Soft actuators endowed with self-sensing capability become highly sought after in recent years.Ti3C2Tx MXene is expected to be used in the development of self-sensing actuators due to its outstanding physical and chem...Soft actuators endowed with self-sensing capability become highly sought after in recent years.Ti3C2Tx MXene is expected to be used in the development of self-sensing actuators due to its outstanding physical and chemical properties.However,achieving precise deformation feedback of MXene-based actuators remains a challenge,as the resistance change of MXene is not only affected by deformation,but also by temperature,and the decoupling is difficult.Here,a composite ink with temperature self-compensation(0.00125%·°C^(−1) of temperature coefficient of resistance)is fabricated by combining MXene and graphite with opposite temperature coefficients of resistance.The composite ink can be written on a variety of substrates,including glass,cellulose paper,and various polymers.Based on this,an ink-cellulose/polymer composite actuator with self-sensing function is actualized.The actuator can achieve accurate real-time deformation feedback by monitoring the resistance signal of ink-cellulose layer,which shows a high linear sensitivity(gauge factor~14.5,coefficient of determination(R^(2))>0.99),thereby realizing the perception of touch behavior and distinguishing objects with different weights,softness,and roughness.Besides,a series of biomimetic devices and soft robots with programmable movements(rolling and self-sustained oscillating)are also demonstrated.The results offer new insights for the development of the self-sensing actuators.展开更多
The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sens...The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sensing actuated gradient hydrogel that combines ultrafast actuation and high sensitivity for remote interaction with robotic hand. The gradient network structure, achieved through a wettability difference method involving the rapid precipitation of MoO_(2) nanosheets, introduces hydrophilic disparities between two sides within hydrogel. This distinctive approach bestows the hydrogel with ultrafast thermo-responsive actuation(21° s^(-1)) and enhanced photothermal efficiency(increase by 3.7 ℃ s^(-1) under 808 nm near-infrared). Moreover, the local cross-linking of sodium alginate with Ca^(2+) endows the hydrogel with programmable deformability and information display capabilities. Additionally, the hydrogel exhibits high sensitivity(gauge factor 3.94 within a wide strain range of 600%), fast response times(140 ms) and good cycling stability. Leveraging these exceptional properties, we incorporate the hydrogel into various soft actuators, including soft gripper, artificial iris, and bioinspired jellyfish, as well as wearable electronics capable of precise human motion and physiological signal detection. Furthermore, through the synergistic combination of remarkable actuation and sensitivity, we realize a self-sensing touch bioinspired tongue. Notably, by employing quantitative analysis of actuation-sensing, we realize remote interaction between soft-hard robot via the Internet of Things. The multifunctional self-sensing actuated gradient hydrogel presented in this study provides a new insight for advanced somatosensory materials, self-feedback intelligent soft robots and human–machine interactions.展开更多
This paper introduces a self-sensing anthropomorphic robot hand driven by Twisted String Actuators(TSAs).The use of TSAs provides several advantages such as muscle-like structures,high transmission ratios,large output...This paper introduces a self-sensing anthropomorphic robot hand driven by Twisted String Actuators(TSAs).The use of TSAs provides several advantages such as muscle-like structures,high transmission ratios,large output forces,high efficiency,compactness,inherent compliance,and the ability to transmit power over distances.However,conventional sensors used in TSA-actuated robotic hands increase stiffness,mass,volume,and complexity,making feedback control challenging.To address this issue,a novel self-sensing approach is proposed using strain-sensing string based on Conductive Polymer Composite(CPC).By measuring the resistance changes in the strain-sensing string,the bending angle of the robot hand's fingers can be estimated,enabling closed-loop control without external sensors.The developed self-sensing anthropomorphic robot hand comprises a 3D-printed structure with five fingers,a palm,five self-sensing TSAs,and a 3D-printed forearm.Experimental studies validate the self-sensing properties of the TSA and the anthropomorphic robot hand.Additionally,a real-time Virtual Reality(VR)monitoring system is implemented for visualizing and monitoring the robot hand's movements using its self-sensing capabilities.This research contributes valuable insights and advancements to the field of intelligent prosthetics and robotic end grippers.展开更多
Double-integrator multi-agent systems(MASs)might not achieve dynamical consensus,even if only partial agents suffer from self-sensing function failures(SSFFs).SSFFs might be asynchronous in real engineering applicatio...Double-integrator multi-agent systems(MASs)might not achieve dynamical consensus,even if only partial agents suffer from self-sensing function failures(SSFFs).SSFFs might be asynchronous in real engineering application.The existing fault-tolerant dynamical consensus protocol suitable for synchronous SSFFs cannot be directly used to tackle fault-tolerant dynamical consensus of double-integrator MASs with partial agents subject to asynchronous SSFFs.Motivated by these facts,this paper explores a new fault-tolerant dynamical consensus protocol suitable for asynchronous SSFFs.First,multi-hop communication together with the idea of treating asynchronous SSFFs as multiple piecewise synchronous SSFFs is used for recovering the connectivity of network topology among all normal agents.Second,a fault-tolerant dynamical consensus protocol is designed for double-integrator MASs by utilizing the history information of an agent subject to SSFF for computing its own state information at the instants when its minimum-hop normal neighbor set changes.Then,it is theoretically proved that if the strategy of network topology connectivity recovery and the fault-tolerant dynamical consensus protocol with proper time-varying gains are used simultaneously,double-integrator MASs with all normal agents and all agents subject to SSFFs can reach dynamical consensus.Finally,comparison numerical simulations are given to illustrate the effectiveness of the theoretical results.展开更多
Dear Editor,This letter addresses the impulse game problem for a general scope of deterministic,multi-player,nonzero-sum differential games wherein all participants adopt impulse controls.Our objective is to formulate...Dear Editor,This letter addresses the impulse game problem for a general scope of deterministic,multi-player,nonzero-sum differential games wherein all participants adopt impulse controls.Our objective is to formulate this impulse game problem with the modified objective function including interaction costs among the players in a discontinuous fashion,and subsequently,to derive a verification theorem for identifying the feedback Nash equilibrium strategy.展开更多
