We present a formulation of the single-trajectory entropy using the trajectories ensemble. The single-trajectory entropy is affected by its surrounding trajectories via the distribution function. The single-trajectory...We present a formulation of the single-trajectory entropy using the trajectories ensemble. The single-trajectory entropy is affected by its surrounding trajectories via the distribution function. The single-trajectory entropies are studied in two typical potentials, i.e., harmonic potential and double-well potential, and in viscous environment by interacting trajectory method. The results of the trajectory methods are in agreement well with the numerical methods(Monte Carlo simulation and difference equation). The single-trajectory entropies increasing(decreasing) could be caused by absorption(emission) heat from(to) the thermal environment. Also, some interesting trajectories, which correspond to the rare evens in the processes, are demonstrated.展开更多
The growth trajectory of hailstones within clouds has remained elusive due to the inability to trace them directly,impeding the comprehension of their underlying growth mechanisms.This study investigated hailstone ver...The growth trajectory of hailstones within clouds has remained elusive due to the inability to trace them directly,impeding the comprehension of their underlying growth mechanisms.This study investigated hailstone vertical growth trajectories by detecting the stable isotope signatures(2H and 18O compositions)of different shells in 27 hailstones from 9hailstorms,which allowed us to capture the ambient temperature during hailstone growth.The vertical growth trajectories were obtained by comparing the isotopic compositions of water condensate in clouds,derived from the Adiabatic Model,with those measured in hailstones.Although hailstone growth was primarily observed in the–10°C to–30°C temperature layer,the embryo formation height and subsequent growth trajectories significantly varied among hailstones.Embryos formed over a wide range of temperatures(–8.7°C to–33.4°C);four originated at temperatures above–15°C and 16originated at temperatures below–20°C,suggesting ice nuclei composed of bioproteins and mineral dust,respectively.Among the 27 measured hailstones,3 exhibited minimal vertical movement,16 exhibited a monotonic rise or fall,and the remaining 8 exhibited alternating up-down trajectories;only one experienced“recycling”during up-down drifting.Trajectory analysis revealed that similar-sized hailstones from a single storm tended to form at similar heights,whereas those larger than 25 mm in diameter exhibited at least one period of upward growth.Vertical trajectories derived from isotopic analysis were corroborated by radar hydrometeor observations.展开更多
The environment of low-altitude urban airspace is complex and variable due to numerous obstacles,non-cooperative aircraft,and birds.Unmanned Aerial Vehicles(UAVs)leveraging environmental information to achieve three-d...The environment of low-altitude urban airspace is complex and variable due to numerous obstacles,non-cooperative aircraft,and birds.Unmanned Aerial Vehicles(UAVs)leveraging environmental information to achieve three-dimension collision-free trajectory planning is the prerequisite to ensure airspace security.However,the timely information of surrounding situation is difficult to acquire by UAVs,which further brings security risks.As a mature technology leveraged in traditional civil aviation,the Automatic Dependent Surveillance-Broadcast(ADS-B)realizes continuous surveillance of the information of aircraft.Consequently,we leverage ADS-B for surveillance and information broadcasting,and divide the aerial airspace into multiple sub-airspaces to improve flight safety in UAV trajectory planning.In detail,we propose the secure Sub-airSpaces Planning(SSP)algorithm and Particle Swarm Optimization Rapidly-exploring Random Trees(PSO-RRT)algorithm for the UAV trajectory planning in law-altitude airspace.The performance of the proposed algorithm is verified by simulations and the results show that SSP reduces both the maximum number of UAVs in the sub-airspace and the length of the trajectory,and PSO-RRT reduces the cost of UAV trajectory in the sub-airspace.展开更多
In this paper,we investigate a multi-UAV aided NOMA communication system,where multiple UAV-mounted aerial base stations are employed to serve ground users in the downlink NOMA communication,and each UAV serves its as...In this paper,we investigate a multi-UAV aided NOMA communication system,where multiple UAV-mounted aerial base stations are employed to serve ground users in the downlink NOMA communication,and each UAV serves its associated users on its own bandwidth.We aim at maximizing the overall common throughput in a finite time period.Such a problem is a typical mixed integer nonlinear problem,which involves both continuous-variable and combinatorial optimizations.To efficiently solve this problem,we propose a two-layer algorithm,which separately tackles continuous-variable and combinatorial optimization.Specifically,in the inner layer given one user association scheme,subproblems of bandwidth allocation,power allocation and trajectory design are solved based on alternating optimization.In the outer layer,a small number of candidate user association schemes are generated from an initial scheme and the best solution can be determined by comparing all the candidate schemes.In particular,a clustering algorithm based on K-means is applied to produce all candidate user association schemes,the successive convex optimization technique is adopted in the power allocation subproblem and a logistic function approximation approach is employed in the trajectory design subproblem.Simulation results show that the proposed NOMA scheme outperforms three baseline schemes in downlink common throughput,including one solution proposed in an existing literature.展开更多
Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally intractable.This paper proposes a Safe Flight Corridor constrained Sequent...Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally intractable.This paper proposes a Safe Flight Corridor constrained Sequential Convex Programming(SFC-SCP)to improve the computation efficiency and reliability of trajectory generation.SFC-SCP combines the front-end convex polyhedron SFC construction and back-end SCP-based trajectory optimization.A Sparse A^(*)Search(SAS)driven SFC construction method is designed to efficiently generate polyhedron SFC according to the geometric relation among obstacles and collision-free waypoints.Via transforming the nonconvex obstacle-avoidance constraints to linear inequality constraints,SFC can mitigate infeasibility of trajectory planning and reduce computation complexity.Then,SCP casts the nonlinear trajectory optimization subject to SFC into convex programming subproblems to decrease the problem complexity.In addition,a convex optimizer based on interior point method is customized,where the search direction is calculated via successive elimination to further improve efficiency.Simulation experiments on dense obstacle scenarios show that SFC-SCP can generate dynamically feasible safe trajectory rapidly.Comparative studies with state-of-the-art SCP-based methods demonstrate the efficiency and reliability merits of SFC-SCP.Besides,the customized convex optimizer outperforms off-the-shelf optimizers in terms of computation time.展开更多
