115 research outputs found
Utilizing Systematic Design and Shape Memory Alloys to Enhance Actuation of Modular High-Frequency Origami Robots
Shape memory alloys (SMAs) describe a group of smart metallic materials that can be deformed by external magnetic, thermal, or mechanical influence and then returned to a predetermined shape through the cycling of temperature or stress. They have several advantages, such as having excellent mechanical properties, being low cost, and being easily manufactured, while also providing a compact size, completely silent operation, high work density, and requiring less maintenance over time. SMAs can undergo sold-to-solid phase transformations, and it is because of these phase transformations that they can experience shape memory effect (SME); or the ability to recover from a deformed shape to an initially determined shape through the cycling of temperature. However, since SME requires the cycling of temperature to actuate SMAs, the actuation frequency of these materials has been slow for small-scale applications, as actuation speed is limited by the time it takes to transition from a higher temperature (actuated, pre-determined state) to a lower temperature (flexible, reconfigurable state). While SMAs are known to be highly advantageous, their main drawback is that they are one of the slowest actuation methods in the field of origami robotics. SMAs cannot actuate quickly enough cyclically due to the long cooling times required to get from their austenite (higher temperature, actuated, pre-determined state) phase to their martensite (lower temperature, flexible, reconfigurable state) phase. Researchers have attempted to achieve a higher actuation speed in previous projects by using active cooling agents. However, this study investigated the use of SMAs to initiate high-frequency cyclic movement through a small-scale origami fold without an active cooling source. This study used a combination of different system design parameters to mechanically hasten the actuation speed of a folding hinge with no cooling component present. Through only design and a complete understanding of the SMAs, this study achieved consistent and relatively high results (\u3e1.5 Hz) of an actuation speed for a system of this size. This study discovered knowledge regarding the composition, material properties, and actuation limits of SMAs, and a new systematic design method was proposed for creating origami robots
Modular soft pneumatic actuator system design for compliance matching
The future of robotics is personal. Never before has technology been as pervasive as it is today, with advanced mobile electronics hardware and multi-level network connectivity pushing âsmartâ devices deeper into our daily lives through home automation systems, virtual assistants, and wearable activity monitoring. As the suite of personal technology around us continues to grow in this way, augmenting and offloading the burden of routine activities of daily living, the notion that this trend will extend to robotics seems inevitable. Transitioning robots from their current principal domain of industrial factory settings to domestic, workplace, or public environments is not simply a matter of relocation or reprogramming, however. The key differences between âtraditionalâ types of robots and those which would best serve personal, proximal, human interactive applications demand a new approach to their design. Chief among these are requirements for safety, adaptability, reliability, reconfigurability, and to a more practical extent, usability. These properties frame the context and objectives of my thesis work, which seeks to provide solutions and answers to not only how these features might be achieved in personal robotic systems, but as well what benefits they can afford. I approach the investigation of these questions from a perspective of compliance matching of hardware systems to their applications, by providing methods to achieve mechanical attributes complimentary to their environment and end-use. These features are fundamental to the burgeoning field of Soft Robotics, wherein flexible, compliant materials are used as the basis for the structure, actuation, sensing, and control of complete robotic systems. Combined with pressurized air as a power source, soft pneumatic actuator (SPA) based systems offers new and novel methods of exploiting the intrinsic compliance of soft material components in robotic systems. While this strategy seems to answer many of the needs for human-safe robotic applications, it also brings new questions and challenges: What are the needs and applications personal robots may best serve? Are soft pneumatic actuators capable of these tasks, or âusefulâ work output and performance? How can SPA based systems be applied to provide complex functionality needed for operation in diverse, real-world environments? What are the theoretical and practical challenges in implementing scalable, multiple degrees of freedom systems, and how can they be overcome? I present solutions to these problems in my thesis work, elucidated through scientific design, testing and evaluation of robotic prototypes which leverage and demonstrate three key features: 1) Intrinsic compliance: provided by passive elastic and flexible component material properties, 2) Extrinsic compliance: rendered through high number of independent, controllable degrees of freedom, and 3) Complementary design: exhibited by modular, plug and play architectures which combine both attributes to achieve compliant systems. Through these core projects and others listed below I have been engaged in soft robotic technology, its application, and solutions to the challenges which are critical to providing a path forward within the soft robotics field, as well as for the future of personal robotics as a whole toward creating a better society
A Review of SMA-Based Actuators for Bidirectional Rotational Motion: Application to Origami Robots
Shape memory alloys (SMAs) are a group of metallic alloys capable of sustaining large inelastic strains that can be recovered when subjected to a specific process between two distinct phases. Regarding their unique and outstanding properties, SMAs have drawn considerable attention in various domains and recently became appropriate candidates for origami robots, that require bi-directional rotational motion actuation with limited operational space. However, longitudinal motion-driven actuators are frequently investigated and commonly mentioned, whereas studies in SMA-based rotational motion actuation is still very limited in the literature. This work provides a review of different research efforts related to SMA-based actuators for bi-directional rotational motion (BRM), thus provides a survey and classification of current approaches and design tools that can be applied to origami robots in order to achieve shape-changing. For this purpose, analytical tools for description of actuator behaviour are presented, followed by characterisation and performance prediction. Afterward, the actuators’ design methods, sensing, and controlling strategies are discussed. Finally, open challenges are discussed
Integrated design approach for responsive solar-shadings in double skin facades in hot arid climate
Ph. D. Thesis.To deliver climate adaptive architecture, current trends in architecture are directed
towards dynamic and responsive building skins. ‘Responsive building skin’ is used to describe
the ability of building envelopes to adapt in real time in response to external environmental
conditions. Recent attention has focused on ‘soft robotics’ approach which uses soft and/or
extensible materials to deform with muscle‐like actuation, mimicking biological systems.