This study constructs a reflective feedback model based on a pedagogical agent(PA)and explores its impact on students’problem-solving ability and cognitive load.A quasi-experimental design was used in the study,with ...This study constructs a reflective feedback model based on a pedagogical agent(PA)and explores its impact on students’problem-solving ability and cognitive load.A quasi-experimental design was used in the study,with 84 students from a middle school selected as the research subjects(44 in the experimental group and 40 in the control group).The experimental group used the reflective feedback model,while the control group used the factual feedback model.The results show that,compared with factual feedback,the reflective feedback model based on the pedagogical agent significantly improves students’problem-solving ability,especially at the action and thinking levels.In addition,this model effectively reduces students’cognitive load,especially in terms of internal and external load.展开更多
The output feedback active disturbance rejection control of a valve-controlled cylinder electro-hydraulic servo system is investigated in this paper.First,a comprehensive nonlinear mathematical model that encompasses ...The output feedback active disturbance rejection control of a valve-controlled cylinder electro-hydraulic servo system is investigated in this paper.First,a comprehensive nonlinear mathematical model that encompasses both matched and mismatched disturbances is formulated.Due to the fact that only position information can be measured,a linear Extended State Observer(ESO)is introduced to estimate unknown states and matched disturbances,while a dedicated disturbance observer is constructed to estimate mismatched disturbances.Different from the traditional observer results,the design of the disturbance observer used in this study is carried out under the constraint of output feedback.Furthermore,an output feedback nonlinear controller is proposed leveraging the aforementioned observers to achieve accurate trajectory tracking.To mitigate the inherent differential explosion problem of the traditional backstepping framework,a finite-time stable command filter is incorporated.Simultaneously,considering transient filtering errors,a set of error compensation signals are designed to counter their negative impact effectively.Theoretical analysis affirms that the proposed control strategy ensures the boundedness of all signals within the closed-loop system.Additionally,under the specific condition of only time-invariant disturbances in the system,the conclusion of asymptotic stability is established.Finally,the algorithm’s efficacy is validated through comparative experiments.展开更多
Written feedback in English writing classes serves as the primary mode of feedback.By comparing direct corrective feedback and indirect corrective feedback in addressing content and form,this paper argues that indirec...Written feedback in English writing classes serves as the primary mode of feedback.By comparing direct corrective feedback and indirect corrective feedback in addressing content and form,this paper argues that indirect corrective feedback better aligns with the needs of English majors.Multiple factors influence the choice of written feedback methods,and teachers should carefully select the most appropriate approach based on student characteristics to maximize the effectiveness of feedback.展开更多
Although substantial research shows the effectiveness of written corrective feedback(WCF)in treating simple grammar structures,more research is still needed to refute Truscott’s claim that WCF may not work on complex...Although substantial research shows the effectiveness of written corrective feedback(WCF)in treating simple grammar structures,more research is still needed to refute Truscott’s claim that WCF may not work on complex grammar structures.Similarly,a previous body of research has shown that the degree of explicitness of feedback moderates the efficacy of WCF.However,most WCF studies have systematically manipulated only direct corrective feedback.The current study was therefore conducted to fill these gaps in the literature.To this end,five intact classes of Functional English were recruited and later randomly assigned to four treatment groups:DCF,DCF+ME,ICF,and ICF+ME,and one control group that received no feedback.All the groups took part in three WCF treatment sessions,during which they wrote two different pieces:a news report and a picture description.Later,only the treatment groups received the WCF.The WCF’s effectiveness was measured by writing tests and grammaticality judgment tasks(GJT).The results demonstrated that WCF helped L2 learners improve their grammatical accuracy of passive voice tenses.The study further showed that the group that received the most explicit type of WCF fared better than the ones that received the least explicit type of WCF.Important pedagogical implications for ESL/EFL teachers are discussed.展开更多
Direct comparison of the difference in biomass between live and sterilized soils may result in deviations in biological plant-soil feedback(B-PSF)due to changes induced by sterilization in bulk soil microorganisms,soi...Direct comparison of the difference in biomass between live and sterilized soils may result in deviations in biological plant-soil feedback(B-PSF)due to changes induced by sterilization in bulk soil microorganisms,soil structure,and nutrient availability.The sterilization-induced deviation(sterilization-effect,SS_(c))to often-used method B-PSF_(ou) was corrected by adding a parallel experiment without conditioning by any plants(B-PSF_(c)).Plant-soil feedback experiments were conducted for two plants with contrasting in root traits and rhizosphere microbial community to test the reliability of the method(Kalidium foliatum and Reaumuria songaric).The specific root length(SRL),root tissue density(RTD)and of R.songarica was higher compared to that of K.foliatum,but the root diameter(RAD)of it was significantly lower than that of K.foliatum.The plasticity of root traits of K.foliatum was stronger than that of R.songarica.The B-PSF_(ou) of K.foliatum was four times negative than B-PSF_(c),whereas there was no statistically significant difference of B-PSF_(ou) and B-PSF_(c) for R.songarica.The correlation between B-PSF_(c) and the relative abundance of pathogens and EcMF was found to be stronger compared to B-PSF_(ou).We proposed method corrects the deviation in B-PSF.The variation of deviation between species may be related to root traits.展开更多
In order to identify the tilt direction of the self-mixing signals under weak feedback regime interfered by noise,a deep learning method is proposed.The one-dimensional U-Net(1D U-Net)neural network can identify the d...In order to identify the tilt direction of the self-mixing signals under weak feedback regime interfered by noise,a deep learning method is proposed.The one-dimensional U-Net(1D U-Net)neural network can identify the direction of the self-mixing fringes accurately and quickly.In the process of measurement,the measurement signal can be normalized and then the neural network can be used to discriminate the direction.Simulation and experimental results show that the proposed method is suitable for self-mixing interference signals with noise in the whole weak feedback regime,and can maintain a high discrimination accuracy for signals interfered by 5 dB large noise.Combined with fringe counting method,accurate and rapid displacement reconstruction can be realized.展开更多