Objective We aimed to investigate the patterns of fasting blood glucose(FBG)trajectories and analyze the relationship between various occupational hazard factors and FBG trajectories in male steelworkers.Methods The s...Objective We aimed to investigate the patterns of fasting blood glucose(FBG)trajectories and analyze the relationship between various occupational hazard factors and FBG trajectories in male steelworkers.Methods The study cohort included 3,728 workers who met the selection criteria for the Tanggang Occupational Cohort(TGOC)between 2017 and 2022.A group-based trajectory model was used to identify the FBG trajectories.Environmental risk scores(ERS)were constructed using regression coefficients from the occupational hazard model as weights.Univariate and multivariate logistic regression analyses were performed to explore the effects of occupational hazard factors using the ERS on FBG trajectories.Results FBG trajectories were categorized into three groups.An association was observed between high temperature,noise exposure,and FBG trajectory(P<0.05).Using the first quartile group of ERS1 as a reference,the fourth quartile group of ERS1 had an increased risk of medium and high FBG by 1.90and 2.21 times,respectively(odds ratio[OR]=1.90,95%confidence interval[CI]:1.17–3.10;OR=2.21,95%CI:1.09–4.45).Conclusion An association was observed between occupational hazards based on ERS and FBG trajectories.The risk of FBG trajectory levels increase with an increase in ERS.展开更多
Foreign-funded overseas industrial parks(OIPs)are crucial for attracting foreign investment and promoting globalization in developing countries.However,large-scale land acquisition for these parks generates conflicts ...Foreign-funded overseas industrial parks(OIPs)are crucial for attracting foreign investment and promoting globalization in developing countries.However,large-scale land acquisition for these parks generates conflicts between developers and local stakeholders,increasing development costs.A qualitative multicase study was conducted in this study to analyze the land transaction trajectories of China's OIPs.Four OIPs were selected to reveal the underlying mechanisms from the perspectives of institutional arrangements,governance mechanisms,and enterprise heterogeneity.The findings indicate that in host countries with insufficient institutional development,local governments are more inclined to directly engage in OIP land acquisition.High-level intergovernmental mechanisms facilitate land acquisition processes,although their efficacy depends largely on administrative power allocation across parks in host countries.The results also indicate that enterprise characteristics significantly influence land acquisition,where microscale private enterprises lacking political connections often employ low-cost,bottom-up strategies by leveraging international experience.In summary,policy-makers in developing countries should prioritize enhancing OIP governance to mitigate transaction costs,promote diversified land supply,and optimize land allocation.By depicting China's OIP land acquisition processes,this study deepens the academic understanding of OIP governance in developing countries and related international land transactions,offering practical OIP management insights for governments in both host and parent countries.展开更多
Aimed at the demand of contingency return at any time during the near-moon phase in the manned lunar landing missions,a fast calculation method for three-impulse contingency return trajectories is proposed.Firstly,a t...Aimed at the demand of contingency return at any time during the near-moon phase in the manned lunar landing missions,a fast calculation method for three-impulse contingency return trajectories is proposed.Firstly,a three-impulse contingency return trajectory scheme is presented by combining the Lambert transfer and maneuver at the special point.Secondly,a calculation model of three-impulse contingency return trajectories is established.Then,fast calculation methods are proposed by adopting the high-order Taylor expansion of differential algebra in the twobody trajectory dynamics model and perturbed trajectory dynamics model.Finally,the performance of the proposed methods is verified by numerical simulation.The results indicate that the fast calculation method of two-body trajectory has higher calculation efficiency compared to the semi-analytical calculation method under a certain accuracy condition.Due to its high efficiency,the characteristics of the three-impulse contingency return trajectories under different contingency scenarios are further analyzed expeditiously.These findings can be used for the design of contingency return trajectories in future manned lunar landing missions.展开更多
BACKGROUND Neck pain,a primary symptom of cervical spondylosis,affects patients'physical and mental health,reducing their quality of life.Pain and emotional state interact;however,their longitudinal interrelations...BACKGROUND Neck pain,a primary symptom of cervical spondylosis,affects patients'physical and mental health,reducing their quality of life.Pain and emotional state interact;however,their longitudinal interrelationship remains unclear.In this study,we applied a dual-trajectory model to assess how neck pain and emotional state evolve together over time and how clinical interventions,particularly acupuncture,influence these trajectories.AIM To investigate the longitudinal relationship between neck pain and emotional state in patients with cervical spondylosis.METHODS This prospective cohort study included 472 patients with cervical spondylosis from eight Chinese hospitals.Participants received acupuncture or medication and were followed up at baseline,and at 1,2,4,6,and 8 weeks.Neck pain and emotional distress were assessed using the Northwick Park Neck Pain Questionnaire(NPQ)and the affective subscale of the Short-Form McGill Pain Questionnaire(SF-MPQ),respectively.Group-based trajectory models and dual trajectory analysis were used to identify and correlate pain-emotion trajectories.Multivariate logistic regression identified predictors of group membership.RESULTS Three trajectory groups were identified for NPQ and SF-MPQ scores(low,medium,and high).Higher NPQ trajectory was associated with older age(OR=1.058,P<0.001)and was significantly reduced by acupuncture(OR=0.382,P<0.001).Similarly,acupuncture lowered the odds of high SF-MPQ trajectory membership(OR=0.336,P<0.001),while age increased it(OR=1.037,P<0.001).Dual-trajectory analysis revealed bidirectional associations:69.1%of patients with low NPQ had low SF-MPQ scores,and 42.6%of patients with high SF-MPQ also had high NPQ scores.Gender was a predictor for medium SF-MPQ trajectory(OR=1.629,P=0.094).Occupation and education levels differed significantly across the trajectory groups(P<0.05).CONCLUSION Over time,neck pain and emotional distress are closely associated in patients with cervical spondylosis.Acupuncture alleviates both outcomes significantly,while age is a risk factor.Integrated approaches to pain and emotional management are encouraged.展开更多
In this study,it is aimed to develop a generic model which calculates the trajectory of the ejection seat from the jet aircraft,by taking into account the parameters that will affect the seat movement such as the seat...In this study,it is aimed to develop a generic model which calculates the trajectory of the ejection seat from the jet aircraft,by taking into account the parameters that will affect the seat movement such as the seat’s launch speed,ejection direction,ejection angle,altitude of the aircraft,distance/height from the aircraft rudder and canopy,pilot and ejection seat weight.With the model algorithm proposed,the ejection seat trajectory model was developed on MATLAB.The ejection seat trajectory model is based on point mass trajectory mathematical model.In this study,an analytical study of the problem has been made for modeling the flight trajectory of the ejection seat after it has been ejected.Past studies were used as a basis for validation and simulation.By writing a generic MATLAB code,a user interface was developed and presented to the user as a module.This generic code that has been developed could be used for simulations by users in the future by revising it in accordance with their own job descriptions.展开更多
