231 research outputs found
A new meta-module for efficient reconfiguration of hinged-units modular robots
We present a robust and compact meta-module for edge-hinged modular robot units such as M-TRAN,
SuperBot, SMORES, UBot, PolyBot and CKBot, as well as for central-point-hinged ones such as Molecubes and
Roombots. Thanks to the rotational degrees of freedom of these units, the novel meta-module is able to expand
and contract, as to double/halve its length in each dimension. Moreover, for a large class of edge-hinged robots the
proposed meta-module also performs the scrunch/relax and transfer operations required by any tunneling-based
reconfiguration strategy, such as those designed for Crystalline and Telecube robots. These results make it possible to
apply efficient geometric reconfiguration algorithms to this type of robots. We prove the size of this new meta-module to
be optimal. Its robustness and performance substantially improve over previous results.Peer ReviewedPostprint (author's final draft
A modal approach to hyper-redundant manipulator kinematics
This paper presents novel and efficient kinematic modeling techniques for “hyper-redundant” robots. This approach is based on a “backbone curve” that captures the robot's macroscopic geometric features. The inverse kinematic, or “hyper-redundancy resolution,” problem reduces to determining the time varying backbone curve behavior. To efficiently solve the inverse kinematics problem, the authors introduce a “modal” approach, in which a set of intrinsic backbone curve shape functions are restricted to a modal form. The singularities of the modal approach, modal non-degeneracy conditions, and modal switching are considered. For discretely segmented morphologies, the authors introduce “fitting” algorithms that determine the actuator displacements that cause the discrete manipulator to adhere to the backbone curve. These techniques are demonstrated with planar and spatial mechanism examples. They have also been implemented on a 30 degree-of-freedom robot prototype
AN INVESTIGATION INTO THE DESIGN AND CONSTRUCTION OF A LOW REYNOLDS NUMBER SWIMMER
This work was motivated by the goal of building a robot capable of swimming on a microscopic scale by changing its shape. Two approaches to low Reynolds number swimming are studied. A deformable sphere is investigated which uses a method of construction called tensegrity to allow changes in shape. We found a method of matching tensegrity spheres to desired shapes and investigated the use of shape memory alloy coils as tensile elements. We propose a model for a box-shaped deformable swimmer, and a prototype is built and tested. The negative results from the prototype tests are then investigated by measuring the drag forces caused by pushing different block sizes through high viscosity fluid. Based on our experimental results we validate our approach and recommend design modifications for a second generation robot
Heterogeneous Self-Reconfiguring Robotics: Ph.D. Thesis Proposal
Self-reconfiguring robots are modular systems that can change shape, or reconfigure, to match structure to task. They comprise many small, discrete, often identical modules that connect together and that are minimally actuated. Global shape transformation is achieved by composing local motions. Systems with a single module type, known as homogeneous systems, gain fault tolerance, robustness and low production cost from module interchangeability. However, we are interested in heterogeneous systems, which include multiple types of modules such as those with sensors, batteries or wheels. We believe that heterogeneous systems offer the same benefits as homogeneous systems with the added ability to match not only structure to task, but also capability to task. Although significant results have been achieved in understanding homogeneous systems, research in heterogeneous systems is challenging as key algorithmic issues remain unexplored. We propose in this thesis to investigate questions in four main areas: 1) how to classify heterogeneous systems, 2) how to develop efficient heterogeneous reconfiguration algorithms with desired characteristics, 3) how to characterize the complexity of key algorithmic problems, and 4) how to apply these heterogeneous algorithms to perform useful new tasks in simulation and in the physical world. Our goal is to develop an algorithmic basis for heterogeneous systems. This has theoretical significance in that it addresses a major open problem in the field, and practical significance in providing self-reconfiguring robots with increased capabilities
Propulsion and control of deformable bodies in an ideal fluid
Motivated by considerations of shape changing propulsion of underwater robotic vehicles, this paper analyses the mechanics of deformable bodies operating in an ideal fluid. The application of methods from geometric mechanics results in a compact and insightful formulation of the problem. We develop an explicit formula for the fluid mechanical connection, in terms of the fluid potential function, for this class of systems. The connection can be used to analyze many issues in motion planning and control. The theory is illustrated by application to an amoeba-like device
MUSME 2011 4 th International Symposium on Multibody Systems and Mechatronics
El libro de actas recoge las aportaciones de los autores a través de los correspondientes artículos a la Dinámica de Sistemas Multicuerpo y la Mecatrónica (Musme). Estas disciplinas se han convertido en una importante herramienta para diseñar máquinas, analizar prototipos virtuales y realizar análisis CAD sobre complejos sistemas mecánicos articulados multicuerpo. La dinámica de sistemas multicuerpo comprende un gran número de aspectos que incluyen la mecánica, dinámica estructural, matemáticas aplicadas, métodos de control, ciencia de los ordenadores y mecatrónica. Los artículos recogidos en el libro de actas están relacionados con alguno de los siguientes tópicos del congreso:
Análisis y síntesis de mecanismos
; Diseño de algoritmos para sistemas mecatrónicos
; Procedimientos de simulación y resultados
; Prototipos y rendimiento
; Robots y micromáquinas
; Validaciones experimentales
; Teoría de simulación mecatrónica
; Sistemas mecatrónicos
; Control de sistemas mecatrónicosUniversitat Politècnica de València (2011). MUSME 2011 4 th International Symposium on Multibody Systems and Mechatronics. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/13224Archivo delegad
Deep learning in medical image registration: introduction and survey
Image registration (IR) is a process that deforms images to align them with
respect to a reference space, making it easier for medical practitioners to
