Currently,research in multi-body dynamics predominantly focuses on symmetric parallel mechanisms with multiple branches.However,for the working mechanism(WM)of a face-shovel hydraulic excavator,an asymmetric mechanism...Currently,research in multi-body dynamics predominantly focuses on symmetric parallel mechanisms with multiple branches.However,for the working mechanism(WM)of a face-shovel hydraulic excavator,an asymmetric mechanism with multiple closed loops,there is a significant lack of research on dynamic models that account for the mass and inertia of all its moving components.The main focus of this study is to research a dynamic model of multi-closed-loop multi-body planar mechanism considering all moving components.This paper introduces a novel WM for a face-shovel excavator,featuring 4 loops and 12 links.By loop decomposition,the kinematic equations of the 11 primary moving components of the WM,including position,velocity,angular velocity,acceleration,and angular acceleration,are accurately formulated.For comparative analysis,a simplified dynamic model of WM was established,considering only the boom,stick,and bucket.The complete dynamic models based on the virtual work principle were also established.The correctness of both the simplified and complete dynamic models was verified through numerical simulations in Adams software.A comparison of simplified and complete dynamic simulation results shows that the new complete dynamic model has the advantage of accuracy.This research proposes a kinematic and dynamic modeling method with reference significance for the kinematic and dynamic analysis of planar complex multi-loop mechanisms,laying a foundation for performance analysis and the design of excavator WMs.展开更多
点云配准广泛应用于机器人检测和场景重建中不同测量位姿数据的融合。然而,针对高铁车体等大尺度场景中常见的平面特征,传统基于点对点距离和点到平面距离的配准方法在初始姿态不佳时易陷入局部极小值。为解决这些问题,提出了一种基于...点云配准广泛应用于机器人检测和场景重建中不同测量位姿数据的融合。然而,针对高铁车体等大尺度场景中常见的平面特征,传统基于点对点距离和点到平面距离的配准方法在初始姿态不佳时易陷入局部极小值。为解决这些问题,提出了一种基于共面约束的鲁棒多维点云配准方法。首先,对二维平面特征中的点云进行投影,并定义二维点对点(point-to-point in twodimension,PTP-2D)距离以约束不同平面特征之间的距离。该约束能够有效规避局部极小值,但会引发平移向量解的非唯一性。因此,引入三维点到点(point-to-point in three-dimension,PTP-3D)约束以限定平移向量解集,并进一步定义多维点到点距离(point-to-point in multidimension,PTP-MD)平衡收敛速度与配准精度。为验证PTP-MD方法的有效性,将其与四种经典配准方法在高速列车车身点云上进行了对比。试验结果表明,相比于传统的点云匹配方法,该方法能够显著摆脱局部极小值。展开更多
Tunneling planer Hall (TPH) effect in Ni8( Fe19/Al2O3/NixFe1-x trilayer junction is different from general planer Hall effect in single-layer film or two-layer junction. This effect concerns the spin-polarized transpo...Tunneling planer Hall (TPH) effect in Ni8( Fe19/Al2O3/NixFe1-x trilayer junction is different from general planer Hall effect in single-layer film or two-layer junction. This effect concerns the spin-polarized transport,so that the TPH voltage depends on the angle between magnetic vectors of two ferromagnetic layers. The TPH effect is reported to be influenced by composition and magnetic properties of FM layers and the thickness of the insulating layer.展开更多
基金Supported by Natural Science Foundation of China(Grant Nos.51975544,52205036)Industry-University Cooperation Collaborative Education Project of Ministry of Education(Grant No.220904701054946).
文摘Currently,research in multi-body dynamics predominantly focuses on symmetric parallel mechanisms with multiple branches.However,for the working mechanism(WM)of a face-shovel hydraulic excavator,an asymmetric mechanism with multiple closed loops,there is a significant lack of research on dynamic models that account for the mass and inertia of all its moving components.The main focus of this study is to research a dynamic model of multi-closed-loop multi-body planar mechanism considering all moving components.This paper introduces a novel WM for a face-shovel excavator,featuring 4 loops and 12 links.By loop decomposition,the kinematic equations of the 11 primary moving components of the WM,including position,velocity,angular velocity,acceleration,and angular acceleration,are accurately formulated.For comparative analysis,a simplified dynamic model of WM was established,considering only the boom,stick,and bucket.The complete dynamic models based on the virtual work principle were also established.The correctness of both the simplified and complete dynamic models was verified through numerical simulations in Adams software.A comparison of simplified and complete dynamic simulation results shows that the new complete dynamic model has the advantage of accuracy.This research proposes a kinematic and dynamic modeling method with reference significance for the kinematic and dynamic analysis of planar complex multi-loop mechanisms,laying a foundation for performance analysis and the design of excavator WMs.
文摘点云配准广泛应用于机器人检测和场景重建中不同测量位姿数据的融合。然而,针对高铁车体等大尺度场景中常见的平面特征,传统基于点对点距离和点到平面距离的配准方法在初始姿态不佳时易陷入局部极小值。为解决这些问题,提出了一种基于共面约束的鲁棒多维点云配准方法。首先,对二维平面特征中的点云进行投影,并定义二维点对点(point-to-point in twodimension,PTP-2D)距离以约束不同平面特征之间的距离。该约束能够有效规避局部极小值,但会引发平移向量解的非唯一性。因此,引入三维点到点(point-to-point in three-dimension,PTP-3D)约束以限定平移向量解集,并进一步定义多维点到点距离(point-to-point in multidimension,PTP-MD)平衡收敛速度与配准精度。为验证PTP-MD方法的有效性,将其与四种经典配准方法在高速列车车身点云上进行了对比。试验结果表明,相比于传统的点云匹配方法,该方法能够显著摆脱局部极小值。
文摘Tunneling planer Hall (TPH) effect in Ni8( Fe19/Al2O3/NixFe1-x trilayer junction is different from general planer Hall effect in single-layer film or two-layer junction. This effect concerns the spin-polarized transport,so that the TPH voltage depends on the angle between magnetic vectors of two ferromagnetic layers. The TPH effect is reported to be influenced by composition and magnetic properties of FM layers and the thickness of the insulating layer.
