The biomimetic locust robot hopping vehicle has promising applications in planet exploration and reconnaissance. This paper explores the bionic dynamics model of locust jumping by using high-speed video and force anal...The biomimetic locust robot hopping vehicle has promising applications in planet exploration and reconnaissance. This paper explores the bionic dynamics model of locust jumping by using high-speed video and force analysis. This paper applies hybrid rigid-flexible mechanisms to bionic locust hopping and studies its dynamics with emphasis laid on the relationship between force and jumping performance. The hybrid rigid-flexible model is introduced in the analysis of locust mechanism to address the principles of dynamics that govern locust joints and mechanisms during energy storage and take-off. The dynamic response of the biomimetic mechanism is studied by considering the flexi- bility according to the locust jumping dynamics mechanism. A multi-rigid-body dynamics model of locust jumping is established and analyzed based on Lagrange method; elastic knee and tarsus mechanisms that were proposed in previous works are analyzed alongside the original bionic joint configurations and their machinery principles. This work offers primary theories for take-off dynamics and establishes a theoretical basis for future studies and engineering applications.展开更多
The click beetle can jump up with a hinge when it is on the dorsal side.This jumping mechanism is simple and suitable as an inspiration for designing a simple,small,and reliable hopping robot.We report a single-legged...The click beetle can jump up with a hinge when it is on the dorsal side.This jumping mechanism is simple and suitable as an inspiration for designing a simple,small,and reliable hopping robot.We report a single-legged robot inspired by the jumping mechanism of click beetles.It is 85 mm high,60 mm long,and 41 mm wide,and weighs about 49 g.The robot has good hopping performance that the hopping height is about 4 times-4.3 times of its body height.It is capable for rescue missions that require to enter enclosed spaces through cracks and narrow channels.In addition,hopping dynamics of the robot is important to understand its jumping mechanism and improve the robot’s hopping performance.But existing dynamic study does not complete the analysis including all stages in the hopping which are pre-hopping,take-off,and air-flying.We propose the decomposition method to study dynamics of the three stages separately,and synthesize them with related parameters.The dynamic synthesis of multi-motion states in a hopping cycle of the single-legged hopping robot is implemented.The hopping performance and dynamic synthesis theory of the robot are verified by simulations and experiments.Our study helps lay the foundation for design and hopping control of simple hopping robot systems.展开更多
A non-equilibrium steady state can be characterized by a nonzero but stationary flux driven by a static external force. Under a weak external force, the drift velocity is difficult to detect because the drift motion i...A non-equilibrium steady state can be characterized by a nonzero but stationary flux driven by a static external force. Under a weak external force, the drift velocity is difficult to detect because the drift motion is feeble and submerged in the intense thermal diffusion. In this article, we employ an accurate method in molecular dynamics simulation to determine the drift velocity of a particle driven by a weak external force in a one-dimensional periodic potential. With the calculated drift velocity, we found that the mobility and diffusion of the particle obey the Einstein relation, whereas their temperature dependences deviate from the Arrhenius law. A microscopic hopping mechanism was proposed to explain the non-Arrhenius behavior. Moreover, the position distribution of the particle in the potential well was found to deviate from the Boltzmann equation in a non-equilibrium steady state. The non-Boltzmann behavior may be attributed to the thermostat which introduces an effective "viscous" drag opposite to the drift direction of the particle.展开更多
Thermoelectric Power Studies of Cadmium Substituted Copper Ferrites of various compositions were investigated from room temperature to well beyond the curie temperature by differential method. The Seebeck coefficient ...Thermoelectric Power Studies of Cadmium Substituted Copper Ferrites of various compositions were investigated from room temperature to well beyond the curie temperature by differential method. The Seebeck coefficient is negative for all compositions showing that these ferrites behave as n-type semi conductors. Plots of Seebeck coefficient verses tem- perature shows maximum at Curie temperature. On the basis of these results an explanation for the conduction mechanism in Cu-Cd mixed ferrites is suggested.展开更多
