1,044 research outputs found
Automated sequence and motion planning for robotic spatial extrusion of 3D trusses
While robotic spatial extrusion has demonstrated a new and efficient means to
fabricate 3D truss structures in architectural scale, a major challenge remains
in automatically planning extrusion sequence and robotic motion for trusses
with unconstrained topologies. This paper presents the first attempt in the
field to rigorously formulate the extrusion sequence and motion planning (SAMP)
problem, using a CSP encoding. Furthermore, this research proposes a new
hierarchical planning framework to solve the extrusion SAMP problems that
usually have a long planning horizon and 3D configuration complexity. By
decoupling sequence and motion planning, the planning framework is able to
efficiently solve the extrusion sequence, end-effector poses, joint
configurations, and transition trajectories for spatial trusses with
nonstandard topologies. This paper also presents the first detailed computation
data to reveal the runtime bottleneck on solving SAMP problems, which provides
insight and comparing baseline for future algorithmic development. Together
with the algorithmic results, this paper also presents an open-source and
modularized software implementation called Choreo that is machine-agnostic. To
demonstrate the power of this algorithmic framework, three case studies,
including real fabrication and simulation results, are presented.Comment: 24 pages, 16 figure
Exploiting Multi Stability of Compliant Locking Mechanism for Reconfigurable Articulation in Robotic Arm
This study analyzes a biology inspired approach of utilizing a compliant unit actuator to simplify the control requirements for a soft robotic arm. A robot arm is constructed from a series of compliant unit actuators that precisely actuate between two stable states. The extended state can be characterized as a rigid link with a high bending stiffness. The compressed state can be characterized as a flexible joint with a low bending stiffness. Without the use of an external power source, the bistable mechanism remains in each of the stable states. The unit actuator can demonstrate pseudo-linkage kinematics that require less control parameters than entirely soft manipulators. An advantage of using compliant mechanisms to design a robotic arm is that the bending stiffness ratio between the extended and compressed states is related to the frame and flexural member geometry. Post buckling characteristics of thin flexural members, combined with a cantilever style frame design gives the unit actuator versatile advantages over existing actuator designs like layer jamming and shape memory polymers. To achieve efficient movement with the optimized unit actuator design, experimental validation was performed, and a robotic arm prototype was fabricated. The tendon-driven robotic arm consisted of three modules and proved the capability of transforming and rotating in the eight configurations. The deformations of the robotic arm are accurately predicted by the kinematic model and validate the compliant mechanism arm and simple control system
A shape memory alloy-based biomimetic robotic hand : design, modelling and experimental evaluation
Every year more the 400,000 people are subject to an upper limb amputation. Projections foresee that this number may double by the 2050. Infections, trauma, cancer, or complications that arise in blood vessels represent the main causes for amputations. The access to prosthetic care is worldwide extremely limited. This is mainly due to the high cost both of commercially available prostheses and of the rehabilitation procedure which every prostheses user has to endure. Aside from high costs, commercially available hand prostheses have faced high rejection rates, mainly due to the their heavy weight, noisy operation and also to the unnatural feel of the fingers. To overcome these limitations, new materials, such as Shape Memory Alloys (SMAs), have been considered as potential candidate actuators for these kind of devices. In order to provide a contribution in the development of performant and easily affordable hand prostheses, the development of a novel and cost-effective five-fingered hand prototype actuated by Shape Memory Alloy (SMA) wires is presented in this work. The dissertation starts with the description of a first generation of a SMA actuated finger. Structure assemblage and performances in term of force, motion and reactiveness are investigated to highlight advantages and disadvantages of the prototype. In order to improve the achievable performances, a second generation of SMA actuated finger having soft features is introduced. Its structure, a five-fingered