Due to the unique locomotion,the head-shaking problem of biomimetic robotic fish inevitably occurs during rectilinear locomotion,which strongly hinders its practical applications.In this paper,we experimentally study ...Due to the unique locomotion,the head-shaking problem of biomimetic robotic fish inevitably occurs during rectilinear locomotion,which strongly hinders its practical applications.In this paper,we experimentally study this problem by proposing the method of coordination control between the caudal fin and anal fin.First,an untethered biomimetic robotic fish,equipped with an anal fin,a caudal fin and two pectoral fins,is developed as the experimental platform.Second,a Central Pattern Generator(CPG)-based controller is used to coordinate the motions of the anal fin and caudal fin.Third,extensive experiments are conducted to explore different combinations of the flapping frequencies,the flapping amplitudes,and the phase differences between the anal fin and caudal fin.Notably,through proper control of the anal fin,the amplitude of the yaw motion can be as small as 4.32°,which sees a 65%improvement compared to the scenario without anal fin,and a 57%improvement compared to that with a stationary anal fin.This paper provides a novel way to alleviate the head-shaking problem for biomimetic robotic fish,and first test this method on an untethered,freely swimming robotic platform,which can shed light on the development of underwater robotics.展开更多
Untethered microrobots have attracted extensive attention due to their potential for biomedical applications and micromanipulation at the small scale.Soft microrobots are of great research importance because of their ...Untethered microrobots have attracted extensive attention due to their potential for biomedical applications and micromanipulation at the small scale.Soft microrobots are of great research importance because of their highly deformable ability to achieve not only multiple locomotion mechanisms but also minimal invasion to the environment.However,the existing microrobots are still limited in their ability to locomote and cross obstacles in unstructured environments compared to conventional legged robots.Nature provides much inspiration for developing miniature robots.Here,we propose a bionic quadruped soft thin-film microrobot with a nonmagnetic soft body and 4 magnetic flexible legs.The quadruped soft microrobot can achieve multiple controllable locomotion modes in the external magnetic field.The experiment demonstrated the robot’s excellent obstacle-crossing ability by walking on the surface with steps and moving in the bottom of a stomach model with gullies.In particular,by controlling the conical angle of the external conical magnetic field,microbeads gripping,transportation,and release of the microrobot were demonstrated.In the future,the quadruped microrobot with excellent obstacle-crossing and gripping capabilities will be relevant for biomedical applications and micromanipulation.展开更多
Robustness and generalization are two challenging problems for learning point cloud representation.To tackle these problems,we first design a novel geometry coding model,which can effectively use an invariant eigengra...Robustness and generalization are two challenging problems for learning point cloud representation.To tackle these problems,we first design a novel geometry coding model,which can effectively use an invariant eigengraph to group points with similar geometric information,even when such points are far from each other.We also introduce a large-scale point cloud dataset,PCNet184.It consists of 184 categories and 51,915 synthetic objects,which brings new challenges for point cloud classification,and provides a new benchmark to assess point cloud cross-domain generalization.Finally,we perform extensive experiments on point cloud classification,using ModelNet40,ScanObjectNN,and our PCNet184,and segmentation,using ShapeNetPart and S3DIS.Our method achieves comparable performance to state-of-the-art methods on these datasets,for both supervised and unsupervised learning.Code and our dataset are available at https://github.com/MingyeXu/PCNet184.展开更多
The loss of hand functions in upper limb amputees severely restricts their mobility in daily life.Wearing a humanoid prosthetic hand would be an effective way of restoring lost hand functions.In a prosthetic hand desi...The loss of hand functions in upper limb amputees severely restricts their mobility in daily life.Wearing a humanoid prosthetic hand would be an effective way of restoring lost hand functions.In a prosthetic hand design,replicating the natural and dexterous grasping functions with a few actuators remains a big challenge.In this study,a function-oriented optimization design(FOD)method is proposed for the design of a tendon-driven humanoid prosthetic hand.An optimization function of different functional conditions of full-phalanx contact,total contact force,and force isotropy was constructed based on the kinetostatic model of a prosthetic finger for the evaluation of grasping performance.Using a genetic algorithm,the optimal geometric parameters of the prosthetic finger could be determined for specific functional requirements.Optimal results reveal that the structure of the prosthetic finger is significantly different when designed for different functional requirements and grasping target sizes.A prosthetic finger was fabricated and tested with grasping experiments.The mean absolute percentage error between the theoretical value and the experimental result is less than 10%,demonstrating that the kinetostatic model of the prosthetic finger is effective and makes the FOD method possible.This study suggests that the FOD method enables the systematic evaluation of grasping performance for prosthetic hands in the design stage,which could improve the design efficiency and help prosthetic hands meet the design requirements.展开更多
