2,100 research outputs found
Passively Adaptive Radiative Switch for Thermoregulation in Buildings
With the ever-growing need to reduce energy consumption, building materials
that passively heat or cool are gaining importance. However, many buildings
require both heating and cooling, even within the same day. To date, few
technologies can automatically switch between passive heating and cooling, and
those that can require a large temperature range to cycle states (>15o C),
making them ineffective for daily switching. We present a passively adaptive
radiative switch that leverages the expansion in phase-change energy storage
materials to actuate the motion of louvers and can cycle states in less than 3o
C. The black selective-absorber louvers induce high heat gain when closed, yet
when open, expose a white, emissive surface for low heat gain. During an
outdoor test in which temperature was held steady, our device reduced the
energetic cost of cooling by 3.1x and heating by 2.6x compared to non-switching
devices. Our concept opens the door for passively adaptive thermoregulating
building materials.Comment: 32 pages with supplementary information include
A Dexterous Tip-extending Robot with Variable-length Shape-locking
Soft, tip-extending "vine" robots offer a unique mode of inspection and
manipulation in highly constrained environments. For practicality, it is
desirable that the distal end of the robot can be manipulated freely, while the
body remains stationary. However, in previous vine robots, either the shape of
the body was fixed after growth with no ability to manipulate the distal end,
or the whole body moved together with the tip. Here, we present a concept for
shape-locking that enables a vine robot to move only its distal tip, while the
body is locked in place. This is achieved using two inextensible, pressurized,
tip-extending, chambers that "grow" along the sides of the robot body,
preserving curvature in the section where they have been deployed. The length
of the locked and free sections can be varied by controlling the extension and
retraction of these chambers. We present models describing this shape-locking
mechanism and workspace of the robot in both free and constrained environments.
We experimentally validate these models, showing an increased dexterous
workspace compared to previous vine robots. Our shape-locking concept allows
improved performance for vine robots, advancing the field of soft robotics for
inspection and manipulation in highly constrained environments.Comment: 7 pages,10 figures. Accepted to IEEE International Conference on
Rootics and Automation (ICRA) 202
Modeling, Reduction, and Control of a Helically Actuated Inertial Soft Robotic Arm via the Koopman Operator
Soft robots promise improved safety and capability over rigid robots when
deployed in complex, delicate, and dynamic environments. However, the infinite
degrees of freedom and highly nonlinear dynamics of these systems severely
complicate their modeling and control. As a step toward addressing this open
challenge, we apply the data-driven, Hankel Dynamic Mode Decomposition (HDMD)
with time delay observables to the model identification of a highly inertial,
helical soft robotic arm with a high number of underactuated degrees of
freedom. The resulting model is linear and hence amenable to control via a
Linear Quadratic Regulator (LQR). Using our test bed device, a dynamic,
lightweight pneumatic fabric arm with an inertial mass at the tip, we show that
the combination of HDMD and LQR allows us to command our robot to achieve
arbitrary poses using only open loop control. We further show that Koopman
spectral analysis gives us a dimensionally reduced basis of modes which
decreases computational complexity without sacrificing predictive power.Comment: Submitted to IEEE International Conference on Robotics and
Automation, 202
Shared-Control Teleoperation Paradigms on a Soft Growing Robot Manipulator
Semi-autonomous telerobotic systems allow both humans and robots to exploit
their strengths, while enabling personalized execution of a task. However, for
new soft robots with degrees of freedom dissimilar to those of human operators,
it is unknown how the control of a task should be divided between the human and
robot. This work presents a set of interaction paradigms between a human and a
soft growing robot manipulator, and demonstrates them in both real and
simulated scenarios. The robot can grow and retract by eversion and inversion
of its tubular body, a property we exploit to implement interaction paradigms.
We implemented and tested six different paradigms of human-robot interaction,
beginning with full teleoperation and gradually adding automation to various
aspects of the task execution. All paradigms were demonstrated by two expert
and two naive operators. Results show that humans and the soft robot
manipulator can split control along degrees of freedom while acting
simultaneously. In the simple pick-and-place task studied in this work,
performance improves as the control is gradually given to the robot, because
the robot can correct certain human errors. However, human engagement and
enjoyment may be maximized when the task is at least partially shared. Finally,
when the human operator is assisted by haptic feedback based on soft robot
position errors, we observed that the improvement in performance is highly
dependent on the expertise of the human operator.Comment: 15 pages, 14 figure
Soft Robotics. Bio-inspired Antagonistic Stiffening
Soft robotic structures might play a major role in the 4th industrial revolution. Researchers have demonstrated advantages of soft robotics over traditional robots made of rigid links and joints in several application areas including manufacturing, healthcare, and surgical interventions. However, soft robots have limited ability to exert larger forces and change their stiffness on demand over a wide range. Stiffness can be achieved as a result of the equilibrium of an active and a passive reaction force or of two active forces antagonistically collaborating. This paper presents a novel design paradigm for a fabric-based Variable Stiffness System including potential applications
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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