Spinal cord injury necessitates effective rehabilitation strategies, with exercise therapies showing promise in promoting recovery. This study investigated the impact of rehabilitation exercise on functional recovery ...Spinal cord injury necessitates effective rehabilitation strategies, with exercise therapies showing promise in promoting recovery. This study investigated the impact of rehabilitation exercise on functional recovery and morphological changes following thoracic contusive spinal cord injury. After a 7-day recovery period after spinal cord injury, mice were assigned to either a trained group(10 weeks of voluntary running wheel or forced treadmill exercise) or an untrained group. Bi-weekly assessments revealed that the exercise-trained group, particularly the voluntary wheel exercise subgroup, displayed significantly improved locomotor recovery, more plasticity of dopaminergic and serotonin modulation compared with the untrained group. Additionally, exercise interventions led to gait pattern restoration and enhanced transcranial magnetic motor-evoked potentials. Despite consistent injury areas across groups, exercise training promoted terminal innervation of descending axons. In summary, voluntary wheel exercise shows promise for enhancing outcomes after thoracic contusive spinal cord injury, emphasizing the role of exercise modality in promoting recovery and morphological changes in spinal cord injuries. Our findings will influence future strategies for rehabilitation exercises, restoring functional movement after spinal cord injury.展开更多
Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed railways.They can cause significant wheel-rail dynamic interactions,leading to wheel-rail ...Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed railways.They can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and deterioration.Few researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry irregularities.However,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric shape.In this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from Beijing to Shanghai.The vertical dynamic forces in the time and frequency domains were compared under different running speeds.These forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed model.Finally,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is found.The results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the literature.The ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.展开更多
Nowadays,using mobile robots in different applications has been very important.However,the environment in which they operate can cause the wheels to slip or the robot body to slide,causing the assigned task not to be ...Nowadays,using mobile robots in different applications has been very important.However,the environment in which they operate can cause the wheels to slip or the robot body to slide,causing the assigned task not to be performed successfully.Therefore,the need arises to mathematically determine these external perturbations to predict the behavior of the mobile robot.Based on the above mentioned facts,this work focuses on obtaining the kinematic model of an omnidirectional mobile robot considering lateral and longitudinal sliding disturbances of the body and wheel slippage.To mitigate the effect of the disturbances,a control strategy is considered based on the design of a generalized proportional integral observer(GPIO)that allows the estimation of such perturbations.Then,an active disturbance rejection control(ADRC)methodology is implemented to solve the trajectory tracking problem,and it is theoretically proved that the tracking errors converge to a vicinity near the origin.Numerical simulations and real-time experiments validate the obtained perturbed model and the control strategy performance,achieving the desired trajectory tracking despite these perturbations.展开更多
Non-pneumatic wheels inherently offer explosion-proof advantages compared to pneumatic wheel.Our team innovatively proposed an“elastic ring-hinge group”type non-pneumatic mechanical elastic wheel(ME-Wheel).To analyz...Non-pneumatic wheels inherently offer explosion-proof advantages compared to pneumatic wheel.Our team innovatively proposed an“elastic ring-hinge group”type non-pneumatic mechanical elastic wheel(ME-Wheel).To analyze the gas flow characteristics around the ME-Wheel,this study analyzed the aerodynamic characteristics of the MEWheel for the first time by using CFD calculation method,and studied the influences of speed,steering angle,camber angle and hinge group on the aerodynamic characteristics of the wheel.Compared with camber angle,steering angle has a more significant effect on the aerodynamic characteristics of non-pneumatic mechanical elastic wheels in terms of lift and drag.Speed has no significant effect on the wheel drag coefficient and lift coefficient.The number of hinge groups has a significant effect on wheel aerodynamic characteristics.The deviations between the maximum and minimum values of drag,lift,drag coefficient,and lift coefficient are 6.06%,8.57%,6.05%,and 8.6%,respectively.This study addresses a critical gap in the design optimization of ME-Wheel,provides a theoretical basis for the aerodynamic optimization of ME-Wheel,and has strong practical significance for the commercial development of nonpneumatic mechanical elastic wheels.展开更多
Conventional deformable wheel systems in robots and other mechatronic systems face significant challenges in achieving miniaturization,intelligence,and integration.To address these issues,we propose a novel integrated...Conventional deformable wheel systems in robots and other mechatronic systems face significant challenges in achieving miniaturization,intelligence,and integration.To address these issues,we propose a novel integrated structural design method and four-dimensional printing strategy for deformable wheels capable of shaping among multiple programmable direct-driven deformation configurations.The load-bearing capacity of the printed wheel is strengthened by employing deformed components in various locations and actuated states.Additionally,a novel analytical design method is presented to determine the structure,actuation,and deformation parameters of each component under complex coupled deformation.Our findings reveal that the designed wheel can transform into three different configurations,exhibiting desired deformations of 12.5%in the radial direction and 19.6%in the axial direction.It also demonstrates robust deformation behavior and structural stability under multi-directional loads.By integrating a terrain sensing system,the designed wheel exhibits highly adaptive deformation capabilities on various terrains,showing great potential for exploring complex environments.展开更多
The wheeled bipedal robots have great application potential in environments with a mixture of structured and unstructured terrain. However, wheeled bipedal robots have problems such as poor balance ability and low mov...The wheeled bipedal robots have great application potential in environments with a mixture of structured and unstructured terrain. However, wheeled bipedal robots have problems such as poor balance ability and low movement level on rough roads. In this paper, a novel and low-cost wheeled bipedal robot with an asymmetrical five-link mechanism is proposed, and the kinematics of the legs and the dynamics of the Wheeled Inverted Pendulum (WIP) are modeled. The primary balance controller of the wheeled bipedal robot is built based on the Linear Quadratic Regulator (LQR) and the compensation method of the virtual pitch angle adjusting the Center of Mass (CoM) position, then the whole-body hybrid torque-position control is established by combining attitude and leg controllers. The stability of the robot’s attitude control and motion is verified with simulations and prototype experiments, which confirm the robot’s ability to pass through complex terrain and resist external interference. The feasibility and reliability of the proposed control model are verified.展开更多
