Conductive hydrogel-based stretchable electronics have been extensively investigated,among which strain sensors are the most prominently studied.While the mechanical properties significantly affect the performance of ...Conductive hydrogel-based stretchable electronics have been extensively investigated,among which strain sensors are the most prominently studied.While the mechanical properties significantly affect the performance of these devices,the systematic correlation between specific mechanical parameters and sensing performance remains rarely explored.This work compares the influences of Young’s modulus and mechanical hysteresis on the sensing performance between highly entangled PAM-Li and double-network PAM-Li-Agar-3 strain sensors.Owing to the brittle agar network,which imparts a higher Young’s modulus and pronounced mechanical hysteresis to the double-network PAMLi-Agar-3 hydrogel,the corresponding sensor requires a greater driving force for deformation and yields signals with poor reproducibility.In comparison,the PAM-Li hydrogel,characterized by highly entangled polymer chains,exhibits a lower Young’s modulus and negligible mechanical hysteresis.Consequently,signals from the PAM-Li strain sensor demonstrate enhanced sensitivity and stability.Therefore,this work demonstrates that a low Young’s modulus and minimal mechanical hysteresis are critical factors for achieving superior sensing performance in strain sensors,as systematically validated through comparative analyses across diverse application scenarios.展开更多
Bolting steel angles at the bottom ends of columns provides a rapid and efficient method for repairing damaged structures,while also offering a viable approach to restore their potential bearing capacity.To validate t...Bolting steel angles at the bottom ends of columns provides a rapid and efficient method for repairing damaged structures,while also offering a viable approach to restore their potential bearing capacity.To validate the suitability of specific strengthening strategies,particularly the utilization of bolted steel angles,three reinforced concrete frame specimens were subjected to hysteresis testing.These specimens all featured RC columns strengthened with steel angle ends.Additionally,one control specimen without steel angle ends was included in the testing.The hysteresis effects of bolting steel angles were discussed in terms of typical failure mode,hysteresis and skeleton curves,stiffness degradation and energy dissipation.The experimental results revealed that the three specimens that had bolted steel angles exhibited ductile failure behavior.Through analysis of hysteresis and skeleton curves,it was observed that the frame demonstrated distinct plasticity,maintaining sufficient load-bearing capacity even after yielding and exhibiting superior displacement ductility performance.Considering equivalent viscous damping,the energy dissipation capacity of the RC frame increased linearly with drift and remained largely unaffected by structural damage.Therefore,bolting steel angles at specified cross-sections proved to be a viable technique for structural repair and restoration.展开更多
Industrial robot dynamics lay the foundation for high-precision and high-speed control, and accurate identification of dynamic parameters is essential for precise dynamic calculations. The choice of friction models is...Industrial robot dynamics lay the foundation for high-precision and high-speed control, and accurate identification of dynamic parameters is essential for precise dynamic calculations. The choice of friction models is a critical component in the identification of industrial robot dynamics. Traditional static friction models struggle to capture the hysteresis effects caused by robot joint elasticity and clearances, leading to large torque prediction errors when the joint velocity crosses zero. Due to the presence of hysteresis effects, the joint velocity crosses zero in the forward direction, and the reverse direction will have different friction patterns. Although the hysteresis effects can be modeled as an ordinary differential equation(ODE), it is difficult to determine the ODE structure that achieves both generalization and accuracy to describe the hysteresis effects of the friction model. To address this issue, we propose the neural hysteresis friction(NHF), which uses neural ODE to model the hysteresis effects in a data-driven manner, thereby mitigating the current inadequacies in the study of dynamic friction characteristics. The experiments on a real 6-axis industrial robot demonstrate that our proposed method can accurately model the friction dynamics during directional switching and outperform other modeling methods. Velocity tracking control experiments show that NHF can effectively reduce tracking errors when the velocity crosses zero.展开更多
Based on the Smit-Suhl formula,we propose a universal approach for solving the magnon-magnon coupling problem in bilayer coupled systems(e.g.,antiferromagnets).This method requires only the energy expression,enabling ...Based on the Smit-Suhl formula,we propose a universal approach for solving the magnon-magnon coupling problem in bilayer coupled systems(e.g.,antiferromagnets).This method requires only the energy expression,enabling the automatic derivation of analytical expressions for the eigenmatrix elements via symbolic computation,eliminating the need for tedious manual calculations.Using this approach,we investigate the impact of magnetic hysteresis on magnon-magnon coupling in a system with interlayer Dzyaloshinskii-Moriya interaction(DMI).The magnetic hysteresis leads to an asymmetric magnetic field dependence of the resonance frequency and alters the number of degeneracy points between the pure optical and acoustic modes.Moreover,it can result in the coupling strength at the gap of the f–H phase diagram being nearly vanishing,contrary to the conventionally expected maximum.These results deepen the understanding of the effect of interlayer DMI on magnon–magnon coupling and the proposed universal method significantly streamlines the solving process of magnon–magnon coupling problems.展开更多
Dear Editor,It is well known that event-triggered control(ETC)is an effective approach in addressing networked control problems for Industry 5.0.Its feasibility,however,is still restricted to canonical nonlinear syste...Dear Editor,It is well known that event-triggered control(ETC)is an effective approach in addressing networked control problems for Industry 5.0.Its feasibility,however,is still restricted to canonical nonlinear systems so far.Considering this,a gradient-based adaptive ETC scheme for noncanonical nonlinear systems is newly developed in this letter,where the hysteresis input constraints are considered also.By proper decomposition,the technical issue of handling ETC-induced measurement errors and hysteresis inputs can be transformed into the robustness problem to bounded disturbance-like terms,which is then addressed by integrating a switching modification strategy in adaptive design and developing a novel augmented error-based analysis framework.Experimental results based on a practical piezoactuator confirm the effectiveness of the proposed scheme.展开更多
The Hydro-Viscous Drive(HVD)speed regulating system finds extensive application in air transport transmission systems to regulate the stepless speed or conduct overload protection.However,its intrinsic hysteretic beha...The Hydro-Viscous Drive(HVD)speed regulating system finds extensive application in air transport transmission systems to regulate the stepless speed or conduct overload protection.However,its intrinsic hysteretic behaviors,such as the asymmetric hysteretic and dead zone,could introduce inaccuracy and delay in control applications,posing challenges to system regulation.This paper investigates a Nonlinear Hysteresis Compensation Control(NHCC)that consists of two parts to control the HVD output speed by operating the valve under different engine operating conditions.In the first part,the Inverse Hysteresis Compensator(IHC)based on major loop data is introduced for the asymmetric hysteresis characterization and compensation of the HVD speed control system of the power generation and distribution,which aims to reduce the hysteresis and dead zone effect and expand the effective input range.In the second part,the Active Disturbance Rejection Controller(ADRC)is employed to mitigate the hysteresis effects of the compensated system and remove the steady-state error,which allows real-time compensation of the estimated perturbations as state feedback to achieve the required performance.An experimental laboratory station has been fabricated to evaluate the proposed method.The test results show that the NHCC method can regulate the fan speed to the desired value(45 r/min at steady state)and broaden the effective input range to the full range under different engine conditions.Besides,the proposed control method can reduce the non-linearity of the input and output curves(from 18%to 4%)and compensate for the asymmetric hysteresis(from 38%to 5%).展开更多