Material embedded actuation can autonomously alter shading systems’ morphology
stimulated by external environmental conditions. Passively thermally‐activated shading
systems offer responsive actuation by solar‐radiation and stratified hot air in a double skin
façade (DSF) without recourse to energy consuming systems.
This research identifies the intersection between bio‐inspiration, folding principles and
smart materials to integrate the underlying mechanisms in responsive solar‐shading systems
and assesses their environmental performance. The thesis proposes an interdisciplinary mixed
methodology linking hands‐on experimentation with environmental performance simulation
of responsive building skins. ‘Practice‐led approach’ is used to explore the design potential of
responsive systems using smart materials. ‘Computational Fluid Dynamics’ (CFD) numerical
methods are used to measure the impact of responsive solar‐shading systems on multiple
environmental factors in a DSF cavity. This helps the design decisions, selection and
customisation of smart materials. Hands‐on experimentation is used to explore various
prototypes, leading to the selection of a folded prototype, to be simulated for environmental
performance. Solar‐shading systems are tested within a DSF, in an hot arid climate. Flat and
folded solar‐shading devices are installed in a DSF cavity with three aperture sizes (30%, 50%
& 70%) to represent the responsive system states. Point‐in‐time simulations are carried at
9:00 am, 12:00 pm and 15:00 pm in peak summer and winter day.
The developed analytical design framework presents different design parameters for
responsive solar‐shading systems to guide decision‐making in research of climate actuated
smart shading systems.
Keywords: Responsive skins, Adaptive facades, Soft robotics, Bio‐inspiration, Origami,
Deployable structures, Actuation, Smart materials, Shape memory alloys, Double skin facades,
Energy efficiency, Digital simulation, CFD Modelling
Enabling technologies for precise aerial manufacturing with unmanned aerial vehicles
The construction industry is currently experiencing a revolution with automation techniques
such as additive manufacturing and robot-enabled construction. Additive Manufacturing (AM)
is a key technology that can o er productivity improvement in the construction industry by
means of o -site prefabrication and on-site construction with automated systems. The key
bene t is that building elements can be fabricated with less materials and higher design freedom
compared to traditional manual methods.
O -site prefabrication with AM has been investigated for some time already, but it has limitations
in terms of logistical issues of components transportation and due to its lack of design
exibility on-site. On-site construction with automated systems, such as static gantry systems
and mobile ground robots performing AM tasks, can o er additional bene ts over o -site
prefabrication, but it needs further research before it will become practical and economical.
Ground-based automated construction systems also have the limitation that they cannot extend
the construction envelope beyond their physical size. The solution of using aerial robots
to liberate the process from the constrained construction envelope has been suggested, albeit
with technological challenges including precision of operation, uncertainty in environmental
interaction and energy e ciency.
This thesis investigates methods of precise manufacturing with aerial robots. In particular,
this work focuses on stabilisation mechanisms and origami-based structural elements that allow
aerial robots to operate in challenging environments. An integrated aerial self-aligning delta
manipulator has been utilised to increase the positioning accuracy of the aerial robots, and
a Material Extrusion (ME) process has been developed for Aerial Additive Manufacturing
(AAM). A 28-layer tower has been additively manufactured by aerial robots to demonstrate the
feasibility of AAM. Rotorigami and a bioinspired landing mechanism demonstrate their abilities
to overcome uncertainty in environmental interaction with impact protection capabilities and
improved robustness for UAV. Design principles using tensile anchoring methods have been
explored, enabling low-power operation and explores possibility of low-power aerial stabilisation.
The results demonstrate that precise aerial manufacturing needs to consider not only just the
robotic aspects, such as
ight control algorithms and mechatronics, but also material behaviour
and environmental interaction as factors for its success.Open Acces
Origami surfaces for kinetic architecture
This thesis departs from the conviction that spaces that can change their
formal configuration through movement may endow buildings of bigger
versatility. Through kinetic architecture may be possible to generate adaptable
buildings able to respond to different functional solicitations in terms of the
used spaces.
