30 research outputs found
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Pneupard: A biomimetic musculoskeletal approach for a feline-inspired quadruped robot
Feline locomotion combines great acrobatic proficiency,
unparalleled balance and higher accelerations than
other animals. Capable of accelerating from 0 to 100 km h−1 in
three seconds, the cheetah (Acinonyx jubatus) is still a mystery
which intrigues scientists. Aiming for a better understanding
of the source of such higher speeds, we develop a biomimetic
platform, where musculoskeletal parameters (range of motion
and moment arms) from the biological system can be evaluated
with air muscles within a lightweight robotic structure. We performed
experiments validating the muscular structure during
a treadmill walk, successfully reproducing animal locomotion
while adopting an EMG based control method.This work was partially supported by KAKENHI Kiban(S) 23220004.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1109/IROS.2013.6696540
Producing alternating gait on uncoupled feline hindlimbs: Muscular unloading rule on a biomimetic robot
Studies on decerebrate walking cats have shown that phase transition is strongly related to muscular sensory signals at limbs. To further investigate the role of such signals terminating the stance phase, we developed a biomimetic feline platform. Adopting link lengths and moment arms from an Acinonyx jubatus, we built a pair of hindlimbs connected to a hindquarter and attached it to a sliding strut, simulating solid forelimbs. Artificial pneumatic muscles simulate biological muscles through a control method based on EMG signals from walking cats (Felis catus). Using the bio-inspired muscular unloading rule, where a decreasing ground reaction force triggers phase transition, stable walking on a treadmill was achieved. Finally, an alternating gait is possible using the unloading rule, withstanding disturbances and systematic muscular changes, not only contributing to our understanding on how cats may walk, but also helping develop better legged robots.The authors acknouledge the Japanese Research Grant KAKENHI Kiban 23220004 and 25540117.This is the author accepted manuscript. The final version is available from Taylor & Francis via http://dx.doi.org/10.1080/01691864.2013.87049
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Exploring muscular contribution during stepping of biomimetic feline hindlimbs
Although robotic locomotion have greatly advanced
over the past years, the abyss that separates such locomotion
from even the simplest animal locomotions prompt us to
approach robotic locomotion taking cues from animals. The animal
musculoskeletal structure, often ignored by roboticists due
to its high redundancy and complexity, might hold the secret
for self-stable locomotion observed in bipeds and quadrupeds.
Aiming to better understand how muscles contribute to selfstable
locomotion we take the feline structure as a model on
a biomimetic approach. Using 6 air muscles per hindlimb to
mimic real muscles, this robot walks stably on a treadmill while
supported by a slider, simulating forelimbs. We individually
evaluate muscle contribution to walking stability, performing a
comparison between mono and biarticular synergistic muscles
at the ankle and concluding that a higher compliance on
the biarticular muscle improved walking stability. A better
understanding of such complex phenomena may help on the
development of better legged robots in the future, truly taking
advantage of concepts developed by nature over the years.This work was partially supported by KAKENHI Kiban(S) 23220004.This is the accepted manuscript. The final version is available at http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6739573&tag=1
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Stable reflex-based walking of forelimbs of a bio-inspired quadruped robot-modeled cheetah
In contrast to the high movement adaptability of
quadruped animals in many environmental conditions, it is
hard for conventional quadruped robots to operate in complex
environment conditions. We investigate the adaptability of
animals’ musculo-skeletal systems, by building a bio-inspired
quadruped robot named ”Pneupard” which duplicates a feline
musculo-skeletal system. In this study, we built Pneupard’s
forelimb which has 14 active muscles, 4 passive muscles and 8
degrees of freedom (DOF). We propose sole reflex-based control
and verify its effectiveness by conducting walking experiments,
in which the robot performed stable walking with a two-dimensional
restriction.This work was partially supported by a Grant-in-Aid for Scientific
Research(23220004) from the Japanese Ministry of Education, Culture,
Sports, Science and Technology.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1109/ROBIO.2013.673973
Electronic structure and molecular orientation of a Zn-tetra-phenyl porphyrin multilayer on Si(111)
The electronic properties and the molecular orientation of
Zn-tetraphenyl-porphyrin films deposited on Si(111) have been investigated
using synchrotron radiation. For the first time we have revealed and assigned
the fine structures in the electronic spectra related to the HOMOs and LUMOs
states. This is particularly important in order to understand the orbital
interactions, the bond formation and the evolution of the electronic properties
with oxidation or reduction of the porphyrins in supramolecular donor-acceptor
complexes used in photovoltaic devices.Comment: text 11 pages, 4 figures submitted for publicatio