An aileron is a crucial control surface for rolling.Any jitter or shaking caused by the aileron mechatronics could have catastrophic consequences for the aircraft’s stability,maneuverability,safety,and lifespan.This ...An aileron is a crucial control surface for rolling.Any jitter or shaking caused by the aileron mechatronics could have catastrophic consequences for the aircraft’s stability,maneuverability,safety,and lifespan.This paper presents a robust solution in the form of a fast flutter suppression digital control logic of edge computing aileron mechatronics(ECAM).We have effectively eliminated passive and active oscillating response biases by integrating nonlinear functional parameters and an antiphase hysteresis Schmitt trigger.Our findings demonstrate that self-tuning nonlinear parameters can optimize stability,robustness,and accuracy.At the same time,the antiphase hysteresis Schmitt trigger effectively rejects flutters without the need for collaborative navigation and guidance.Our hardware-in-the-loop simulation results confirm that this approach can eliminate aircraft jitter and shaking while ensuring expected stability and maneuverability.In conclusion,this nonlinear aileron mechatronics with a Schmitt positive feedback mechanism is a highly effective solution for distributed flight control and active flutter rejection.展开更多
Stretchable strain sensors are a crucial component in various applications,such as wearable devices,human-machine interfaces,and soft robotics.Hence,strain sensors with low hysteresis,high fidelity,and accurate sensin...Stretchable strain sensors are a crucial component in various applications,such as wearable devices,human-machine interfaces,and soft robotics.Hence,strain sensors with low hysteresis,high fidelity,and accurate sensing ability are urgently required for the precise measurement of large and high-frequency dynamic deformations.However,the existing hysteresis of the current functional materials utilized in strain sensors significantly impedes the achievement of these properties.Herein,we introduce an ultralow dynamic hysteresis capacitive strain sensor using a low-hysteresis and high-relative-permittivity ionic liquid-elastomer composite as the dielectric material.Based on the low-hysteresis dielectric,the prepared capacitive strain sensors exhibit ultralow electrical hysteresis(2.20%at a strain rate of 100% s^(-1)and strain of100%)and maintain low electrical hysteresis(4.35%)even under extremely high strain rates and large dynamic strain loads(a strain rate of 500% s^(-1)and strain of 100%).Moreover,the strain sensor manifests exceptional cyclic stability under 50,000 cycles of 100%strain at a strain rate of 200% s^(-1);the response curves remain nearly identical throughout these 50,000 cycles.Furthermore,the ultralowhysteresis strain sensor was successfully applied to accurate and reliable real-time human-machine interactions,revealing its great potential in various fields,including electronic skin,flexible robotics,wearable electronics,and virtual reality.展开更多
The increasingly stringent performance requirements of modern flight vehicles expose the possibilities of their coupled nonlinearities.Nevertheless,the aeroelastic response of a flight vehicle is generally predicted w...The increasingly stringent performance requirements of modern flight vehicles expose the possibilities of their coupled nonlinearities.Nevertheless,the aeroelastic response of a flight vehicle is generally predicted with isolated aerodynamic or structural nonlinearity.In this study,a Three-Degree-of-Freedom(3-DOF)aeroelastic model is proposed,which combines control surface hysteresis stiffness and dynamic stall aerodynamics.A control surface hysteretic model is applied to represent the nonlinear structural dynamics.The Office National d’Etudes et de Recherches Aérospatiales(ONERA)dynamic stall model is extended to a 3-DOF airfoil,considering the dynamic behavior of the control surface.The nonlinear aeroelastic model of a 3-DOF airfoil is described using a monolithic state-space equation.Henon’s event-driven scheme is used to investigate the post-flutter behavior of a 3-DOF airfoil with control surface hysteresis stiffness in a dynamic stall flow.The results indicate that the proposed model improves the numerical precision of nonlinear aerodynamic load by almost double that of the ONERA model that does not consider the dynamic behavior of the control surface.The flutter onset speed of the coupled nonlinear airfoil is overestimated by 10%using decoupled nonlinear analysis.Furthermore,the airfoil is dominated by the structural hysteresis nonlinearity and aerodynamic energy from the plunge motion at low airspeeds.As the airspeed increases,the airfoil is governed by the aerodynamic stall nonlinearity and aerodynamic energy from the pitch motion.The switch of the dominant nonlinearity induces topological changes in the aerodynamic curves,along with a threefold increase in the aerodynamic power.Excited by the increased energy,the airfoil undergoes a period-doubling bifurcation and transition to a higher-amplitude limit cycle.The theoretical results of this study are beneficial for the load design of modern flight vehicles under coupled nonlinear conditions.展开更多
Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effec...Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effective Hamiltonian method in conjuction with the phase-field model, we have successfully reproduced the thermal hysteresis observed in ferroelectric materials during phase transitions. The computational results regarding the electrocaloric effect from these two different computational scales closely align with experimental measurements. Furthermore, we analyze how the first-order ferroelectric phase transition gradually diminishes with an increasing applied electric field, exhibiting characteristics of second-order-like phase transition. By employing the characteristic parameters of thermal hysteresis, we have established a pathway for calculations across different computational scales, thereby providing theoretical support for further investigations into the properties of ferroelectric materials through concurrent multiscale simulations.展开更多
This study aims to investigate the intricate dynamic characteristics of the high-speed duct during the over-under Turbine-Based Combined Cycle(TBCC)inlet mode transition process while operating in an off-design state ...This study aims to investigate the intricate dynamic characteristics of the high-speed duct during the over-under Turbine-Based Combined Cycle(TBCC)inlet mode transition process while operating in an off-design state under throttled conditions.A typical over-under TBCC inlet,designed for a working Mach number range of 0–6 with a transition Mach number of 3.5,is examined through experimental studies in a supersonic wind tunnel with a freestream Mach number of2.9.The investigation focuses on the complex oscillatory flow and unique hysteresis observed in the mode transition process of the high-speed duct under the mildly throttled condition,utilizing highspeed schlieren and dynamic pressure acquisition system.The findings reveal that the high-speed duct undergoes four distinct oscillation stages akin to those in a higher throttled state during the mode transition,albeit with smaller dominant frequency and energy.Moreover,an irregular alternating“big/little buzz”mode is observed in the early stage of the large oscillation stage.Notably,the mildly throttled state exhibits three intriguing hysteresis properties compared to the unthrottled and higher throttled states.Firstly,hysteresis is observed in the shock train motion stage in the duct before unstart,along with the corresponding inverse process.Subsequently,hysteresis is noted in the unstart and restart of the high-speed duct,with a smaller hysteresis interval than in the unthrottled state.Finally,the hysteresis characteristics of oscillation mode switching and the corresponding inverse process are explored.Based on the analysis,the first two hysteresis phenomena are associated with the formation and dissipation of the separation bubble.The significant adverse pressure gradient constrains the cross-sectional capacity of the channel,rendering the disappearance of the separation bubble more challenging.The hysteresis in oscillation mode switching is linked to not only the channel cross-sectional capacity but also the state of the incoming boundary layer.展开更多
