The Experts below are selected from a list of 6078 Experts worldwide ranked by ideXlab platform

Kazuo Tsuchiya - One of the best experts on this subject based on the ideXlab platform.

  • Generation of bipedal walking through interactions among the robot dynamics, the Oscillator dynamics, and the environment: Stability characteristics of a five-link planar biped robot
    Autonomous Robots, 2011
    Co-Authors: Kazuo Tsuchiya
    Abstract:

    We previously developed a locomotion control system for a biped robot using nonlinear Oscillators and verified the performance of this system in order to establish adaptive walking through the interactions among the robot dynamics, the Oscillator dynamics, and the environment. In order to clarify these mechanisms, we investigate the stability characteristics of walking using a five-link planar biped robot with a torso and knee joints that has an Internal Oscillator with a stable limit cycle to generate the joint motions. Herein we conduct numerical simulations and a stability analysis, where we analytically obtain approximate periodic solutions and examine local stability using a Poincaré map. These analyses reveal (1) stability characteristics due to locomotion speed, torso, and knee motion, (2) stability improvement due to the modulation of Oscillator states based on phase resetting using foot-contact information, and (3) the optimal parameter in the Oscillator dynamics for adequately exploiting the interactions among the robot dynamics, the Oscillator dynamics, and the environment in order to increase walking stability. The results of the present study demonstrate the advantage and usefulness of locomotion control using Oscillators through mutual interactions.

  • stability characteristics in walking behavior with two different Oscillatory elements roles of arc foot and Internal Oscillator
    Intelligent Robots and Systems, 2008
    Co-Authors: Shinya Aoi, Yoichi Sato, Kazuo Tsuchiya
    Abstract:

    Simple models with circular arc feet rigidly mounted to the shank of the leg are widely used to investigate bipedal walking behavior. We use a simple walking model with arc feet, whose swing leg is driven by a rhythmic signal from an Internal Oscillator. The dynamical effects of the arc feet resemble flat feet mounted on ankles with a torsional spring, where the circular arc radius of the arc feet has similar dynamical characteristics to the spring stiffness in the ankle torque. Walking behavior generally consists of the falling motion of the body relative to the stance and the swinging motion of the swing leg. However, when the circular radius exceeds a certain threshold, the body motion changes from such divergent behavior to Oscillatory behavior due to the dynamical influence inherent in the arc feet, and the mechanism to create walking behavior greatly changes. Since our model is driven by a rhythmic signal from the Oscillator, the walking behavior is driven by two different Oscillatory elements and the relationship between them plays an important role. In this paper, we clarify the dynamical effect of the relationship on walking stability.

  • IROS - Stability characteristics in walking behavior with two different Oscillatory elements: Roles of arc foot and Internal Oscillator
    2008 IEEE RSJ International Conference on Intelligent Robots and Systems, 2008
    Co-Authors: Shinya Aoi, Yoichi Sato, Kazuo Tsuchiya
    Abstract:

    Simple models with circular arc feet rigidly mounted to the shank of the leg are widely used to investigate bipedal walking behavior. We use a simple walking model with arc feet, whose swing leg is driven by a rhythmic signal from an Internal Oscillator. The dynamical effects of the arc feet resemble flat feet mounted on ankles with a torsional spring, where the circular arc radius of the arc feet has similar dynamical characteristics to the spring stiffness in the ankle torque. Walking behavior generally consists of the falling motion of the body relative to the stance and the swinging motion of the swing leg. However, when the circular radius exceeds a certain threshold, the body motion changes from such divergent behavior to Oscillatory behavior due to the dynamical influence inherent in the arc feet, and the mechanism to create walking behavior greatly changes. Since our model is driven by a rhythmic signal from the Oscillator, the walking behavior is driven by two different Oscillatory elements and the relationship between them plays an important role. In this paper, we clarify the dynamical effect of the relationship on walking stability.

Renato Vicentini - One of the best experts on this subject based on the ideXlab platform.

