The state of polarization(SOP)on high-order Poincaréspheres(HOPSs),characterized by their distinctive phase profiles and polarization distributions,plays a crucial role in both classical and quantum optical appli...The state of polarization(SOP)on high-order Poincaréspheres(HOPSs),characterized by their distinctive phase profiles and polarization distributions,plays a crucial role in both classical and quantum optical applications.However,most existing metasurface-based implementations face inherent limitations:passive designs are restricted to represent a few predefined HOPS SOPs,while programmable versions typically constrain to 1-bit or 2-bit phase control resolution.In this paper,dynamic generation of HOPS beams with arbitrary SOP based on a transmissive space-time-coding metasurface is demonstrated.By combining 1-bit phase discretizations via PIN diodes with a time-coding strategy,the metasurface enables quasi-continuous complexamplitude modulation for harmonic waves in both x-and y-polarizations.Based on near-field diffraction theory,arbitrary SOPs on any HOPSm,n can be precisely generated using a linearly polarized basis,which is independently controlled by FPGA reconfiguration.We experimentally demonstrate that polarization holography on HOPS0,0 achieves high polarization purity>91.28%,and vector vortex beams on HOPS1,3 and HOPS−1,3 exhibit high orbital angular momentum mode purities>91.25%.This methodology holds great potential for structured wavefront shaping,vortex generation,and high-capacity planar photonics.展开更多
The dynamic dexterity is an important issue for manipulator design, some indices were proposed for analyzing dynamic dexterity, but they can evaluate the dynamic performance just at one pose in the workspaee of the ma...The dynamic dexterity is an important issue for manipulator design, some indices were proposed for analyzing dynamic dexterity, but they can evaluate the dynamic performance just at one pose in the workspaee of the manipulator, and can＇t be applied to dynamic design expediently. Much work has been done in the kinematic optimization, but the work in the dynamic optimization is much less. A global dynamic condition number index is proposed and applied to the dynamic optimization design the parallel manipulator. This paper deals with the dynamic manipulability and dynamic optimization of a two degree-of-freedom （DOF） parallel manipulator. The particular velocity and particular angular velocity matrices of each moving part about the part＇s pivot point are derived fi＇om the kinematic formulation of the manipulator, and the inertial force and inertial movement are obtained utilizing Newton-Euler formulation, then the inverse dynamic model of the parallel manipulator is proposed based on the virtual work principle. The general inertial ellipsoid and dynamic manipulability ellipsoid are applied to evaluate the dynamic performance of the manipulator, a global dynamic condition number index based on the condition number of general inertial matrix in the workspace is proposed, and then the link lengths of the manipulator is redesigned to optimize the dynamic manipulability by this index. The dynamic manipulability of the origin mechanism and the optimized mechanism are compared, the result shows that the optimized one is much better. The global dynamic condition number index has good effect in evaluating the dynamic dexterity of the whole workspace, and is efficient in the dynamic optimal design of the parallel manipulator.展开更多
Due to the extremely high manufacturing standards,the integration of quasi-omnidirectional photodetectors and synaptic devices within a single device remains a long-standing challenge.In this work,we have designed a g...Due to the extremely high manufacturing standards,the integration of quasi-omnidirectional photodetectors and synaptic devices within a single device remains a long-standing challenge.In this work,we have designed a graphene/(Al,Ga)N nanowire heterojunction,demonstrating the monolithic integration of self-driven 360°photodetectors and artificial synapses in a dual-mode transparent device successfully.By manipulating the carrier transport dynamics through controlling the bias voltage,the degree of oxygen vacancy ionization can be precisely regulated,ultimately realizing the monolithic dual-mode device.At 0 V bias,the device functions as a fast-response self-driven photodetector with stable optical communication capabilities,achieving 360°quasi-omnidirectional photodetection.Upon applying a bias voltage,the operating mode switches to a synaptic device,which successfully simulates brainlike paired-pulse