Purpose:The study examines the synergy and hysteresis in the evolution of funding and its supported literature,depicts their temporal correlation mechanism,which aids in improving trend predictions.Design/methodology/...Purpose:The study examines the synergy and hysteresis in the evolution of funding and its supported literature,depicts their temporal correlation mechanism,which aids in improving trend predictions.Design/methodology/approach:The study uses the LDA model to identify topics in funding texts and supported papers.A cosine similarity algorithm was employed to estimate the nexus between topics and construct the topic evolution time series.Similarly,the hysteresis effect in topic evolution is analyzed based on topic popularity and content,leading to insights into their temporal correlation mechanism.Findings:The study finds that fund and sponsored paper topics exhibit strong collaboration with a noticeable lag in evolution.The fund topics significantly influence sponsored paper topics after a two-year lag.Moreover,the lag effect is inversely proportional to the topic’s similarity.Research limitations:We use the LDA model to determine the hysteresis effect in topic evolution despite its limitations in handling long-tail words and domain-specific vocabulary.Furthermore,the timing of the emergence of the focal topic in funds is undermined,affecting the findings.Practical implications:These findings enhance the accuracy and scientific validity of trend prediction.Estimating and identifying patterns can help technology managers anticipate future research hotspots,supporting informed decision-making and technology management.Originality/value:This study introduces a research framework to quantitatively and visually analyze the hysteresis effect,revealing the correlation and evolutionary patterns between fund research topics and their funded papers.展开更多
In this study,we consider a single-link flexible manipulator in the presence of an unknown Bouc-Wen type of hysteresis and intermittent actuator faults.First,an inverse hysteresis dynamics model is introduced,and then...In this study,we consider a single-link flexible manipulator in the presence of an unknown Bouc-Wen type of hysteresis and intermittent actuator faults.First,an inverse hysteresis dynamics model is introduced,and then the control input is divided into an expected input and an error compensator.Second,a novel adaptive neural network-based control scheme is proposed to cancel the unknown input hysteresis.Subsequently,by modifying the adaptive laws and local control laws,a fault-tolerant control strategy is applied to address uncertain intermittent actuator faults in a flexible manipulator system.Through the direct Lyapunov theory,the proposed scheme allows the state errors to asymptotically converge to a specified interval.Finally,the effectiveness of the proposed scheme is verified through numerical simulations and experiments.展开更多
Planar positioning systems are widely utilized in micro and nano applications.The challenges in modeling and control of XYΘflexure-based mechanisms include hysteresis of the piezoelectric actuators,couplings among th...Planar positioning systems are widely utilized in micro and nano applications.The challenges in modeling and control of XYΘflexure-based mechanisms include hysteresis of the piezoelectric actuators,couplings among the input axes,and coupled linear and angular motions of the end effector.This paper presents an inverse hysteresis-coupling hybrid model to account for such hysteresis and couplings.First,a specially designed kinematic chain is adopted to transfer the pose of the end effector into the linear motions at three prismatic joints.Second,an inverse hysteresis-coupling hybrid model is developed to linearize and decouple the system via a multilayer feedforward neural network.A fractional-order PID controller is also integrated to improve the motion accuracy of the overall system.Experimental results demonstrate that the proposed method can accurately control the motion of the end effector with improved accuracy and robustness.展开更多
Poly(phthalazinone ether sulfone ketone)(PPESK)is a new-generation high-performance thermoplastic resin that exhibits excellent thermal stability and mechanical properties.However,its damage and failure mechanisms und...Poly(phthalazinone ether sulfone ketone)(PPESK)is a new-generation high-performance thermoplastic resin that exhibits excellent thermal stability and mechanical properties.However,its damage and failure mechanisms under high-temperature and high-strain-rate coupling conditions remain unclear,significantly limiting the engineering applications of PPESK-based composites in extreme environments such as aerospace.To address this issue,in this study,a temperature-controlled split Hopkinson pressure bar experimental platform was developed for dynamic tensile/compressive loading scenarios.Combined with scanning electron microscopy and molecular dynamics simulations,the thermomechanical behavior and failure mechanisms of PPESK were systematically investigated over the temperature range of 293-473 K.The study revealed a novel"dynamic hysteresis brittle behavior"and its underlying"segmental activation±response lag antagonistic mechanism".The results showed that the strain-rate-induced response lag of polymer chain segments significantly weakened the viscous dissipation capacity activated by thermal energy at elevated temperatures.Although high-strain-rate conditions led to notable enhancement in the dynamic strength of the material(with an increase of 8%-233%,reaching 130%-330%at elevated temperatures),the fracture surface morphology tended to become smoother,and brittle fracture characteristics became more pronounced.Based on these findings,a temperature±strain rate hysteresis antagonistic function was constructed,which effectively captured the competitive relationship between temperature-driven relaxation behavior and strain-rateinduced hysteresis in thermoplastic resins.A multiscale damage evolution constitutive model with temperature±rate coupling was subsequently established and numerically implemented via the VUMAT user subroutine.This study not only unveils the nonlinear damage mechanisms of PPESK under combined service temperatures and dynamic/static loading conditions,but also provides a strong theoretical foundation and engineering guidance for the constitutive modeling and parametric design of thermoplastic resin-based materials.展开更多