  • Diel oscillations in cell wall components and soluble sugars as a response to short-day in sugarcane (Saccharum sp.).
    BMC Plant Biology, 2019
    Co-Authors: Leonardo Cardoso Alves, Juan Pablo Portilla Llerena, Paulo Mazzafera, Renato Vicentini
    Abstract:

    Sugarcane is a tropical crop that can accumulate high concentration of sucrose in the stem as a storage carbohydrate. For that reason, sugarcane accounts for approximately 75% of all the sugar produced in the world and has become the main sugar source to produce first-generation bioethanol in Brazil. Daily rhythms cause plants to adapt and coordinate their metabolism to achieve maximum photosynthesis and carbohydrate production throughout the day. Circadian rhythms arise from the interaction of an Internal Oscillator and external stimuli, whereas diel rhythms occur in response to a light-dark cycle. Diel signalling contributes to synchronizing circadian rhythms to photoperiods, and levels of carbohydrates oscillate in a diel fashion. Under regular photoperiods, they are synthesized during the daytime and consumed throughout the night as an energy reserve. However, short days can induce higher rates of synthesis during daytime and lower rates of consumption in the dark. Cell wall carbohydrates are also diurnally regulated, and it has been shown that celluloses, hemicelluloses and pectin are deposited/degraded at different times of the day. To assess the diel carbohydrate profile in young sugarcane plants, we measured soluble sugars and cell wall components along a time course in plants subjected either to a regular day or short day. Short-day influenced sucrose synthesis and cell wall components. In short-day a 44% increase in sucrose concentration was detected in the dark, but was stable during the day. Cellulose, hemicellulose and pectin also fluctuate within a 24 h interval when subjected to a short day. A 38% increase in leaf sheath cellulose was observed from the middle of the day to the first hour of the night. Leaf sheath pectin and hemicellulose also increased from the day to the night, while it decreased in leaves. The presented data show diurnal patterns of soluble sugar metabolism together with temporal regulation of cell wall metabolism for a short day, suggesting that diel signalling has a role in how sugarcane manages sugar accumulation and partitioning. Understanding cell wall synthesis/degradation dynamics may help to improve the yield of sugarcane.

Leonardo Cardoso Alves - One of the best experts on this subject based on the ideXlab platform.

  • Diel oscillations in cell wall components and soluble sugars as a response to short-day in sugarcane (Saccharum sp.).
    BMC Plant Biology, 2019
    Co-Authors: Leonardo Cardoso Alves, Juan Pablo Portilla Llerena, Paulo Mazzafera, Renato Vicentini
    Abstract:

    Sugarcane is a tropical crop that can accumulate high concentration of sucrose in the stem as a storage carbohydrate. For that reason, sugarcane accounts for approximately 75% of all the sugar produced in the world and has become the main sugar source to produce first-generation bioethanol in Brazil. Daily rhythms cause plants to adapt and coordinate their metabolism to achieve maximum photosynthesis and carbohydrate production throughout the day. Circadian rhythms arise from the interaction of an Internal Oscillator and external stimuli, whereas diel rhythms occur in response to a light-dark cycle. Diel signalling contributes to synchronizing circadian rhythms to photoperiods, and levels of carbohydrates oscillate in a diel fashion. Under regular photoperiods, they are synthesized during the daytime and consumed throughout the night as an energy reserve. However, short days can induce higher rates of synthesis during daytime and lower rates of consumption in the dark. Cell wall carbohydrates are also diurnally regulated, and it has been shown that celluloses, hemicelluloses and pectin are deposited/degraded at different times of the day. To assess the diel carbohydrate profile in young sugarcane plants, we measured soluble sugars and cell wall components along a time course in plants subjected either to a regular day or short day. Short-day influenced sucrose synthesis and cell wall components. In short-day a 44% increase in sucrose concentration was detected in the dark, but was stable during the day. Cellulose, hemicellulose and pectin also fluctuate within a 24 h interval when subjected to a short day. A 38% increase in leaf sheath cellulose was observed from the middle of the day to the first hour of the night. Leaf sheath pectin and hemicellulose also increased from the day to the night, while it decreased in leaves. The presented data show diurnal patterns of soluble sugar metabolism together with temporal regulation of cell wall metabolism for a short day, suggesting that diel signalling has a role in how sugarcane manages sugar accumulation and partitioning. Understanding cell wall synthesis/degradation dynamics may help to improve the yield of sugarcane.

Shinya Aoi - One of the best experts on this subject based on the ideXlab platform.