The CuO doped with 5%20% Mn（molar fraction） solids were sintered from CuO and MnO2 powder at high temperature （1 273 K） for 8 h. X-ray diffraction was used to determine the solid crystallinity and to address the f...The CuO doped with 5%20% Mn（molar fraction） solids were sintered from CuO and MnO2 powder at high temperature （1 273 K） for 8 h. X-ray diffraction was used to determine the solid crystallinity and to address the formation of secondary phases. It is found that it is difficult to achieve pure Cu1-xMnxO phase using standard solid phase reaction. However, sintering under a pressure of 27.7 MPa significantly reduces the undesirable second phase CuMn2O4, providing a route to achieve pure Cu1-xMnxO phase. SQUID magnetometry was employed to characterize the magnetic properties. Mn-doped CuO presents ferromagnetic characteristics below 70 K. Electrical transport properties were measured in a current-perpendicular-to-plane（CPP） geometry using the PPMS, which suggests variable-range hopping mechanism.展开更多
The dielectric permittivities(ε′ & ε″) and dielectric loss tangent(tan) are studied for the prepared samples CuFe2O4 and Cu1-xZnxGa0.1Fe1.9O4 spinel ferrites with(0.0 ≤ x ≤ 0.5) from room temperature up to 7...The dielectric permittivities(ε′ & ε″) and dielectric loss tangent(tan) are studied for the prepared samples CuFe2O4 and Cu1-xZnxGa0.1Fe1.9O4 spinel ferrites with(0.0 ≤ x ≤ 0.5) from room temperature up to 700K in the frequency range(102~105Hz).Dielectric anomaly at the transition temperature Tc is pronounced in the relations of dielectric permittivitties with temperature where,the obtained Tc is found to decrease linearly with increasing Zn concentration.The relation of tan with frequency at different temperatures shows relaxation spectra where the relaxation time and the maximum frequency of the hopping conduction mechanism are determined.The variation of(ε′,ε″ and tanδ) with frequency and temperature displays a strong dependence on both gallium and zinc concentrations.The results are explained in light of the cation-anion-cation and cation-cation interactions over the octahedral sites in the spinel structure.展开更多
For quadruped robots with springy legs,a successful jump usually requires both suitable elastic parts and well-designed control algorithms.However,these two problems are mutually restricted and hard to solve at the sa...For quadruped robots with springy legs,a successful jump usually requires both suitable elastic parts and well-designed control algorithms.However,these two problems are mutually restricted and hard to solve at the same time.In this study,we attempt to solve the problem of controller design with the help of a robot without any elastic mounted parts,in which the untethered robot is made to jump on a trampoline.The differences between jumping on hard surfaces with springy legs and jumping on springy surfaces with rigid legs are briefly discussed.An intuitive control law is proposed to balance foot contact forces;in this manner,excessive pitch oscillation during hopping or bounding can be avoided.Hopping height is controlled by tuning the time delay of the leg stretch.Together with other motion generators based on kinematic law,the robot can perform translational and rotational movements while hopping or bounding on the trampoline.Experiments are conducted to validate the effectiveness of the proposed control framework.展开更多
A flexible-rigid hopping mechanism which is inspired by the locust jumping was proposed, and its kinematic characteris- tics were analyzed. A series of experiments were conducted to observe locust morphology and jumpi...A flexible-rigid hopping mechanism which is inspired by the locust jumping was proposed, and its kinematic characteris- tics were analyzed. A series of experiments were conducted to observe locust morphology and jumping process. According to classic mechanics, the jumping process analysis was conducted to build the relationship of the locust jumping parameters. The take-offphase was divided into four stages in detail. Based on the biological observation and kinematics analysis, a mechanical model was proposed to simulate locust jumping. The forces of the flexible-rigid hopping mechanism at each stage were ana- lyzed. The kinematic analysis using pseudo-rigid-body model was described by D-H method. It is confirmed that the proposed bionic mechanism has the similar performance as the locust hind leg in hopping. Moreover, the jumping angle which decides the jumping process was discussed, and its relation with other parameters was established. A calculation case analysis corroborated the method. The results of this paper show that the proposed bionic mechanism which is inspired by the locust hind limb has an excellent kinematics performance, which can provide a foundation for design and motion planning of the hopping robot.展开更多