We theoretically investigate a cooling scheme assisted by a quantum well(QW)and coherent feedback within a hybrid optomechanical system.Although the exciton mode in the QW and the mechanical resonator(MR)are initially...We theoretically investigate a cooling scheme assisted by a quantum well(QW)and coherent feedback within a hybrid optomechanical system.Although the exciton mode in the QW and the mechanical resonator(MR)are initially uncoupled,their interaction via the microcavity field leads to an indirect exciton-mode–mechanical-mode coupling.The coherent feedback loop is applied by feeding back a fraction of the output field of the cavity through a controllable beam splitter to the cavity’s input mirror.It is shown that the cooling capability is enhanced by effectively suppressing the Stokes process through coupling with the QW.Furthermore,the effect of the anti-Stokes process is enhanced through the application of the coherent feedback loop.This particular system configuration enables cooling of the mechanical resonator even in the unresolved sideband regime(USR).This study has some important guiding significance in the field of quantum information processing.展开更多
Background Haptic feedback plays a crucial role in virtual reality(VR)interaction,helping to improve the precision of user operation and enhancing the immersion of the user experience.Instrumental haptic feedback in v...Background Haptic feedback plays a crucial role in virtual reality(VR)interaction,helping to improve the precision of user operation and enhancing the immersion of the user experience.Instrumental haptic feedback in virtual environments is primarily realized using grounded force or vibration feedback devices.However,improvements are required in terms of the active space and feedback realism.Methods We propose a lightweight and flexible haptic feedback glove that can haptically render objects in VR environments via kinesthetic and vibration feedback,thereby enabling users to enjoy a rich virtual piano-playing experience.The kinesthetic feedback of the glove relies on a cable-pulling mechanism that rotates the mechanism and pulls the two cables connected to it,thereby changing the amount of force generated to simulate the hardness or softness of the object.Vibration feedback is provided by small vibration motors embedded in the bottom of the fingertips of the glove.We designed a piano-playing scenario in the virtual environment and conducted user tests.The evaluation metrics were clarity,realism,enjoyment,and satisfaction.Results A total of 14 subjects participated in the test,and the results showed that our proposed glove scored significantly higher on the four evaluation metrics than the nofeedback and vibration feedback methods.Conclusions Our proposed glove significantly enhances the user experience when interacting with virtual objects.展开更多
Force feedback bilateral teleoperation represents a pivotal advancement in control technology,finding widespread application in hazardous material transportation,perilous environments,space and deep-sea exploration,an...Force feedback bilateral teleoperation represents a pivotal advancement in control technology,finding widespread application in hazardous material transportation,perilous environments,space and deep-sea exploration,and healthcare domains.This paper traces the evolutionary trajectory of force feedback bilateral teleoperation from its conceptual inception to its current complexity.It elucidates the fundamental principles underpinning interaction forces and tactile exchanges,with a specific emphasis on the crucial role of tactile devices.In this review,a quantitative analysis of force feedback bilateral teleoperation development trends from 2011 to 2024 has been conducted,utilizing published journal article data as the primary source of information.The review accentuates classical control frameworks and algorithms,while also delving into existing research advancements and prospec-tive breakthrough directions.Moreover,it explores specific practical scenarios ranging from intricate surgeries to hazardous environment exploration,underscoring the technology’s potential to revolutionize industries by augmenting human manipulation of remote systems.This underscores the pivotal role of force feedback bilateral teleoperation as a transformative human-machine interface,capable of shaping flexible control strategies and addressing technological bottlenecks.Future research endeavors in force feedback bilateral teleoperation are expected to prioritize the creation of more immersive experiences,overcoming technical hurdles,fortifying human-machine collaboration,and broadening application domains,particularly within the realms of medical intervention and hazardous environments.With the continuous progression of technology,the integration of human intelligence and robotic capabilities is expected to produce more innovations and breakthroughs in the field of automatic control.展开更多
Channel state information(CSI)is essen-tial to unlock the potential of reconfigurable intelli-gent surfaces(RISs)in wireless communication sys-tems.Since massive RIS elements are typically imple-mented without baseban...Channel state information(CSI)is essen-tial to unlock the potential of reconfigurable intelli-gent surfaces(RISs)in wireless communication sys-tems.Since massive RIS elements are typically imple-mented without baseband signal processing capabili-ties,limited CSI feedback is necessary when design-ing the reflection/refraction coefficients of the RIS.In this article,the unique RIS-assisted channel features,such as the RIS position-dependent channel fluctua-tion,the ultra-high dimensional sub-channel matrix,and the structured sparsity,are distilled from recent advances in limited feedback and used as guidelines for designing feedback schemes.We begin by il-lustrating the use cases and the corresponding chal-lenges associated with RIS feedback.We then discuss how to leverage techniques such as channel customiza-tion,structured-sparsity,autoencoders,and others to reduce feedback overhead and complexity when de-vising feedback schemes.Finally,we identify poten-tial research directions by considering the unresolved challenges,the new RIS architecture,and the integra-tion with multi-modal information and artificial intel-ligence.展开更多
This study investigates the impact of vegetation-climate feedback on the global land monsoon system during the Last Interglacial(LIG,127000 years BP)and the mid-Holocene(MH,6000 years BP)using the earth system model E...This study investigates the impact of vegetation-climate feedback on the global land monsoon system during the Last Interglacial(LIG,127000 years BP)and the mid-Holocene(MH,6000 years BP)using the earth system model EC-Earth3.Our findings indicate that vegetation changes significantly influence the global monsoon area and precipitation patterns,especially in the North African and Indian monsoon regions.The North African monsoon region experienced the most substantial increase in vegetation during both the LIG and MH,resulting in significant increases in monsoonal precipitation by 9.8%and 6.0%,respectively.The vegetation feedback also intensified the Saharan Heat Low,strengthened monsoonal flows,and enhanced precipitation over the North African monsoon region.In contrast,the Indian monsoon region exhibited divergent responses to vegetation changes.During the LIG,precipitation in the Indian monsoon region decreased by 2.2%,while it increased by 1.6%during the MH.These differences highlight the complex and region-specific impacts of vegetation feedback on monsoon systems.Overall,this study demonstrates that vegetation feedback exerts distinct influences on the global monsoon during the MH and LIG.These findings highlight the importance of considering vegetation-climate feedback in understanding past monsoon variability and in predicting future climate change impacts on monsoon systems.展开更多