The problem of trajectory tracking for a class of differentially driven wheeled mobile robots(WMRs)under partial loss of the effectiveness of the actuated wheels is investigated in this paper.Such actuator faults may ...The problem of trajectory tracking for a class of differentially driven wheeled mobile robots(WMRs)under partial loss of the effectiveness of the actuated wheels is investigated in this paper.Such actuator faults may cause the loss of strong controllability of the WMR,such that the conventional fault-tolerant control strategies unworkable.In this paper,a new mixed-gain adaption scheme is devised,which is adopted to adapt the gain of a decoupling prescribed performance controller to adaptively compensate for the loss of the effectiveness of the actuators.Different from the existing gain adaption technique which depends on both the barrier functions and their partial derivatives,ours involves only the barrier functions.This yields a lower magnitude of the resulting control signals.Our controller accomplishes trajectory tracking of the WMR with the prescribed rate and accuracy even in the faulty case,and the control design relies on neither the information of the WMR dynamics and the actuator faults nor the tools for function approximation,parameter identification,and fault detection or estimation.The comparative simulation results justify the theoretical findings.展开更多
The article considers the impact of forestry machines on the soil of the cutting areas and presents the results of the impact of harvesters of different classes(middlesmall,middle and heavy)and configurations of wheel...The article considers the impact of forestry machines on the soil of the cutting areas and presents the results of the impact of harvesters of different classes(middlesmall,middle and heavy)and configurations of wheeled equipment and additional equipment on the soil of the cutting areas in the conditions of Kronoberg County(South of Sweden).Methods to reduce negative impact of wheeled harvesters on the soil of forests are proposed.The aim of the research is to assess the effect of the structural parameters of the wheel harvesters of different class on the soil of the cutting areas.Wheeled harvesters were loaded with 60 kN force.The results of experimental studies of the impact of wheeled harvesters on the forest soil are presented.Recommendations on the possibility of testing the results of research in the conditions of the rental base of the Western part of the North-Western Federal District of the Russian Federation are given.展开更多
The dynamic recrystallization(DRX)behavior and texture formation mechanism in an AZ31 magnesium alloy wheel hub during the spinning process were investigated.Analysis using optical microscopy,electron backscatter diff...The dynamic recrystallization(DRX)behavior and texture formation mechanism in an AZ31 magnesium alloy wheel hub during the spinning process were investigated.Analysis using optical microscopy,electron backscatter diffraction,transmission electron microscopy,and finite element simulation revealed that continuous dynamic recrystallization(CDRX)and grain boundary bulging occurred simultaneously throughout the spinning process,leading to an increased proportion of DRXed grain areas.The newly formed DRXed grains largely retained the orientations of their deformed parent grains.The spinning process had two stages:initially,deformation was driven by basalslip as the roller contacted the alloy and descended to its lowest point.In the later stage,pyramidal<c+a>slips became predominant as additional force was applied along the spinning direction(SD),forming a final texture with the c-axis tilting±15°towards the SD.This texture development led to discernible anisotropy in tensile properties along the SD and the tangential direction(TD).展开更多
Because the grinding temperature is high when grinding using conventional disordered grinding wheels,the grinding quality improvement is limited when using single abrasive ordered grinding wheels,and the wheel prepara...Because the grinding temperature is high when grinding using conventional disordered grinding wheels,the grinding quality improvement is limited when using single abrasive ordered grinding wheels,and the wheel preparation process is complex and costly when using microstructured grinding wheels,abrasive groups ordered grinding wheels are widely investigated.However,there is a paucity of systematic analyses and comprehensive reviews focused on abrasive groups ordered grinding wheels.Therefore,this paper defines abrasive groups ordered grinding wheels and classifies them,based on their unique characteristics,into groups such as abrasive blocks ordered grinding wheel,fine grain structured grinding wheel,abrasive clusters ordered grinding wheel,and abrasive fibers ordered grinding wheel.We provide an overview of the latest advances in wheel structures,preparation methods,and abrasive selection for various types of abrasive groups ordered grinding wheels.Furthermore,we conduct a comparative analysis of the existing types,significant advantages,and challenges associated with the four types of abrasive groups ordered grinding wheels.Looking ahead,given the potential of abrasive groups ordered grinding wheels in reducing grinding force and temperature,we recommend further exploration of their application in combination with special processing techniques.This could pave the way for the development of machining processes that are more environmentally friendly,energy-efficient,and precise.展开更多
During the grinding train operation process,the grinding force between the grinding wheel and the rail is critical in ensuring the grinding quality and efficiency.The coupling vibration among the frame,the grinding wh...During the grinding train operation process,the grinding force between the grinding wheel and the rail is critical in ensuring the grinding quality and efficiency.The coupling vibration among the frame,the grinding wheels,and the wheelsets will seriously affect the stability of the grinding force.In this paper,the coupled mechanical model of the grinding wheel/rail is established based on the contact mechanics theory,which is embedded as a submodel into the dynamic model of the multi-rigid buggy.The interaction among the frame,the grinding wheels and the wheelsets is analysed by setting the convex irregularity on the rail.The grinding effect is evaluated in combination with the subway’s long wave corrugation grinding conditions.The results show that when the grinding buggy passes the convex irregularity,the vibration excited by the wheelset system has a significant impact on the dynamic behavior of the grinding wheels.The vibration of the grinding wheel is mainly transmitted between the grinding wheel and the frame,less affecting the wheelset.For the long wave corrugation of the subway,the grinding effect of the grinding wheel has a certain correlation with the phase angle of the wheelset through the corrugation.The research results provide an important reference for the setting of the grinding pattern.展开更多