BACKGROUND Depression is a significant risk factor for diabetes,particularly type 2 diabetes.However,depressive symptoms differ from clinical depression.Previous research has not fully considered the relationship betw...BACKGROUND Depression is a significant risk factor for diabetes,particularly type 2 diabetes.However,depressive symptoms differ from clinical depression.Previous research has not fully considered the relationship between the trajectory of depressive symptoms and the risk of developing diabetes over time.AIM To investigate the association between depressive symptoms,their trajectories,and the risk of developing diabetes in two prospective cohort studies.METHODS In the first phase we analyzed the association between depressive symptoms and the risk of developing diabetes separately using the Health and Retirement Study(HRS).Depressive symptom trajectories were assessed by examining changes in depressive symptoms at baseline and again 8 years later.We then identified specific depressive symptom trajectories that increased the risk of diabetes in the second phase.Finally,we confirmed the association between depressive symptoms and their trajectories with diabetes risk using the English Longitudinal Study of Ageing(ELSA)as a validation study.Depressive symptom trajectories were categorized into five states based on changes in the modified 8-item Center for Epidemiological Studies-Depression scores:Persistently high;increasing;fluctuating;decreasing;and persistently low.Diabetes mellitus was defined as self-reported,physician-diagnosed diabetes.Cox proportional hazards models were used to assess hazard ratios(HR)and 95%confidence intervals(CI),adjusting for potential confounders.RESULTS In the first phase a total of 27658 participants were included(HRS:18633,ELSA:9025),among whom 6582 had depressive symptoms(HRS:4547,ELSA:2035),6407 had somatic depressive symptoms(HRS:4414,ELSA:1993),and 26415 had cognitive-affective depressive symptoms(HRS:17755,ELSA:8660).We found that overall depressive symptoms(HRS:HR=1.14,95%CI:1.07-1.22;ELSA:HR=1.18,95%CI:1.03-1.34)and somatic depressive symptoms(HRS:HR=1.14,95%CI:1.07-1.22;ELSA:HR=1.25,95%CI:1.10-1.42)increased the risk of diabetes,while cognitive depressive symptoms were not associated with diabetes risk.Over an 8-year follow-up we identified 19729 trajectories of overall,somatic,and cognitive-affective depressive symptoms(HRS:13918,ELSA:5811).In the second phase we found that persistently high(HRS:HR=1.22,95%CI:1.06-1.40,ELSA:HR=1.54,95%CI:1.16-2.05 in total and HRS:HR=1.24,95%CI:1.07-1.43,ELSA:HR=1.79,95%CI:1.36-2.35 in somatic)and fluctuating(HRS:HR=1.09,95%CI:1.01-1.17,ELSA:HR=1.33,95%CI:1.14-1.55 in total and HRS:HR=1.10,95%CI:1.02-1.18,ELSA:HR=1.31,95%CI:1.13-1.53 in somatic)trajectories of overall and somatic depressive symptoms increased the risk of diabetes,while increasing trajectories may also raise diabetes risk.However,decreasing trajectories were not associated with diabetes risk.Cognitive-affective depressive symptoms showed no association with diabetes risk regardless of trajectory changes.Sensitivity analyses confirmed the reliability of the findings.CONCLUSION Persistently high and fluctuating trajectories of overall and somatic depressive symptoms increased the risk of diabetes,while decreasing trajectories were not associated with diabetes risk.In contrast trajectories of cognitiveaffective depressive symptoms show no relationship with diabetes risk.Focusing on depressive symptom trajectories,particularly those of somatic depressive symptoms,represented a viable strategy for future diabetes prevention.展开更多
Multi-robot coordinated towing system is an under-constrained system.The dynamic response of the towing system can not be fully controlled since the rope can only provide a unidirectional constraint force to the suspe...Multi-robot coordinated towing system is an under-constrained system.The dynamic response of the towing system can not be fully controlled since the rope can only provide a unidirectional constraint force to the suspended object.Based on the kinematics of the multi-robot coordinated towing system with fixed-base,the Newton-Euler equations and Udwadia-Kalaba equations were used to establish the dynamics of the towing system.To obtain the motion trajectories with high stability and strong control,the motion trajectories of the towing system were optimized.During the towing,the transition from the relaxation state to the tension state of the rope was treated as a collision between the suspended object and the robot end.The trajectories of the towing system in terms of a single-variable and multiple-variable were solved,respectively.The simulation shows that the optimized trajectories are closer to reality and truly reflect the constraints of the ropes on the suspended object.The research results provide a basis for trajectory planning and control of the towing system.展开更多
Based on a new bilinear equation,we investigated some new dynamic behaviors of the(2+1)-dimensional shallow water wave model,such as hybridization behavior between different solitons,trajectory equations for lump coll...Based on a new bilinear equation,we investigated some new dynamic behaviors of the(2+1)-dimensional shallow water wave model,such as hybridization behavior between different solitons,trajectory equations for lump collisions,and evolution behavior of multi-breathers.Firstly,the N-soliton solution of Ito equation is studied,and some high-order breather waves can be obtained from the N-soliton solutions through paired-complexification of parameters.Secondly,the high-order lump solutions and the hybrid solutions are obtained by employing the long-wave limit method,and the motion velocity and trajectory equations of high-order lump waves are analyzed.Moreover,based on the trajectory equations of the higher-order lump solutions,we give and prove the trajectory theorem of 1-lump before and after interaction with nsoliton.Finally,we obtain some new lump solutions from the multi-solitons by constructing a new test function and using the parameter limit method.Meanwhile,some evolutionary behaviors of the obtained solutions are shown through a large number of three-dimensional graphs with different and appropriate parameters.展开更多
1. Background Driven by ongoing economic expansion and low-altitude aviation development, the global air transportation industry has experienced significant growth in recent decades, resulting in increasing airspace c...1. Background Driven by ongoing economic expansion and low-altitude aviation development, the global air transportation industry has experienced significant growth in recent decades, resulting in increasing airspace complexity, and considerable challenges for Air Traffic Control(ATC). As the fundamental technique of the ATC system, Flight Trajectory Prediction(FTP) forecasts future traffic dynamics to support critical applications(such as conflict detection), and also serves as a cornerstone for future Trajectory-based Operations(TBO).展开更多