This study investigates the nonlinear resonance responses of suspended cables subjected to multi-frequency excitations and time-delayed feedback.Two specific combinations and simultaneous resonances are selected for d...This study investigates the nonlinear resonance responses of suspended cables subjected to multi-frequency excitations and time-delayed feedback.Two specific combinations and simultaneous resonances are selected for detailed examination.Initially,utilizing Hamilton’s variational principle,a nonlinear vibration control model of suspended cables under multi-frequency excitations and longitudinal time-delayed velocity feedback is developed,and the Galerkin method is employed to obtain the discrete model.Subsequently,focusing solely on single-mode discretization,analytical solutions for the two simultaneous resonances are derived using the method of multiple scales.The frequency response equations are derived,and the stability analysis is presented for two simultaneous resonance cases.The results demonstrate that suspended cables exhibit complex nonlinearity under multi-frequency excitations.Multiple solutions under multi-frequency excitation can be distinguished through the frequency–response and the detuning-phase curves.By adjusting the control gain and time delay,the resonance range,response amplitude,and phase of suspended cables can be modified.展开更多
A dual-harmonic acceleration system is utilized to mitigate the space-charge effect in the rapid-cycling synchrotron of the China Spallation Neutron Source upgrade project(CSNS-II).A magnetic alloy(MA)-loaded cavity w...A dual-harmonic acceleration system is utilized to mitigate the space-charge effect in the rapid-cycling synchrotron of the China Spallation Neutron Source upgrade project(CSNS-II).A magnetic alloy(MA)-loaded cavity with a high accelerating gradient is developed to satisfy the requirements of dual-harmonic acceleration and provide the necessary second-harmonic cavity voltage.However,the MA-loaded cavity exhibits a wideband frequency response,resulting in numerous higher harmonics in the radio-frequency(RF)voltage.These higher harmonics are caused by both the beam-loading effect and distorted amplifier current,which distort the RF bucket,increase the power dissipation in the cavity,and lower the gradient.To address these issues,a multiharmonic independent feedback-control approach is implemented to compensate for higher harmonics.The effectiveness of this control strategy is validated experimentally.This study provides details regarding the feedback-control design and presents the commissioning results.展开更多
Purpose–This study aims to propose a novel identification method to accurately estimate linear and nonlinear dynamics in permanent magnet synchronous linear motor(PMSLM)based on the time-domain analysis of relay feed...Purpose–This study aims to propose a novel identification method to accurately estimate linear and nonlinear dynamics in permanent magnet synchronous linear motor(PMSLM)based on the time-domain analysis of relay feedback.Design/methodology/approach–A mathematical model of the PMSLM-based servo-mechanical system was first established,incorporating the aforementioned nonlinearities.The model’s velocity response was derived by analyzing its behavior as a first-order system under arbitrary input.To induce oscillatory dynamics,an ideal relay with artificially introduced dead-time components was then integrated into the servo-mechanism.Depending on the oscillations and the time-domain analysis,nonlinear formulas were deduced according to the velocity response of the servo-mechanism.Afterwards,the unknown model parameters can be solved on account of the cost function which utilizes the discrepancy between nominal position characteristics and temporary position characteristics,both of which are extracted from the oscillations.The proposed recognition method was validated through a twostage process:(1)numerical simulation and calculation,followed by(2)real-time experimental verification on a direct-drive servo platform.Subsequently,leveraging the identification results,a novel control strategy was developed and its tracking performance was benchmarked against conventional control schemes.Findings–Simulation results demonstrate that the proposed method achieves estimation accuracy within 8%.Building on this,a novel control strategy is developed by incorporating both friction pulsation and force pulsation identification results into the feedforward compensator.Comparative experiments reveal that this strategy significantly enhances tracking and positioning performance over traditional control schemes.In a word,this new identification method can be used in different process control and servo control systems.Moreover,parameter auto-tuning,feed forward compensation or disturbance observer can be investigated based on the obtained information to improve the system stability and control accuracy.Originality/value–It is of great significance for the performance improvement of rail transit motor control equipment,such as electro-mechanical braking systems.By enhancing the efficiency of motor control,the performance of the product will be more outstanding.展开更多
Phenology shifts influence regional climate by altering energy,and water fluxes through biophysical processes.However,a quantitative understanding of the phenological control on vegetation’s biophysical feedbacks to ...Phenology shifts influence regional climate by altering energy,and water fluxes through biophysical processes.However,a quantitative understanding of the phenological control on vegetation’s biophysical feedbacks to re gional climate remains elusive.Using long-term remote sensing observations and Weather Research and Fore casting(WRF)model simulations,we investigated vegetation phenology changes from 2003 to 2020 and quan tified their biophysical controls on the regional climate in Northeast China.Our findings elucidated that earlier green-up contributed to a prolonged growing season in forests,while advanced green-up and delayed dormancy extended the growing season in croplands.This prolonged presence and increased maximum green cover in tensified climate-vegetation interactions,resulting in more significant surface cooling in croplands compared to forests.Surface cooling from forest phenology changes was prominent during May’s green-up(-0.53±0.07°C),while crop phenology changes induced cooling throughout the growing season,particularly in June(-0.47±0.15°C),July(-0.48±0.11°C),and September(-0.28±0.09°C).Furthermore,we unraveled the contributions of different biophysical pathways to temperature feedback using a two-resistance attribution model,with aero dynamic resistance emerging as the dominant factor.Crucially,our findings underscored that the land surface temperature(LST)sensitivity,exhibited substantially higher values in croplands rather than temperate forests.These strong sensitivities,coupled with the projected continuation of phenology shifts,portend further growing season cooling in croplands.These findings contribute to a more comprehensive understanding of the intricate feedback mechanisms between vegetation phenology and surface temperature,emphasizing the significance of vegetation phenology dynamics in shaping regional climate pattern and seasonality.展开更多
基金supported by the National Key R&D Program of China(NO.2024YFB3409900)the China Postdoctoral Science Foundation(No.2023M730845)the Heilongjiang Postdoctoral Fund(No.LBH-Z23182).