facilitation,short-/long-term plasticity processes,and learning/forgetting behaviors.The device demonstrates an exceptionally high UV/visible rejection ratio of 1.29×10^(4),coupled with an ultra-low dark current of less than 1 pA.Furthermore,this device has a low power consumption of 2.5×10^(−14)J per synaptic event,indicating an energy efficiency comparable to synaptic processes in the human brain.Moreover,nonlinear photoconductivity lets the device become a neuromorphic sensor for preprocessing images,enhancing recognition accuracy.Importantly,by leveraging the long-memory characteristic of the devices in open-circuit voltage mode,the devices have been successfully applied to guide humanoid robots in performing direction distinguishing and motion learning.This work provides new insights into the integrated manufacturing of multifunctional monolithic devices and foresees their immense potential in upcoming advanced,low-power neuromorphic computing systems.展开更多
A quadruped robot with a manipulator that combines dynamic motion and manipulation capabilities will greatly expand its application scenarios.However,the addition of the manipulator raises the center of mass of the qu...A quadruped robot with a manipulator that combines dynamic motion and manipulation capabilities will greatly expand its application scenarios.However,the addition of the manipulator raises the center of mass of the quadruped robot,increasing complexity in motion control and posing new challenges for maintaining balance on sloped terrains.To address this,a balance control method based on whole-body synergy is proposed in this study,emphasizing adaptive adjustment of the robot system’s overall balance through effective utilization of the manipulator’s active motion.By establishing a mapping relationship between the manipulator and the robot’s attitude angle under system equilibrium,the desired manipulator motion is guided by real-time estimates of terrain angles during motion,enhancing motion efficiency while ensuring robot balance.Furthermore,to enhance motion tracking accuracy,the optimization of system angular momentum and manipulator manipulability is incorporated into hierarchical optimization tasks,improving manipulator controllability and overall system performance.Simulation and experimental results demonstrate that the quadruped robot with a manipulator exhibits reduced velocity and attitude angle fluctuations,as well as smoother foot-end force dynamics during climbing motions with the addition of manipulator adaptive adjustment.These results validate the effectiveness and superiority of the manipulator-based adaptive adjustment strategy proposed in this paper.展开更多
基金National Natural Science Foundation of China(62271056,62171186,62201037)Technology Innovation Center of Infrared Remote Sensing Metrology Technology of State Administration for Market Regulation(AKYKF2423)+5 种基金National Key Research and Development Program of China(2022YFF0604801)Beijing Natural Science Foundation Haidian Original Innovation Joint Fund(L222042)Open Research Fund of State Key Laboratory of Millimeter Waves(K202326)Open Research Fund of State Key Laboratory of Space-Ground Integrated Information Technology(6142221200201)Basic Research Foundation of Beijing Institute of Technology,China(BITBLR2020014)111 Project of China(B14010).
文摘The state of polarization(SOP)on high-order Poincaréspheres(HOPSs),characterized by their distinctive phase profiles and polarization distributions,plays a crucial role in both classical and quantum optical applications.However,most existing metasurface-based implementations face inherent limitations:passive designs are restricted to represent a few predefined HOPS SOPs,while programmable versions typically constrain to 1-bit or 2-bit phase control resolution.In this paper,dynamic generation of HOPS beams with arbitrary SOP based on a transmissive space-time-coding metasurface is demonstrated.By combining 1-bit phase discretizations via PIN diodes with a time-coding strategy,the metasurface enables quasi-continuous complexamplitude modulation for harmonic waves in both x-and y-polarizations.Based on near-field diffraction theory,arbitrary SOPs on any HOPSm,n can be precisely generated using a linearly polarized basis,which is independently controlled by FPGA reconfiguration.We experimentally demonstrate that polarization holography on HOPS0,0 achieves high polarization purity>91.28%,and vector vortex beams on HOPS1,3 and HOPS−1,3 exhibit high orbital angular momentum mode purities>91.25%.This methodology holds great potential for structured wavefront shaping,vortex generation,and high-capacity planar photonics.