Polyaniline(PANi)hydrogels have a wide range of applications in artificial skin,flexible robotics,and movement monitoring.Nevertheless,limited by the modulus mismatch between rigid PANi and the soft hydrogel matrix,th...Polyaniline(PANi)hydrogels have a wide range of applications in artificial skin,flexible robotics,and movement monitoring.Nevertheless,limited by the modulus mismatch between rigid PANi and the soft hydrogel matrix,the high strength and toughness of the PANi hydrogel are mutually exclusive.Although the introduction of sacrificial bonds into the hydrogel network can alleviate this contradiction to a certain extent,it always causes pronounced energy hysteresis during hydrogel deformation.Inspired by the energy storage and release of macroscopic springs,in this work,we propose a molecular entanglement approach for the fabrication of PANi hydrogels featuring high toughness and low hysteresis,where flexible poly(ethylene glycol)(PEG)is entangled with chemically cross-linked poly(acrylic acid)(PAA)as a hydrogel matrix,and rigid PANi as a conductive filler.The resultant PAA/PEG/PANi hydrogel exhibited high mechanical properties(fracture strength of 0.75 MPa and toughness of 4.81 MJ·m^(-3))and a low energy dissipation ratio(28.2%when stretching to 300%).Moreover,the PAA/PEG/PANi hydrogel possesses a good electrical response to external forces and can be employed as a strain sensor to monitor human joint movements by producing specific electrical signals.This work provides a straightforward strategy for preparing tough conductive PANi hydrogels with low hysteresis,showing potential for the development of healthcare devices.展开更多
The incompatibility between large electro-strain and low-strain hysteresis,in addition to the poor tem-perature stability of piezoelectric ceramics,limits the development of high-precision piezoelectric actu-ators.In ...The incompatibility between large electro-strain and low-strain hysteresis,in addition to the poor tem-perature stability of piezoelectric ceramics,limits the development of high-precision piezoelectric actu-ators.In this work,Bi_(0.465)Na_(0.465)Ba_(0.07)Ti_(1−2 x)Ga_(x)Sb_(x)O_(3)(abbreviated as BNBT7-x GS,x=0,0.01,0.02,0.03,0.04,and 0.06)ceramics were designed.Specifically,when x=0.02,the ceramics exhibit a critical state in the relaxor ferroelectric system with a typical relaxor P−E loop and an I−E curve of four peaks.At this composition,the room temperature strain is 0.40%,which is capable of enhancing the electro-strain and reducing the hysteresis simultaneously.Furthermore,over the wide temperature range from 30 to 180℃,the minimum strain hysteresis(H_(ys))is 7.13%,and the maximum strain variation is only 16.8%,demonstrating ultra-high temperature stability.This work introduces a model for addressing the dilemma between good electro-strain properties and insufficient temperature stability in lead-free piezoelectric ceramics,crucial for the development of modern high-precision actuators.展开更多
Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuato...Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuators.Existing methods for fitting hysteresis loops include operator class,differential equation class,and machine learning class.The modeling cost of operator class and differential equation class methods is high,the model complexity is high,and the process of machine learning,such as neural network calculation,is opaque.The physical model framework cannot be directly extracted.Therefore,the sparse identification of nonlinear dynamics(SINDy)algorithm is proposed to fit hysteresis loops.Furthermore,the SINDy algorithm is improved.While the SINDy algorithm builds an orthogonal candidate database for modeling,the sparse regression model is simplified,and the Relay operator is introduced for piecewise fitting to solve the distortion problem of the SINDy algorithm fitting singularities.The Relay-SINDy algorithm proposed in this paper is applied to fitting hysteresis loops.Good performance is obtained with the experimental results of open and closed loops.Compared with the existing methods,the modeling cost and model complexity are reduced,and the modeling accuracy of the hysteresis loop is improved.展开更多
The complex nonlinear characteristics of pneumatic soft actuators,such as asymmetric hysteresis,rate-dependence,and mechanical load-dependence,pose a challenge in accurately modeling their dynamics.To address this cha...The complex nonlinear characteristics of pneumatic soft actuators,such as asymmetric hysteresis,rate-dependence,and mechanical load-dependence,pose a challenge in accurately modeling their dynamics.To address this challenge,this paper proposes a comprehensive dynamic model aimed at describing bidirectional asymmetric hysteresis,rate-dependent,and mechanical load-dependent characteristics of a vertical pneumatic bellows actuator(PBA)system.The dynamic model contains a hysteresis submodel and a load-dependent dynamic submodel.The hysteresis submodel consists of several sets of weighted double-side play(DSP)and weighted dead-zone(DZ)operators connected in series,and it is used to model the bidirectional asymmetric hysteresis of the system.The load-dependent dynamic submodel is built based on the gated recurrent unit(GRU)neural network,and it is used to fit the nonlinear relationship between the displacement of the system and the frequency of the input air pressure as well as the mechanical load.The model parameters of the hysteresis submodel and the loaddependent dynamic submodel are determined by intelligent optimization method and neural network training method,reseparately.The fitness value(FV)between the output of the dynamic model and the experimental data is calculated to be 96.1736%,demonstrating that the parameters of the dynamic model are valid.We conduct six set of experiments to compare the model output with the experimental data,and calculate the root-meansquare errors and the maximum error,respectively.The experimental results show that,the root-mean-square error remains consistently below 2.7700%,while the maximum error remains below 8.4000%across all experiments,thereby substantiating the validity and generality of the proposed model.展开更多
This paper investigates the problem of dynamic event-triggered control for a class of large-scale nonlinear systems.In particular,both neutral delays and unknown backlash-like hysteresis are considered.This requires t...This paper investigates the problem of dynamic event-triggered control for a class of large-scale nonlinear systems.In particular,both neutral delays and unknown backlash-like hysteresis are considered.This requires to integrate a compensation mechanism into the event-triggered control architecture.To this end,dynamic gain and adaptive control techniques are introduced to address the effects of neutral delays,unknown hysteresis and parameter uncertainties simultaneously.By introducing a non-negative internal dynamic variable,a dynamic event-triggered controller is designed using the hyperbolic tangent function to reduce the communication burden.By means of the Lyapunov–Krasovskii method,it is demonstrated that all signals of the closed-loop system are globally bounded and eventually converge to a tunable bounded region.Moreover,the Zeno behavior is avoided.Finally,a simulation example is presented to verify the validity of the control scheme.展开更多
基金supported by the National Natural Science Foundation of China(52303145,52403083)the Natural Science Foundation of Sichuan Province(2025ZNSFSC1400)supported by the start-up funding at Chengdu University(T202207)。
文摘Conductive hydrogel-based stretchable electronics have been extensively investigated,among which strain sensors are the most prominently studied.While the mechanical properties significantly affect the performance of these devices,the systematic correlation between specific mechanical parameters and sensing performance remains rarely explored.This work compares the influences of Young’s modulus and mechanical hysteresis on the sensing performance between highly entangled PAM-Li and double-network PAM-Li-Agar-3 strain sensors.Owing to the brittle agar network,which imparts a higher Young’s modulus and pronounced mechanical hysteresis to the double-network PAMLi-Agar-3 hydrogel,the corresponding sensor requires a greater driving force for deformation and yields signals with poor reproducibility.In comparison,the PAM-Li hydrogel,characterized by highly entangled polymer chains,exhibits a lower Young’s modulus and negligible mechanical hysteresis.Consequently,signals from the PAM-Li strain sensor demonstrate enhanced sensitivity and stability.Therefore,this work demonstrates that a low Young’s modulus and minimal mechanical hysteresis are critical factors for achieving superior sensing performance in strain sensors,as systematically validated through comparative analyses across diverse application scenarios.