基金supported by the National Natural Science Foundation of China(51375035 and 51075014)the Research Fund for the Doctoral Program of Higher Education of China(20121102110021)
文摘The biomimetic locust robot hopping vehicle has promising applications in planet exploration and reconnaissance. This paper explores the bionic dynamics model of locust jumping by using high-speed video and force analysis. This paper applies hybrid rigid-flexible mechanisms to bionic locust hopping and studies its dynamics with emphasis laid on the relationship between force and jumping performance. The hybrid rigid-flexible model is introduced in the analysis of locust mechanism to address the principles of dynamics that govern locust joints and mechanisms during energy storage and take-off. The dynamic response of the biomimetic mechanism is studied by considering the flexi- bility according to the locust jumping dynamics mechanism. A multi-rigid-body dynamics model of locust jumping is established and analyzed based on Lagrange method; elastic knee and tarsus mechanisms that were proposed in previous works are analyzed alongside the original bionic joint configurations and their machinery principles. This work offers primary theories for take-off dynamics and establishes a theoretical basis for future studies and engineering applications.
基金This work was financially supported by National Natural Science Foundation of China(Nos.51875528 and 41506116)Zhejiang Provincial Natural Science Foundation of China(No.LY20E050018)+1 种基金China Post-doctoral Science Foundation(No.2016M591991)and Science Foundation of Zhejiang Sci-Tech University(ZSTU)(No.17022183-Y).
文摘The click beetle can jump up with a hinge when it is on the dorsal side.This jumping mechanism is simple and suitable as an inspiration for designing a simple,small,and reliable hopping robot.We report a single-legged robot inspired by the jumping mechanism of click beetles.It is 85 mm high,60 mm long,and 41 mm wide,and weighs about 49 g.The robot has good hopping performance that the hopping height is about 4 times-4.3 times of its body height.It is capable for rescue missions that require to enter enclosed spaces through cracks and narrow channels.In addition,hopping dynamics of the robot is important to understand its jumping mechanism and improve the robot’s hopping performance.But existing dynamic study does not complete the analysis including all stages in the hopping which are pre-hopping,take-off,and air-flying.We propose the decomposition method to study dynamics of the three stages separately,and synthesize them with related parameters.The dynamic synthesis of multi-motion states in a hopping cycle of the single-legged hopping robot is implemented.The hopping performance and dynamic synthesis theory of the robot are verified by simulations and experiments.Our study helps lay the foundation for design and hopping control of simple hopping robot systems.
基金Supported by the National Basic Research Program of China 973 Program,under Grant No.2013CB932804the National Natural Science Foundation of China under Nos.11274319 and 11121403
文摘A non-equilibrium steady state can be characterized by a nonzero but stationary flux driven by a static external force. Under a weak external force, the drift velocity is difficult to detect because the drift motion is feeble and submerged in the intense thermal diffusion. In this article, we employ an accurate method in molecular dynamics simulation to determine the drift velocity of a particle driven by a weak external force in a one-dimensional periodic potential. With the calculated drift velocity, we found that the mobility and diffusion of the particle obey the Einstein relation, whereas their temperature dependences deviate from the Arrhenius law. A microscopic hopping mechanism was proposed to explain the non-Arrhenius behavior. Moreover, the position distribution of the particle in the potential well was found to deviate from the Boltzmann equation in a non-equilibrium steady state. The non-Boltzmann behavior may be attributed to the thermostat which introduces an effective "viscous" drag opposite to the drift direction of the particle.
文摘Thermoelectric Power Studies of Cadmium Substituted Copper Ferrites of various compositions were investigated from room temperature to well beyond the curie temperature by differential method. The Seebeck coefficient is negative for all compositions showing that these ferrites behave as n-type semi conductors. Plots of Seebeck coefficient verses tem- perature shows maximum at Curie temperature. On the basis of these results an explanation for the conduction mechanism in Cu-Cd mixed ferrites is suggested.