This study sought to analyze the occupational habits of immigrant workers in the formal Brazilian labor market from a sociological perspective.It was understood that a study on occupation should observe professional a...This study sought to analyze the occupational habits of immigrant workers in the formal Brazilian labor market from a sociological perspective.It was understood that a study on occupation should observe professional and employment history,which may include an analysis over time of workers in the same profession or in periods of professional mobility.In order to understand occupational trajectories and related aspects,this study used data that were collected through semi-structured interviews and surveys with immigrant workers who were employed in the Brazilian formal labor market.The interviews and surveys revealed a strong polarization among the immigrant workers present in Brazil-while a small part holds highly skilled occupations,the majority participate at the base of the productivity hierarchy.展开更多
The hyper-redundant manipulator(HRM)can explore narrow and curved pipelines by leveraging its high flexibility and redundancy.However,planning collision-free motion trajectories for HRMs in confined environments remai...The hyper-redundant manipulator(HRM)can explore narrow and curved pipelines by leveraging its high flexibility and redundancy.However,planning collision-free motion trajectories for HRMs in confined environments remains a significant challenge.To address this issue,a pipeline inspection approach that combines nonlinear model predictive control(NMPC)with the snake-inspired crawling algorithm(SCA)is proposed.The approach consists of three processes:insertion,inspection,and exit.The insertion and exit processes utilize the SCA,inspired by snake motion,to significantly reduce path planning time.The inspection process employs NMPC to generate collision-free motion.The prototype HRM is developed,and inspection experiments are conducted in various complex pipeline scenarios to validate the effectiveness and feasibility of the proposed method.Experimental results demonstrate that the approach effectively minimizes the computational cost of path planning,offering a practical solution for HRM applications in pipeline inspection.展开更多
Background:Infected pancreatic necrosis(IPN)is a highly morbid local complication following necrotizing pancreatitis.Early enteral nutrition has been proven to be effective in preventing IPN.This study aimed to assess...Background:Infected pancreatic necrosis(IPN)is a highly morbid local complication following necrotizing pancreatitis.Early enteral nutrition has been proven to be effective in preventing IPN.This study aimed to assess the association between the trajectory of prealbumin(PAB)during the early phase of acute pancreatitis(AP)and the incidence of IPN and other clinical outcomes.Methods:This retrospective,dual-centered study screened patients with AP admitted to the Center of Acute Pancreatitis,Jinling Hospital and the Affiliated Hospital of Zunyi Medical University from January 2018 to December 2022.The PAB levels during the first week after admission were collected.The primary outcome was the incidence of IPN within 90 days after AP onset.Group-based trajectory modelling was performed to describe the trajectory of PAB levels over time.A Cox proportional hazard model was used to facilitate the interpretation of the time-varying hazard ratio(HR)between PAB and outcomes.Fine-Gray sub-distribution hazard model was adopted for sensitivity analysis.Results:A total of 373 patients were included,of whom 82(22.0%)were diagnosed with IPN within 90 days.The trajectory model assigned 232 patients to the low-level PAB(L-PAB)group and 141 to the high-level PAB(H-PAB)group.The incidence of 90-day IPN in the L-PAB group was significantly higher than that in the H-PAB group(26.7%vs.14.2%,P=0.005).The multivariate Cox regression model showed that a high PAB trajectory was associated with a lower incidence of IPN(HR=0.52,95%CI:0.30-0.89;P=0.017)after adjustment for potential confounders.In the sensitivity analysis,taking death as a com-peting risk,high PAB trajectory remained significantly associated with a lower incidence of IPN in the Fine-Gray model(HR=0.55,95%CI:0.33-0.92;P=0.022).Conclusions:A high PAB trajectory within the first week of AP was significantly associated with a lower incidence of IPN within 90 days after AP onset.Dynamic monitoring of PAB levels in the early phase of AP may play an important role in stratifying patients at high risk of developing IPN.展开更多
This paper presents some results of stress field reconstruction in the Nankai Trough subduction zone located within the area bounded by 136.3°–137°E and 33°–33.5°N where 12 scientific wells were ...This paper presents some results of stress field reconstruction in the Nankai Trough subduction zone located within the area bounded by 136.3°–137°E and 33°–33.5°N where 12 scientific wells were drilled during Nankai Trough Seismogenic Zone Experiment expeditions of the Integrated Ocean Drilling Program and International Ocean Discovery Program.We use the logging data to derive orientations of the maximum principal stress axis at different depths followed by the reconstruction of stress orientations in each individual well.From these data,we further derive average stress orientations along the wells and use these data to reconstruct the stress trajectory field taking into account the presence of Megasplay fault.The results are shown as the stress trajectories of the maximum principal horizontal stresses.They are generally consistent with data the World Stress Map Project data.展开更多
The automatic and rapid generation of excavation trajectories is the foundation for achieving an intelligent excavator.To obtain high-performance trajectories that enhance operational capacity while avoiding the numer...The automatic and rapid generation of excavation trajectories is the foundation for achieving an intelligent excavator.To obtain high-performance trajectories that enhance operational capacity while avoiding the numerous issues present in existing methods for generating effective excavation paths,this paper proposes a trajectory generation method for excavators based on imitation learning,using the mole as a bionic prototype.Given the high excavation efficiency of moles,this paper first analyzes the structural characteristics of the mole’s forelimbs,its digging principles,morphology,and trajectory patterns.Subsequently,a higher-order polynomial is employed to fit and optimize the mole’s excavation trajectory.Next,imitation learning is conducted on sample trajectories based on Dynamic Movement Primitives,followed by the introduction of an obstacle avoidance algorithm.Simulation experiments and comparisons demonstrate that the mole-inspired trajectory method used in this paper performs well and possesses the ability to generate obstacle avoidance trajectories,as well as the convenience of transferring across different machine models.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
基金supported by the National Natural Science Foundation of China (Grant No. 12234013)the Natural Science Foundation of Shandong Province (Grant No. ZR2021LLZ009)。
文摘We present a formulation of the single-trajectory entropy using the trajectories ensemble. The single-trajectory entropy is affected by its surrounding trajectories via the distribution function. The single-trajectory entropies are studied in two typical potentials, i.e., harmonic potential and double-well potential, and in viscous environment by interacting trajectory method. The results of the trajectory methods are in agreement well with the numerical methods(Monte Carlo simulation and difference equation). The single-trajectory entropies increasing(decreasing) could be caused by absorption(emission) heat from(to) the thermal environment. Also, some interesting trajectories, which correspond to the rare evens in the processes, are demonstrated.