基金National Key R&D Program of China under Grant No.2023YFC3805100Technologies R&D Project of China Construction First Group Corporation Limited under Grant No.PT-2022-09National Natural Science Foundation of China under Grant No.52178126。
文摘Bolting steel angles at the bottom ends of columns provides a rapid and efficient method for repairing damaged structures,while also offering a viable approach to restore their potential bearing capacity.To validate the suitability of specific strengthening strategies,particularly the utilization of bolted steel angles,three reinforced concrete frame specimens were subjected to hysteresis testing.These specimens all featured RC columns strengthened with steel angle ends.Additionally,one control specimen without steel angle ends was included in the testing.The hysteresis effects of bolting steel angles were discussed in terms of typical failure mode,hysteresis and skeleton curves,stiffness degradation and energy dissipation.The experimental results revealed that the three specimens that had bolted steel angles exhibited ductile failure behavior.Through analysis of hysteresis and skeleton curves,it was observed that the frame demonstrated distinct plasticity,maintaining sufficient load-bearing capacity even after yielding and exhibiting superior displacement ductility performance.Considering equivalent viscous damping,the energy dissipation capacity of the RC frame increased linearly with drift and remained largely unaffected by structural damage.Therefore,bolting steel angles at specified cross-sections proved to be a viable technique for structural repair and restoration.
基金supported by the National Natural Science Foundation of China (Grant No.52188102)。
文摘Industrial robot dynamics lay the foundation for high-precision and high-speed control, and accurate identification of dynamic parameters is essential for precise dynamic calculations. The choice of friction models is a critical component in the identification of industrial robot dynamics. Traditional static friction models struggle to capture the hysteresis effects caused by robot joint elasticity and clearances, leading to large torque prediction errors when the joint velocity crosses zero. Due to the presence of hysteresis effects, the joint velocity crosses zero in the forward direction, and the reverse direction will have different friction patterns. Although the hysteresis effects can be modeled as an ordinary differential equation(ODE), it is difficult to determine the ODE structure that achieves both generalization and accuracy to describe the hysteresis effects of the friction model. To address this issue, we propose the neural hysteresis friction(NHF), which uses neural ODE to model the hysteresis effects in a data-driven manner, thereby mitigating the current inadequacies in the study of dynamic friction characteristics. The experiments on a real 6-axis industrial robot demonstrate that our proposed method can accurately model the friction dynamics during directional switching and outperform other modeling methods. Velocity tracking control experiments show that NHF can effectively reduce tracking errors when the velocity crosses zero.
基金supported by the National Key Research and Development Program of China (MOST)(Grant No.2022YFA1402800)the Chinese Academy of Sciences (CAS) Presidents International Fellowship Initiative (PIFI)(Grant No.2025PG0006)+3 种基金the National Natural Science Foundation of China (NSFC)(Grant Nos.51831012,12274437,and 52161160334)the CAS Project for Young Scientists in Basic Research (Grant No.YSBR-084)the CAS Youth Interdisciplinary Teamthe China Postdoctoral Science Foundation (Grant No.2025M773402)。
文摘Based on the Smit-Suhl formula,we propose a universal approach for solving the magnon-magnon coupling problem in bilayer coupled systems(e.g.,antiferromagnets).This method requires only the energy expression,enabling the automatic derivation of analytical expressions for the eigenmatrix elements via symbolic computation,eliminating the need for tedious manual calculations.Using this approach,we investigate the impact of magnetic hysteresis on magnon-magnon coupling in a system with interlayer Dzyaloshinskii-Moriya interaction(DMI).The magnetic hysteresis leads to an asymmetric magnetic field dependence of the resonance frequency and alters the number of degeneracy points between the pure optical and acoustic modes.Moreover,it can result in the coupling strength at the gap of the f–H phase diagram being nearly vanishing,contrary to the conventionally expected maximum.These results deepen the understanding of the effect of interlayer DMI on magnon–magnon coupling and the proposed universal method significantly streamlines the solving process of magnon–magnon coupling problems.
文摘Dear Editor,It is well known that event-triggered control(ETC)is an effective approach in addressing networked control problems for Industry 5.0.Its feasibility,however,is still restricted to canonical nonlinear systems so far.Considering this,a gradient-based adaptive ETC scheme for noncanonical nonlinear systems is newly developed in this letter,where the hysteresis input constraints are considered also.By proper decomposition,the technical issue of handling ETC-induced measurement errors and hysteresis inputs can be transformed into the robustness problem to bounded disturbance-like terms,which is then addressed by integrating a switching modification strategy in adaptive design and developing a novel augmented error-based analysis framework.Experimental results based on a practical piezoactuator confirm the effectiveness of the proposed scheme.
文摘The Hydro-Viscous Drive(HVD)speed regulating system finds extensive application in air transport transmission systems to regulate the stepless speed or conduct overload protection.However,its intrinsic hysteretic behaviors,such as the asymmetric hysteretic and dead zone,could introduce inaccuracy and delay in control applications,posing challenges to system regulation.This paper investigates a Nonlinear Hysteresis Compensation Control(NHCC)that consists of two parts to control the HVD output speed by operating the valve under different engine operating conditions.In the first part,the Inverse Hysteresis Compensator(IHC)based on major loop data is introduced for the asymmetric hysteresis characterization and compensation of the HVD speed control system of the power generation and distribution,which aims to reduce the hysteresis and dead zone effect and expand the effective input range.In the second part,the Active Disturbance Rejection Controller(ADRC)is employed to mitigate the hysteresis effects of the compensated system and remove the steady-state error,which allows real-time compensation of the estimated perturbations as state feedback to achieve the required performance.An experimental laboratory station has been fabricated to evaluate the proposed method.The test results show that the NHCC method can regulate the fan speed to the desired value(45 r/min at steady state)and broaden the effective input range to the full range under different engine conditions.Besides,the proposed control method can reduce the non-linearity of the input and output curves(from 18%to 4%)and compensate for the asymmetric hysteresis(from 38%to 5%).
