747 research outputs found
Anisotropic body compliance facilitates robotic sidewinding in complex environments
Sidewinding, a locomotion strategy characterized by the coordination of
lateral and vertical body undulations, is frequently observed in rattlesnakes
and has been successfully reconstructed by limbless robotic systems for
effective movement across diverse terrestrial terrains. However, the
integration of compliant mechanisms into sidewinding limbless robots remains
less explored, posing challenges for navigation in complex, rheologically
diverse environments. Inspired by a notable control simplification via
mechanical intelligence in lateral undulation, which offloads feedback control
to passive body mechanics and interactions with the environment, we present an
innovative design of a mechanically intelligent limbless robot for sidewinding.
This robot features a decentralized bilateral cable actuation system that
resembles organismal muscle actuation mechanisms. We develop a feedforward
controller that incorporates programmable body compliance into the sidewinding
gait template. Our experimental results highlight the emergence of mechanical
intelligence when the robot is equipped with an appropriate level of body
compliance. This allows the robot to 1) locomote more energetically
efficiently, as evidenced by a reduced cost of transport, and 2) navigate
through terrain heterogeneities, all achieved in an open-loop manner, without
the need for environmental awareness
Robust self-propulsion in sand using simply controlled vibrating cubes
Much of the Earth and many surfaces of extraterrestrial bodies are composed
of in-cohesive particle matter. Locomoting on granular terrain is challenging
for common robotic devices, either wheeled or legged. In this work, we discover
a robust alternative locomotion mechanism on granular media -- generating
movement via self-vibration. To demonstrate the effectiveness of this
locomotion mechanism, we develop a cube-shaped robot with an embedded vibratory
motor and conduct systematic experiments on diverse granular terrains of
various particle properties. We investigate how locomotion changes as a
function of vibration frequency/intensity on granular terrains. Compared to
hard surfaces, we find such a vibratory locomotion mechanism enables the robot
to move faster, and more stable on granular surfaces, facilitated by the
interaction between the body and surrounding granules. The simplicity in
structural design and controls of this robotic system indicates that vibratory
locomotion can be a valuable alternative way to produce robust locomotion on
granular terrains. We further demonstrate that such cube-shape robots can be
used as modular units for morphologically structured vibratory robots with
capabilities of maneuverable forward and turning motions, showing potential
practical scenarios for robotic systems
Mechanical Intelligence Simplifies Control in Terrestrial Limbless Locomotion
Limbless locomotors, from microscopic worms to macroscopic snakes, traverse
complex, heterogeneous natural environments typically using undulatory body
wave propagation. Theoretical and robophysical models typically emphasize body
kinematics and active neural/electronic control. However, we contend that
because such approaches often neglect the role of passive, mechanically
controlled processes (those involving "mechanical intelligence"), they fail to
reproduce the performance of even the simplest organisms. To uncover principles
of how mechanical intelligence aids limbless locomotion in heterogeneous
terradynamic regimes, here we conduct a comparative study of locomotion in a
model of heterogeneous terrain (lattices of rigid posts). We used a model
biological system, the highly studied nematode worm Caenorhabditis elegans, and
a robophysical device whose bilateral actuator morphology models that of
limbless organisms across scales. The robot's kinematics quantitatively
reproduced the performance of the nematodes with purely open-loop control;
mechanical intelligence simplified control of obstacle navigation and
exploitation by reducing the need for active sensing and feedback. An active
behavior observed in C. elegans, undulatory wave reversal upon head collisions,
robustified locomotion via exploitation of the systems' mechanical
intelligence. Our study provides insights into how neurally simple limbless
organisms like nematodes can leverage mechanical intelligence via appropriately
tuned bilateral actuation to locomote in complex environments. These principles
likely apply to neurally more sophisticated organisms and also provide a design
and control paradigm for limbless robots for applications like search and
rescue and planetary exploration.Comment: Published in Science Robotic
Application of Diamond Detectors in Tracking of Heavy Ion Slowed Down Radioactive Beams
Results of irradiation of thin Chemical Vapor Deposition (CVD) diamond detectors with low energy: p,α and 7Li beams are presented. Energy resolution: ΔE/E<1% of a single crystal detector was achieved. A coincident measurement with two diamond detectors showed time resolution of 100 ps and efficiency above 70%. Despite a high beam flux reaching 109 particles/s cm2 the tested detectors showed low dead-time and satisfactory radiation hardness. Perspectives of applying thin CVD diamond detectors in monitoring of a slowed down radioactive beam (RIB) are discussed.Spanish Ministry of Education and Science (MEC) FFPA2003-05958 and PA-2005-0446
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