A CFD-based Numerical Virtual Flight(NVF)simulator is presented,which integrates an unsteady flow solver on moving hybrid grids,a Rigid-Body Dynamics(RBD)solver and a module of the Flight Control System(FCS).A techni...A CFD-based Numerical Virtual Flight(NVF)simulator is presented,which integrates an unsteady flow solver on moving hybrid grids,a Rigid-Body Dynamics(RBD)solver and a module of the Flight Control System(FCS).A technique of dynamic hybrid grids is developed to control the active control surfaces with body morphing,with a technique of parallel unstructured dynamic overlapping grids generating proper moving grids over the deflecting control surfaces(e.g.the afterbody rudders of a missile).For the flow/kinematic coupled problems,the 6 Degree-Of-Freedom(DOF)equations are solved by an explicit or implicit method coupled with the URANS CFD solver.The module of the control law is explicitly coupled into the NVF simulator and then improved by the simulation of the pitching maneuver process of a maneuverable missile model.A nonlinear dynamic inversion method is then implemented to design the control law for the pitching process of the maneuverable missile model.Simulations and analysis of the pitching maneuver process are carried out by the NVF simulator to improve the flight control law.Higher control response performance is obtained by adjusting the gain factors and adding an integrator into the control loop.展开更多
Mobility,environmental adaptability,and functionality are essential attributes of robots,but these become challenging for small-scale on-water robots,also referred to as S-aquabots.Herein,we propose a programmable Mar...Mobility,environmental adaptability,and functionality are essential attributes of robots,but these become challenging for small-scale on-water robots,also referred to as S-aquabots.Herein,we propose a programmable Marangoni motor(PM-motor)to propel centimeter-scale S-aquabots with high maneuverability and adaptability.Lightweight,compact,flexible hybrid electronics are used to precisely release ethanol to achieve controllable propulsion,smart sensing,and wireless communication functions.The PM-motor utilizes the surface tension gradient generated by the ethanol,which is released from leaf-inspired veins and improves fuel efficiency by 3.5 times when compared with traditional Marangoni effect-propelled robots.As a result,the device’s endurance is up to~226 s for a navigation distance of~5 m with just 1.2 mL ethanol.Benefiting from the leaf-like shape and negligible noise production,the S-aquabots can also blend well with their surroundings.Autonomous response capability is demonstrated by guiding an S-aquabot with laser spots to complete a butterfly-shaped trajectory.Equipped with a mini-camera or digital sensors,untethered S-aquabots deployed on an outdoor pool can capture real-time videos or monitor long-term environmental conditions.This work is beneficial for inspiring insightful design strategies to develop S-aquabots with high practical potential.展开更多
BACKGROUND Repeated application of the Pringle maneuver is a key obstacle to safe minimally invasive repeat liver resection(MISRLR).However,limited technical guidance is available.AIM To study the utility of newly dev...BACKGROUND Repeated application of the Pringle maneuver is a key obstacle to safe minimally invasive repeat liver resection(MISRLR).However,limited technical guidance is available.AIM To study the utility of newly developed Pringle taping method guided by liver surface in MISRLR.METHODS We retrospectively reviewed 72 cases of MISRLR performed by a single surgeon at two centers from August 2015 to July 2024.Beginning in October 2019,a liver surface-guided encirclement of hepatoduodenal ligament(LSEH)was used for repeat Pringle taping.Perioperative outcomes including Pringle taping success,operative time,blood loss,conversion rate,morbidity,and mortality were assessed.RESULTS Laparoscopic and robotic approaches were used in 63 patients and 9 patients,respectively.The median operative time,blood loss,and hospital stay were 331.5 minutes,70 mL,and 8 days,respectively.Open conversion occurred in two cases(2.8%)due to severe adhesions and right renal vein injury.Clavien-Dindo grade≥III complications occurred in 5.6%of cases with no mortality.Anti-adhesion barriers were used in 54 patients(75.0%).LSEH was attempted in 57 cases,improving Pringle taping success from 33.0%to 91.4%(P<0.001).LSEH succeeded in all patients with prior open liver resection(n=11).Among 6 patients in whom LSEH failed,3 patients(50.0%)had undergone a third liver resection,and 1 patient had a history of distal gastrectomy with choledochoduodenostomy.CONCLUSION The newly developed LSEH technique for Pringle taping in MISRLR was feasible,enhancing safety and reproducibility even in patients with a history of open liver resection.展开更多