文摘Soft actuators endowed with self-sensing capability become highly sought after in recent years.Ti3C2Tx MXene is expected to be used in the development of self-sensing actuators due to its outstanding physical and chemical properties.However,achieving precise deformation feedback of MXene-based actuators remains a challenge,as the resistance change of MXene is not only affected by deformation,but also by temperature,and the decoupling is difficult.Here,a composite ink with temperature self-compensation(0.00125%·°C^(−1) of temperature coefficient of resistance)is fabricated by combining MXene and graphite with opposite temperature coefficients of resistance.The composite ink can be written on a variety of substrates,including glass,cellulose paper,and various polymers.Based on this,an ink-cellulose/polymer composite actuator with self-sensing function is actualized.The actuator can achieve accurate real-time deformation feedback by monitoring the resistance signal of ink-cellulose layer,which shows a high linear sensitivity(gauge factor~14.5,coefficient of determination(R^(2))>0.99),thereby realizing the perception of touch behavior and distinguishing objects with different weights,softness,and roughness.Besides,a series of biomimetic devices and soft robots with programmable movements(rolling and self-sustained oscillating)are also demonstrated.The results offer new insights for the development of the self-sensing actuators.
基金The financial support from the National Natural Science Foundation of China (32201179)Guangdong Basic and Applied Basic Research Foundation (2020A1515110126 and 2021A1515010130)+1 种基金the Fundamental Research Funds for the Central Universities (N2319005)Ningbo Science and Technology Major Project (2021Z027) is gratefully acknowledged。
文摘The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sensing actuated gradient hydrogel that combines ultrafast actuation and high sensitivity for remote interaction with robotic hand. The gradient network structure, achieved through a wettability difference method involving the rapid precipitation of MoO_(2) nanosheets, introduces hydrophilic disparities between two sides within hydrogel. This distinctive approach bestows the hydrogel with ultrafast thermo-responsive actuation(21° s^(-1)) and enhanced photothermal efficiency(increase by 3.7 ℃ s^(-1) under 808 nm near-infrared). Moreover, the local cross-linking of sodium alginate with Ca^(2+) endows the hydrogel with programmable deformability and information display capabilities. Additionally, the hydrogel exhibits high sensitivity(gauge factor 3.94 within a wide strain range of 600%), fast response times(140 ms) and good cycling stability. Leveraging these exceptional properties, we incorporate the hydrogel into various soft actuators, including soft gripper, artificial iris, and bioinspired jellyfish, as well as wearable electronics capable of precise human motion and physiological signal detection. Furthermore, through the synergistic combination of remarkable actuation and sensitivity, we realize a self-sensing touch bioinspired tongue. Notably, by employing quantitative analysis of actuation-sensing, we realize remote interaction between soft-hard robot via the Internet of Things. The multifunctional self-sensing actuated gradient hydrogel presented in this study provides a new insight for advanced somatosensory materials, self-feedback intelligent soft robots and human–machine interactions.
基金supported by the Anhui Provincial Key Research and Development Program No.2022f04020008National Natural Science Foundation of China No.62301522Anhui Provincial Nature Science Foundation No.1908085MF196.
文摘This paper introduces a self-sensing anthropomorphic robot hand driven by Twisted String Actuators(TSAs).The use of TSAs provides several advantages such as muscle-like structures,high transmission ratios,large output forces,high efficiency,compactness,inherent compliance,and the ability to transmit power over distances.However,conventional sensors used in TSA-actuated robotic hands increase stiffness,mass,volume,and complexity,making feedback control challenging.To address this issue,a novel self-sensing approach is proposed using strain-sensing string based on Conductive Polymer Composite(CPC).By measuring the resistance changes in the strain-sensing string,the bending angle of the robot hand's fingers can be estimated,enabling closed-loop control without external sensors.The developed self-sensing anthropomorphic robot hand comprises a 3D-printed structure with five fingers,a palm,five self-sensing TSAs,and a 3D-printed forearm.Experimental studies validate the self-sensing properties of the TSA and the anthropomorphic robot hand.Additionally,a real-time Virtual Reality(VR)monitoring system is implemented for visualizing and monitoring the robot hand's movements using its self-sensing capabilities.This research contributes valuable insights and advancements to the field of intelligent prosthetics and robotic end grippers.
基金National Natural Science Foundation of China(No.61876073)Fundamental Research Funds for the Central Universities of China(No.JUSRP21920)。
文摘Double-integrator multi-agent systems(MASs)might not achieve dynamical consensus,even if only partial agents suffer from self-sensing function failures(SSFFs).SSFFs might be asynchronous in real engineering application.The existing fault-tolerant dynamical consensus protocol suitable for synchronous SSFFs cannot be directly used to tackle fault-tolerant dynamical consensus of double-integrator MASs with partial agents subject to asynchronous SSFFs.Motivated by these facts,this paper explores a new fault-tolerant dynamical consensus protocol suitable for asynchronous SSFFs.First,multi-hop communication together with the idea of treating asynchronous SSFFs as multiple piecewise synchronous SSFFs is used for recovering the connectivity of network topology among all normal agents.Second,a fault-tolerant dynamical consensus protocol is designed for double-integrator MASs by utilizing the history information of an agent subject to SSFF for computing its own state information at the instants when its minimum-hop normal neighbor set changes.Then,it is theoretically proved that if the strategy of network topology connectivity recovery and the fault-tolerant dynamical consensus protocol with proper time-varying gains are used simultaneously,double-integrator MASs with all normal agents and all agents subject to SSFFs can reach dynamical consensus.Finally,comparison numerical simulations are given to illustrate the effectiveness of the theoretical results.
基金supported in part by the National Natural Science Foundation of China(62173051)the Fundamental Research Funds for the Central Universities(2024CDJCGJ012,2023CDJXY-010)+1 种基金the Chongqing Technology Innovation and Application Development Special Key Project(CSTB2022TIADCUX0015,CSTB2022TIAD-KPX0162)the China Postdoctoral Science Foundation(2024M763865)
文摘Dear Editor,This letter addresses the impulse game problem for a general scope of deterministic,multi-player,nonzero-sum differential games wherein all participants adopt impulse controls.Our objective is to formulate this impulse game problem with the modified objective function including interaction costs among the players in a discontinuous fashion,and subsequently,to derive a verification theorem for identifying the feedback Nash equilibrium strategy.
基金023 Zhejiang Provincial Department of Education General Project:Research on an interdisciplinary teaching model to promote the development of computational thinking in the context of the new curriculum standards[Grant NO:Y202351596]Key Project of Zhejiang Provincial Education Science Planning:Research on an interdisciplinary teaching model to promote students’computational thinking from multiple analytical perspectives[Grant NO:2025SB103].
