121 research outputs found
The Problem of Adhesion Methods and Locomotion Mechanism Development for Wall-Climbing Robots
This review considers a problem in the development of mobile robot adhesion
methods with vertical surfaces and the appropriate locomotion mechanism design.
The evolution of adhesion methods for wall-climbing robots (based on friction,
magnetic forces, air pressure, electrostatic adhesion, molecular forces,
rheological properties of fluids and their combinations) and their locomotion
principles (wheeled, tracked, walking, sliding framed and hybrid) is studied.
Wall-climbing robots are classified according to the applications, adhesion
methods and locomotion mechanisms. The advantages and disadvantages of various
adhesion methods and locomotion mechanisms are analyzed in terms of mobility,
noiselessness, autonomy and energy efficiency. Focus is placed on the physical
and technical aspects of the adhesion methods and the possibility of combining
adhesion and locomotion methods
Switchable Adhesion of Soft Composites Induced by a Magnetic Field
Switchable adhesives have the potential to improve the manufacturing and
recycling of parts and to enable new modes of motility for soft robots. Here,
we demonstrate magnetically-switchable adhesion of a two-phase composite to
non-magnetic objects. The composite's continuous phase is a silicone elastomer,
and the dispersed phase is a magneto-rheological fluid. The composite is simple
to prepare, and to mould to different shapes. When a magnetic field is applied,
the magneto-rheological fluid develops a yield stress, which dramatically
enhances the composite's adhesive properties. We demonstrate up to a nine-fold
increase of the pull-off force of non-magnetic objects in the presence of a 250
mT field
Adhesion modulation In bio-inspired micropatterned adhesives by electrical fields
With steps towards Industry 4.0, it becomes imperative to the development of next-generation industrial assembly lines, to be able to modulate adhesion dynamically for handling complex and diverse substrates. The inspiration for the design and functionality of such adhesive pads comes from gecko’s remarkable ability to traverse rough and smooth topographies with great ease and agility. The emphasis in this thesis was to equip artificial micropatterned adhesives with such functionalities of tunability and devise an on-demand release mechanism. The project evaluates the potential of electric fields in this direction. The first part of this work focusses on integrating electric fields with polymeric micropatterns and studying the synergistic effect of Van der Waals and electrostatic forces. An in-house electroadhesion set up was built to measure the pull-off forces with and without electric fields. As a function of the applied voltage, adhesion forces can be tuned. The second part of the work demonstrates a novel route that exploits the in-plane actuation of the dielectric elastomeric actuators integrated with microstructure to induce peeling in them. Voltage-dependent actuation has been harnessed to generate the requisite peel force to detach the micropatterns. Overall, the findings of this thesis combine disciplines of electroadhesion, electroactuation, and reversible dry adhesives to gain dynamic control over adhesion.Im Einklang mit dem Fortschreiten in Richtung Industrie 4.0, wird es auch für die Entwicklung von industriellen Montagelinien der nächsten Generation unerlässlich sein, die Handhabung komplexer und unterschiedlicher Objekte zu flexibilisieren. Bioinspirierte Haftpads nach dem Vorbild des Gecko könnten zukünftig hierzu wesentlich beitragen. Der Schwerpunkt dieser Arbeit bestand darin, künstliche mikrostrukturierte Haftpads mit einem elektrisch schaltbaren Adhäsions- und Ablösemechanismus zu funktionalisieren, um die Grundlage für einen schnell schaltbaren, intelligenten Greifer zu schaffen. Der erste Teil dieser Arbeit konzentriert sich auf die Kombination elektrischer Felder mit elastomeren Mikrostrukturen und die Untersuchung der synergistischen Wirkung von Van der Waals- und elektrostatischen Kräften. Zur Messung der Adhäsion wurde ein individueller Aufbau realisiert und mit diesem die Feldstärkeabhängigkeit der Haftkräfte nachgewiesen. Der zweite Teil der Arbeit demonstriert einen neuartigen Ablösemechanismus unter Ausnutzung der lateralen Bewegung dielektrischer elastomerer Aktuatoren, um so ein Abschälen der Haftpads vom Substrat zu induzieren. Durch Variation der elektrischen Spannung wurde untersucht, wie sich diese auf die Ablösegeschwindigkeit der Haftpads auswirkt. Insgesamt kombinieren die Ergebnisse dieser Arbeit die Disziplinen Elektroadhäsion, Elektroaktuation und reversible trockene Klebstoffe, um so eine dynamische Kontrolle über die Adhäsion zu erhalten
A Survey of Technologies and Applications for Climbing Robots Locomotion and Adhesion
The interest in the development of climbing robots has grown rapidly in the last years. Climbing
robots are useful devices that can be adopted in a variety of applications, such as maintenance
and inspection in the process and construction industries. These systems are mainly
adopted in places where direct access by a human operator is very expensive, because of the
need for scaffolding, or very dangerous, due to the presence of an hostile environment. The
main motivations are to increase the operation efficiency, by eliminating the costly assembly
of scaffolding, or to protect human health and safety in hazardous tasks. Several climbing
robots have already been developed, and other are under development, for applications ranging
from cleaning to inspection of difficult to reach constructions.