The momentum wheel assumes a dominant role as an inertial actuator for satellite attitude control systems.Due to the effects of structural aging and external interference,the momentum wheel may experience the gradual ...The momentum wheel assumes a dominant role as an inertial actuator for satellite attitude control systems.Due to the effects of structural aging and external interference,the momentum wheel may experience the gradual emergence of irreversible faults.These fault features will become apparent in the telemetry signal transmitted by the momentum wheel.This paper introduces ADTWformer,a lightweight model for long-term prediction of time series,to analyze the time evolution trend and multi-dimensional data coupling mechanism of satellite momentum wheel faults.Moreover,the incorporation of the approximate Markov blanket with the maximum information coefficient presents a novel methodology for performing correlation analysis,providing significant perspectives from a data-centric standpoint.Ultimately,the creation of an adaptive alarm mechanism allows for the successful attainment of the momentum wheel fault warning by detecting the changes in the health status curves.The analysis methodology outlined in this article has exhibited positive results in identifying instances of satellite momentum wheel failure in two scenarios,thereby showcasing considerable promise for large-scale applications.展开更多
Objective:To analyze the application effect of the Behavior Change Wheel(BCW)theory in fall prevention management for elderly inpatients.Methods:One hundred elderly inpatients admitted to Kunshan Fourth People’s Hosp...Objective:To analyze the application effect of the Behavior Change Wheel(BCW)theory in fall prevention management for elderly inpatients.Methods:One hundred elderly inpatients admitted to Kunshan Fourth People’s Hospital from January 2019 to April 2024 were selected and divided into an experimental group(fall prevention management intervention based on BCW theory)and a control group(routine fall prevention management intervention)using random sampling,with 50 patients in each group.The differences in knowledge,attitude,and behavior levels of fall prevention,prevention efficacy,and the incidence of falls and fall-related injuries during hospitalization,6 months after discharge,and 1 year after discharge were compared between the two groups.Results:Compared with before the intervention,the scores of the fall prevention knowledge,attitude,and behavior scale(knowledge dimension,attitude dimension,behavior dimension,and total score)for elderly inpatients in both groups increased,and the improvement in the experimental group was greater than that in the control group(P<0.05).After the intervention,the revised fall efficacy scale score was higher in the experimental group compared to the control group(P<0.05).The incidence of falls during hospitalization,6 months after discharge,and 1 year after discharge,as well as the rate of fall-related injuries 6 months and 1 year after discharge,were lower in the experimental group than in the control group(P<0.05).There was no statistically significant difference in the rate of fall-related injuries during hospitalization between the two groups(P>0.05).Conclusion:The fall prevention management intervention based on BCW theory has good application value in elderly inpatients.It effectively improves patients’knowledge,attitudes,and behavior levels regarding fall prevention,significantly enhances their self-prevention efficacy,and demonstrates good results in reducing the incidence of falls during hospitalization and after discharge.展开更多
With the rapid urbanization and exponential population growth in China,two-wheeled vehicles have become a popular mode of transportation,particularly for short-distance travel.However,due to a lack of safety awareness...With the rapid urbanization and exponential population growth in China,two-wheeled vehicles have become a popular mode of transportation,particularly for short-distance travel.However,due to a lack of safety awareness,traffic violations by two-wheeled vehicle riders have become a widespread concern,contributing to urban traffic risks.Currently,significant human and material resources are being allocated to monitor and intercept non-compliant riders to ensure safe driving behavior.To enhance the safety,efficiency,and cost-effectiveness of traffic monitoring,automated detection systems based on image processing algorithms can be employed to identify traffic violations from eye-level video footage.In this study,we propose a robust detection algorithm specifically designed for two-wheeled vehicles,which serves as a fundamental step toward intelligent traffic monitoring.Our approach integrates a novel convolutional and attention mechanism to improve detection accuracy and efficiency.Additionally,we introduce a semi-supervised training strategy that leverages a large number of unlabeled images to enhance the model’s learning capability by extracting valuable background information.This method enables the model to generalize effectively to diverse urban environments and varying lighting conditions.We evaluate our proposed algorithm on a custom-built dataset,and experimental results demonstrate its superior performance,achieving an average precision(AP)of 95%and a recall(R)of 90.6%.Furthermore,the model maintains a computational efficiency of only 25.7 GFLOPs while achieving a high processing speed of 249 FPS,making it highly suitable for deployment on edge devices.Compared to existing detection methods,our approach significantly enhances the accuracy and robustness of two-wheeled vehicle identification while ensuring real-time performance.展开更多
The wheel wear of light rail trains is difficult to predict due to poor information and small data samples.However,the amount of wear gradually increases with the running mileage.The grey future prediction model is su...The wheel wear of light rail trains is difficult to predict due to poor information and small data samples.However,the amount of wear gradually increases with the running mileage.The grey future prediction model is supposed to deal with this problem effectively.In this study,we propose an improved non-equidistant grey model GM(1,1)with background values optimized by a genetic algorithm(GA).While the grey model is not good enough to track data series with features of randomness and nonlinearity,the residual error series of the GA-GM(1,1)model is corrected through a back propagation neural network(BPNN).To further improve the performance of the GA-GM(1,1)-BPNN model,a particle swarm optimization(PSO)algorithm is implemented to train the weight and bias in the neural network.The traditional non-equidistant GM(1,1)model and the proposed GA-GM(1,1),GA-GM(1,1)-BPNN,and GA-GM(1,1)-PSO-BPNN models were used to predict the wheel diameter and wheel flange wear of the Changchun light rail train and their validity and rationality were verified.Benefitting from the optimization effects of the GA,neural network,and PSO algorithm,the performance ranking of the four methods from highest to lowest was GA-GM(1,1)-PSO-BPNN>GA-GM(1,1)-BPNN>GA-GM(1,1)>GM(1,1)in both the fitting and prediction zones.The GA-GM(1,1)-PSO-BPNN model performed best,with the lowest fitting and forecasting maximum relative error,mean absolute error,mean absolute percentage error,and mean squared error of all four models.Therefore,it is the most effective and stable model in field application of light rail train wheel wear prediction.展开更多