文摘This study constructs a reflective feedback model based on a pedagogical agent(PA)and explores its impact on students’problem-solving ability and cognitive load.A quasi-experimental design was used in the study,with 84 students from a middle school selected as the research subjects(44 in the experimental group and 40 in the control group).The experimental group used the reflective feedback model,while the control group used the factual feedback model.The results show that,compared with factual feedback,the reflective feedback model based on the pedagogical agent significantly improves students’problem-solving ability,especially at the action and thinking levels.In addition,this model effectively reduces students’cognitive load,especially in terms of internal and external load.
基金supported by the National Key R&D Program of China(No.2021YFB2011300)the Special Funds Project for the Transformation of Scientific and Technological Achievements of Jiangsu Province,China(No.BA2023039)+1 种基金the National Natural Science Foundation of China(No.52075262)the Fundamental Research Funds for the Central Universities,China(No.30922010706).
文摘The output feedback active disturbance rejection control of a valve-controlled cylinder electro-hydraulic servo system is investigated in this paper.First,a comprehensive nonlinear mathematical model that encompasses both matched and mismatched disturbances is formulated.Due to the fact that only position information can be measured,a linear Extended State Observer(ESO)is introduced to estimate unknown states and matched disturbances,while a dedicated disturbance observer is constructed to estimate mismatched disturbances.Different from the traditional observer results,the design of the disturbance observer used in this study is carried out under the constraint of output feedback.Furthermore,an output feedback nonlinear controller is proposed leveraging the aforementioned observers to achieve accurate trajectory tracking.To mitigate the inherent differential explosion problem of the traditional backstepping framework,a finite-time stable command filter is incorporated.Simultaneously,considering transient filtering errors,a set of error compensation signals are designed to counter their negative impact effectively.Theoretical analysis affirms that the proposed control strategy ensures the boundedness of all signals within the closed-loop system.Additionally,under the specific condition of only time-invariant disturbances in the system,the conclusion of asymptotic stability is established.Finally,the algorithm’s efficacy is validated through comparative experiments.
文摘Written feedback in English writing classes serves as the primary mode of feedback.By comparing direct corrective feedback and indirect corrective feedback in addressing content and form,this paper argues that indirect corrective feedback better aligns with the needs of English majors.Multiple factors influence the choice of written feedback methods,and teachers should carefully select the most appropriate approach based on student characteristics to maximize the effectiveness of feedback.
文摘Although substantial research shows the effectiveness of written corrective feedback(WCF)in treating simple grammar structures,more research is still needed to refute Truscott’s claim that WCF may not work on complex grammar structures.Similarly,a previous body of research has shown that the degree of explicitness of feedback moderates the efficacy of WCF.However,most WCF studies have systematically manipulated only direct corrective feedback.The current study was therefore conducted to fill these gaps in the literature.To this end,five intact classes of Functional English were recruited and later randomly assigned to four treatment groups:DCF,DCF+ME,ICF,and ICF+ME,and one control group that received no feedback.All the groups took part in three WCF treatment sessions,during which they wrote two different pieces:a news report and a picture description.Later,only the treatment groups received the WCF.The WCF’s effectiveness was measured by writing tests and grammaticality judgment tasks(GJT).The results demonstrated that WCF helped L2 learners improve their grammatical accuracy of passive voice tenses.The study further showed that the group that received the most explicit type of WCF fared better than the ones that received the least explicit type of WCF.Important pedagogical implications for ESL/EFL teachers are discussed.
基金supported by Gansu Province Science and Technology Project(Grant No.21JR7RA070)the Natural Science Foundation of Gansu Province,China(Grant No.22JR5RA051)the Central Government Guides Local Funds Project for Science and Technology Development(Grant No.23ZYQHO_(2)98).
文摘Direct comparison of the difference in biomass between live and sterilized soils may result in deviations in biological plant-soil feedback(B-PSF)due to changes induced by sterilization in bulk soil microorganisms,soil structure,and nutrient availability.The sterilization-induced deviation(sterilization-effect,SS_(c))to often-used method B-PSF_(ou) was corrected by adding a parallel experiment without conditioning by any plants(B-PSF_(c)).Plant-soil feedback experiments were conducted for two plants with contrasting in root traits and rhizosphere microbial community to test the reliability of the method(Kalidium foliatum and Reaumuria songaric).The specific root length(SRL),root tissue density(RTD)and of R.songarica was higher compared to that of K.foliatum,but the root diameter(RAD)of it was significantly lower than that of K.foliatum.The plasticity of root traits of K.foliatum was stronger than that of R.songarica.The B-PSF_(ou) of K.foliatum was four times negative than B-PSF_(c),whereas there was no statistically significant difference of B-PSF_(ou) and B-PSF_(c) for R.songarica.The correlation between B-PSF_(c) and the relative abundance of pathogens and EcMF was found to be stronger compared to B-PSF_(ou).We proposed method corrects the deviation in B-PSF.The variation of deviation between species may be related to root traits.
文摘In order to identify the tilt direction of the self-mixing signals under weak feedback regime interfered by noise,a deep learning method is proposed.The one-dimensional U-Net(1D U-Net)neural network can identify the direction of the self-mixing fringes accurately and quickly.In the process of measurement,the measurement signal can be normalized and then the neural network can be used to discriminate the direction.Simulation and experimental results show that the proposed method is suitable for self-mixing interference signals with noise in the whole weak feedback regime,and can maintain a high discrimination accuracy for signals interfered by 5 dB large noise.Combined with fringe counting method,accurate and rapid displacement reconstruction can be realized.
基金supported by the National Natural Science Foundation of China(Grant Nos.62061028 and 62461035)the Key Project of Natural Science Foundation of Jiangxi Province(Grant No.20232ACB202003)+2 种基金the Finance Science and Technology Special“contract system”Project of Nanchang University Jiangxi Province(Grant No.ZBG20230418015)the Natural Science Foundation of Chongqing(Grant No.CSTB2024NSCQ-MSX0412)the Opening Project of Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology(Grant No.ammt2021A-4).