The generalized Kerker effects have attracted increasing interests in recent years due to their abilities to manipulate the far-field properties of metasurfaces.However,the dual-polarized generalized Kerker effect ena...The generalized Kerker effects have attracted increasing interests in recent years due to their abilities to manipulate the far-field properties of metasurfaces.However,the dual-polarized generalized Kerker effect enabling different tailoring of orthogonally-polarized electromagnetic waves has not yet been reported.Herein,we demonstrate polarization-controlled dual resonant lattice Kerker effects in periodic silicon nanodisks.By varying the incident angle,the electric dipole and magnetic dipole surface lattice resonances can spectrally overlap,causing zero reflectance and unitary transmittance,i.e.,the resonant lattice Kerker effect.The incident angle for achieving this effect can be tuned differently for s-and p-polarizations over large regions by varying the nanodisk size or the lattice periods.The proposed dual-polarized resonant lattice Kerker effects open up avenues for polarization-controlled manipulation of the phase and wavefront of light with metasurfaces.展开更多
基金funded by Natural Science Foundation of Guangdong Province(#2020A1515110692)National Natural Science Foundation of China(#51905113),Guangxi Natural Science Foundation(#2021GXNSFAA220095),Shenzhen Institute of Artificial Intelligence and Robotics for Society,SIAT Innovation Program for Excellent Young Researchers,and SIAT-CUHK Joint Laboratory of Precision Engineering.
文摘Due to the unique locomotion,the head-shaking problem of biomimetic robotic fish inevitably occurs during rectilinear locomotion,which strongly hinders its practical applications.In this paper,we experimentally study this problem by proposing the method of coordination control between the caudal fin and anal fin.First,an untethered biomimetic robotic fish,equipped with an anal fin,a caudal fin and two pectoral fins,is developed as the experimental platform.Second,a Central Pattern Generator(CPG)-based controller is used to coordinate the motions of the anal fin and caudal fin.Third,extensive experiments are conducted to explore different combinations of the flapping frequencies,the flapping amplitudes,and the phase differences between the anal fin and caudal fin.Notably,through proper control of the anal fin,the amplitude of the yaw motion can be as small as 4.32°,which sees a 65%improvement compared to the scenario without anal fin,and a 57%improvement compared to that with a stationary anal fin.This paper provides a novel way to alleviate the head-shaking problem for biomimetic robotic fish,and first test this method on an untethered,freely swimming robotic platform,which can shed light on the development of underwater robotics.
基金supported in part by National Key Re search and Development Project under Grant SQ2020YFB130100in part by the National Natural Science Foundation of China under Grants 62022087 and U22A2064+5 种基金in part by the Shenzhen Science and Technology Innovation Commission under Shenzhen Fundamental Research Program under Grant JCYJ20220818101611025in part by the Youth In novation Promotion Association of CAS,in part by the Special Support Project for Outstanding Young Scholars of Guangdong Province under Grant 2019TQ05X933in part by the CAS-Croucher Funding Scheme for Joint Laboratories under Grant 172644KYSB20200044the Croucher Foundation Grant with reference no.CAS20403in part by the Shenzhen Institute of Artificial Intelligence and Robotics for Society,in part by DMETKF2022008in part by SIAT-CUHK Joint Laboratory of Robotics and Intelligent Systems.
文摘Untethered microrobots have attracted extensive attention due to their potential for biomedical applications and micromanipulation at the small scale.Soft microrobots are of great research importance because of their highly deformable ability to achieve not only multiple locomotion mechanisms but also minimal invasion to the environment.However,the existing microrobots are still limited in their ability to locomote and cross obstacles in unstructured environments compared to conventional legged robots.Nature provides much inspiration for developing miniature robots.Here,we propose a bionic quadruped soft thin-film microrobot with a nonmagnetic soft body and 4 magnetic flexible legs.The quadruped soft microrobot can achieve multiple controllable locomotion modes in the external magnetic field.The experiment demonstrated the robot’s excellent obstacle-crossing ability by walking on the surface with steps and moving in the bottom of a stomach model with gullies.In particular,by controlling the conical angle of the external conical magnetic field,microbeads gripping,transportation,and release of the microrobot were demonstrated.In the future,the quadruped microrobot with excellent obstacle-crossing and gripping capabilities will be relevant for biomedical applications and micromanipulation.