This paper proposes an attitude control strategy for a flexible satellite equipped with an orthogonal cluster of three-dimensional(3D)magnetically suspended wheels(MSWs).The mathematical model for the satellite incorp...This paper proposes an attitude control strategy for a flexible satellite equipped with an orthogonal cluster of three-dimensional(3D)magnetically suspended wheels(MSWs).The mathematical model for the satellite incorporating flexible appendages and an orthogonal cluster of magnetically suspended reaction wheel actuators is initially developed.After that,an adaptive attitude controller is designed with a switching surface of variable structure,an adaptive law for estimating inertia matrix uncertainty,and a fuzzy disturbance observer for estimating disturbance torques.Additionally,a Moore-Penrose-based steering law is proposed to derive the tilt angle commands of the orthogonal configuration of the 3D MSW to follow the designed control signal.Finally,numerical simulations are presented to validate the effectiveness of the proposed control strategy.展开更多
In this paper, we present a comprehensive model for the prediction of the evolution of high-speed train wheel profiles due to wear. The model consists of four modules： a multi-body model implemented with the commerci...In this paper, we present a comprehensive model for the prediction of the evolution of high-speed train wheel profiles due to wear. The model consists of four modules： a multi-body model implemented with the commercial multi-body software SIMPACK to evaluate the dynamic response of the vehicle and track; a local contact model based on Hertzian theory and a novel method, named FaStrip （Sichani et al., 2016）, to calculate the normal and tangential forces, respectively; a wear model proposed by the University of Sheffield （known as the USFD wear function） to estimate the amount of material removed and its distribution along the wheel profile; and a smoothing and updating strategy. A simulation of the wheel wear of the high-speed train CRH3 in service on the Wuhan-Guangzhou railway line was performed. A virtual railway line based on the statistics of the line was used to represent the entire real track. The model was validated using the wheel wear data of the CRH3 operating on the Wuhan- Guangzhou line, monitored by the authors＇ research group. The results of the predictions and measurements were in good agreement.展开更多
In order to improve the curving performance of the conventional wheelset in sharp curves and resolve the steering ability problem of the independently rotating wheel in large radius curves and tangent lines, a differe...In order to improve the curving performance of the conventional wheelset in sharp curves and resolve the steering ability problem of the independently rotating wheel in large radius curves and tangent lines, a differential cou- pling wheelset （DCW） was developed in this work. The DCW was composed of two independently rotating wheels （IRWs） coupled by a clutch-type limited slip differential. The differential contains a static pre-stress clutch, which could lock both sides of IRWs of the DCW to ensure a good steering performance in curves with large radius and tangent track. In contrast, the clutch could unlock the two IRWs of the DCW in a sharp curve to endue it with the characteristic of an IRW, so that the vehicles can go through the tight curve smoothly. To study the dynamic performance of the DCW, a multi-body dynamic model of single bogie with DCWs was established. The self-centering capability, hunting stability, and self-steering performance on a curved track were analyzed and then compared with those of the conventional wheelset and IRW. Finally, the effect of coupling parameters of the DCW on the dynamic performance was investigated.展开更多
The wheel-rail relationship in turnout is more complicated than that in ordinary track. Profile wear and machining errors of the wheelset cause deviations Of the rolling radius on different wheels. Therefore, wheelset...The wheel-rail relationship in turnout is more complicated than that in ordinary track. Profile wear and machining errors of the wheelset cause deviations Of the rolling radius on different wheels. Therefore, wheelsets move to the direction of smaller diameter wheels in search of a new stable state and to change the condition before entering the turnout. Thc main aim of the present work is to examine the wheel-turnout rail dynamic interaction combined with the static contact behaviour. Calculations are performed on a high-speed vehicle CRH2 and the No. 12 turnout of the passenger dedicated line. The wheel-turnout contac! geometric relationship and normal contact behaviour under wheel diameter difference are assessed by the trace principle and finite element method. A high-speed vehicle-turnout coupling dynamic model is established based on SIMPACK software to analyse the wheel-rail dynamic interaction, riding comfort, and wear. Both the wheel diameter amplitudes and distribution patterns are accounted for. The simulation shows that wheel diameter difference can greatly disturb the positions＇ variation of wheel-rail contact points and affect the normal contact behaviour on switch rails by changing the load transition position. The effect of wheel diameter diffierence on wheel-turnout rail dynamic interaction can be divided into three according to its amplitude： when the wheel diameter difference is within 0-1.5 mm, the wheel flange comes into contact with the switch rail in advance, causing a rapidly increased lateral wheel-rail force; when it is within 1.5 2.5 mm, trains are subject to instability under equivalent in-phase wheel diameter difference; when it is larger than 2.5 mm, the continuous flange-switch rail contact helps strengthen the vehicle stability, but increases the wheel-rail wear. It is recommended to control the wheel diameter difference to within 2.5 mm but limit it to 2 mm if it is distributed in-phase.展开更多
基金supported by the NIH (R01NS103481, R01NS111776, and R01NS131489)Indiana Department of Health (ISDH58180)(all to WW)。
文摘Spinal cord injury necessitates effective rehabilitation strategies, with exercise therapies showing promise in promoting recovery. This study investigated the impact of rehabilitation exercise on functional recovery and morphological changes following thoracic contusive spinal cord injury. After a 7-day recovery period after spinal cord injury, mice were assigned to either a trained group(10 weeks of voluntary running wheel or forced treadmill exercise) or an untrained group. Bi-weekly assessments revealed that the exercise-trained group, particularly the voluntary wheel exercise subgroup, displayed significantly improved locomotor recovery, more plasticity of dopaminergic and serotonin modulation compared with the untrained group. Additionally, exercise interventions led to gait pattern restoration and enhanced transcranial magnetic motor-evoked potentials. Despite consistent injury areas across groups, exercise training promoted terminal innervation of descending axons. In summary, voluntary wheel exercise shows promise for enhancing outcomes after thoracic contusive spinal cord injury, emphasizing the role of exercise modality in promoting recovery and morphological changes in spinal cord injuries. Our findings will influence future strategies for rehabilitation exercises, restoring functional movement after spinal cord injury.