文摘We theoretically investigate a cooling scheme assisted by a quantum well(QW)and coherent feedback within a hybrid optomechanical system.Although the exciton mode in the QW and the mechanical resonator(MR)are initially uncoupled,their interaction via the microcavity field leads to an indirect exciton-mode–mechanical-mode coupling.The coherent feedback loop is applied by feeding back a fraction of the output field of the cavity through a controllable beam splitter to the cavity’s input mirror.It is shown that the cooling capability is enhanced by effectively suppressing the Stokes process through coupling with the QW.Furthermore,the effect of the anti-Stokes process is enhanced through the application of the coherent feedback loop.This particular system configuration enables cooling of the mechanical resonator even in the unresolved sideband regime(USR).This study has some important guiding significance in the field of quantum information processing.
基金Supported by the Natienal Natural Science Foundation of China(U23A20287).
文摘Background Haptic feedback plays a crucial role in virtual reality(VR)interaction,helping to improve the precision of user operation and enhancing the immersion of the user experience.Instrumental haptic feedback in virtual environments is primarily realized using grounded force or vibration feedback devices.However,improvements are required in terms of the active space and feedback realism.Methods We propose a lightweight and flexible haptic feedback glove that can haptically render objects in VR environments via kinesthetic and vibration feedback,thereby enabling users to enjoy a rich virtual piano-playing experience.The kinesthetic feedback of the glove relies on a cable-pulling mechanism that rotates the mechanism and pulls the two cables connected to it,thereby changing the amount of force generated to simulate the hardness or softness of the object.Vibration feedback is provided by small vibration motors embedded in the bottom of the fingertips of the glove.We designed a piano-playing scenario in the virtual environment and conducted user tests.The evaluation metrics were clarity,realism,enjoyment,and satisfaction.Results A total of 14 subjects participated in the test,and the results showed that our proposed glove scored significantly higher on the four evaluation metrics than the nofeedback and vibration feedback methods.Conclusions Our proposed glove significantly enhances the user experience when interacting with virtual objects.
基金supported by the MSIT(Ministry of Science and ICT),Republic of Korea,under the Convergence Security Core Talent Training Business Support Program(IITP-2024-RS-2024-00423071)supervised by the IITP(Institute of Information&Communications Technology Planning&Evaluation)supported by Sichuan Science and Technology Program(2023YFSY0026,2023YFH0004).
文摘Force feedback bilateral teleoperation represents a pivotal advancement in control technology,finding widespread application in hazardous material transportation,perilous environments,space and deep-sea exploration,and healthcare domains.This paper traces the evolutionary trajectory of force feedback bilateral teleoperation from its conceptual inception to its current complexity.It elucidates the fundamental principles underpinning interaction forces and tactile exchanges,with a specific emphasis on the crucial role of tactile devices.In this review,a quantitative analysis of force feedback bilateral teleoperation development trends from 2011 to 2024 has been conducted,utilizing published journal article data as the primary source of information.The review accentuates classical control frameworks and algorithms,while also delving into existing research advancements and prospec-tive breakthrough directions.Moreover,it explores specific practical scenarios ranging from intricate surgeries to hazardous environment exploration,underscoring the technology’s potential to revolutionize industries by augmenting human manipulation of remote systems.This underscores the pivotal role of force feedback bilateral teleoperation as a transformative human-machine interface,capable of shaping flexible control strategies and addressing technological bottlenecks.Future research endeavors in force feedback bilateral teleoperation are expected to prioritize the creation of more immersive experiences,overcoming technical hurdles,fortifying human-machine collaboration,and broadening application domains,particularly within the realms of medical intervention and hazardous environments.With the continuous progression of technology,the integration of human intelligence and robotic capabilities is expected to produce more innovations and breakthroughs in the field of automatic control.
基金supported in part by the Key Technologies Research and Development Program of Jiangsu(Prospective and Key Technologies for Industry)under Grant BE2023022 and BE2023022-1in part by National Natural Science Foundation of China(NSFC)under Grant 62401137,62401640,and 62231009+3 种基金in part by the Natural Science Foundation of Jiangsu Province under Grant BK20241281in part by the China National Postdoctoral Program for Innovative Talents under Grant BX20230065 and 2024M750421in part by the Jiangsu Excellent Postdoctoral Program under Grant 2023ZB476in part by the Guangdong Basic and Applied Basic Research Foundation under Grant 2023A1515110732.
文摘Channel state information(CSI)is essen-tial to unlock the potential of reconfigurable intelli-gent surfaces(RISs)in wireless communication sys-tems.Since massive RIS elements are typically imple-mented without baseband signal processing capabili-ties,limited CSI feedback is necessary when design-ing the reflection/refraction coefficients of the RIS.In this article,the unique RIS-assisted channel features,such as the RIS position-dependent channel fluctua-tion,the ultra-high dimensional sub-channel matrix,and the structured sparsity,are distilled from recent advances in limited feedback and used as guidelines for designing feedback schemes.We begin by il-lustrating the use cases and the corresponding chal-lenges associated with RIS feedback.We then discuss how to leverage techniques such as channel customiza-tion,structured-sparsity,autoencoders,and others to reduce feedback overhead and complexity when de-vising feedback schemes.Finally,we identify poten-tial research directions by considering the unresolved challenges,the new RIS architecture,and the integra-tion with multi-modal information and artificial intel-ligence.
基金supported by the Swedish Research Council(Vetenskapsradet,Grant No.202203129)the Project of Youth Science and Technology Fund of Gansu Province(Grant No.24JRRA439)partially funded by the Swedish Research Council(Vetenskapsradet,Grant No.2022-06725)。
文摘This study investigates the impact of vegetation-climate feedback on the global land monsoon system during the Last Interglacial(LIG,127000 years BP)and the mid-Holocene(MH,6000 years BP)using the earth system model EC-Earth3.Our findings indicate that vegetation changes significantly influence the global monsoon area and precipitation patterns,especially in the North African and Indian monsoon regions.The North African monsoon region experienced the most substantial increase in vegetation during both the LIG and MH,resulting in significant increases in monsoonal precipitation by 9.8%and 6.0%,respectively.The vegetation feedback also intensified the Saharan Heat Low,strengthened monsoonal flows,and enhanced precipitation over the North African monsoon region.In contrast,the Indian monsoon region exhibited divergent responses to vegetation changes.During the LIG,precipitation in the Indian monsoon region decreased by 2.2%,while it increased by 1.6%during the MH.These differences highlight the complex and region-specific impacts of vegetation feedback on monsoon systems.Overall,this study demonstrates that vegetation feedback exerts distinct influences on the global monsoon during the MH and LIG.These findings highlight the importance of considering vegetation-climate feedback in understanding past monsoon variability and in predicting future climate change impacts on monsoon systems.