基金Projects(50472092 50325209 50232030) supported by the National Natural Science Foundations of China
文摘The CuO doped with 5%20% Mn（molar fraction） solids were sintered from CuO and MnO2 powder at high temperature （1 273 K） for 8 h. X-ray diffraction was used to determine the solid crystallinity and to address the formation of secondary phases. It is found that it is difficult to achieve pure Cu1-xMnxO phase using standard solid phase reaction. However, sintering under a pressure of 27.7 MPa significantly reduces the undesirable second phase CuMn2O4, providing a route to achieve pure Cu1-xMnxO phase. SQUID magnetometry was employed to characterize the magnetic properties. Mn-doped CuO presents ferromagnetic characteristics below 70 K. Electrical transport properties were measured in a current-perpendicular-to-plane（CPP） geometry using the PPMS, which suggests variable-range hopping mechanism.
文摘The dielectric permittivities(ε′ & ε″) and dielectric loss tangent(tan) are studied for the prepared samples CuFe2O4 and Cu1-xZnxGa0.1Fe1.9O4 spinel ferrites with(0.0 ≤ x ≤ 0.5) from room temperature up to 700K in the frequency range(102~105Hz).Dielectric anomaly at the transition temperature Tc is pronounced in the relations of dielectric permittivitties with temperature where,the obtained Tc is found to decrease linearly with increasing Zn concentration.The relation of tan with frequency at different temperatures shows relaxation spectra where the relaxation time and the maximum frequency of the hopping conduction mechanism are determined.The variation of(ε′,ε″ and tanδ) with frequency and temperature displays a strong dependence on both gallium and zinc concentrations.The results are explained in light of the cation-anion-cation and cation-cation interactions over the octahedral sites in the spinel structure.
基金Financial support was provided by the Zhejiang Provincial Natural Science Foundation(Grant No.Y18F030012)the Science and Technology Project of Zhejiang Province(Grant No.2019C01043)+1 种基金the National Natural Science Foundation of China(Grant No.61836015)the State Key Laboratory of Industrial Control Technology(ICT1807)。
文摘For quadruped robots with springy legs,a successful jump usually requires both suitable elastic parts and well-designed control algorithms.However,these two problems are mutually restricted and hard to solve at the same time.In this study,we attempt to solve the problem of controller design with the help of a robot without any elastic mounted parts,in which the untethered robot is made to jump on a trampoline.The differences between jumping on hard surfaces with springy legs and jumping on springy surfaces with rigid legs are briefly discussed.An intuitive control law is proposed to balance foot contact forces;in this manner,excessive pitch oscillation during hopping or bounding can be avoided.Hopping height is controlled by tuning the time delay of the leg stretch.Together with other motion generators based on kinematic law,the robot can perform translational and rotational movements while hopping or bounding on the trampoline.Experiments are conducted to validate the effectiveness of the proposed control framework.
基金This work is financially supported by the National Natural Science Foundation of China （Grant No. 51075014）.
文摘A flexible-rigid hopping mechanism which is inspired by the locust jumping was proposed, and its kinematic characteris- tics were analyzed. A series of experiments were conducted to observe locust morphology and jumping process. According to classic mechanics, the jumping process analysis was conducted to build the relationship of the locust jumping parameters. The take-offphase was divided into four stages in detail. Based on the biological observation and kinematics analysis, a mechanical model was proposed to simulate locust jumping. The forces of the flexible-rigid hopping mechanism at each stage were ana- lyzed. The kinematic analysis using pseudo-rigid-body model was described by D-H method. It is confirmed that the proposed bionic mechanism has the similar performance as the locust hind leg in hopping. Moreover, the jumping angle which decides the jumping process was discussed, and its relation with other parameters was established. A calculation case analysis corroborated the method. The results of this paper show that the proposed bionic mechanism which is inspired by the locust hind limb has an excellent kinematics performance, which can provide a foundation for design and motion planning of the hopping robot.
