The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human–robot interaction.This compliance reduces the risk of damage to the manipulated object and its surroun...The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human–robot interaction.This compliance reduces the risk of damage to the manipulated object and its surroundings.However,continuum robots possess theoretically infinite degrees of freedom,and this high flexibility usually leads to complex deformations when subjected to external forces and positional constraints.Describing these complex deformations is the main challenge in modeling continuum robots.In this study,we investigated a novel variable curvature modeling method for continuum robots,considering external forces and positional constraints.The robot configuration curve is described using the developed mechanical model,and then the robot is fitted to the curve.A ten-section continuum robot prototype with a length of 1 m was developed in order to validate the model.The feasibility and accuracy of the model were verified by the ability of the robot to reach target points and track complex trajectories with a load.This work was able to serve as a new perspective for the design analysis and motion control of continuum robots.展开更多
The two coupled governing differential equations for the out-of-plane vibrations of non-uniform beams with variable curvature are derived via the Hamilton’s principle.These equations are expressed in terms of flexura...The two coupled governing differential equations for the out-of-plane vibrations of non-uniform beams with variable curvature are derived via the Hamilton’s principle.These equations are expressed in terms of flexural and torsional displacements simultaneously.In this study,the analytical method is proposed.Firstly,two physical parameters are introduced to simplify the analysis.One derives the explicit relations between the flexural and the torsional displacements which can also be used to reduce the difficulty in experimental measurements.Based on the relation,the two governing characteristic differential equations with variable coefficients can be uncoupled into a sixth-order ordinary differential equation in terms of the flexural displacement only.When the material and geometric properties of the beam are in arbitrary polynomial forms,the exact solutions with regard to the outof-plane vibrations of non-uniform beams with variable curvature can be obtained by the recurrence formula.In addition,the mode transition mechanism is revealed and the influence of several parameters on the vibration of the non-uniform beam with variable curvature is explored.展开更多
In this paper, a new complex variable defined as “precursive time” able to correlate general relativity (GR) and quantum field theory (QFT) in a single principle was characterized. The thesis was elaborated accordin...In this paper, a new complex variable defined as “precursive time” able to correlate general relativity (GR) and quantum field theory (QFT) in a single principle was characterized. The thesis was elaborated according to a hypothesis coherent with the “Einstein’s General Theory of Relativity”, making use of a new mathematical-topological variety called “time-space” developed on the properties of the hypersphere and explained mathematically through the quaternion of Hurwitz-Lipschitz algebra. In this publication we pay attention to the interaction between the weak nuclear force theory (EWT) and the nuclear mass of the Standard Model.展开更多
The stretch bending of L-section variable-curvature SUS301L stainless-steel roof bending beams for metro vehicles was numerically simulated.The causes of defects such as wrinkling,section distortion,and poor contour a...The stretch bending of L-section variable-curvature SUS301L stainless-steel roof bending beams for metro vehicles was numerically simulated.The causes of defects such as wrinkling,section distortion,and poor contour accuracy were analysed,and the corresponding control methods were proposed.The simulation results demonstrated that wrinkling in the small-arc segment could be eliminated by setting the die clearance and adjusting the elongation reasonably.Owing to the sidewall shrinkage of the profile in the process of stretch bending,the die groove depth was correspondingly reduced.Each section of the profile was effectively supported by the bottom of the die groove,and the section distortion could be controlled.Springback was the main reason for the poor contour accuracy,which could be compensated by modifying the die surface based on the springback value.Using the above defect control methods,forming experiments were performed on a new type of stretch bending die with variable die clearance and groove depth developed in this work.Finally,high-quality components were obtained,which verified the efficacy of the defect control methods.展开更多
针对模态柔度及其衍生指标具有对结构损伤高灵敏性的特点,为研究基于柔度类指标的损伤识别方法在变截面连续梁桥上的适用性,提出一种基于柔度曲率面积差的桥梁损伤识别新指标。首先利用结构振型和固有频率构建柔度矩阵,其次对柔度矩阵...针对模态柔度及其衍生指标具有对结构损伤高灵敏性的特点,为研究基于柔度类指标的损伤识别方法在变截面连续梁桥上的适用性,提出一种基于柔度曲率面积差的桥梁损伤识别新指标。首先利用结构振型和固有频率构建柔度矩阵,其次对柔度矩阵进行行列两次差分得到柔度曲率矩阵,然后提取损伤前后柔度曲率矩阵主对角元素构建柔度曲率面积差(Flexibility curvature area difference,FCAD)指标,以三跨变截面连续梁桥有限元模型为研究对象,对不同损伤工况进行模拟分析以验证方法的可行性和有效性,通过引入不同强度噪声来验证该方法的抗噪性。研究结果表明:柔度曲率面积差方法可有效对三跨变截面连续梁桥的损伤进行定位,且所提方法具有较好的噪声鲁棒性。展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51975566,61821005,U1908214)Key Research Program of Frontier Sciences,CAS,China(Grant No.ZDBS-LY-JSC011).