This paper presents the design of an asymmetrically variable wingtip anhedral angles morphing aircraft,inspired by biomimetic mechanisms,to enhance lateral maneuver capability.Firstly,we establish a lateral dynamic mo...This paper presents the design of an asymmetrically variable wingtip anhedral angles morphing aircraft,inspired by biomimetic mechanisms,to enhance lateral maneuver capability.Firstly,we establish a lateral dynamic model considering additional forces and moments resulting during the morphing process,and convert it into a Multiple Input Multiple Output(MIMO)virtual control system by importing virtual inputs.Secondly,a classical dynamics inversion controller is designed for the outer-loop system.A new Global Fast Terminal Incremental Sliding Mode Controller(NDO-GFTISMC)is proposed for the inner-loop system,in which an adaptive law is implemented to weaken control surface chattering,and a Nonlinear Disturbance Observer(NDO)is integrated to compensate for unknown disturbances.The whole control system is proven semiglobally uniformly ultimately bounded based on the multi-Lyapunov function method.Furthermore,we consider tracking errors and self-characteristics of actuators,a quadratic programmingbased dynamic control allocation law is designed,which allocates virtual control inputs to the asymmetrically deformed wingtip and rudder.Actuator dynamic models are incorporated to ensure physical realizability of designed allocation law.Finally,comparative experimental results validate the effectiveness of the designed control system and control allocation law.The NDO-GFTISMC features faster convergence,stronger robustness,and 81.25%and 75.0%reduction in maximum state tracking error under uncertainty compared to the Incremental Nonlinear Dynamic Inversion Controller based on NDO(NDO-INDI)and Incremental Sliding Mode Controller based on NDO(NDO-ISMC),respectively.The design of the morphing aircraft significantly enhances lateral maneuver capability,maintaining a substantial control margin during lateral maneuvering,reducing the burden of the rudder surface,and effectively solving the actuator saturation problem of traditional aircraft during lateral maneuvering.展开更多
The problem of collision avoidance for non-cooperative targets has received significant attention from researchers in recent years.Non-cooperative targets exhibit uncertain states and unpredictable behaviors,making co...The problem of collision avoidance for non-cooperative targets has received significant attention from researchers in recent years.Non-cooperative targets exhibit uncertain states and unpredictable behaviors,making collision avoidance significantly more challenging than that for space debris.Much existing research focuses on the continuous thrust model,whereas the impulsive maneuver model is more appropriate for long-duration and long-distance avoidance missions.Additionally,it is important to minimize the impact on the original mission while avoiding noncooperative targets.On the other hand,the existing avoidance algorithms are computationally complex and time-consuming especially with the limited computing capability of the on-board computer,posing challenges for practical engineering applications.To conquer these difficulties,this paper makes the following key contributions:(A)a turn-based(sequential decision-making)limited-area impulsive collision avoidance model considering the time delay of precision orbit determination is established for the first time;(B)a novel Selection Probability Learning Adaptive Search-depth Search Tree(SPL-ASST)algorithm is proposed for non-cooperative target avoidance,which improves the decision-making efficiency by introducing an adaptive-search-depth mechanism and a neural network into the traditional Monte Carlo Tree Search(MCTS).Numerical simulations confirm the effectiveness and efficiency of the proposed method.展开更多
The paper presents a two-layer,disturbance-resistant,and fault-tolerant affine formation maneuver control scheme that accomplishes the surrounding of a dynamic target with multiple underactuated Quadrotor Unmanned Aer...The paper presents a two-layer,disturbance-resistant,and fault-tolerant affine formation maneuver control scheme that accomplishes the surrounding of a dynamic target with multiple underactuated Quadrotor Unmanned Aerial Vehicles(QUAVs).This scheme mainly consists of predefinedtime estimators and fixed-time tracking controllers,with a hybrid Laplacian matrix describing the communication among these QUAVs.At the first layer,we devise predefined time estimators for leading and following QUAVs,enabling accurate estimation of desired information.In the second layer,we initially devise a fixed-time hybrid observer to estimate unknown disturbances and actuator faults.Fixedtime translational tracking controllers are then proposed,and the intermediary control input from these controllers is used to extract the desired attitude and angular velocities for the fixed-time rotational tracking controllers.We employ an exact tracking differentiator to handle variables that are challenging to differentiate directly.The paper includes a demonstration of the control system stability through mathematical proof,as well as the presentation of simulation results and comparative simulations.展开更多
Muscle Shortening Maneuver(MSM)is a rehabilitation technique successfully applied to several pathological conditions.The concept is to passively elongate and shorten the target muscle group of the affected limb.As a r...Muscle Shortening Maneuver(MSM)is a rehabilitation technique successfully applied to several pathological conditions.The concept is to passively elongate and shorten the target muscle group of the affected limb.As a result,the functionality(muscle strength and range of motion)of that limb is improved.The existing system induces these oscillations manually or without any feedback control,which can compromise the effectiveness and standardization of MSM.In this paper,we present a mechatronic system that can precisely deliver motion oscillations to the upper limb for a controllable execution of MSM.First,we collected the parameters(frequency and amplitude of the oscillations)from a system where a motor was heuristically used by a well-experienced therapist to induce the oscillations(without any feedback control).Based on these specifications,we chose the motor and rebuilt the experimental setup,implementing a sliding mode control with a sliding perturbation observer.With our system,the operator can choose a given frequency and amplitude of the oscillations within the range we experimentally observed.We tested our system with ten participants of different anthropometry.We found that our system can accurately reproduce oscillations in the frequency range 0.8 to 1.2 Hz and amplitude range 2 to 6 cm,with a maximum percentage normalized root mean square error around 7%.展开更多