The research proposes the exploration of rigidly folding origami surfaces as
the means to materialize reconfigurable spaces through motion. This specific
kind of tessellated surfaces are the result of the transformation of a flat
element, without any special structural skill, into a self-supporting element
through folds in the material, which gives them the aptitude to undertake
various configurations depending on the crease pattern design and welldefined
rules for folding according to rigid kinematics.
The research follows a methodology based on multidisciplinary, practical
experiments supported on digital tools for formal exploration and simulation.
The developed experiments allow to propose a workflow, from concept to
fabrication, of kinetic structures made through rigidly folding regular origami
surfaces. The workflow is a step-by-step process that allows to take a logical
path which passes through the main involved areas, namely origami geometry
and parameterization, materials and digital fabrication and mechanisms and
control.
The investigation demonstrates that rigidly folding origami surfaces can be
used as dynamic structures to materialize reconfigurable spaces at different
scales and also that the use of pantographic systems as a mechanism
associated to specific parts of the origami surface permits the achievement of
synchronized motion and possibility of locking the structure at specific stages
of the folding.A presente tese parte da convicção de que os espaços que são capazes de
mudar a sua configuração formal através de movimento podem dotar os
edifícios de maior versatilidade. Através da arquitectura cinética pode ser
possível a geração de edifícios adaptáveis, capazes de responder a
diferentes solicitações funcionais, em termos do espaço utilizado.
Esta investigação propõe a exploração de superfícies de origami, dobráveis
de forma rígida, como meio de materialização de espaços reconfiguráveis
através de movimento. Este tipo de superfícies tesseladas são o resultado da
transformação de um elemento plano, sem capacidade estrutural que, através
de dobras no material, ganha propriedades de auto-suporte. Dependendo do
padrão de dobragem e segundo regras de dobragem bem definidas de acordo
com uma cinemática rígida, a superfície ganha a capacidade de assumir
diferentes configurações.
A investigação segue uma metodologia baseada em experiências práticas e
multidisciplinares apoiada em ferramentas digitais para a exploração formal e
simulação. Através das experiências desenvolvidas é proposto um processo
de trabalho, desde a conceptualização à construção, de estruturas cinéticas
baseadas em superfícies dobráveis de origami rígido de padrão regular. O
processo de trabalho proposto corresponde a um procedimento passo-apasso
que permite seguir um percurso lógico que atravessa as principais
áreas envolvidas, nomeadamente geometria do origami e parametrização,
materiais e fabricação digital e ainda mecanismos e controle.
A dissertação demonstra que as superfícies de origami dobradas de forma
rígida podem ser utilizadas como estruturas dinâmicas para materializar
espaços reconfiguráveis a diferentes escalas. Demonstra ainda que a
utilização de sistemas pantográficos como mecanismos associados a partes
específicas da superfície permite atingir um movimento sincronizado e a
possibilidade de bloquear o movimento em estados específicos da dobragem
Limpet II: A Modular, Untethered Soft Robot
The ability to navigate complex unstructured environments and carry out inspection tasks requires robots to be capable of climbing inclined surfaces and to be equipped with a sensor payload. These features are desirable for robots that are used to inspect and monitor offshore energy platforms. Existing climbing robots mostly use rigid actuators, and robots that use soft actuators are not fully untethered yet. Another major problem with current climbing robots is that they are not built in a modular fashion, which makes it harder to adapt the system to new tasks, to repair the system, and to replace and reconfigure modules. This work presents a 450 g and a 250 × 250 × 140 mm modular, untethered hybrid hard/soft robot—Limpet II. The Limpet II uses a hybrid electromagnetic module as its core module to allow adhesion and locomotion capabilities. The adhesion capability is based on negative pressure adhesion utilizing suction cups. The locomotion capability is based on slip-stick locomotion. The Limpet II also has a sensor payload with nine different sensing modalities, which can be used to inspect and monitor offshore structures and the conditions surrounding them. Since the Limpet II is designed as a modular system, the modules can be reconfigured to achieve multiple tasks. To demonstrate its potential for inspection of offshore platforms, we show that the Limpet II is capable of responding to different sensory inputs, repositioning itself within its environment, adhering to structures made of different materials, and climbing inclined surfaces
Reconfigurable Antennas
In this new book, we present a collection of the advanced developments in reconfigurable antennas and metasurfaces. It begins with a review of reconfigurability technologies, and proceeds to the presentation of a series of reconfigurable antennas, UWB MIMO antennas and reconfigurable arrays. Then, reconfigurable metasurfaces are introduced and the latest advances are presented and discussed
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