基金This work was partially supported by the National Natural Science Foundation of China(Grant Nos.61876176 and U1813218)the Joint Lab of CAS–HK,the Shenzhen Research Program(Grant No.RCJC20200714114557087)+1 种基金the Shanghai Committee of Science and Technology(Grant No.21DZ1100100)Shenzhen Institute of Artificial Intelligence and Robotics for Society.
文摘Robustness and generalization are two challenging problems for learning point cloud representation.To tackle these problems,we first design a novel geometry coding model,which can effectively use an invariant eigengraph to group points with similar geometric information,even when such points are far from each other.We also introduce a large-scale point cloud dataset,PCNet184.It consists of 184 categories and 51,915 synthetic objects,which brings new challenges for point cloud classification,and provides a new benchmark to assess point cloud cross-domain generalization.Finally,we perform extensive experiments on point cloud classification,using ModelNet40,ScanObjectNN,and our PCNet184,and segmentation,using ShapeNetPart and S3DIS.Our method achieves comparable performance to state-of-the-art methods on these datasets,for both supervised and unsupervised learning.Code and our dataset are available at https://github.com/MingyeXu/PCNet184.
基金This work was supported in part by the Key-Area Research and Development Program of Guangdong Province,China(Grant No.2020B0909020004)the National Key R&D Program of China(Grant No.2020YFC2007900)the Shenzhen Science and Technology Program,China(Grant No.CJGJZD20200617103002006).
文摘The loss of hand functions in upper limb amputees severely restricts their mobility in daily life.Wearing a humanoid prosthetic hand would be an effective way of restoring lost hand functions.In a prosthetic hand design,replicating the natural and dexterous grasping functions with a few actuators remains a big challenge.In this study,a function-oriented optimization design(FOD)method is proposed for the design of a tendon-driven humanoid prosthetic hand.An optimization function of different functional conditions of full-phalanx contact,total contact force,and force isotropy was constructed based on the kinetostatic model of a prosthetic finger for the evaluation of grasping performance.Using a genetic algorithm,the optimal geometric parameters of the prosthetic finger could be determined for specific functional requirements.Optimal results reveal that the structure of the prosthetic finger is significantly different when designed for different functional requirements and grasping target sizes.A prosthetic finger was fabricated and tested with grasping experiments.The mean absolute percentage error between the theoretical value and the experimental result is less than 10%,demonstrating that the kinetostatic model of the prosthetic finger is effective and makes the FOD method possible.This study suggests that the FOD method enables the systematic evaluation of grasping performance for prosthetic hands in the design stage,which could improve the design efficiency and help prosthetic hands meet the design requirements.
基金supported by the Natural Science Foundation of Guangdong Province(No.2022A1515010086)the Shenzhen Research Foundation(No.JCYJ20180507182444250)the Shenzhen Institute of Artificial Intelligence and Robotics for Society,and the State Key Laboratory of Advanced Optical Communication Systems and Networks,China(No.2020GZKF004).
文摘The generalized Kerker effects have attracted increasing interests in recent years due to their abilities to manipulate the far-field properties of metasurfaces.However,the dual-polarized generalized Kerker effect enabling different tailoring of orthogonally-polarized electromagnetic waves has not yet been reported.Herein,we demonstrate polarization-controlled dual resonant lattice Kerker effects in periodic silicon nanodisks.By varying the incident angle,the electric dipole and magnetic dipole surface lattice resonances can spectrally overlap,causing zero reflectance and unitary transmittance,i.e.,the resonant lattice Kerker effect.The incident angle for achieving this effect can be tuned differently for s-and p-polarizations over large regions by varying the nanodisk size or the lattice periods.The proposed dual-polarized resonant lattice Kerker effects open up avenues for polarization-controlled manipulation of the phase and wavefront of light with metasurfaces.
