simulator (SATPS), designed to match the dynamics, static response, and visualization of the heart during TP. The SATPS includes three main subsystems: (i) An anatomically accurate soft right atrium uses FREEs to mimic atrial contraction and provide realistic dynamic force feedback to the operator. (ii) A replaceable, puncturable fossa ovalis simulates the tissue properties of the real fossa to provide accurate force feedback during tenting and puncture. (iii) A simulated intracardiac echocardiography environment gives the user live visual feedback representative of an ultrasound monitor during an actual TP procedure. Subsystems of the SATPS were validated with benchtop tests. In a system validation study, experienced clinicians rated the SATPS as realistic and useful for training fellows in TP. Novel FREE designs will be enabled by new tools in the form of a parametrized finite-element model and low-cost additive manufacturing. The curved FREEs introduced in the SATPS atrium were investigated using finite-element analysis (FEA). A custom software was developed to procedurally generate FREEs with user-defined parameters and three-dimensional centerline paths. The program interfaces with commercial FEA software for analysis and extracts FEA output for post-processing, allowing for exploration of kinematic trends. Prototyping curved FREEs or other geometrically-complex soft actuators will be enabled by a low-cost soft materials 3D printer designed to print elastomers of multiple stiffnesses with a water-soluble support material.
Graduation Semester
2022-05
Type of Resource
Thesis
Handle URL
https://hdl.handle.net/2142/115815
Copyright and License Information
Copyright 2022 Nicholas A. Thompson

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