examine various medical images in a standardized reference frame, such as
having the same rotation and scale. This document introduces image registration
using a simple numeric example. It provides a definition of image registration
along with a space-oriented symbolic representation. This review covers various
aspects of image transformations, including affine, deformable, invertible, and
bidirectional transformations, as well as medical image registration algorithms
such as Voxelmorph, Demons, SyN, Iterative Closest Point, and SynthMorph. It
also explores atlas-based registration and multistage image registration
techniques, including coarse-fine and pyramid approaches. Furthermore, this
survey paper discusses medical image registration taxonomies, datasets,
evaluation measures, such as correlation-based metrics, segmentation-based
metrics, processing time, and model size. It also explores applications in
image-guided surgery, motion tracking, and tumor diagnosis. Finally, the
document addresses future research directions, including the further
development of transformers
Topology based representations for motion synthesis and planning
Robot motion can be described in several alternative representations, including
joint configuration or end-effector spaces. These representations are often used for
manipulation or navigation tasks but they are not suitable for tasks that involve
close interaction with the environment. In these scenarios, collisions and relative
poses of the robot and its surroundings create a complex planning space. To deal
with this complexity, we exploit several representations that capture the state of
the interaction, rather than the state of the robot. Borrowing notions of topology invariances
and homotopy classes, we design task spaces based on winding numbers
and writhe for synthesizing winding motion, and electro-static fields for planning
reaching and grasping motion. Our experiments show that these representations
capture the motion, preserving its qualitative properties, while generalising over
finer geometrical detail. Based on the same motivation, we utilise a scale and
rotation invariant representation for locally preserving distances, called interaction
mesh. The interaction mesh allows for transferring motion between robots of
different scales (motion re-targeting), between humans and robots (teleoperation)
and between different environments (motion adaptation). To estimate the state of
the environment we employ real-time sensing techniques utilizing dense stereo
tracking, magnetic tracking sensors and inertia measurements units.
We combine and exploit these representations for synthesis and generalization
of motion in dynamic environments. The benefit of this method is on problems
where direct planning in joint space is extremely hard whereas local optimal control
exploiting topology and metric of these novel representations can efficiently
compute optimal trajectories. We formulate this approach in the framework of
optimal control as an approximate inference problem. This allows for consistent
combination of multiple task spaces (e.g. end-effector, joint space and the abstract
task spaces we investigate in this thesis).
Motion generalization to novel situations and kinematics is similarly performed
by projecting motion from abstract representations to joint configuration space.
This technique, based on operational space control, allows us to adapt the motion
in real time. This process of real-time re-mapping generates robust motion, thus
reducing the amount of re-planning.We have implemented our approach as a part
of an open source project called the Extensible Optimisation library (EXOTica).
This software allows for defining motion synthesis problems by combining task
representations and presenting this problem to various motion planners using a
common interface. Using EXOTica, we perform comparisons between different
representations and different planners to validate that these representations truly
improve the motion planning
Innovative robot hand designs of reduced complexity for dexterous manipulation
This thesis investigates the mechanical design of robot hands to sensibly reduce the system complexity in terms of the number of actuators and sensors, and control needs for performing grasping and in-hand manipulations of unknown objects.
Human hands are known to be the most complex, versatile, dexterous manipulators in nature, from being able to operate sophisticated surgery to carry out a wide variety of daily activity tasks (e.g. preparing food, changing cloths, playing instruments, to name some). However, the understanding of why human hands can perform such fascinating tasks still eludes complete comprehension.
Since at least the end of the sixteenth century, scientists and engineers have tried to match the sensory and motor functions of the human hand. As a result, many contemporary humanoid and anthropomorphic robot hands have been developed to closely replicate the appearance and dexterity of human hands, in many cases using sophisticated designs that integrate multiple sensors and actuators---which make them prone to error and difficult to operate and control, particularly under uncertainty.
In recent years, several simplification approaches and solutions have been proposed to develop more effective and reliable dexterous robot hands. These techniques, which have been based on using underactuated mechanical designs, kinematic synergies, or compliant materials, to name some, have opened up new ways to integrate hardware enhancements to facilitate grasping and dexterous manipulation control and improve reliability and robustness.
Following this line of thought, this thesis studies four robot hand hardware aspects for enhancing grasping and manipulation, with a particular focus on dexterous in-hand manipulation. Namely: i) the use of passive soft fingertips; ii) the use of rigid and soft active surfaces in robot fingers; iii) the use of robot hand topologies to create particular in-hand manipulation trajectories; and iv) the decoupling of grasping and in-hand manipulation by introducing a reconfigurable palm.
In summary, the findings from this thesis provide important notions for understanding the significance of mechanical and hardware elements in the performance and control of human manipulation. These findings show great potential in developing robust, easily programmable, and economically viable robot hands capable of performing dexterous manipulations under uncertainty, while exhibiting a valuable subset of functions of the human hand.Open Acces
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