288 research outputs found
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Compaction through Buckling in 2D Periodic, Soft and Porous Structures: Effect of Pore Shape
Soft cellular structures that comprise a solid matrix with a square array of holes open avenues for the design of novel soft and foldable structures. Our results demonstrate that by simply changing the shape of the holes the response of porous structure can be easily tuned and soft structures with optimal compaction can be designed.Engineering and Applied Science
Détermination immunohistochimique de l'expression de p27Kip1 dans les tumeurs mammaires canines
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal
Shape Memory Soft Robotics with Yield Stress Fluids
Biological movement is a source of inspiration for designing soft robots that use fluidic actuation for adaptive gripping and locomotion. While many biological systems use networks of non-Newtonian fluid for movement, to date, most soft robots use Newtonian fluids or pneumatics. Herein, yield stress fluids to manufacture and operate soft devices are exploited, particularly to create soft actuators that exhibit shape memory. Our soft robots are fabricated through embedded 3D printing where the suspension media is a yield stress fluid. Moreover, this complex fluid is encapsulated and used as the hydraulic transmission fluid. Diagnostic designs are developed to characterize the force and shape memory of the yield stress fluid, and the findings are used to create a gripper common in modern soft robotic applications. The diagnostic devices have deformable reservoirs that demonstrate force response, flow behavior, and deformation profiles dependent on the yield stress features of the transmission fluid. The actuation using the yield stress fluid from the retained suspension media creates avenues for partial shape retention and unconventional expansion from localized fluid flow. Looking toward the future of soft robotics, these fabrication and operational approaches using yield stress fluids can provide greater tunability for applications requiring nonlinear actuation and shape memory.</p
Multi-step self-guided pathways for shape-changing metamaterials
Multi-step pathways, constituted of a sequence of reconfigurations, are
central to a wide variety of natural and man-made systems. Such pathways
autonomously execute in self-guided processes such as protein folding and
self-assembly, but require external control in macroscopic mechanical systems,
provided by, e.g., actuators in robotics or manual folding in origami. Here we
introduce shape-changing mechanical metamaterials, that exhibit self-guided
multi-step pathways in response to global uniform compression. Their design
combines strongly nonlinear mechanical elements with a multimodal architecture
that allows for a sequence of topological reconfigurations, i.e., modifications
of the topology caused by the formation of internal self-contacts. We realized
such metamaterials by digital manufacturing, and show that the pathway and
final configuration can be controlled by rational design of the nonlinear
mechanical elements. We furthermore demonstrate that self-contacts suppress
pathway errors. Finally, we demonstrate how hierarchical architectures allow to
extend the number of distinct reconfiguration steps. Our work establishes
general principles for designing mechanical pathways, opening new avenues for
self-folding media, pluripotent materials, and pliable devices in, e.g.,
stretchable electronics and soft robotics.Comment: 16 pages, 3 main figures, 10 extended data figures. See
https://youtu.be/8m1QfkMFL0I for an explanatory vide
A fluidic relaxation oscillator for reprogrammable sequential actuation in soft robots
Despite exciting developments in soft robotics, fully autonomous systems remain elusive. Fluidic circuits could enable fully embedded control of soft robots without using electronics. In this work, we introduce a simple and compact soft valve with intentional hysteresis, analogous to an electronic relaxation oscillator. By integrating the valve with a soft actuator, we transform a continuous inflow to cyclic activation. Importantly, we show that our circuits can activate up to five actuators in various sequences and that we can physically reprogram the activation order by varying the (initial) conditions in the fluidic circuit. Moreover, we show the feasibility of our approach under more realistic conditions by building a four-legged robot. Our work paves the way toward fully autonomous soft robots that can interact with their environment to reprogram their behavior, e.g., to trigger targeted drug release inside our body or to change gait to move past obstacles
A Retrofit Sensing Strategy for Soft Fluidic Robots
Soft robots are intrinsically capable of adapting to different environments
by changing their shape in response to interaction forces with the environment.
However, sensing and feedback are still required for higher level decisions and
autonomy. Most sensing technologies developed for soft robots involve the
integration of separate sensing elements in soft actuators, which presents a
considerable challenge for both the fabrication and robustness of soft robots
due to the interface between hard and soft components and the complexity of the
assembly. To circumvent this, here we present a versatile sensing strategy that
can be retrofitted to existing soft fluidic devices without the need for design
changes. We achieve this by measuring the fluidic input that is required to
activate a soft actuator and relating this input to its deformed state during
interaction with the environment. We demonstrate the versatility of our sensing
strategy by tactile sensing of the size, shape, surface roughness and stiffness
of objects. Moreover, we demonstrate our approach by retrofitting it to a range
of existing pneumatic soft actuators and grippers powered by positive and
negative pressure. Finally, we show the robustness of our fluidic sensing
strategy in closed-loop control of a soft gripper for practical applications
such as sorting and fruit picking. Based on these results, we conclude that as
long as the interaction of the actuator with the environment results in a shape
change of the interval volume, soft fluidic actuators require no embedded
sensors and design modifications to implement sensing. We believe that the
relative simplicity, versatility, broad applicability and robustness of our
sensing strategy will catalyze new functionalities in soft interactive devices
and systems, thereby accelerating the use of soft robotics in real world
applications
A characteristic lengthscale causes anomalous size effects and boundary programmability in mechanical metamaterials
The architecture of mechanical metamaterialsis designed to harness geometry,
non-linearity and topology to obtain advanced functionalities such as shape
morphing, programmability and one-way propagation. While a purely geometric
framework successfully captures the physics of small systems under idealized
conditions, large systems or heterogeneous driving conditions remain
essentially unexplored. Here we uncover strong anomalies in the mechanics of a
broad class of metamaterials, such as auxetics, shape-changers or topological
insulators: a non-monotonic variation of their stiffness with system size, and
the ability of textured boundaries to completely alter their properties. These
striking features stem from the competition between rotation-based
deformations---relevant for small systems---and ordinary elasticity, and are
controlled by a characteristic length scale which is entirely tunable by the
architectural details. Our study provides new vistas for designing, controlling
and programming the mechanics of metamaterials in the thermodynamic limit.Comment: Main text has 4 pages, 4 figures + Methods and Supplementary
Informatio
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