基金supported in part by the Aeronautical Science Foundation of China under Grant 2022Z005057001the Joint Research Fund of Shanghai Commercial Aircraft System Engineering Science and Technology Innovation Center under CASEF-2023-M19.
文摘An aileron is a crucial control surface for rolling.Any jitter or shaking caused by the aileron mechatronics could have catastrophic consequences for the aircraft’s stability,maneuverability,safety,and lifespan.This paper presents a robust solution in the form of a fast flutter suppression digital control logic of edge computing aileron mechatronics(ECAM).We have effectively eliminated passive and active oscillating response biases by integrating nonlinear functional parameters and an antiphase hysteresis Schmitt trigger.Our findings demonstrate that self-tuning nonlinear parameters can optimize stability,robustness,and accuracy.At the same time,the antiphase hysteresis Schmitt trigger effectively rejects flutters without the need for collaborative navigation and guidance.Our hardware-in-the-loop simulation results confirm that this approach can eliminate aircraft jitter and shaking while ensuring expected stability and maneuverability.In conclusion,this nonlinear aileron mechatronics with a Schmitt positive feedback mechanism is a highly effective solution for distributed flight control and active flutter rejection.
基金financially supported by the National Natural Science Foundation of China(Nos.52250398,52125205 and U20A20166)the Natural Science Foundation of Beijing Municipality(No.2222088)+1 种基金Shenzhen Science and Technology Program(No.KQTD20170810105439418)the Fundamental Research Funds for the Central Universities
文摘Stretchable strain sensors are a crucial component in various applications,such as wearable devices,human-machine interfaces,and soft robotics.Hence,strain sensors with low hysteresis,high fidelity,and accurate sensing ability are urgently required for the precise measurement of large and high-frequency dynamic deformations.However,the existing hysteresis of the current functional materials utilized in strain sensors significantly impedes the achievement of these properties.Herein,we introduce an ultralow dynamic hysteresis capacitive strain sensor using a low-hysteresis and high-relative-permittivity ionic liquid-elastomer composite as the dielectric material.Based on the low-hysteresis dielectric,the prepared capacitive strain sensors exhibit ultralow electrical hysteresis(2.20%at a strain rate of 100% s^(-1)and strain of100%)and maintain low electrical hysteresis(4.35%)even under extremely high strain rates and large dynamic strain loads(a strain rate of 500% s^(-1)and strain of 100%).Moreover,the strain sensor manifests exceptional cyclic stability under 50,000 cycles of 100%strain at a strain rate of 200% s^(-1);the response curves remain nearly identical throughout these 50,000 cycles.Furthermore,the ultralowhysteresis strain sensor was successfully applied to accurate and reliable real-time human-machine interactions,revealing its great potential in various fields,including electronic skin,flexible robotics,wearable electronics,and virtual reality.
文摘The increasingly stringent performance requirements of modern flight vehicles expose the possibilities of their coupled nonlinearities.Nevertheless,the aeroelastic response of a flight vehicle is generally predicted with isolated aerodynamic or structural nonlinearity.In this study,a Three-Degree-of-Freedom(3-DOF)aeroelastic model is proposed,which combines control surface hysteresis stiffness and dynamic stall aerodynamics.A control surface hysteretic model is applied to represent the nonlinear structural dynamics.The Office National d’Etudes et de Recherches Aérospatiales(ONERA)dynamic stall model is extended to a 3-DOF airfoil,considering the dynamic behavior of the control surface.The nonlinear aeroelastic model of a 3-DOF airfoil is described using a monolithic state-space equation.Henon’s event-driven scheme is used to investigate the post-flutter behavior of a 3-DOF airfoil with control surface hysteresis stiffness in a dynamic stall flow.The results indicate that the proposed model improves the numerical precision of nonlinear aerodynamic load by almost double that of the ONERA model that does not consider the dynamic behavior of the control surface.The flutter onset speed of the coupled nonlinear airfoil is overestimated by 10%using decoupled nonlinear analysis.Furthermore,the airfoil is dominated by the structural hysteresis nonlinearity and aerodynamic energy from the plunge motion at low airspeeds.As the airspeed increases,the airfoil is governed by the aerodynamic stall nonlinearity and aerodynamic energy from the pitch motion.The switch of the dominant nonlinearity induces topological changes in the aerodynamic curves,along with a threefold increase in the aerodynamic power.Excited by the increased energy,the airfoil undergoes a period-doubling bifurcation and transition to a higher-amplitude limit cycle.The theoretical results of this study are beneficial for the load design of modern flight vehicles under coupled nonlinear conditions.
基金Project supported financially by the National Natural Science Foundation of China (Grant No. 52372100)the National Key Research and Development Program of China (Grant No. 2019YFA0307900)。
文摘Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effective Hamiltonian method in conjuction with the phase-field model, we have successfully reproduced the thermal hysteresis observed in ferroelectric materials during phase transitions. The computational results regarding the electrocaloric effect from these two different computational scales closely align with experimental measurements. Furthermore, we analyze how the first-order ferroelectric phase transition gradually diminishes with an increasing applied electric field, exhibiting characteristics of second-order-like phase transition. By employing the characteristic parameters of thermal hysteresis, we have established a pathway for calculations across different computational scales, thereby providing theoretical support for further investigations into the properties of ferroelectric materials through concurrent multiscale simulations.
基金funded by the National Natural Science Foundation of China(Nos.12025202,U20A2070,12172175)the National Science and Technology Major Project,China(No.J2019-Ⅱ-0014-0035)+2 种基金the Postdoctoral Fellowship Program of CPSF,China(No.GZB20230970)the Science Center for Gas Turbine Project,China(Nos.P2022-C-II-002-001,P2022-A-II-002-001)the Young Scientific and Technological Talents Project of Jiangsu Association for Science and Technology,China(No.TJ-2021-052)。
文摘This study aims to investigate the intricate dynamic characteristics of the high-speed duct during the over-under Turbine-Based Combined Cycle(TBCC)inlet mode transition process while operating in an off-design state under throttled conditions.A typical over-under TBCC inlet,designed for a working Mach number range of 0–6 with a transition Mach number of 3.5,is examined through experimental studies in a supersonic wind tunnel with a freestream Mach number of2.9.The investigation focuses on the complex oscillatory flow and unique hysteresis observed in the mode transition process of the high-speed duct under the mildly throttled condition,utilizing highspeed schlieren and dynamic pressure acquisition system.The findings reveal that the high-speed duct undergoes four distinct oscillation stages akin to those in a higher throttled state during the mode transition,albeit with smaller dominant frequency and energy.Moreover,an irregular alternating“big/little buzz”mode is observed in the early stage of the large oscillation stage.Notably,the mildly throttled state exhibits three intriguing hysteresis properties compared to the unthrottled and higher throttled states.Firstly,hysteresis is observed in the shock train motion stage in the duct before unstart,along with the corresponding inverse process.Subsequently,hysteresis is noted in the unstart and restart of the high-speed duct,with a smaller hysteresis interval than in the unthrottled state.Finally,the hysteresis characteristics of oscillation mode switching and the corresponding inverse process are explored.Based on the analysis,the first two hysteresis phenomena are associated with the formation and dissipation of the separation bubble.The significant adverse pressure gradient constrains the cross-sectional capacity of the channel,rendering the disappearance of the separation bubble more challenging.The hysteresis in oscillation mode switching is linked to not only the channel cross-sectional capacity but also the state of the incoming boundary layer.