文摘The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human–robot interaction.This compliance reduces the risk of damage to the manipulated object and its surroundings.However,continuum robots possess theoretically infinite degrees of freedom,and this high flexibility usually leads to complex deformations when subjected to external forces and positional constraints.Describing these complex deformations is the main challenge in modeling continuum robots.In this study,we investigated a novel variable curvature modeling method for continuum robots,considering external forces and positional constraints.The robot configuration curve is described using the developed mechanical model,and then the robot is fitted to the curve.A ten-section continuum robot prototype with a length of 1 m was developed in order to validate the model.The feasibility and accuracy of the model were verified by the ability of the robot to reach target points and track complex trajectories with a load.This work was able to serve as a new perspective for the design analysis and motion control of continuum robots.
文摘The two coupled governing differential equations for the out-of-plane vibrations of non-uniform beams with variable curvature are derived via the Hamilton’s principle.These equations are expressed in terms of flexural and torsional displacements simultaneously.In this study,the analytical method is proposed.Firstly,two physical parameters are introduced to simplify the analysis.One derives the explicit relations between the flexural and the torsional displacements which can also be used to reduce the difficulty in experimental measurements.Based on the relation,the two governing characteristic differential equations with variable coefficients can be uncoupled into a sixth-order ordinary differential equation in terms of the flexural displacement only.When the material and geometric properties of the beam are in arbitrary polynomial forms,the exact solutions with regard to the outof-plane vibrations of non-uniform beams with variable curvature can be obtained by the recurrence formula.In addition,the mode transition mechanism is revealed and the influence of several parameters on the vibration of the non-uniform beam with variable curvature is explored.
文摘In this paper, a new complex variable defined as “precursive time” able to correlate general relativity (GR) and quantum field theory (QFT) in a single principle was characterized. The thesis was elaborated according to a hypothesis coherent with the “Einstein’s General Theory of Relativity”, making use of a new mathematical-topological variety called “time-space” developed on the properties of the hypersphere and explained mathematically through the quaternion of Hurwitz-Lipschitz algebra. In this publication we pay attention to the interaction between the weak nuclear force theory (EWT) and the nuclear mass of the Standard Model.
基金the National Natural Science Foundation of China(51101072)Technology Development Program of Jilin Province(20150307015GX and 20160204058GX).
文摘The stretch bending of L-section variable-curvature SUS301L stainless-steel roof bending beams for metro vehicles was numerically simulated.The causes of defects such as wrinkling,section distortion,and poor contour accuracy were analysed,and the corresponding control methods were proposed.The simulation results demonstrated that wrinkling in the small-arc segment could be eliminated by setting the die clearance and adjusting the elongation reasonably.Owing to the sidewall shrinkage of the profile in the process of stretch bending,the die groove depth was correspondingly reduced.Each section of the profile was effectively supported by the bottom of the die groove,and the section distortion could be controlled.Springback was the main reason for the poor contour accuracy,which could be compensated by modifying the die surface based on the springback value.Using the above defect control methods,forming experiments were performed on a new type of stretch bending die with variable die clearance and groove depth developed in this work.Finally,high-quality components were obtained,which verified the efficacy of the defect control methods.
文摘针对模态柔度及其衍生指标具有对结构损伤高灵敏性的特点,为研究基于柔度类指标的损伤识别方法在变截面连续梁桥上的适用性,提出一种基于柔度曲率面积差的桥梁损伤识别新指标。首先利用结构振型和固有频率构建柔度矩阵,其次对柔度矩阵进行行列两次差分得到柔度曲率矩阵,然后提取损伤前后柔度曲率矩阵主对角元素构建柔度曲率面积差(Flexibility curvature area difference,FCAD)指标,以三跨变截面连续梁桥有限元模型为研究对象,对不同损伤工况进行模拟分析以验证方法的可行性和有效性,通过引入不同强度噪声来验证该方法的抗噪性。研究结果表明:柔度曲率面积差方法可有效对三跨变截面连续梁桥的损伤进行定位,且所提方法具有较好的噪声鲁棒性。