1) Introduction: Ventilation disorders of the middle ear play a major role in everyday clinical ENT-practice and sometimes represent a major therapeutic challenge. In addition to the conventional therapy of tympanosto...1) Introduction: Ventilation disorders of the middle ear play a major role in everyday clinical ENT-practice and sometimes represent a major therapeutic challenge. In addition to the conventional therapy of tympanostomy tube insertion, tuboplasty (TP) offers a less invasive option for treating this problem. The study should examine whether TP can be performed in a rural setting. 2) Material and methods: This is a prospective, monocentric study of patients scheduled for TP because of tubal ventilation disorder (TVD) in a rural region of Germany. The diagnosis was established after a thorough clinical examination and by assessing the possibility of performing the Valsalva maneuver, the tympanogram type, recording the middle ear pressure and air-bone gap. The subjective impairment caused by the TVD was evaluated using the EDTQ-7 questionnaire pre- and approximately 3 months postoperatively. 3) Results: Sixty-two patients with 92 TP were included with a mean age of 44.1 years. The EDTQ-7 score decreased highly significantly from 3.6 to 1.7 (p < 0.0001) without correlating with parameters such as age, sex, BMI, allergies or smoking. Middle ear pressure fell in average by −87 daPa, resulting in an improvement of the tympanogram type. The preoperative air-bone gap of 10.2 dB also was reduced significantly in most patients to 8.0 dB after the procedure. No notable complications occurred beside a sore throat due to the use of a laryngeal mask for ventilation during anesthesia in two cases. 4) Conclusion: In our experience, TP represents a less invasive and, in many cases, successful alternative to the established tympanostomy tube insertion with the advantage of an intact eardrum. It can also be offered and successfully performed in a rural setting.展开更多
The concept of the spacecraft Reachable Domain(RD)has garnered significant scholarly attention due to its crucial role in space situational awareness and on-orbit service applications.While the existing research has l...The concept of the spacecraft Reachable Domain(RD)has garnered significant scholarly attention due to its crucial role in space situational awareness and on-orbit service applications.While the existing research has largely focused on single-impulse RD analysis,the challenge of Multi-Impulse RD(MIRD)remains a key area of interest.This study introduces a methodology for the precise calculation of spacecraft MIRD.The reachability constraints specific to MIRD are first formulated through coordinate transformations.Two restricted maneuvering strategies are examined.The derivation of two extremum conditions allows for determining the accessible orientation range and the nodes encompassing the MIRD.Subsequently,four nonlinear programming models are developed to address two types of MIRD by skillfully relaxing constraints using scale factors.Numerical results validate the robustness and effectiveness of the proposed approach,showing substantial agreement with Monte Carlo simulations and confirming its applicability to spacecraft on various elliptical orbits.展开更多
1 The grandfather was choking on a mouthful of food,unable to breathe and unable to cough.The grandson,recalling the important lesson learned during the 8-13 Project organized by the Italian Red Cross⁃Poggi⁃Sermide Co...1 The grandfather was choking on a mouthful of food,unable to breathe and unable to cough.The grandson,recalling the important lesson learned during the 8-13 Project organized by the Italian Red Cross⁃Poggi⁃Sermide Committee,suggested performing the Heimlich manoeuvre(海姆立克急救法)on the elderly man.展开更多
Aiming at the missile avoidance problem of the unmanned aerial vehicle(UAV)in complex obstacle environments,this work proposes a collision-avoidance method based on receding horizon optimization.The proposed method ge...Aiming at the missile avoidance problem of the unmanned aerial vehicle(UAV)in complex obstacle environments,this work proposes a collision-avoidance method based on receding horizon optimization.The proposed method generated a specific trajectory for the UAV to effectively induce the proportional navigation missile to successfully intercept the obstacle,thereby accomplishing the evasive maneuver.The evasive maneuver was divided into two distinct stages,namely the collision-inducing phase and the fast departure phase.The obstacle potential field-based target selection algorithm was employed to identify the most appropriate target obstacle,while the induced trajectory was determined through a combination of receding horizon optimization and the hp-adaptive pseudo-spectral method.Simulation experiments were carried out under three different types of obstacle environments and one multiobstacle environment,and the simulation results show that the method proposed in this paper greatly improves the success rate of UAV evasive maneuvers,proving the effectiveness of this method.展开更多