基金supported by the National Natural Science Foundation of China(Grant No.42030607)the Beijing Municipal Science and Technology Commission(Grant No.Z251100004525005)the National Science Foundation/National Center for Atmospheric Research,and NASA(Grant No.80NSSC22M0129)。
文摘The growth trajectory of hailstones within clouds has remained elusive due to the inability to trace them directly,impeding the comprehension of their underlying growth mechanisms.This study investigated hailstone vertical growth trajectories by detecting the stable isotope signatures(2H and 18O compositions)of different shells in 27 hailstones from 9hailstorms,which allowed us to capture the ambient temperature during hailstone growth.The vertical growth trajectories were obtained by comparing the isotopic compositions of water condensate in clouds,derived from the Adiabatic Model,with those measured in hailstones.Although hailstone growth was primarily observed in the–10°C to–30°C temperature layer,the embryo formation height and subsequent growth trajectories significantly varied among hailstones.Embryos formed over a wide range of temperatures(–8.7°C to–33.4°C);four originated at temperatures above–15°C and 16originated at temperatures below–20°C,suggesting ice nuclei composed of bioproteins and mineral dust,respectively.Among the 27 measured hailstones,3 exhibited minimal vertical movement,16 exhibited a monotonic rise or fall,and the remaining 8 exhibited alternating up-down trajectories;only one experienced“recycling”during up-down drifting.Trajectory analysis revealed that similar-sized hailstones from a single storm tended to form at similar heights,whereas those larger than 25 mm in diameter exhibited at least one period of upward growth.Vertical trajectories derived from isotopic analysis were corroborated by radar hydrometeor observations.
基金supported by the National Key R&D Program of China(No.2022YFB3104502)the National Natural Science Foundation of China(No.62301251)+2 种基金the Natural Science Foundation of Jiangsu Province of China under Project(No.BK20220883)the open research fund of National Mobile Communications Research Laboratory,Southeast University,China(No.2024D04)the Young Elite Scientists Sponsorship Program by CAST(No.2023QNRC001).
文摘The environment of low-altitude urban airspace is complex and variable due to numerous obstacles,non-cooperative aircraft,and birds.Unmanned Aerial Vehicles(UAVs)leveraging environmental information to achieve three-dimension collision-free trajectory planning is the prerequisite to ensure airspace security.However,the timely information of surrounding situation is difficult to acquire by UAVs,which further brings security risks.As a mature technology leveraged in traditional civil aviation,the Automatic Dependent Surveillance-Broadcast(ADS-B)realizes continuous surveillance of the information of aircraft.Consequently,we leverage ADS-B for surveillance and information broadcasting,and divide the aerial airspace into multiple sub-airspaces to improve flight safety in UAV trajectory planning.In detail,we propose the secure Sub-airSpaces Planning(SSP)algorithm and Particle Swarm Optimization Rapidly-exploring Random Trees(PSO-RRT)algorithm for the UAV trajectory planning in law-altitude airspace.The performance of the proposed algorithm is verified by simulations and the results show that SSP reduces both the maximum number of UAVs in the sub-airspace and the length of the trajectory,and PSO-RRT reduces the cost of UAV trajectory in the sub-airspace.
基金supported by Beijing Natural Science Fund–Haidian Original Innovation Joint Fund(L232040 and L232045).
文摘In this paper,we investigate a multi-UAV aided NOMA communication system,where multiple UAV-mounted aerial base stations are employed to serve ground users in the downlink NOMA communication,and each UAV serves its associated users on its own bandwidth.We aim at maximizing the overall common throughput in a finite time period.Such a problem is a typical mixed integer nonlinear problem,which involves both continuous-variable and combinatorial optimizations.To efficiently solve this problem,we propose a two-layer algorithm,which separately tackles continuous-variable and combinatorial optimization.Specifically,in the inner layer given one user association scheme,subproblems of bandwidth allocation,power allocation and trajectory design are solved based on alternating optimization.In the outer layer,a small number of candidate user association schemes are generated from an initial scheme and the best solution can be determined by comparing all the candidate schemes.In particular,a clustering algorithm based on K-means is applied to produce all candidate user association schemes,the successive convex optimization technique is adopted in the power allocation subproblem and a logistic function approximation approach is employed in the trajectory design subproblem.Simulation results show that the proposed NOMA scheme outperforms three baseline schemes in downlink common throughput,including one solution proposed in an existing literature.
基金supported by the National Natural Science Foundation of China(No.62203256)。
文摘Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally intractable.This paper proposes a Safe Flight Corridor constrained Sequential Convex Programming(SFC-SCP)to improve the computation efficiency and reliability of trajectory generation.SFC-SCP combines the front-end convex polyhedron SFC construction and back-end SCP-based trajectory optimization.A Sparse A^(*)Search(SAS)driven SFC construction method is designed to efficiently generate polyhedron SFC according to the geometric relation among obstacles and collision-free waypoints.Via transforming the nonconvex obstacle-avoidance constraints to linear inequality constraints,SFC can mitigate infeasibility of trajectory planning and reduce computation complexity.Then,SCP casts the nonlinear trajectory optimization subject to SFC into convex programming subproblems to decrease the problem complexity.In addition,a convex optimizer based on interior point method is customized,where the search direction is calculated via successive elimination to further improve efficiency.Simulation experiments on dense obstacle scenarios show that SFC-SCP can generate dynamically feasible safe trajectory rapidly.Comparative studies with state-of-the-art SCP-based methods demonstrate the efficiency and reliability merits of SFC-SCP.Besides,the customized convex optimizer outperforms off-the-shelf optimizers in terms of computation time.
