Study of the compliance and system integration of bistable structures for use as actuation mechanisms in bioinspired adaptive systems

Gustafson, Kimberly J.

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https://hdl.handle.net/2142/105749 Copy

Description

Title

Study of the compliance and system integration of bistable structures for use as actuation mechanisms in bioinspired adaptive systems

Author(s)

Gustafson, Kimberly J.

Issue Date

2019-06-14

Director of Research (if dissertation) or Advisor (if thesis)

Wissa, Aimy A

Committee Member(s)

Alleyne, Andrew G

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• actuation
• bistable
• compliant
• truss mechanism
• buckling
• system integration
• origami
• crawling robot
• dynamic model
• kinematic model
• model-based design framework

Abstract

Bistable structures are desirable for actuation mechanisms because they allow for the efficient use of actuators by reducing the power required to change and maintain equilibrium positions. There is currently an increased interest in compliant bistable structures, especially for use in the fields of soft robotics and human-robot interaction. Introducing compliance to bistable actuation mechanisms significantly increases the complexity of both modeling the actuation mechanism and synergistically incorporating the mechanism into a system design. This work investigates the effects of compliance on a bistable buckling mechanism and synergistically incorporates a pseudo-compliant origami mechanism into the system level model of an origami-enabled crawling robot. A compliant bistable truss mechanism is proposed as a linear actuation mechanism to control the spacing between wingtips on small aerial vehicles. Prototypes of the truss mechanism are fabricated using a Stratasys Objet 3D printer, and the force-displacement profile of the mechanisms are measured using a universal testing machine. The force-displacement responses of the mechanisms demonstrate that increasing the compliance of the bistable beam element that buckles as the truss mechanism is compressed increases the bistability of the mechanism and decreases the force required to actuate the mechanism. In addition, adjusting the compliance of the boundary conditions of the bistable element allows for even finer tuning of the mechanism actuation force and bistability. A rudimentary finite element model is developed for the bistable element to show the feasibility of modeling the nonlinearities from the high compliance materials and large deformations experienced by the truss mechanism. The second contribution of this work is the incorporation of a bistable origami actuation mechanism into a system model of a crawling robot. A dynamic locomotion model for an origami-enabled robot is developed from an energy analysis of the mechanical robot components. The results of the dynamic model are compared to a kinematic model of the robot and the experimentally measured locomotion of the robot. The dynamic and kinematic models perform similarly for small robot advances (less than 25% of an expansion cycle), but the dynamic model demonstrates superior tracking of the robot locomotion for larger advances as the system losses increase. The measured maximum error between the experimental results and the dynamic model is 15% compared to the 40% error measured for the kinematic model. Finally, a demonstration is given for how the dynamic model can be used to select the robot design parameters and provide the foundation of a much-needed framework for the design of origami-enabled robots. This work investigates some of the challenges introduced by compliant bistable actuation mechanisms, including the effects of compliance on the bistability and actuation force of the traditionally well understood buckling beam as well as the integration of compliant actuation mechanisms into models that can be used for the design of systems enabled by compliant structures.

Graduation Semester

2019-08

Type of Resource

text

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http://hdl.handle.net/2142/105749

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© Copyright by Kimberly J. Gustafson 2019 All Right Reserved

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