A wall climbing robot should not only be light, but also have large payload, so that it may
reduce excessive adhesion forces and carry instrumentations during navigation. These machines
should be capable of travelling over different types of surfaces, with different inclinations,
such as floors, walls, or ceilings, and to walk between such surfaces (Elliot et al. (2006);
Sattar et al. (2002)). Furthermore, they should be able of adapting and reconfiguring for various
environment conditions and to be self-contained.
Up to now, considerable research was devoted to these machines and various types of experimental
models were already proposed (according to Chen et al. (2006), over 200 prototypes
aimed at such applications had been developed in the world by the year 2006). However,
we have to notice that the application of climbing robots is still limited. Apart from a couple
successful industrialized products, most are only prototypes and few of them can be found
in common use due to unsatisfactory performance in on-site tests (regarding aspects such as
their speed, cost and reliability). Chen et al. (2006) present the main design problems affecting
the system performance of climbing robots and also suggest solutions to these problems.
The major two issues in the design of wall climbing robots are their locomotion and adhesion
methods.
With respect to the locomotion type, four types are often considered: the crawler, the wheeled,
the legged and the propulsion robots. Although the crawler type is able to move relatively
faster, it is not adequate to be applied in rough environments. On the other hand, the legged
type easily copes with obstacles found in the environment, whereas generally its speed is
lower and requires complex control systems.
Regarding the adhesion to the surface, the robots should be able to produce a secure gripping
force using a light-weight mechanism. The adhesion method is generally classified into four groups: suction force, magnetic, gripping to the surface and thrust force type. Nevertheless,
recently new methods for assuring the adhesion, based in biological findings, were proposed.
The vacuum type principle is light and easy to control though it presents the problem of
supplying compressed air. An alternative, with costs in terms of weight, is the adoption of
a vacuum pump. The magnetic type principle implies heavy actuators and is used only for
ferromagnetic surfaces. The thrust force type robots make use of the forces developed by
thrusters to adhere to the surfaces, but are used in very restricted and specific applications.
Bearing these facts in mind, this chapter presents a survey of different applications and technologies
adopted for the implementation of climbing robots locomotion and adhesion to surfaces,
focusing on the new technologies that are recently being developed to fulfill these objectives.