hand prosthesis having intrinsically elastic fingers, capable to grasp several types of objects with a considerable force, and an entirely 3D printed structure is then presented. Comparing this prototype with the most important prostheses developed so far, relevant advantages especially in term of noiseless actuation, cost, weight, responsiveness and force can be highlighted. A finite element based framework is then developed, to enable additional structure optimization and further improve the SMA finger performances. On the same time, a concentrated parameters physics-based model is formulated to allow, in the future, an easier control of the device, characterized by strong nonlinearities mainly due to the Shape Memory alloy hysteretic behavior.Jedes Jahr werden weltweit bei mehr als 400.000 Menschen Amputationen der oberen Gliedmaßen durchgeführt. Prognosen gehen davon aus, dass sich diese Zahl bis zum Jahr 2050 verdoppeln wird. Hauptursachen der Amputationen sind Infektionen, Unfälle, Krebs oder Durchblutungsstörungen. Der Zugang zu prothetischer Versorgung ist besonders in den Entwicklungsländern stark eingeschränkt. Dies liegt vor allem an den hohen Kosten sowohl der im Handel erhältlichen Prothesen als auch des Rehabilitationsprozesses, den jeder Prothesenträger durchlaufen muss. Neben den hohen Kosten haben kommerziell erhältliche Handprothesen aufgrund ihres hohen Gewichts, des lauten Betriebes und auch des unnatürlichen Gefühls hohe Ablehnungsraten. Um diese Einschränkungen zu überwinden, wurden neue Materialien, wie z.B. Formgedächtnislegierungen (SMAs), als potenzielle Materialien für den Antrieb von Prothesen untersucht . Um einen Beitrag zur Entwicklung von leistungsfähigen und erschwinglichen Handprothesen zu leisten, wird in dieser Arbeit die Entwicklung eines neuartigen und kostengünstigen Fünf-Finger-Handprototyps vorgestellt, der durch Drähte aus Formgedächtnislegierungen aktiviert wird. Die Doktorarbeit beginnt mit der Beschreibung der ersten Generation eines SMA-aktivierten Fingers. Zuerst wird der Aufbau und das Wirkungsprinzip des SMA Fingers erläutert und die Leistungs- und Bewegungsfähigkeit des Systems untersucht sowie Vor- und Nachteile des Prototyps dargestellt. Anschließend, um die erreichbare Leistungsfähigkeit zu verbessern, wird eine zweite Generation von SMA-gesteuerten Fingern vorgestellt, die eine vollständig in 3D gedruckte Struktur aufweisen. Diese Fünffinger-Handprothese mit inhärent elastischen Fingern ermöglicht nicht nur das Greifen unterschiedlich geformter Objekte sondern auch das Heben und Halten schwerer Gegenstände. Dieser neuartige Prototyp wird mit den wichtigsten bisher entwickelten Prothesen verglichen und die relevanten Vorteile insbesondere in Bezug auf geräuschlose Ansteuerung, Kosten, Gewicht, Reaktionszeit und Kraft hervorgehoben. Abschließend wird ein Finite-Elemente-Modell entwickelt, mit Hilfe dessen die Fingerstruktur weiter optimiert und die Leistungsfähigkeit des SMA-Fingers noch verbessert werden kann. Zusätzlich wird ein Konzentriertes-Parameter-Modell formuliert, um, in der Zukunft, eine leichtere Regelung des Systems zu ermöglichen. Dieses ist notwendig, da der SMA-Finger starke Nichtlinearitäten aufweist, die auf das hysteretische Verhalten der Formgedächtnislegierung zurückzuführen sind
Design, modeling and implementation of a soft robotic neck for humanoid robots
Mención Internacional en el título de doctorSoft humanoid robotics is an emerging field that combines the flexibility and safety of soft
robotics with the form and functionality of humanoid robotics. This thesis explores the potential
for collaboration between these two fields with a focus on the development of soft joints for the
humanoid robot TEO. The aim is to improve the robot’s adaptability and movement, which are
essential for an efficient interaction with its environment.
The research described in this thesis involves the development of a simple and easily transportable
soft robotic neck for the robot, based on a 2 Degree of Freedom (DOF) Cable Driven
Parallel Mechanism (CDPM). For its final integration into TEO, the proposed design is later
refined, resulting in an efficiently scaled prototype able to face significant payloads.
The nonlinear behaviour of the joints, due mainly to the elastic nature of their soft links,
makes their modeling a challenging issue, which is addressed in this thesis from two perspectives:
first, the direct and inverse kinematic models of the soft joints are analytically studied,
based on CDPM mathematical models; second, a data-driven system identification is performed
based on machine learning techniques. Both approaches are deeply studied and compared, both
in simulation and experimentally.
