Hypocycloid and epicycloid motions of irregular grains （pine pollen） are observed for the first time in a dust plasma in a two-dimensional （2D） horizontal plane. These cycloid motions can be regarded as a combinat...Hypocycloid and epicycloid motions of irregular grains （pine pollen） are observed for the first time in a dust plasma in a two-dimensional （2D） horizontal plane. These cycloid motions can be regarded as a combination of a primary circle and a secondary circle. An inverse Magnus force originating from the spin of the irregular grain gives rise to the primary circle. Radial confinement resulting from the electrostatic force and the ion drag force, together with inverse Magnus force, plays an important role in the formation of the secondary circle. In addition, the cyclotron radius is seen to change periodically during the cycloid motion. Force analysis and comparison experiments have shown that the cycloid motions are distinctive features of an irregular grain immersed in a plasma.展开更多
Hypocycloid and epicycloid motions of aggregates consisted of one large and one small grains are experimentally observed in an rf dust plasma.The cycloid motions are regarded as combination of a primary circle and a s...Hypocycloid and epicycloid motions of aggregates consisted of one large and one small grains are experimentally observed in an rf dust plasma.The cycloid motions are regarded as combination of a primary circle and a secondary circle.Measurements with high spatiotemporal resolution show that the secondary circle is determined by the initial angle velocity of the dropped aggregate.The primary circle originates from the asymmetry of the aggregate.The small grain in the aggregate always leads the large one as they travelling,which results from the difference of the natural frequency of the two grains.Comparative experiments with regular microspheres show that the cycloid motions are distinctive features of aggregates immersed in a plasma.展开更多
In order to reduce cucumber harvesting cost and improve economic benefits,a cucumber harvesting robot was developed.The cucumber harvesting robot consists of a vehicle,a 4-DOF articulated manipulator,an end-effector,a...In order to reduce cucumber harvesting cost and improve economic benefits,a cucumber harvesting robot was developed.The cucumber harvesting robot consists of a vehicle,a 4-DOF articulated manipulator,an end-effector,an upper monitor,a vision system and four DC servo drive systems.The Kinematics of the cucumber harvesting robot manipulator was constructed using D-H coordinate frame model.And the inverse kinematics which provides a foundation for trajectory planning has been solved with inverse transform technique.The cycloidal motion,which has properties of continuity and zero velocity and acceleration at the ports of the bounded interval,was adopted as a feasible approach to plan trajectory in joint space of the cucumber harvesting robot manipulator.Moreover,hardware and software based on CAN-bus communication between the upper monitor and the joint controllers have been designed.Experimental results show that the upper monitor communicates with the four joint controllers efficiently by CAN-bus,and the integrated errors of four joint angles do not exceed four degrees.Probable factors resulting in the errors were analyzed and the corresponding solutions for improving precision are proposed.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11205044 and 11405042)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2011201006 and A2012201015)+2 种基金the Research Foundation of Education Bureau of Hebei Province,China(Grant No.Y2012009)the Program for Young Principal Investigators of Hebei Provincethe Midwest Universities Comprehensive Strength Promotion Project
文摘Hypocycloid and epicycloid motions of irregular grains （pine pollen） are observed for the first time in a dust plasma in a two-dimensional （2D） horizontal plane. These cycloid motions can be regarded as a combination of a primary circle and a secondary circle. An inverse Magnus force originating from the spin of the irregular grain gives rise to the primary circle. Radial confinement resulting from the electrostatic force and the ion drag force, together with inverse Magnus force, plays an important role in the formation of the secondary circle. In addition, the cyclotron radius is seen to change periodically during the cycloid motion. Force analysis and comparison experiments have shown that the cycloid motions are distinctive features of an irregular grain immersed in a plasma.
基金supported by National Natural Science Foundation of China(Nos.1120504411405042)+6 种基金the Natural Science Foundation of Hebei ProvinceChina(Nos.A2011201006A2012201015)the Research Foundation of Education Bureau of Hebei ProvinceChina(Nos.Y2012009ZD2015025)the Midwest Universities Comprehensive Strength Promotion Project of China
文摘Hypocycloid and epicycloid motions of aggregates consisted of one large and one small grains are experimentally observed in an rf dust plasma.The cycloid motions are regarded as combination of a primary circle and a secondary circle.Measurements with high spatiotemporal resolution show that the secondary circle is determined by the initial angle velocity of the dropped aggregate.The primary circle originates from the asymmetry of the aggregate.The small grain in the aggregate always leads the large one as they travelling,which results from the difference of the natural frequency of the two grains.Comparative experiments with regular microspheres show that the cycloid motions are distinctive features of aggregates immersed in a plasma.
基金the Natural Science Foundation of China(50575206)the National High-Tech Research and Development(863)Program of China(2007AA04Z222)。
文摘In order to reduce cucumber harvesting cost and improve economic benefits,a cucumber harvesting robot was developed.The cucumber harvesting robot consists of a vehicle,a 4-DOF articulated manipulator,an end-effector,an upper monitor,a vision system and four DC servo drive systems.The Kinematics of the cucumber harvesting robot manipulator was constructed using D-H coordinate frame model.And the inverse kinematics which provides a foundation for trajectory planning has been solved with inverse transform technique.The cycloidal motion,which has properties of continuity and zero velocity and acceleration at the ports of the bounded interval,was adopted as a feasible approach to plan trajectory in joint space of the cucumber harvesting robot manipulator.Moreover,hardware and software based on CAN-bus communication between the upper monitor and the joint controllers have been designed.Experimental results show that the upper monitor communicates with the four joint controllers efficiently by CAN-bus,and the integrated errors of four joint angles do not exceed four degrees.Probable factors resulting in the errors were analyzed and the corresponding solutions for improving precision are proposed.
