91 research outputs found
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Muscle roles on directional change during hopping of a biomimetic feline hindlimb
Cats, from tiny domestic cats (Felix Catus) to big
tigers (Panthera Tigris), are well known for their great acrobatic
skills and hunting ability. Aiming to better understand how
the feline family interacts with the environment, we adopt
a biomimetic approach on a hopping feline hindlimb. Using
air muscles to simulate the compliance of biological muscles,
this robotic hindlimb has seven muscles and changes hopping
direction. We individually evaluate and estimate muscles contribution
to the jumping direction. Finally, we successfully control
the hopping direction using a non-linear curve fitting from experimental
results, hopefully contributing to the understanding
of our biological counterpart.This work was partially supported by KAKENHI Kiban(S) 23220004This is the accepted manuscript. The final version's available at http://dx.doi.org/10.1109/ROBIO.2012.6491108
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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 hâ1 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
animalsâ musculo-skeletal systems, by building a bio-inspired
quadruped robot named âPneupardâ which duplicates a feline
musculo-skeletal system. In this study, we built Pneupardâs
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
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Development of a minimalistic pneumatic quadruped robot for fast locomotion
In this paper, we describe the development of the
quadruped robot âKenâ with the minimalistic and lightweight
body design for achieving fast locomotion. We use McKibben
pneumatic artificial muscles as actuators, providing high frequency
and wide stride motion of limbs, also avoiding problems
with overheating. We conducted a preliminary experiment,
finding out that the robot can swing its limb over 7.5 Hz
without amplitude reduction, nor heat problems. Moreover, the
robot realized a several steps of bouncing gait by using simple
CPG-based open loop controller, indicating that the robot can
generate enough torque to kick the ground and limb contraction
to avoid stumbling.This work was partially supported by KAKENHI 23220004, KAKENHI
24000012 and KAKENHI 23700233.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1109/ROBIO.2012.6490984
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
Barrier formation at metal/organic interfaces: dipole formation and the Charge Neutrality Level
The barrier formation for metal/organic semiconductor interfaces is analyzed
within the Induced Density of Interface States (IDIS) model. Using weak
chemisorption theory, we calculate the induced density of states in the organic
energy gap and show that it is high enough to control the barrier formation. We
calculate the Charge Neutrality Levels of several organic molecules (PTCDA,
PTCBI and CBP) and the interface Fermi level for their contact with a Au(111)
surface. We find an excellent agreement with the experimental evidence and
conclude that the barrier formation is due to the charge transfer between the
metal and the states induced in the organic energy gap.Comment: 7 pages, Proceedings of ICFSI-9, Madrid, Spain (September 2003),
special issue of Applied Surface Science (in press
Growth, Yield and Mineral Composition of Three Rice Varieties Cultivated under Salt-Affected Conditions
A pot experiment was conducted to study the relative performance of IR 6,KS 282 and IR 10198-66-2 rice varieties cultivated under salt-affected conditions at EC of 6.0,9.0 12.0 dS m(-1) in a sandy clay loam soil havig ECe of 1.6 dS m(-1) treated as control. Six seedlings of 39-day old transplaned to each pot having 12 kg soil. The fertilizer as nitrophos and potassium sulphate at the rate of 57.0, 25.0 and 50.0 mg N,P and K kg(-1) soil respectively was applied at the time of transplanting while zinc sulphate at the rate of 5 mg Zn kg(-1) soil and 43.0 mg N kg(-1) of soil as additional dose were applied 19 and 30 days after transplanting respectively. Normal plant protection measures like number of tillers, panicles, paddy grains, filled and unifilled grains, yield per plant and sterility were recorded and shoot and straw samples were analysed for sodium, potassium, calcium and chloride contents. It was observed that growth and yield of all the varieties were reduced significantly with increasing soil salinity. Na/K and Na/Ca rations in shoot and straw increased significantly with increasing soil salinity. It was also observed that higher values of Na/K and Na/Ca rations in shoots affected growth parameters while higher values of these rations in straw affected yield components and grain yield. However, IR 6 having relatively lower values of Na/K and Na/Ca rations proved to be the most salt-tolerant rice among the three varieties studied
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