The chapter is organized as follows. Section two presents several applications of
climbing robots. Sections three and four present the main locomotion principles, and the
main "conventional" technologies for adhering to surfaces, respectively. Section five describes
recent biological inspired technologies for robot adhesion to surfaces. Section six introduces
several new architectures for climbing robots. Finally, section seven outlines the main conclusions
New Technologies for Climbing Robots Adhesion to Surfaces
The interest in the development of climbing robots is growing steadily. The main motivations are to increase the operation e ciency, by eliminating the costly assembly of sca olding, or to protect human health and safety in hazardous tasks. Climbing robots have already been developed for applications ranging from cleaning to inspection of constructions di cult to reach. These robots should be capable of travelling over di erent types of surfaces, with di erent inclinations, such as oors, walls, ceilings, and to walk between such surfaces. Furthermore, they should be able of adapting and recon guring for di erent environment conditions and to be self-contained. Regarding the adhesion to the surface, the robots should be able to produce a secure gripping force using a light-weight mechanism. This paper presents a survey of di erent technologies proposed and adopted for climbing robots adhesion to surfaces, focusing on the new technologies that are recently being developed to ful ll these objectives.N/
Tunable Reversible Dry Adhesion of Elastomeric Post Enabled by Stiffness Tuning of Microfluidic LMPA Thin Film
The goal of this study is to investigate the effects and underlying mechanisms of stiffness tuning on tunable reversible dry adhesion of an elastomeric post. This research introduces a novel device constructed out of a soft elastomer, polydemethylsiloxane (PDMS), with micro channels injected with low melting point alloy (LMPA) that can soften by applying a voltage. In contrast to traditional handling devices, such as metallic robot handlers, this soft gripper enables compliant manipulation of delicate fragile objects such as a thin glass slide. In this thesis, the design and fabrication of the elastomeric posts and the effects of three adhesion testing conditions will be presented. The first testing condition provided the baseline adhesion values that would be later referenced to certify adhesion reversibility. The second condition demonstrates the device’s ability to change adhesion forces on the spot, or dynamically. The third condition displays the ability of the device to maintain this adhesion change when activated and deactivated repeatedly. Theoretical Finite Element modeling provides insights indicating a maximum adhesion when varying one critical geometrical parameter, which was later confirmed with experiments. Experimental results prove the device’s capability of dynamically tunable reversible dry adhesion. This novel approach to tunable dry adhesion exhibits the feasibility of soft grippers that would not require complicated systems for activation but instead only need low power and simple circuitry, and thus have potential to function as effective soft gripping devices
Advanced Bionic Attachment Equipment Inspired by the Attachment Performance of Aquatic Organisms: A Review
In nature, aquatic organisms have evolved various attachment systems, and their attachment ability has become a specific and mysterious survival skill for them. Therefore, it is significant to study and use their unique attachment surfaces and outstanding attachment characteristics for reference and develop new attachment equipment with excellent performance. Based on this, in this review, the unique non-smooth surface morphologies of their suction cups are classified and the key roles of these special surface morphologies in the attachment process are introduced in detail. The recent research on the attachment capacity of aquatic suction cups and other related attachment studies are described. Emphatically, the research progress of advanced bionic attachment equipment and technology in recent years, including attachment robots, flexible grasping manipulators, suction cup accessories, micro-suction cup patches, etc., is summarized. Finally, the existing problems and challenges in the field of biomimetic attachment are analyzed, and the focus and direction of biomimetic attachment research in the future are pointed out
Development of microstructures for application on a controllable bioinspired adhesive mechanism for gripping system in pick-n-place task
Dissertação de mestrado integrado em Engenharia MecânicaA natureza oferece uma variedade de ideias para uma adesão transitória e reversível a
diferentes substratos. Até agora, os soft dry adhesives (SDAs) bioinspirados mais estudados
são superfícies com matrizes de micropilares. A inspiração veio de espécies terrestres, como
as osgas, cujas almofadas dos pés são cobertas por intrincadas fibrilhas que permitem uma
forte adesão (que se deve a forças intermoleculares) bem como uma fácil libertação.
Um dos objetivos atuais dos esforços da investigação é transferir a solução da natureza
para estruturas artificiais que possam um dia encontrar aplicações tecnológicas. Este trabalho
visa replicar os comportamentos de agarra e libertação das osgas, utilizando como base as
suas estruturas fibrilares pegajosas. Para este objetivo, serão utilizadas várias técnicas de
fabrico e ensaios experimentais para determinar o melhor protocolo para a criação de
microestruturas. Foram estudados micropilares cilíndricos lisos e micropilares com forma de
cogumelo, tendo sido escolhidos estes últimos dado que aderem melhor aos substratos lisos
em comparação com pilares cilíndricos.