基金supported by National Natural Science Foundation of China(No.72104110 No.72274113)Basic Science(Natural Science)Research Projects in Higher Education Institutions in Jiangsu Province(No.22KJB630011)+2 种基金General Project of Philosophy and Social Sciences Research in Jiangsu Universities(No.2022SJYB0253)Taishan Scholar Foundation of Shandong province of China(tsqn202103069)Shandong Provincial Natural Science Foundation(No.ZR202111130115)。
文摘Purpose:The study examines the synergy and hysteresis in the evolution of funding and its supported literature,depicts their temporal correlation mechanism,which aids in improving trend predictions.Design/methodology/approach:The study uses the LDA model to identify topics in funding texts and supported papers.A cosine similarity algorithm was employed to estimate the nexus between topics and construct the topic evolution time series.Similarly,the hysteresis effect in topic evolution is analyzed based on topic popularity and content,leading to insights into their temporal correlation mechanism.Findings:The study finds that fund and sponsored paper topics exhibit strong collaboration with a noticeable lag in evolution.The fund topics significantly influence sponsored paper topics after a two-year lag.Moreover,the lag effect is inversely proportional to the topic’s similarity.Research limitations:We use the LDA model to determine the hysteresis effect in topic evolution despite its limitations in handling long-tail words and domain-specific vocabulary.Furthermore,the timing of the emergence of the focal topic in funds is undermined,affecting the findings.Practical implications:These findings enhance the accuracy and scientific validity of trend prediction.Estimating and identifying patterns can help technology managers anticipate future research hotspots,supporting informed decision-making and technology management.Originality/value:This study introduces a research framework to quantitatively and visually analyze the hysteresis effect,revealing the correlation and evolutionary patterns between fund research topics and their funded papers.
基金supported in part by the National Key Research and Development Program of China(2023YFB4706400)the National Natural Science Foundation of China(62273112,62073030,62203161)+6 种基金the Guangdong Basic and Applied Basic Research Foundation(2023B1515120018,2023B1515120019)the Open Project of Xiangjiang Laboratory(23XJ03012)the Natural Science Foundation of Hunan Province(2024JJ5087)the Natural Science Foundation of Jiangxi Province(20232BAB212024)the National Research Foundation of Korea funded by the Ministry of Science and ICT,South Korea(IRIS-2023-00207954)the Science and Technology Planning Project of Guangzhou,China(2023A03J0120)the Guangzhou University Research Project(RC2023037)
文摘In this study,we consider a single-link flexible manipulator in the presence of an unknown Bouc-Wen type of hysteresis and intermittent actuator faults.First,an inverse hysteresis dynamics model is introduced,and then the control input is divided into an expected input and an error compensator.Second,a novel adaptive neural network-based control scheme is proposed to cancel the unknown input hysteresis.Subsequently,by modifying the adaptive laws and local control laws,a fault-tolerant control strategy is applied to address uncertain intermittent actuator faults in a flexible manipulator system.Through the direct Lyapunov theory,the proposed scheme allows the state errors to asymptotically converge to a specified interval.Finally,the effectiveness of the proposed scheme is verified through numerical simulations and experiments.
基金supported in part by the Open Fund of State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment,Guangdong University of Technology(Grant No.JMDZ2021007)in part by the Guangdong International Cooperation Program of Science and Technology(Grant No.2022A0505050078).
文摘Planar positioning systems are widely utilized in micro and nano applications.The challenges in modeling and control of XYΘflexure-based mechanisms include hysteresis of the piezoelectric actuators,couplings among the input axes,and coupled linear and angular motions of the end effector.This paper presents an inverse hysteresis-coupling hybrid model to account for such hysteresis and couplings.First,a specially designed kinematic chain is adopted to transfer the pose of the end effector into the linear motions at three prismatic joints.Second,an inverse hysteresis-coupling hybrid model is developed to linearize and decouple the system via a multilayer feedforward neural network.A fractional-order PID controller is also integrated to improve the motion accuracy of the overall system.Experimental results demonstrate that the proposed method can accurately control the motion of the end effector with improved accuracy and robustness.
基金supported by National Key Research and Development Program"Advanced Structures and Composite Materials"Special Project[Grant No.2024YFB3712800]the Fundamental Research Funds for the Central Universities[Grant No.DUT22-LAB605]Liaoning Province's"Unveiling the List and Leading the Way"Science and Technology Research and Development Special Project[Grant No.2022JH1/10400043]。
文摘Poly(phthalazinone ether sulfone ketone)(PPESK)is a new-generation high-performance thermoplastic resin that exhibits excellent thermal stability and mechanical properties.However,its damage and failure mechanisms under high-temperature and high-strain-rate coupling conditions remain unclear,significantly limiting the engineering applications of PPESK-based composites in extreme environments such as aerospace.To address this issue,in this study,a temperature-controlled split Hopkinson pressure bar experimental platform was developed for dynamic tensile/compressive loading scenarios.Combined with scanning electron microscopy and molecular dynamics simulations,the thermomechanical behavior and failure mechanisms of PPESK were systematically investigated over the temperature range of 293-473 K.The study revealed a novel"dynamic hysteresis brittle behavior"and its underlying"segmental activation±response lag antagonistic mechanism".The results showed that the strain-rate-induced response lag of polymer chain segments significantly weakened the viscous dissipation capacity activated by thermal energy at elevated temperatures.Although high-strain-rate conditions led to notable enhancement in the dynamic strength of the material(with an increase of 8%-233%,reaching 130%-330%at elevated temperatures),the fracture surface morphology tended to become smoother,and brittle fracture characteristics became more pronounced.Based on these findings,a temperature±strain rate hysteresis antagonistic function was constructed,which effectively captured the competitive relationship between temperature-driven relaxation behavior and strain-rateinduced hysteresis in thermoplastic resins.A multiscale damage evolution constitutive model with temperature±rate coupling was subsequently established and numerically implemented via the VUMAT user subroutine.This study not only unveils the nonlinear damage mechanisms of PPESK under combined service temperatures and dynamic/static loading conditions,but also provides a strong theoretical foundation and engineering guidance for the constitutive modeling and parametric design of thermoplastic resin-based materials.