基金supported by Natural Science Foundation of China(52178441)the Scientific Research Projects of the China Academy of Railway Sciences Co.,Ltd.(Grant No.2022YJ043).
文摘Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed railways.They can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and deterioration.Few researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry irregularities.However,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric shape.In this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from Beijing to Shanghai.The vertical dynamic forces in the time and frequency domains were compared under different running speeds.These forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed model.Finally,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is found.The results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the literature.The ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.
基金supported by Instituto Politécnico Nacional-Secretaría de Investigación y Posgrado under grant 20253806in part by project UNAM PAPIME PE104125.
文摘Nowadays,using mobile robots in different applications has been very important.However,the environment in which they operate can cause the wheels to slip or the robot body to slide,causing the assigned task not to be performed successfully.Therefore,the need arises to mathematically determine these external perturbations to predict the behavior of the mobile robot.Based on the above mentioned facts,this work focuses on obtaining the kinematic model of an omnidirectional mobile robot considering lateral and longitudinal sliding disturbances of the body and wheel slippage.To mitigate the effect of the disturbances,a control strategy is considered based on the design of a generalized proportional integral observer(GPIO)that allows the estimation of such perturbations.Then,an active disturbance rejection control(ADRC)methodology is implemented to solve the trajectory tracking problem,and it is theoretically proved that the tracking errors converge to a vicinity near the origin.Numerical simulations and real-time experiments validate the obtained perturbed model and the control strategy performance,achieving the desired trajectory tracking despite these perturbations.
基金Supported by National Natural Science Foundation of China(Grant Nos.52472411,52272397)the Key Research&Development and Achievement Transformation Program of Wuhu(Grant No.2023YF010)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX25_0566).
文摘Non-pneumatic wheels inherently offer explosion-proof advantages compared to pneumatic wheel.Our team innovatively proposed an“elastic ring-hinge group”type non-pneumatic mechanical elastic wheel(ME-Wheel).To analyze the gas flow characteristics around the ME-Wheel,this study analyzed the aerodynamic characteristics of the MEWheel for the first time by using CFD calculation method,and studied the influences of speed,steering angle,camber angle and hinge group on the aerodynamic characteristics of the wheel.Compared with camber angle,steering angle has a more significant effect on the aerodynamic characteristics of non-pneumatic mechanical elastic wheels in terms of lift and drag.Speed has no significant effect on the wheel drag coefficient and lift coefficient.The number of hinge groups has a significant effect on wheel aerodynamic characteristics.The deviations between the maximum and minimum values of drag,lift,drag coefficient,and lift coefficient are 6.06%,8.57%,6.05%,and 8.6%,respectively.This study addresses a critical gap in the design optimization of ME-Wheel,provides a theoretical basis for the aerodynamic optimization of ME-Wheel,and has strong practical significance for the commercial development of nonpneumatic mechanical elastic wheels.
基金supported by the National Key Research and Development Program of China(Grant No 2022YFB4600102)the National Natural Science Foundation of China(Grant No.U23A20637 and Grant No 52275561)。
文摘Conventional deformable wheel systems in robots and other mechatronic systems face significant challenges in achieving miniaturization,intelligence,and integration.To address these issues,we propose a novel integrated structural design method and four-dimensional printing strategy for deformable wheels capable of shaping among multiple programmable direct-driven deformation configurations.The load-bearing capacity of the printed wheel is strengthened by employing deformed components in various locations and actuated states.Additionally,a novel analytical design method is presented to determine the structure,actuation,and deformation parameters of each component under complex coupled deformation.Our findings reveal that the designed wheel can transform into three different configurations,exhibiting desired deformations of 12.5%in the radial direction and 19.6%in the axial direction.It also demonstrates robust deformation behavior and structural stability under multi-directional loads.By integrating a terrain sensing system,the designed wheel exhibits highly adaptive deformation capabilities on various terrains,showing great potential for exploring complex environments.
基金supported in part by the National Natural Science Foundationof China under Grant(61801122)Natural Science Foundation of FujianProvince(2022J01542).
文摘The wheeled bipedal robots have great application potential in environments with a mixture of structured and unstructured terrain. However, wheeled bipedal robots have problems such as poor balance ability and low movement level on rough roads. In this paper, a novel and low-cost wheeled bipedal robot with an asymmetrical five-link mechanism is proposed, and the kinematics of the legs and the dynamics of the Wheeled Inverted Pendulum (WIP) are modeled. The primary balance controller of the wheeled bipedal robot is built based on the Linear Quadratic Regulator (LQR) and the compensation method of the virtual pitch angle adjusting the Center of Mass (CoM) position, then the whole-body hybrid torque-position control is established by combining attitude and leg controllers. The stability of the robot’s attitude control and motion is verified with simulations and prototype experiments, which confirm the robot’s ability to pass through complex terrain and resist external interference. The feasibility and reliability of the proposed control model are verified.
