1,566 research outputs found
A "Sidewinding" Locomotion Gait for Hyper-Redundant Robots
This paper considers the kinematics of a novel form of hyper-redundant mobile robot locomotion which is analogous to the 'sidewinding' locomotion of desert snakes. This form of locomotion can be generated by a repetitive travel wave of mechanism bending. Using a continuous backbone curve model, we develop algorithms which enable travel in a uniform direction as well as changes in direction
Anisotropic collisions of dipolar Bose-Einstein condensates in the universal regime
We report the measurement of collisions between two Bose-Einstein condensates
with strong dipolar interactions. The collision velocity is significantly
larger than the internal velocity distribution widths of the individual
condensates, and thus, with the condensates being sufficiently dilute, a halo
corresponding to the two-body differential scattering cross section is
observed. The results demonstrate a novel regime of quantum scattering,
relevant to dipolar interactions, in which a large number of angular momentum
states become coupled during the collision. We perform Monte-Carlo simulations
to provide a detailed comparison between theoretical two-body cross sections
and the experimental observations.Comment: 10 pages, 5 figure
A Miniature Robot for Isolating and Tracking Neurons in Extracellular Cortical Recordings
This paper presents a miniature robot device and control algorithm that can autonomously position electrodes in cortical tissue for isolation and tracking of extracellular signals of individual neurons. Autonomous electrode positioning can significantly enhance the efficiency and quality of acute electrophysiolgical experiments aimed at basic understanding of the nervous system. Future miniaturized systems of this sort could also overcome some of the inherent difficulties in estabilishing long-lasting neural interfaces that are needed for practical realization of neural prostheses. The paper describes the robot's design and summarizes the overall structure of the control system that governs the electrode positioning process. We present a new sequential clustering algorithm that is key to improving our system's performance, and which may have other applications in robotics. Experimental results in macaque cortex demonstrate the validity of our approach
The Fractal Hand-II: Reviving a Classic Mechanism for Contemporary Grasping Challenges
This paper, and its companion, propose a new fractal robotic gripper, drawing
inspiration from the century-old Fractal Vise. The unusual synergistic
properties allow it to passively conform to diverse objects using only one
actuator. Designed to be easily integrated with prevailing parallel jaw
grippers, it alleviates the complexities tied to perception and grasp planning,
especially when dealing with unpredictable object poses and geometries. We
build on the foundational principles of the Fractal Vise to a broader class of
gripping mechanisms, and also address the limitations that had led to its
obscurity. Two Fractal Fingers, coupled by a closing actuator, can form an
adaptive and synergistic Fractal Hand. We articulate a design methodology for
low cost, easy to fabricate, large workspace, and compliant Fractal Fingers.
The companion paper delves into the kinematics and grasping properties of a
specific class of Fractal Fingers and Hands.Comment: This paper is prepared for ICRA 202
Anisotropic expansion of a thermal dipolar Bose gas
We report on the anisotropic expansion of ultracold bosonic dysprosium gases
at temperatures above quantum degeneracy and develop a quantitative theory to
describe this behavior. The theory expresses the post-expansion aspect ratio in
terms of temperature and microscopic collisional properties by incorporating
Hartree-Fock mean-field interactions, hydrodynamic effects, and
Bose-enhancement factors. Our results extend the utility of expansion imaging
by providing accurate thermometry for dipolar thermal Bose gases, reducing
error in expansion thermometry from tens of percent to only a few percent.
Furthermore, we present a simple method to determine scattering lengths in
dipolar gases, including near a Feshbach resonance, through observation of
thermal gas expansion.Comment: main text and supplement, 11 pages total, 4 figure
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