基金supported by the Key Research and Development Program of the Ministry of Science and Technology of China(grant number:2016YF0900605)the Key Research and Development Program of Hebei Province(grant number:192777129D)+1 种基金the Joint Fund for Iron and Steel of the Natural Science Foundation of Hebei Province(grant number:H2016209058)the National Natural Science Foundation for Regional Joint Fund of China(grant number:U22A20364)。
文摘Objective We aimed to investigate the patterns of fasting blood glucose(FBG)trajectories and analyze the relationship between various occupational hazard factors and FBG trajectories in male steelworkers.Methods The study cohort included 3,728 workers who met the selection criteria for the Tanggang Occupational Cohort(TGOC)between 2017 and 2022.A group-based trajectory model was used to identify the FBG trajectories.Environmental risk scores(ERS)were constructed using regression coefficients from the occupational hazard model as weights.Univariate and multivariate logistic regression analyses were performed to explore the effects of occupational hazard factors using the ERS on FBG trajectories.Results FBG trajectories were categorized into three groups.An association was observed between high temperature,noise exposure,and FBG trajectory(P<0.05).Using the first quartile group of ERS1 as a reference,the fourth quartile group of ERS1 had an increased risk of medium and high FBG by 1.90and 2.21 times,respectively(odds ratio[OR]=1.90,95%confidence interval[CI]:1.17–3.10;OR=2.21,95%CI:1.09–4.45).Conclusion An association was observed between occupational hazards based on ERS and FBG trajectories.The risk of FBG trajectory levels increase with an increase in ERS.
基金Philosophy and Social Science Planning Projects in Yunnan Province,No.QN202428China Postdoctoral Science Foundation,No.2024M752918。
文摘Foreign-funded overseas industrial parks(OIPs)are crucial for attracting foreign investment and promoting globalization in developing countries.However,large-scale land acquisition for these parks generates conflicts between developers and local stakeholders,increasing development costs.A qualitative multicase study was conducted in this study to analyze the land transaction trajectories of China's OIPs.Four OIPs were selected to reveal the underlying mechanisms from the perspectives of institutional arrangements,governance mechanisms,and enterprise heterogeneity.The findings indicate that in host countries with insufficient institutional development,local governments are more inclined to directly engage in OIP land acquisition.High-level intergovernmental mechanisms facilitate land acquisition processes,although their efficacy depends largely on administrative power allocation across parks in host countries.The results also indicate that enterprise characteristics significantly influence land acquisition,where microscale private enterprises lacking political connections often employ low-cost,bottom-up strategies by leveraging international experience.In summary,policy-makers in developing countries should prioritize enhancing OIP governance to mitigate transaction costs,promote diversified land supply,and optimize land allocation.By depicting China's OIP land acquisition processes,this study deepens the academic understanding of OIP governance in developing countries and related international land transactions,offering practical OIP management insights for governments in both host and parent countries.
基金co-supported by the National Natural Science Foundation of China(No.12072365)the Technology Innovation Team of Manned Space Engineering,China。
文摘Aimed at the demand of contingency return at any time during the near-moon phase in the manned lunar landing missions,a fast calculation method for three-impulse contingency return trajectories is proposed.Firstly,a three-impulse contingency return trajectory scheme is presented by combining the Lambert transfer and maneuver at the special point.Secondly,a calculation model of three-impulse contingency return trajectories is established.Then,fast calculation methods are proposed by adopting the high-order Taylor expansion of differential algebra in the twobody trajectory dynamics model and perturbed trajectory dynamics model.Finally,the performance of the proposed methods is verified by numerical simulation.The results indicate that the fast calculation method of two-body trajectory has higher calculation efficiency compared to the semi-analytical calculation method under a certain accuracy condition.Due to its high efficiency,the characteristics of the three-impulse contingency return trajectories under different contingency scenarios are further analyzed expeditiously.These findings can be used for the design of contingency return trajectories in future manned lunar landing missions.
基金Supported by 2022 Chinese Medicine Scientific Research Project of Hebei Administration of Traditional Chinese Medicine,No.20221572025 Annual Scientific Research Project of Higher Education Institutions in Hebei Province,No.QN2025654.
文摘BACKGROUND Neck pain,a primary symptom of cervical spondylosis,affects patients'physical and mental health,reducing their quality of life.Pain and emotional state interact;however,their longitudinal interrelationship remains unclear.In this study,we applied a dual-trajectory model to assess how neck pain and emotional state evolve together over time and how clinical interventions,particularly acupuncture,influence these trajectories.AIM To investigate the longitudinal relationship between neck pain and emotional state in patients with cervical spondylosis.METHODS This prospective cohort study included 472 patients with cervical spondylosis from eight Chinese hospitals.Participants received acupuncture or medication and were followed up at baseline,and at 1,2,4,6,and 8 weeks.Neck pain and emotional distress were assessed using the Northwick Park Neck Pain Questionnaire(NPQ)and the affective subscale of the Short-Form McGill Pain Questionnaire(SF-MPQ),respectively.Group-based trajectory models and dual trajectory analysis were used to identify and correlate pain-emotion trajectories.Multivariate logistic regression identified predictors of group membership.RESULTS Three trajectory groups were identified for NPQ and SF-MPQ scores(low,medium,and high).Higher NPQ trajectory was associated with older age(OR=1.058,P<0.001)and was significantly reduced by acupuncture(OR=0.382,P<0.001).Similarly,acupuncture lowered the odds of high SF-MPQ trajectory membership(OR=0.336,P<0.001),while age increased it(OR=1.037,P<0.001).Dual-trajectory analysis revealed bidirectional associations:69.1%of patients with low NPQ had low SF-MPQ scores,and 42.6%of patients with high SF-MPQ also had high NPQ scores.Gender was a predictor for medium SF-MPQ trajectory(OR=1.629,P=0.094).Occupation and education levels differed significantly across the trajectory groups(P<0.05).CONCLUSION Over time,neck pain and emotional distress are closely associated in patients with cervical spondylosis.Acupuncture alleviates both outcomes significantly,while age is a risk factor.Integrated approaches to pain and emotional management are encouraged.