基金supported in part by the National Natural Science Foundation of China under Grants 61991404,62103093 and 62473089the Research Program of the Liaoning Liaohe Laboratory,China under Grant LLL23ZZ-05-01+5 种基金the Key Research and Development Program of Liaoning Province of China under Grant 2023JH26/10200011the 111 Project 2.0 of China under Grant B08015,the National Key Research and Development Program of China under Grant 2022YFB3305905the Xingliao Talent Program of Liaoning Province of China under Grant XLYC2203130the Natural Science Foundation of Liaoning Province of China under Grants 2024JH3/10200012 and 2023-MS-087the Open Research Project of the State Key Laboratory of Industrial Control Technology of China under Grant ICT2024B12the Fundamental Research Funds for the Central Universities of China under Grants N2108003 and N2424004.
文摘The problem of trajectory tracking for a class of differentially driven wheeled mobile robots(WMRs)under partial loss of the effectiveness of the actuated wheels is investigated in this paper.Such actuator faults may cause the loss of strong controllability of the WMR,such that the conventional fault-tolerant control strategies unworkable.In this paper,a new mixed-gain adaption scheme is devised,which is adopted to adapt the gain of a decoupling prescribed performance controller to adaptively compensate for the loss of the effectiveness of the actuators.Different from the existing gain adaption technique which depends on both the barrier functions and their partial derivatives,ours involves only the barrier functions.This yields a lower magnitude of the resulting control signals.Our controller accomplishes trajectory tracking of the WMR with the prescribed rate and accuracy even in the faulty case,and the control design relies on neither the information of the WMR dynamics and the actuator faults nor the tools for function approximation,parameter identification,and fault detection or estimation.The comparative simulation results justify the theoretical findings.
文摘The article considers the impact of forestry machines on the soil of the cutting areas and presents the results of the impact of harvesters of different classes(middlesmall,middle and heavy)and configurations of wheeled equipment and additional equipment on the soil of the cutting areas in the conditions of Kronoberg County(South of Sweden).Methods to reduce negative impact of wheeled harvesters on the soil of forests are proposed.The aim of the research is to assess the effect of the structural parameters of the wheel harvesters of different class on the soil of the cutting areas.Wheeled harvesters were loaded with 60 kN force.The results of experimental studies of the impact of wheeled harvesters on the forest soil are presented.Recommendations on the possibility of testing the results of research in the conditions of the rental base of the Western part of the North-Western Federal District of the Russian Federation are given.
基金funded by the National Natural Science Foundation of China(No.52204407)the Natural Science Foundation of Jiangsu Province,China(No.BK20220595)the China Postdoctoral Science Foundation(No.2022M723689)。
文摘The dynamic recrystallization(DRX)behavior and texture formation mechanism in an AZ31 magnesium alloy wheel hub during the spinning process were investigated.Analysis using optical microscopy,electron backscatter diffraction,transmission electron microscopy,and finite element simulation revealed that continuous dynamic recrystallization(CDRX)and grain boundary bulging occurred simultaneously throughout the spinning process,leading to an increased proportion of DRXed grain areas.The newly formed DRXed grains largely retained the orientations of their deformed parent grains.The spinning process had two stages:initially,deformation was driven by basalslip as the roller contacted the alloy and descended to its lowest point.In the later stage,pyramidal<c+a>slips became predominant as additional force was applied along the spinning direction(SD),forming a final texture with the c-axis tilting±15°towards the SD.This texture development led to discernible anisotropy in tensile properties along the SD and the tangential direction(TD).
基金Supported by National Natural Science Foundation of China(Grant No.52175401)Hunan Provincial Postgraduate Scientific Research Innovation Project(Grant No.QL20230244)+1 种基金Enterprise Innovation and Development Joint Program of National Natural Science Foundation of China(Grant No.U20B2032)Hunan Provincial Science and Technology Innovation Program(Grant No.2022RC1050).
文摘Because the grinding temperature is high when grinding using conventional disordered grinding wheels,the grinding quality improvement is limited when using single abrasive ordered grinding wheels,and the wheel preparation process is complex and costly when using microstructured grinding wheels,abrasive groups ordered grinding wheels are widely investigated.However,there is a paucity of systematic analyses and comprehensive reviews focused on abrasive groups ordered grinding wheels.Therefore,this paper defines abrasive groups ordered grinding wheels and classifies them,based on their unique characteristics,into groups such as abrasive blocks ordered grinding wheel,fine grain structured grinding wheel,abrasive clusters ordered grinding wheel,and abrasive fibers ordered grinding wheel.We provide an overview of the latest advances in wheel structures,preparation methods,and abrasive selection for various types of abrasive groups ordered grinding wheels.Furthermore,we conduct a comparative analysis of the existing types,significant advantages,and challenges associated with the four types of abrasive groups ordered grinding wheels.Looking ahead,given the potential of abrasive groups ordered grinding wheels in reducing grinding force and temperature,we recommend further exploration of their application in combination with special processing techniques.This could pave the way for the development of machining processes that are more environmentally friendly,energy-efficient,and precise.
基金Supported by National Natural Science Foundation of China(Grant No.52475137)Sichuan Provincial Science and Technology Program(Grant No.2024YFHZ0280)Sichuan Provincial Nature and Science Foundation Innovation Research Group Project(Grant No.2023NSFSC1975).
文摘During the grinding train operation process,the grinding force between the grinding wheel and the rail is critical in ensuring the grinding quality and efficiency.The coupling vibration among the frame,the grinding wheels,and the wheelsets will seriously affect the stability of the grinding force.In this paper,the coupled mechanical model of the grinding wheel/rail is established based on the contact mechanics theory,which is embedded as a submodel into the dynamic model of the multi-rigid buggy.The interaction among the frame,the grinding wheels and the wheelsets is analysed by setting the convex irregularity on the rail.The grinding effect is evaluated in combination with the subway’s long wave corrugation grinding conditions.The results show that when the grinding buggy passes the convex irregularity,the vibration excited by the wheelset system has a significant impact on the dynamic behavior of the grinding wheels.The vibration of the grinding wheel is mainly transmitted between the grinding wheel and the frame,less affecting the wheelset.For the long wave corrugation of the subway,the grinding effect of the grinding wheel has a certain correlation with the phase angle of the wheelset through the corrugation.The research results provide an important reference for the setting of the grinding pattern.