In addition to the soft neck, this thesis also addresses the design and prototyping of a soft
arm capable of handling external loads. The proposed design is also tendon-driven and has a
morphology with two main bending configurations, which provides more versatility compared
to the soft neck.
In summary, this work contributes to the growing field of soft humanoid robotics through
the development of soft joints and their application to the humanoid robot TEO, showcasing the
potential of soft robotics to improve the adaptability, flexibility, and safety of humanoid robots.
The development of these soft joints is a significant achievement and the research presented in this thesis paves the way for further exploration and development in this field.La robótica humanoide blanda es un campo emergente que combina la flexibilidad y seguridad
de la robótica blanda con la forma y funcionalidad de la robótica humanoide. Esta
tesis explora el potencial de colaboración entre estos dos campos centrándose en el desarrollo
de una articulación blanda para el cuello del robot humanoide TEO. El objetivo es mejorar la
adaptabilidad y el movimiento del robot, esenciales para una interacción eficaz con su entorno.
La investigación descrita en esta tesis consiste en el desarrollo de un prototipo sencillo
y fácilmente transportable de cuello blando para el robot, basado en un mecanismo paralelo
actuado por cable de 2 grados de libertad. Para su integración final en TEO, el diseño propuesto
es posteriormente refinado, resultando en un prototipo eficientemente escalado capaz de manejar
cargas significativas.
El comportamiemto no lineal de estas articulaciones, debido fundamentalmente a la naturaleza
elástica de sus eslabones blandos, hacen de su modelado un gran reto, que en esta tesis
se aborda desde dos perspectivas diferentes: primero, los modelos cinemáticos directo e inverso
de las articulaciones blandas se estudian analíticamente, basándose en modelos matemáticos de
mecanismos paralelos actuados por cable; segundo, se aborda el problema de la identificación
del sistema mediante técnicas basadas en machine learning. Ambas propuestas se estudian y
comparan en profundidad, tanto en simulación como experimentalmente.
Además del cuello blando, esta tesis también aborda el diseño de un brazo robótico blando
capaz de manejar cargas externas. El diseño propuesto está igualmente basado en accionamiento
por tendones y tiene una morfología con dos configuraciones principales de flexión, lo que
proporciona una mayor versatilidad en comparación con el cuello robótico blando.
En resumen, este trabajo contribuye al creciente campo de la robótica humanoide blanda
mediante el desarrollo de articulaciones blandas y su aplicación al robot humanoide TEO, mostrando el potencial de la robótica blanda para mejorar la adaptabilidad, flexibilidad y seguridad
de los robots humanoides. El desarrollo de estas articulaciones es una contribución
significativa y la investigación presentada en esta tesis allana el camino hacia nuevos desarrollos
y retos en este campo.Programa de Doctorado en Ingeniería Eléctrica, Electrónica y Automática por la Universidad Carlos III de MadridPresidenta: Cecilia Elisabet García Cena.- Secretario: Dorin Sabin Copaci.- Vocal: Martin Fodstad Stole
Efficient Jacobian-Based Inverse Kinematics With Sim-to-Real Transfer of Soft Robots by Learning
This paper presents an efficient learning-based method to solve the inverse
kinematic (IK) problem on soft robots with highly non-linear deformation. The
major challenge of efficiently computing IK for such robots is due to the lack
of analytical formulation for either forward or inverse kinematics. To address
this challenge, we employ neural networks to learn both the mapping function of
forward kinematics and also the Jacobian of this function. As a result,
Jacobian-based iteration can be applied to solve the IK problem. A sim-to-real
training transfer strategy is conducted to make this approach more practical.
We first generate a large number of samples in a simulation environment for
learning both the kinematic and the Jacobian networks of a soft robot design.
Thereafter, a sim-to-real layer of differentiable neurons is employed to map
the results of simulation to the physical hardware, where this sim-to-real
layer can be learned from a very limited number of training samples generated
on the hardware. The effectiveness of our approach has been verified on
pneumatic-driven soft robots for path following and interactive positioning
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