O presente trabalho começou por delinear o estado de arte, no qual se investiga o
desenvolvimento de SDAs bioinspirados e as suas qualidades adesivas. Além disso, também
foram abordados os fundamentos de adesão fibrilar. Prosseguiu-se para o desenvolvimento
de amostras em polidimetilsiloxano (PDMS) com o objetivo de caracterizar este material num
equipamento de ensaio universal (UTM).
Neste trabalho foram examinadas várias técnicas de microfabricação. Tendo em
consideração a dimensão das micropartículas utilizadas, foram produzidas microestruturas
utilizando uma metodologia de baixo custo. Foram utilizados e testados vários tipos de
métodos para fabricar os moldes, ou seja, para produzir pilares cilíndricos lisos foi utilizada
fresagem e para produzir micropilares em forma de cogumelo foi utilizada impressão 3D.
Devido à sua forma, os micropilares em forma de cogumelo requerem uma dupla moldagem,
com um molde intermediário constituído por um material altamente flexível.
Finalmente, com o auxílio do UTM para realizar testes de aderência, foi avaliada a
eficiência das microestruturas.Nature offers a variety of ideas for transient and reversible adhesion to different
substrates. Geckos and insects use hairy structures whose adhesion is due to intermolecular
forces. So far, the most widely studied SDAs are surfaces with arrays of micropillars. The
inspiration came from terrestrial species including lizards and geckos whose toe pads are
covered by intricate fibrils that enable strong attachment as well as easy release.
The current goal of research and development efforts is to transfer nature's solution
into artificial structures that might someday be applied in different technologies. Hence, this
work aims to replicate the grasping and releasing behaviors of geckos using their fibrillar sticky
structures as a basis. In order to achieve this goal, different kinds of designs, fabrications, and
testing will be used to determine the best protocol for creating microstructures. Smooth
cylindrical and mushroom-shaped micropillars were studied. The latter were chosen because
they adhere to smooth substrates better than cylindrical micropillars.
This work began by outlining the state of the art on the development of soft dry
adhesives (SDAs) with natural inspiration and an examination of their dry adhesive properties.
Additionally, the fundamentals of fibrillar adhesion were also covered. The work then
proceeded to the development of polydimethylsiloxane (PDMS) specimens with the goal of
characterizing this material in a universal testing machine (UTM).
A number of microfabrication techniques were examined. Based on the size of the
employed microparticles, microstructures were produced applying a low-cost method.
Different methods were employed depending on the shape of the molds, i. e., to produce
cylindrical flat pillars, it was used a CNC milling machine whereas to produce mushroom
shaped micropillars, it was used 3D printing. Due to their design, the micropillars with the
mushroom shape required double molding with an intermediary mold made of a highly
flexible material.
Finally, using the UTM to perform adhesion tests, the efficiency of the microstructure
was evaluated
A Perching Mechanism for Flying Robots Using a Fibre-Based Adhesive
Robots capable of hover flight in constrained indoor environments have many applications, however their range is constrained by the high energetic cost of airborne locomotion. Perching allows flying robots to scan their environment without the need to remain aloft. This paper presents the design of a mechanism that allows indoor flying robots to attach to vertical surfaces. To date, solutions that enable flying robot with perching capabilities either require high precision control of the dynamics of the robot or a mechanism robust to high energy impacts. We propose in this article a perching mechanism comprising a compliant deployable pad and a passive self-alignment system, that does not require any active control during the attachment procedure. More specifically, a perching mechanism using fibre-based dry adhesives was implemented on a 300~g flying platform. An adhesive pad was first modeled and optimized in shape for maximum attachment force at the low pre-load forces inherent to hovering platforms. It was then mounted on a deployable mechanism that stays within the structure of the robot during flight and can be deployed when a perching maneuver is initiated. Finally, the perching mechanism is integrated onto a real flying robot and successful perching maneuvers are demonstrated as a proof of concept
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