基金supported by the Science Center Program of National Natural Science Foundation of China(62188101)the National Natural Science Foundation of China(61833009,61690212,51875119)+1 种基金the Heilongjiang Touyan Teamthe Guangdong Major Project of Basic and Applied Basic Research(2019B030302001)
文摘The momentum wheel assumes a dominant role as an inertial actuator for satellite attitude control systems.Due to the effects of structural aging and external interference,the momentum wheel may experience the gradual emergence of irreversible faults.These fault features will become apparent in the telemetry signal transmitted by the momentum wheel.This paper introduces ADTWformer,a lightweight model for long-term prediction of time series,to analyze the time evolution trend and multi-dimensional data coupling mechanism of satellite momentum wheel faults.Moreover,the incorporation of the approximate Markov blanket with the maximum information coefficient presents a novel methodology for performing correlation analysis,providing significant perspectives from a data-centric standpoint.Ultimately,the creation of an adaptive alarm mechanism allows for the successful attainment of the momentum wheel fault warning by detecting the changes in the health status curves.The analysis methodology outlined in this article has exhibited positive results in identifying instances of satellite momentum wheel failure in two scenarios,thereby showcasing considerable promise for large-scale applications.
基金Application of Behavior Change Wheel(BCW)Theory in Fall Prevention Management for Elderly Hospitalized Patients(Key Research and Development Program of Kunshan City,Jiangsu Province(KS2372))。
文摘Objective:To analyze the application effect of the Behavior Change Wheel(BCW)theory in fall prevention management for elderly inpatients.Methods:One hundred elderly inpatients admitted to Kunshan Fourth People’s Hospital from January 2019 to April 2024 were selected and divided into an experimental group(fall prevention management intervention based on BCW theory)and a control group(routine fall prevention management intervention)using random sampling,with 50 patients in each group.The differences in knowledge,attitude,and behavior levels of fall prevention,prevention efficacy,and the incidence of falls and fall-related injuries during hospitalization,6 months after discharge,and 1 year after discharge were compared between the two groups.Results:Compared with before the intervention,the scores of the fall prevention knowledge,attitude,and behavior scale(knowledge dimension,attitude dimension,behavior dimension,and total score)for elderly inpatients in both groups increased,and the improvement in the experimental group was greater than that in the control group(P<0.05).After the intervention,the revised fall efficacy scale score was higher in the experimental group compared to the control group(P<0.05).The incidence of falls during hospitalization,6 months after discharge,and 1 year after discharge,as well as the rate of fall-related injuries 6 months and 1 year after discharge,were lower in the experimental group than in the control group(P<0.05).There was no statistically significant difference in the rate of fall-related injuries during hospitalization between the two groups(P>0.05).Conclusion:The fall prevention management intervention based on BCW theory has good application value in elderly inpatients.It effectively improves patients’knowledge,attitudes,and behavior levels regarding fall prevention,significantly enhances their self-prevention efficacy,and demonstrates good results in reducing the incidence of falls during hospitalization and after discharge.
基金supported by the Natural Science Foundation Project of Fujian Province,China(Grant No.2023J011439 and No.2019J01859).
文摘With the rapid urbanization and exponential population growth in China,two-wheeled vehicles have become a popular mode of transportation,particularly for short-distance travel.However,due to a lack of safety awareness,traffic violations by two-wheeled vehicle riders have become a widespread concern,contributing to urban traffic risks.Currently,significant human and material resources are being allocated to monitor and intercept non-compliant riders to ensure safe driving behavior.To enhance the safety,efficiency,and cost-effectiveness of traffic monitoring,automated detection systems based on image processing algorithms can be employed to identify traffic violations from eye-level video footage.In this study,we propose a robust detection algorithm specifically designed for two-wheeled vehicles,which serves as a fundamental step toward intelligent traffic monitoring.Our approach integrates a novel convolutional and attention mechanism to improve detection accuracy and efficiency.Additionally,we introduce a semi-supervised training strategy that leverages a large number of unlabeled images to enhance the model’s learning capability by extracting valuable background information.This method enables the model to generalize effectively to diverse urban environments and varying lighting conditions.We evaluate our proposed algorithm on a custom-built dataset,and experimental results demonstrate its superior performance,achieving an average precision(AP)of 95%and a recall(R)of 90.6%.Furthermore,the model maintains a computational efficiency of only 25.7 GFLOPs while achieving a high processing speed of 249 FPS,making it highly suitable for deployment on edge devices.Compared to existing detection methods,our approach significantly enhances the accuracy and robustness of two-wheeled vehicle identification while ensuring real-time performance.
基金supported by the National Natural Science Foundation of China(No.52178436)the Shanghai Collaborative Innovation Research Center for Multi-network&Multi-modal Rail Transit,China.
文摘The wheel wear of light rail trains is difficult to predict due to poor information and small data samples.However,the amount of wear gradually increases with the running mileage.The grey future prediction model is supposed to deal with this problem effectively.In this study,we propose an improved non-equidistant grey model GM(1,1)with background values optimized by a genetic algorithm(GA).While the grey model is not good enough to track data series with features of randomness and nonlinearity,the residual error series of the GA-GM(1,1)model is corrected through a back propagation neural network(BPNN).To further improve the performance of the GA-GM(1,1)-BPNN model,a particle swarm optimization(PSO)algorithm is implemented to train the weight and bias in the neural network.The traditional non-equidistant GM(1,1)model and the proposed GA-GM(1,1),GA-GM(1,1)-BPNN,and GA-GM(1,1)-PSO-BPNN models were used to predict the wheel diameter and wheel flange wear of the Changchun light rail train and their validity and rationality were verified.Benefitting from the optimization effects of the GA,neural network,and PSO algorithm,the performance ranking of the four methods from highest to lowest was GA-GM(1,1)-PSO-BPNN>GA-GM(1,1)-BPNN>GA-GM(1,1)>GM(1,1)in both the fitting and prediction zones.The GA-GM(1,1)-PSO-BPNN model performed best,with the lowest fitting and forecasting maximum relative error,mean absolute error,mean absolute percentage error,and mean squared error of all four models.Therefore,it is the most effective and stable model in field application of light rail train wheel wear prediction.
