1,648 research outputs found
The impact of information sharing, random yield, correlation, and lead times in closed loop supply chains
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordWe investigate the impact of advance notice of product returns on the performance of a decentralised closed loop supply chain. The market demands and the product returns are stochastic and are correlated with each other. The returned products are converted into "as-good-as-new" products and used, together with new products, to satisfy the market demand. The remanufacturing process takes time and is subject to a random yield. We investigate the benefit of the manufacturer obtaining advance notice of product returns from the remanufacturer. We demonstrate that lead times, random yields and the parameters describing the returns play a significant role in the benefit of the advance notice scheme. Our mathematical results offer insights into the benefits of lead time reduction and the adoption of information sharing schemes.Japan Society for the Promotion of Scienc
Realization of three-dimensional walking of a cheetah-modeled bio-inspired quadruped robot
Adaptability of quadruped animals is not solely
reached by brain control, but by the interaction between its
body, environment, and control. Especially, morphology of the
body is supposed to contribute largely to the adaptability. We
have tried to understand quadrupedal locomotion by building
a bio-inspired quadruped robot named ”Pneupard”, which has
a feline-like muscular-skeletal structure. In our previous study,
we successfully realized alternative gait of hindlimbs by reflex
control based on the sole touch information, which is called an
unloading rule, and that of forelimbs as well. In this paper, we
finally connect forelimbs and hindlimbs by a rigid spine, and
conduct 3D walking experiments only with the simple unloading
rule. Through several preliminary experiments, we realize that
the touch information on the sole is the most critical for stable
3D walking.This work was partially supported by Grant-in-Aid for Scientific Research
on 23220004, 25540117 of Japan.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1109/ROBIO.2014.7090426
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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
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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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
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Quadrupedal locomotion based on a muscular activation pattern with stretch-reflex
Cyclical locomotion, such as walking, hopping and
running, is known to be generated at the spinal cord, guiding
human and animal strides over different gaits. Over the last
years, many researchers concentrated their study on the origin
of such signals, replicating them by either controlling joint
angles or torques. In this work, we use a quadruped pneumatic
robot to reproduce stable walking on a treadmill through a
muscular activation pattern. Unlike previous studies, neither
angles or torques are taken into consideration. Similarly to
biological morphology, with variating moment arms, muscles
contract rhythmically and their inherent compliance adapts
to the floor. Proportional feedback upon touching the floor
(stretch-reflex) is also tested, and its effects are explained. In the
future, this methodology can be used to produce adaptive gait
and improve current robotic by exploring interaction between
control and soft bodies.This work was aided by KAKENHI Kiban(S) 23220004 and 25540117.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1109/ROBIO.2014.7090425
The impact of freight transport capacity limitations on supply chain dynamics
We investigate how capacity limitations in the transportation system affect the dynamic behaviour of supply chains. We are interested in the more recently defined, 'backlash' effect. Using a system dynamics simulation approach, we replicate the well-known Beer Game supply chain for different transport capacity management scenarios. The results indicate that transport capacity limitations negatively impact on inventory and backlog costs, although there is a positive impact on the 'backlash' effect. We show that it is possible for both backlog and inventory to simultaneous occur, a situation which does not arise with the uncapacitated scenario. A vertical collaborative approach to transport provision is able to overcome such a trade-off. © 2013 Taylor & Francis
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