基金supported by National Natural Science Foundation of China (Grant No. 50605041, No. 50775125)National Basic Research Program of China (973 Program, Grant No. 2006CB705400)
文摘The dynamic dexterity is an important issue for manipulator design, some indices were proposed for analyzing dynamic dexterity, but they can evaluate the dynamic performance just at one pose in the workspaee of the manipulator, and can＇t be applied to dynamic design expediently. Much work has been done in the kinematic optimization, but the work in the dynamic optimization is much less. A global dynamic condition number index is proposed and applied to the dynamic optimization design the parallel manipulator. This paper deals with the dynamic manipulability and dynamic optimization of a two degree-of-freedom （DOF） parallel manipulator. The particular velocity and particular angular velocity matrices of each moving part about the part＇s pivot point are derived fi＇om the kinematic formulation of the manipulator, and the inertial force and inertial movement are obtained utilizing Newton-Euler formulation, then the inverse dynamic model of the parallel manipulator is proposed based on the virtual work principle. The general inertial ellipsoid and dynamic manipulability ellipsoid are applied to evaluate the dynamic performance of the manipulator, a global dynamic condition number index based on the condition number of general inertial matrix in the workspace is proposed, and then the link lengths of the manipulator is redesigned to optimize the dynamic manipulability by this index. The dynamic manipulability of the origin mechanism and the optimized mechanism are compared, the result shows that the optimized one is much better. The global dynamic condition number index has good effect in evaluating the dynamic dexterity of the whole workspace, and is efficient in the dynamic optimal design of the parallel manipulator.
基金National Natural Science Foundation of China(No.62174172)Key Laboratory of Nanodevices of Jiangsu Province(No.ZS2302)+6 种基金China Postdoctoral Science Foundation(Nos.2023TQ0238 and 2023M742560)Suzhou Fundamental Research Project(SSD2024003)Science and Technology Youth Talent Project of Jiangsu Province(No.JSTJ-2024-016)Guangdong Basic and Applied Basic Research Foundation(2025A1515012907)CIE-Smartchip research fund(2024-03)Key Research Program of Frontier Sciences,CAS(No.ZDBS-LY-JSC034)the Students’Innovation and Entrepreneurship Foundation of USTC(CY2024X003B).
文摘Due to the extremely high manufacturing standards,the integration of quasi-omnidirectional photodetectors and synaptic devices within a single device remains a long-standing challenge.In this work,we have designed a graphene/(Al,Ga)N nanowire heterojunction,demonstrating the monolithic integration of self-driven 360°photodetectors and artificial synapses in a dual-mode transparent device successfully.By manipulating the carrier transport dynamics through controlling the bias voltage,the degree of oxygen vacancy ionization can be precisely regulated,ultimately realizing the monolithic dual-mode device.At 0 V bias,the device functions as a fast-response self-driven photodetector with stable optical communication capabilities,achieving 360°quasi-omnidirectional photodetection.Upon applying a bias voltage,the operating mode switches to a synaptic device,which successfully simulates brainlike paired-pulse facilitation,short-/long-term plasticity processes,and learning/forgetting behaviors.The device demonstrates an exceptionally high UV/visible rejection ratio of 1.29×10^(4),coupled with an ultra-low dark current of less than 1 pA.Furthermore,this device has a low power consumption of 2.5×10^(−14)J per synaptic event,indicating an energy efficiency comparable to synaptic processes in the human brain.Moreover,nonlinear photoconductivity lets the device become a neuromorphic sensor for preprocessing images,enhancing recognition accuracy.Importantly,by leveraging the long-memory characteristic of the devices in open-circuit voltage mode,the devices have been successfully applied to guide humanoid robots in performing direction distinguishing and motion learning.This work provides new insights into the integrated manufacturing of multifunctional monolithic devices and foresees their immense potential in upcoming advanced,low-power neuromorphic computing systems.
基金supported by the Gansu Youth Science and Technology Fund(24JRRA189).
文摘A quadruped robot with a manipulator that combines dynamic motion and manipulation capabilities will greatly expand its application scenarios.However,the addition of the manipulator raises the center of mass of the quadruped robot,increasing complexity in motion control and posing new challenges for maintaining balance on sloped terrains.To address this,a balance control method based on whole-body synergy is proposed in this study,emphasizing adaptive adjustment of the robot system’s overall balance through effective utilization of the manipulator’s active motion.By establishing a mapping relationship between the manipulator and the robot’s attitude angle under system equilibrium,the desired manipulator motion is guided by real-time estimates of terrain angles during motion,enhancing motion efficiency while ensuring robot balance.Furthermore,to enhance motion tracking accuracy,the optimization of system angular momentum and manipulator manipulability is incorporated into hierarchical optimization tasks,improving manipulator controllability and overall system performance.Simulation and experimental results demonstrate that the quadruped robot with a manipulator exhibits reduced velocity and attitude angle fluctuations,as well as smoother foot-end force dynamics during climbing motions with the addition of manipulator adaptive adjustment.These results validate the effectiveness and superiority of the manipulator-based adaptive adjustment strategy proposed in this paper.