基金Project supported by the National Natural Science Foundation of China(Nos.W2433004 and 12472015)the Research Fund of the State Key Laboratory of Mechanics and Control of Mechanical Structures(Nanjing University of Aeronautics and Astronautics)(No.MCMS-I-0122K01).
文摘This paper proposes an attitude control strategy for a flexible satellite equipped with an orthogonal cluster of three-dimensional(3D)magnetically suspended wheels(MSWs).The mathematical model for the satellite incorporating flexible appendages and an orthogonal cluster of magnetically suspended reaction wheel actuators is initially developed.After that,an adaptive attitude controller is designed with a switching surface of variable structure,an adaptive law for estimating inertia matrix uncertainty,and a fuzzy disturbance observer for estimating disturbance torques.Additionally,a Moore-Penrose-based steering law is proposed to derive the tilt angle commands of the orthogonal configuration of the 3D MSW to follow the designed control signal.Finally,numerical simulations are presented to validate the effectiveness of the proposed control strategy.
基金Project supported by the National Natural Science Foundation of China （Nos. U 1434201, 51275427, and 51605394）, and the Scientific Research Foundation of State Key Laboratory of Traction Power （No. 2015TPL_T01 ）, China
文摘In this paper, we present a comprehensive model for the prediction of the evolution of high-speed train wheel profiles due to wear. The model consists of four modules： a multi-body model implemented with the commercial multi-body software SIMPACK to evaluate the dynamic response of the vehicle and track; a local contact model based on Hertzian theory and a novel method, named FaStrip （Sichani et al., 2016）, to calculate the normal and tangential forces, respectively; a wear model proposed by the University of Sheffield （known as the USFD wear function） to estimate the amount of material removed and its distribution along the wheel profile; and a smoothing and updating strategy. A simulation of the wheel wear of the high-speed train CRH3 in service on the Wuhan-Guangzhou railway line was performed. A virtual railway line based on the statistics of the line was used to represent the entire real track. The model was validated using the wheel wear data of the CRH3 operating on the Wuhan- Guangzhou line, monitored by the authors＇ research group. The results of the predictions and measurements were in good agreement.
基金supported by the National Key Technology R&D Program of China (No. 2009BAG12A02)the National Basic Research Program of China (No. 2011CB711106)+2 种基金the Program for Innovative Research Team in University (No. IRT1178)the Program for New Century Excellent Talents in University (No. NCET-10-0664)the National Key Technology R&D Program (No. 2009BAG12A01)
文摘In order to improve the curving performance of the conventional wheelset in sharp curves and resolve the steering ability problem of the independently rotating wheel in large radius curves and tangent lines, a differential cou- pling wheelset （DCW） was developed in this work. The DCW was composed of two independently rotating wheels （IRWs） coupled by a clutch-type limited slip differential. The differential contains a static pre-stress clutch, which could lock both sides of IRWs of the DCW to ensure a good steering performance in curves with large radius and tangent track. In contrast, the clutch could unlock the two IRWs of the DCW in a sharp curve to endue it with the characteristic of an IRW, so that the vehicles can go through the tight curve smoothly. To study the dynamic performance of the DCW, a multi-body dynamic model of single bogie with DCWs was established. The self-centering capability, hunting stability, and self-steering performance on a curved track were analyzed and then compared with those of the conventional wheelset and IRW. Finally, the effect of coupling parameters of the DCW on the dynamic performance was investigated.
基金Project supported by the National Natural Science Foundation of China （Nos. 51425804, U 1334203, 51608459, and 51378439） and the China Postdoctoral Science Foundation （No. 2016M590898）
文摘The wheel-rail relationship in turnout is more complicated than that in ordinary track. Profile wear and machining errors of the wheelset cause deviations Of the rolling radius on different wheels. Therefore, wheelsets move to the direction of smaller diameter wheels in search of a new stable state and to change the condition before entering the turnout. Thc main aim of the present work is to examine the wheel-turnout rail dynamic interaction combined with the static contact behaviour. Calculations are performed on a high-speed vehicle CRH2 and the No. 12 turnout of the passenger dedicated line. The wheel-turnout contac! geometric relationship and normal contact behaviour under wheel diameter difference are assessed by the trace principle and finite element method. A high-speed vehicle-turnout coupling dynamic model is established based on SIMPACK software to analyse the wheel-rail dynamic interaction, riding comfort, and wear. Both the wheel diameter amplitudes and distribution patterns are accounted for. The simulation shows that wheel diameter difference can greatly disturb the positions＇ variation of wheel-rail contact points and affect the normal contact behaviour on switch rails by changing the load transition position. The effect of wheel diameter diffierence on wheel-turnout rail dynamic interaction can be divided into three according to its amplitude： when the wheel diameter difference is within 0-1.5 mm, the wheel flange comes into contact with the switch rail in advance, causing a rapidly increased lateral wheel-rail force; when it is within 1.5 2.5 mm, trains are subject to instability under equivalent in-phase wheel diameter difference; when it is larger than 2.5 mm, the continuous flange-switch rail contact helps strengthen the vehicle stability, but increases the wheel-rail wear. It is recommended to control the wheel diameter difference to within 2.5 mm but limit it to 2 mm if it is distributed in-phase.