文摘In this study,it is aimed to develop a generic model which calculates the trajectory of the ejection seat from the jet aircraft,by taking into account the parameters that will affect the seat movement such as the seat’s launch speed,ejection direction,ejection angle,altitude of the aircraft,distance/height from the aircraft rudder and canopy,pilot and ejection seat weight.With the model algorithm proposed,the ejection seat trajectory model was developed on MATLAB.The ejection seat trajectory model is based on point mass trajectory mathematical model.In this study,an analytical study of the problem has been made for modeling the flight trajectory of the ejection seat after it has been ejected.Past studies were used as a basis for validation and simulation.By writing a generic MATLAB code,a user interface was developed and presented to the user as a module.This generic code that has been developed could be used for simulations by users in the future by revising it in accordance with their own job descriptions.
文摘BACKGROUND Depression is a significant risk factor for diabetes,particularly type 2 diabetes.However,depressive symptoms differ from clinical depression.Previous research has not fully considered the relationship between the trajectory of depressive symptoms and the risk of developing diabetes over time.AIM To investigate the association between depressive symptoms,their trajectories,and the risk of developing diabetes in two prospective cohort studies.METHODS In the first phase we analyzed the association between depressive symptoms and the risk of developing diabetes separately using the Health and Retirement Study(HRS).Depressive symptom trajectories were assessed by examining changes in depressive symptoms at baseline and again 8 years later.We then identified specific depressive symptom trajectories that increased the risk of diabetes in the second phase.Finally,we confirmed the association between depressive symptoms and their trajectories with diabetes risk using the English Longitudinal Study of Ageing(ELSA)as a validation study.Depressive symptom trajectories were categorized into five states based on changes in the modified 8-item Center for Epidemiological Studies-Depression scores:Persistently high;increasing;fluctuating;decreasing;and persistently low.Diabetes mellitus was defined as self-reported,physician-diagnosed diabetes.Cox proportional hazards models were used to assess hazard ratios(HR)and 95%confidence intervals(CI),adjusting for potential confounders.RESULTS In the first phase a total of 27658 participants were included(HRS:18633,ELSA:9025),among whom 6582 had depressive symptoms(HRS:4547,ELSA:2035),6407 had somatic depressive symptoms(HRS:4414,ELSA:1993),and 26415 had cognitive-affective depressive symptoms(HRS:17755,ELSA:8660).We found that overall depressive symptoms(HRS:HR=1.14,95%CI:1.07-1.22;ELSA:HR=1.18,95%CI:1.03-1.34)and somatic depressive symptoms(HRS:HR=1.14,95%CI:1.07-1.22;ELSA:HR=1.25,95%CI:1.10-1.42)increased the risk of diabetes,while cognitive depressive symptoms were not associated with diabetes risk.Over an 8-year follow-up we identified 19729 trajectories of overall,somatic,and cognitive-affective depressive symptoms(HRS:13918,ELSA:5811).In the second phase we found that persistently high(HRS:HR=1.22,95%CI:1.06-1.40,ELSA:HR=1.54,95%CI:1.16-2.05 in total and HRS:HR=1.24,95%CI:1.07-1.43,ELSA:HR=1.79,95%CI:1.36-2.35 in somatic)and fluctuating(HRS:HR=1.09,95%CI:1.01-1.17,ELSA:HR=1.33,95%CI:1.14-1.55 in total and HRS:HR=1.10,95%CI:1.02-1.18,ELSA:HR=1.31,95%CI:1.13-1.53 in somatic)trajectories of overall and somatic depressive symptoms increased the risk of diabetes,while increasing trajectories may also raise diabetes risk.However,decreasing trajectories were not associated with diabetes risk.Cognitive-affective depressive symptoms showed no association with diabetes risk regardless of trajectory changes.Sensitivity analyses confirmed the reliability of the findings.CONCLUSION Persistently high and fluctuating trajectories of overall and somatic depressive symptoms increased the risk of diabetes,while decreasing trajectories were not associated with diabetes risk.In contrast trajectories of cognitiveaffective depressive symptoms show no relationship with diabetes risk.Focusing on depressive symptom trajectories,particularly those of somatic depressive symptoms,represented a viable strategy for future diabetes prevention.
基金the National Natural Science Foundation of China(No.51965032)the Natural Science Foundation of Gansu Province of China(No.22JR5RA319)+1 种基金the Science and Technology Foundation of Gansu Province of China(No.21YF5WA060)the Excellent Doctoral Student Foundation of Gansu Province of China(No.23JRRA842)。
文摘Multi-robot coordinated towing system is an under-constrained system.The dynamic response of the towing system can not be fully controlled since the rope can only provide a unidirectional constraint force to the suspended object.Based on the kinematics of the multi-robot coordinated towing system with fixed-base,the Newton-Euler equations and Udwadia-Kalaba equations were used to establish the dynamics of the towing system.To obtain the motion trajectories with high stability and strong control,the motion trajectories of the towing system were optimized.During the towing,the transition from the relaxation state to the tension state of the rope was treated as a collision between the suspended object and the robot end.The trajectories of the towing system in terms of a single-variable and multiple-variable were solved,respectively.The simulation shows that the optimized trajectories are closer to reality and truly reflect the constraints of the ropes on the suspended object.The research results provide a basis for trajectory planning and control of the towing system.
基金Project supported by the National Natural Science Foundation of China(Grant No.12461047)the Scientific Research Project of the Hunan Education Department(Grant No.24B0478).