基金financially supported by the Beijing Natural Science Foundation(No.L233016)。
文摘Polyaniline(PANi)hydrogels have a wide range of applications in artificial skin,flexible robotics,and movement monitoring.Nevertheless,limited by the modulus mismatch between rigid PANi and the soft hydrogel matrix,the high strength and toughness of the PANi hydrogel are mutually exclusive.Although the introduction of sacrificial bonds into the hydrogel network can alleviate this contradiction to a certain extent,it always causes pronounced energy hysteresis during hydrogel deformation.Inspired by the energy storage and release of macroscopic springs,in this work,we propose a molecular entanglement approach for the fabrication of PANi hydrogels featuring high toughness and low hysteresis,where flexible poly(ethylene glycol)(PEG)is entangled with chemically cross-linked poly(acrylic acid)(PAA)as a hydrogel matrix,and rigid PANi as a conductive filler.The resultant PAA/PEG/PANi hydrogel exhibited high mechanical properties(fracture strength of 0.75 MPa and toughness of 4.81 MJ·m^(-3))and a low energy dissipation ratio(28.2%when stretching to 300%).Moreover,the PAA/PEG/PANi hydrogel possesses a good electrical response to external forces and can be employed as a strain sensor to monitor human joint movements by producing specific electrical signals.This work provides a straightforward strategy for preparing tough conductive PANi hydrogels with low hysteresis,showing potential for the development of healthcare devices.
基金financially supported by the National Natural Science Foundation of China(No.U2006218)the Project of“20 Items of University”of Jinan(No.T202009)the Taishan Scholars Program(No.tstp20221130).
文摘The incompatibility between large electro-strain and low-strain hysteresis,in addition to the poor tem-perature stability of piezoelectric ceramics,limits the development of high-precision piezoelectric actu-ators.In this work,Bi_(0.465)Na_(0.465)Ba_(0.07)Ti_(1−2 x)Ga_(x)Sb_(x)O_(3)(abbreviated as BNBT7-x GS,x=0,0.01,0.02,0.03,0.04,and 0.06)ceramics were designed.Specifically,when x=0.02,the ceramics exhibit a critical state in the relaxor ferroelectric system with a typical relaxor P−E loop and an I−E curve of four peaks.At this composition,the room temperature strain is 0.40%,which is capable of enhancing the electro-strain and reducing the hysteresis simultaneously.Furthermore,over the wide temperature range from 30 to 180℃,the minimum strain hysteresis(H_(ys))is 7.13%,and the maximum strain variation is only 16.8%,demonstrating ultra-high temperature stability.This work introduces a model for addressing the dilemma between good electro-strain properties and insufficient temperature stability in lead-free piezoelectric ceramics,crucial for the development of modern high-precision actuators.
基金National Natural Science Foundation of China(62203118)。
文摘Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuators.Existing methods for fitting hysteresis loops include operator class,differential equation class,and machine learning class.The modeling cost of operator class and differential equation class methods is high,the model complexity is high,and the process of machine learning,such as neural network calculation,is opaque.The physical model framework cannot be directly extracted.Therefore,the sparse identification of nonlinear dynamics(SINDy)algorithm is proposed to fit hysteresis loops.Furthermore,the SINDy algorithm is improved.While the SINDy algorithm builds an orthogonal candidate database for modeling,the sparse regression model is simplified,and the Relay operator is introduced for piecewise fitting to solve the distortion problem of the SINDy algorithm fitting singularities.The Relay-SINDy algorithm proposed in this paper is applied to fitting hysteresis loops.Good performance is obtained with the experimental results of open and closed loops.Compared with the existing methods,the modeling cost and model complexity are reduced,and the modeling accuracy of the hysteresis loop is improved.
基金supported in part by the Young Scientists Fund of National Natural Science Foundation of China(62203408)the Hubei Provincial Natural Science Foundation of China(2015CFA010)+1 种基金the 111 Project(B17040)China Scholarship Council(202206410070).
文摘The complex nonlinear characteristics of pneumatic soft actuators,such as asymmetric hysteresis,rate-dependence,and mechanical load-dependence,pose a challenge in accurately modeling their dynamics.To address this challenge,this paper proposes a comprehensive dynamic model aimed at describing bidirectional asymmetric hysteresis,rate-dependent,and mechanical load-dependent characteristics of a vertical pneumatic bellows actuator(PBA)system.The dynamic model contains a hysteresis submodel and a load-dependent dynamic submodel.The hysteresis submodel consists of several sets of weighted double-side play(DSP)and weighted dead-zone(DZ)operators connected in series,and it is used to model the bidirectional asymmetric hysteresis of the system.The load-dependent dynamic submodel is built based on the gated recurrent unit(GRU)neural network,and it is used to fit the nonlinear relationship between the displacement of the system and the frequency of the input air pressure as well as the mechanical load.The model parameters of the hysteresis submodel and the loaddependent dynamic submodel are determined by intelligent optimization method and neural network training method,reseparately.The fitness value(FV)between the output of the dynamic model and the experimental data is calculated to be 96.1736%,demonstrating that the parameters of the dynamic model are valid.We conduct six set of experiments to compare the model output with the experimental data,and calculate the root-meansquare errors and the maximum error,respectively.The experimental results show that,the root-mean-square error remains consistently below 2.7700%,while the maximum error remains below 8.4000%across all experiments,thereby substantiating the validity and generality of the proposed model.
基金supported by the National Natural Science Foundation of China under Grant 62073190the Science Center Program of National Natural Science Foundation of China under Grant 62188101.
文摘This paper investigates the problem of dynamic event-triggered control for a class of large-scale nonlinear systems.In particular,both neutral delays and unknown backlash-like hysteresis are considered.This requires to integrate a compensation mechanism into the event-triggered control architecture.To this end,dynamic gain and adaptive control techniques are introduced to address the effects of neutral delays,unknown hysteresis and parameter uncertainties simultaneously.By introducing a non-negative internal dynamic variable,a dynamic event-triggered controller is designed using the hyperbolic tangent function to reduce the communication burden.By means of the Lyapunov–Krasovskii method,it is demonstrated that all signals of the closed-loop system are globally bounded and eventually converge to a tunable bounded region.Moreover,the Zeno behavior is avoided.Finally,a simulation example is presented to verify the validity of the control scheme.