基金supported in part by the National Natural Science Foundation of China(Grant No.12432001)Natural Science Foundation of Hunan Province(Grant Nos.2023JJ60527,2023JJ30152,and 2023JJ30259)the Natural Science Foundation of Changsha(KQ2202133).
文摘This study investigates the nonlinear resonance responses of suspended cables subjected to multi-frequency excitations and time-delayed feedback.Two specific combinations and simultaneous resonances are selected for detailed examination.Initially,utilizing Hamilton’s variational principle,a nonlinear vibration control model of suspended cables under multi-frequency excitations and longitudinal time-delayed velocity feedback is developed,and the Galerkin method is employed to obtain the discrete model.Subsequently,focusing solely on single-mode discretization,analytical solutions for the two simultaneous resonances are derived using the method of multiple scales.The frequency response equations are derived,and the stability analysis is presented for two simultaneous resonance cases.The results demonstrate that suspended cables exhibit complex nonlinearity under multi-frequency excitations.Multiple solutions under multi-frequency excitation can be distinguished through the frequency–response and the detuning-phase curves.By adjusting the control gain and time delay,the resonance range,response amplitude,and phase of suspended cables can be modified.
基金supported by the National Natural Science Foundation of China(Nos.11875270 and 12205317)the Youth Innovation Promotion Association,Chinese Academy of Sciences(No.2018015)。
文摘A dual-harmonic acceleration system is utilized to mitigate the space-charge effect in the rapid-cycling synchrotron of the China Spallation Neutron Source upgrade project(CSNS-II).A magnetic alloy(MA)-loaded cavity with a high accelerating gradient is developed to satisfy the requirements of dual-harmonic acceleration and provide the necessary second-harmonic cavity voltage.However,the MA-loaded cavity exhibits a wideband frequency response,resulting in numerous higher harmonics in the radio-frequency(RF)voltage.These higher harmonics are caused by both the beam-loading effect and distorted amplifier current,which distort the RF bucket,increase the power dissipation in the cavity,and lower the gradient.To address these issues,a multiharmonic independent feedback-control approach is implemented to compensate for higher harmonics.The effectiveness of this control strategy is validated experimentally.This study provides details regarding the feedback-control design and presents the commissioning results.
文摘Purpose–This study aims to propose a novel identification method to accurately estimate linear and nonlinear dynamics in permanent magnet synchronous linear motor(PMSLM)based on the time-domain analysis of relay feedback.Design/methodology/approach–A mathematical model of the PMSLM-based servo-mechanical system was first established,incorporating the aforementioned nonlinearities.The model’s velocity response was derived by analyzing its behavior as a first-order system under arbitrary input.To induce oscillatory dynamics,an ideal relay with artificially introduced dead-time components was then integrated into the servo-mechanism.Depending on the oscillations and the time-domain analysis,nonlinear formulas were deduced according to the velocity response of the servo-mechanism.Afterwards,the unknown model parameters can be solved on account of the cost function which utilizes the discrepancy between nominal position characteristics and temporary position characteristics,both of which are extracted from the oscillations.The proposed recognition method was validated through a twostage process:(1)numerical simulation and calculation,followed by(2)real-time experimental verification on a direct-drive servo platform.Subsequently,leveraging the identification results,a novel control strategy was developed and its tracking performance was benchmarked against conventional control schemes.Findings–Simulation results demonstrate that the proposed method achieves estimation accuracy within 8%.Building on this,a novel control strategy is developed by incorporating both friction pulsation and force pulsation identification results into the feedforward compensator.Comparative experiments reveal that this strategy significantly enhances tracking and positioning performance over traditional control schemes.In a word,this new identification method can be used in different process control and servo control systems.Moreover,parameter auto-tuning,feed forward compensation or disturbance observer can be investigated based on the obtained information to improve the system stability and control accuracy.Originality/value–It is of great significance for the performance improvement of rail transit motor control equipment,such as electro-mechanical braking systems.By enhancing the efficiency of motor control,the performance of the product will be more outstanding.
基金supported by the Strategic Pri-ority Research Program(A)of the Chinese Academy of Sciences(Grant No.XDA28080503)the National Natural Science Foundation of China(Grant No.42071025)+1 种基金the Youth Innovation Promotion Associa-tion of Chinese Academy of Sciences(Grant No.2023240)the Pacific Northwest National Laboratory which is operated for DOE by Battelle Memorial Institute under Contract DE-A06-76RLO 1830.
文摘Phenology shifts influence regional climate by altering energy,and water fluxes through biophysical processes.However,a quantitative understanding of the phenological control on vegetation’s biophysical feedbacks to re gional climate remains elusive.Using long-term remote sensing observations and Weather Research and Fore casting(WRF)model simulations,we investigated vegetation phenology changes from 2003 to 2020 and quan tified their biophysical controls on the regional climate in Northeast China.Our findings elucidated that earlier green-up contributed to a prolonged growing season in forests,while advanced green-up and delayed dormancy extended the growing season in croplands.This prolonged presence and increased maximum green cover in tensified climate-vegetation interactions,resulting in more significant surface cooling in croplands compared to forests.Surface cooling from forest phenology changes was prominent during May’s green-up(-0.53±0.07°C),while crop phenology changes induced cooling throughout the growing season,particularly in June(-0.47±0.15°C),July(-0.48±0.11°C),and September(-0.28±0.09°C).Furthermore,we unraveled the contributions of different biophysical pathways to temperature feedback using a two-resistance attribution model,with aero dynamic resistance emerging as the dominant factor.Crucially,our findings underscored that the land surface temperature(LST)sensitivity,exhibited substantially higher values in croplands rather than temperate forests.These strong sensitivities,coupled with the projected continuation of phenology shifts,portend further growing season cooling in croplands.These findings contribute to a more comprehensive understanding of the intricate feedback mechanisms between vegetation phenology and surface temperature,emphasizing the significance of vegetation phenology dynamics in shaping regional climate pattern and seasonality.