  • stability characteristics in walking behavior with two different Oscillatory elements roles of arc foot and Internal Oscillator
    Intelligent Robots and Systems, 2008
    Co-Authors: Shinya Aoi, Yoichi Sato, Kazuo Tsuchiya
    Abstract:

    Simple models with circular arc feet rigidly mounted to the shank of the leg are widely used to investigate bipedal walking behavior. We use a simple walking model with arc feet, whose swing leg is driven by a rhythmic signal from an Internal Oscillator. The dynamical effects of the arc feet resemble flat feet mounted on ankles with a torsional spring, where the circular arc radius of the arc feet has similar dynamical characteristics to the spring stiffness in the ankle torque. Walking behavior generally consists of the falling motion of the body relative to the stance and the swinging motion of the swing leg. However, when the circular radius exceeds a certain threshold, the body motion changes from such divergent behavior to Oscillatory behavior due to the dynamical influence inherent in the arc feet, and the mechanism to create walking behavior greatly changes. Since our model is driven by a rhythmic signal from the Oscillator, the walking behavior is driven by two different Oscillatory elements and the relationship between them plays an important role. In this paper, we clarify the dynamical effect of the relationship on walking stability.

  • IROS - Stability characteristics in walking behavior with two different Oscillatory elements: Roles of arc foot and Internal Oscillator
    2008 IEEE RSJ International Conference on Intelligent Robots and Systems, 2008
    Co-Authors: Shinya Aoi, Yoichi Sato, Kazuo Tsuchiya
    Abstract:

    Simple models with circular arc feet rigidly mounted to the shank of the leg are widely used to investigate bipedal walking behavior. We use a simple walking model with arc feet, whose swing leg is driven by a rhythmic signal from an Internal Oscillator. The dynamical effects of the arc feet resemble flat feet mounted on ankles with a torsional spring, where the circular arc radius of the arc feet has similar dynamical characteristics to the spring stiffness in the ankle torque. Walking behavior generally consists of the falling motion of the body relative to the stance and the swinging motion of the swing leg. However, when the circular radius exceeds a certain threshold, the body motion changes from such divergent behavior to Oscillatory behavior due to the dynamical influence inherent in the arc feet, and the mechanism to create walking behavior greatly changes. Since our model is driven by a rhythmic signal from the Oscillator, the walking behavior is driven by two different Oscillatory elements and the relationship between them plays an important role. In this paper, we clarify the dynamical effect of the relationship on walking stability.

Paulo Mazzafera - One of the best experts on this subject based on the ideXlab platform.

  • Diel oscillations in cell wall components and soluble sugars as a response to short-day in sugarcane (Saccharum sp.).
    BMC Plant Biology, 2019
    Co-Authors: Leonardo Cardoso Alves, Juan Pablo Portilla Llerena, Paulo Mazzafera, Renato Vicentini
    Abstract:

    Sugarcane is a tropical crop that can accumulate high concentration of sucrose in the stem as a storage carbohydrate. For that reason, sugarcane accounts for approximately 75% of all the sugar produced in the world and has become the main sugar source to produce first-generation bioethanol in Brazil. Daily rhythms cause plants to adapt and coordinate their metabolism to achieve maximum photosynthesis and carbohydrate production throughout the day. Circadian rhythms arise from the interaction of an Internal Oscillator and external stimuli, whereas diel rhythms occur in response to a light-dark cycle. Diel signalling contributes to synchronizing circadian rhythms to photoperiods, and levels of carbohydrates oscillate in a diel fashion. Under regular photoperiods, they are synthesized during the daytime and consumed throughout the night as an energy reserve. However, short days can induce higher rates of synthesis during daytime and lower rates of consumption in the dark. Cell wall carbohydrates are also diurnally regulated, and it has been shown that celluloses, hemicelluloses and pectin are deposited/degraded at different times of the day. To assess the diel carbohydrate profile in young sugarcane plants, we measured soluble sugars and cell wall components along a time course in plants subjected either to a regular day or short day. Short-day influenced sucrose synthesis and cell wall components. In short-day a 44% increase in sucrose concentration was detected in the dark, but was stable during the day. Cellulose, hemicellulose and pectin also fluctuate within a 24 h interval when subjected to a short day. A 38% increase in leaf sheath cellulose was observed from the middle of the day to the first hour of the night. Leaf sheath pectin and hemicellulose also increased from the day to the night, while it decreased in leaves. The presented data show diurnal patterns of soluble sugar metabolism together with temporal regulation of cell wall metabolism for a short day, suggesting that diel signalling has a role in how sugarcane manages sugar accumulation and partitioning. Understanding cell wall synthesis/degradation dynamics may help to improve the yield of sugarcane.