文摘Based on a new bilinear equation,we investigated some new dynamic behaviors of the(2+1)-dimensional shallow water wave model,such as hybridization behavior between different solitons,trajectory equations for lump collisions,and evolution behavior of multi-breathers.Firstly,the N-soliton solution of Ito equation is studied,and some high-order breather waves can be obtained from the N-soliton solutions through paired-complexification of parameters.Secondly,the high-order lump solutions and the hybrid solutions are obtained by employing the long-wave limit method,and the motion velocity and trajectory equations of high-order lump waves are analyzed.Moreover,based on the trajectory equations of the higher-order lump solutions,we give and prove the trajectory theorem of 1-lump before and after interaction with nsoliton.Finally,we obtain some new lump solutions from the multi-solitons by constructing a new test function and using the parameter limit method.Meanwhile,some evolutionary behaviors of the obtained solutions are shown through a large number of three-dimensional graphs with different and appropriate parameters.
文摘1. Background Driven by ongoing economic expansion and low-altitude aviation development, the global air transportation industry has experienced significant growth in recent decades, resulting in increasing airspace complexity, and considerable challenges for Air Traffic Control(ATC). As the fundamental technique of the ATC system, Flight Trajectory Prediction(FTP) forecasts future traffic dynamics to support critical applications(such as conflict detection), and also serves as a cornerstone for future Trajectory-based Operations(TBO).
文摘This study sought to analyze the occupational habits of immigrant workers in the formal Brazilian labor market from a sociological perspective.It was understood that a study on occupation should observe professional and employment history,which may include an analysis over time of workers in the same profession or in periods of professional mobility.In order to understand occupational trajectories and related aspects,this study used data that were collected through semi-structured interviews and surveys with immigrant workers who were employed in the Brazilian formal labor market.The interviews and surveys revealed a strong polarization among the immigrant workers present in Brazil-while a small part holds highly skilled occupations,the majority participate at the base of the productivity hierarchy.
文摘The hyper-redundant manipulator(HRM)can explore narrow and curved pipelines by leveraging its high flexibility and redundancy.However,planning collision-free motion trajectories for HRMs in confined environments remains a significant challenge.To address this issue,a pipeline inspection approach that combines nonlinear model predictive control(NMPC)with the snake-inspired crawling algorithm(SCA)is proposed.The approach consists of three processes:insertion,inspection,and exit.The insertion and exit processes utilize the SCA,inspired by snake motion,to significantly reduce path planning time.The inspection process employs NMPC to generate collision-free motion.The prototype HRM is developed,and inspection experiments are conducted in various complex pipeline scenarios to validate the effectiveness and feasibility of the proposed method.Experimental results demonstrate that the approach effectively minimizes the computational cost of path planning,offering a practical solution for HRM applications in pipeline inspection.
基金supported by a grant from the National Natural Science Foundation of China(82470680).
文摘Background:Infected pancreatic necrosis(IPN)is a highly morbid local complication following necrotizing pancreatitis.Early enteral nutrition has been proven to be effective in preventing IPN.This study aimed to assess the association between the trajectory of prealbumin(PAB)during the early phase of acute pancreatitis(AP)and the incidence of IPN and other clinical outcomes.Methods:This retrospective,dual-centered study screened patients with AP admitted to the Center of Acute Pancreatitis,Jinling Hospital and the Affiliated Hospital of Zunyi Medical University from January 2018 to December 2022.The PAB levels during the first week after admission were collected.The primary outcome was the incidence of IPN within 90 days after AP onset.Group-based trajectory modelling was performed to describe the trajectory of PAB levels over time.A Cox proportional hazard model was used to facilitate the interpretation of the time-varying hazard ratio(HR)between PAB and outcomes.Fine-Gray sub-distribution hazard model was adopted for sensitivity analysis.Results:A total of 373 patients were included,of whom 82(22.0%)were diagnosed with IPN within 90 days.The trajectory model assigned 232 patients to the low-level PAB(L-PAB)group and 141 to the high-level PAB(H-PAB)group.The incidence of 90-day IPN in the L-PAB group was significantly higher than that in the H-PAB group(26.7%vs.14.2%,P=0.005).The multivariate Cox regression model showed that a high PAB trajectory was associated with a lower incidence of IPN(HR=0.52,95%CI:0.30-0.89;P=0.017)after adjustment for potential confounders.In the sensitivity analysis,taking death as a com-peting risk,high PAB trajectory remained significantly associated with a lower incidence of IPN in the Fine-Gray model(HR=0.55,95%CI:0.33-0.92;P=0.022).Conclusions:A high PAB trajectory within the first week of AP was significantly associated with a lower incidence of IPN within 90 days after AP onset.Dynamic monitoring of PAB levels in the early phase of AP may play an important role in stratifying patients at high risk of developing IPN.
文摘This paper presents some results of stress field reconstruction in the Nankai Trough subduction zone located within the area bounded by 136.3°–137°E and 33°–33.5°N where 12 scientific wells were drilled during Nankai Trough Seismogenic Zone Experiment expeditions of the Integrated Ocean Drilling Program and International Ocean Discovery Program.We use the logging data to derive orientations of the maximum principal stress axis at different depths followed by the reconstruction of stress orientations in each individual well.From these data,we further derive average stress orientations along the wells and use these data to reconstruct the stress trajectory field taking into account the presence of Megasplay fault.The results are shown as the stress trajectories of the maximum principal horizontal stresses.They are generally consistent with data the World Stress Map Project data.
基金supported by the National Science Foundation of China(Grant No.52375246,No.52372428,No.52105100)Guangxi Science and Technology Program(Grant No.2023AB09014)Jilin Province Science and Technology Development Program,(Grant No.20230201094GX,No.20230201069GX).
文摘The automatic and rapid generation of excavation trajectories is the foundation for achieving an intelligent excavator.To obtain high-performance trajectories that enhance operational capacity while avoiding the numerous issues present in existing methods for generating effective excavation paths,this paper proposes a trajectory generation method for excavators based on imitation learning,using the mole as a bionic prototype.Given the high excavation efficiency of moles,this paper first analyzes the structural characteristics of the mole’s forelimbs,its digging principles,morphology,and trajectory patterns.Subsequently,a higher-order polynomial is employed to fit and optimize the mole’s excavation trajectory.Next,imitation learning is conducted on sample trajectories based on Dynamic Movement Primitives,followed by the introduction of an obstacle avoidance algorithm.Simulation experiments and comparisons demonstrate that the mole-inspired trajectory method used in this paper performs well and possesses the ability to generate obstacle avoidance trajectories,as well as the convenience of transferring across different machine models.
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.