In order to enhance the penetration performance of hypersonic gliding vehicle,a chaotification method of gliding midcourse based on flight dynamics is proposed.Firstly,a chaotic series⁃based angle of attack(AOA)contro...In order to enhance the penetration performance of hypersonic gliding vehicle,a chaotification method of gliding midcourse based on flight dynamics is proposed.Firstly,a chaotic series⁃based angle of attack(AOA)control algorithm and an AOA switching control algorithm considering flight altitude are proposed in this study based on a simple chaotic system with considerations of AOA constraints and process constraints.Secondly,the Lyapunov exponent Algorithm Of Continuous system is applied to verify the chaotic characteristic of flight trajectories.Thirdly,a stability region analysis method is proposed based on a conservative dynamics,which can be applied to the stability region analysis of general complex dynamics.Finally,the simulations show that both control algorithms can realize the chaotification of trajectories,and the flight trajectories obtained by the AOA switching control algorithm are feasible.展开更多
This paper investigates impulsive orbital attack-defense(AD)games under multiple constraints and victory conditions,involving three spacecraft:attacker,target,and defender.In the AD scenario,the attacker aims to breac...This paper investigates impulsive orbital attack-defense(AD)games under multiple constraints and victory conditions,involving three spacecraft:attacker,target,and defender.In the AD scenario,the attacker aims to breach the defender's interception to rendezvous with the target,while the defender seeks to protect the target by blocking or actively pursuing the attacker.Four different maneuvering constraints and five potential game outcomes are incorporated to more accurately model AD game problems and increase complexity,thereby reducing the effectiveness of traditional methods such as differential games and game-tree searches.To address these challenges,this study proposes a multiagent deep reinforcement learning solution with variable reward functions.Two attack strategies,Direct attack(DA)and Bypass attack(BA),are developed for the attacker,each focusing on different mission priorities.Similarly,two defense strategies,Direct interdiction(DI)and Collinear interdiction(CI),are designed for the defender,each optimizing specific defensive actions through tailored reward functions.Each reward function incorporates both process rewards(e.g.,distance and angle)and outcome rewards,derived from physical principles and validated via geometric analysis.Extensive simulations of four strategy confrontations demonstrate average defensive success rates of 75%for DI vs.DA,40%for DI vs.BA,80%for CI vs.DA,and 70%for CI vs.BA.Results indicate that CI outperforms DI for defenders,while BA outperforms DA for attackers.Moreover,defenders achieve their objectives more effectively under identical maneuvering capabilities.Trajectory evolution analyses further illustrate the effectiveness of the proposed variable reward function-driven strategies.These strategies and analyses offer valuable guidance for practical orbital defense scenarios and lay a foundation for future multi-agent game research.展开更多
This study proposes an automatic control system for Autonomous Underwater Vehicle(AUV)docking,utilizing a digital twin(DT)environment based on the HoloOcean platform,which integrates six-degree-of-freedom(6-DOF)motion...This study proposes an automatic control system for Autonomous Underwater Vehicle(AUV)docking,utilizing a digital twin(DT)environment based on the HoloOcean platform,which integrates six-degree-of-freedom(6-DOF)motion equations and hydrodynamic coefficients to create a realistic simulation.Although conventional model-based and visual servoing approaches often struggle in dynamic underwater environments due to limited adaptability and extensive parameter tuning requirements,deep reinforcement learning(DRL)offers a promising alternative.In the positioning stage,the Twin Delayed Deep Deterministic Policy Gradient(TD3)algorithm is employed for synchronized depth and heading control,which offers stable training,reduced overestimation bias,and superior handling of continuous control compared to other DRL methods.During the searching stage,zig-zag heading motion combined with a state-of-the-art object detection algorithm facilitates docking station localization.For the docking stage,this study proposes an innovative Image-based DDPG(I-DDPG),enhanced and trained in a Unity-MATLAB simulation environment,to achieve visual target tracking.Furthermore,integrating a DT environment enables efficient and safe policy training,reduces dependence on costly real-world tests,and improves sim-to-real transfer performance.Both simulation and real-world experiments were conducted,demonstrating the effectiveness of the system in improving AUV control strategies and supporting the transition from simulation to real-world operations in underwater environments.The results highlight the scalability and robustness of the proposed system,as evidenced by the TD3 controller achieving 25%less oscillation than the adaptive fuzzy controller when reaching the target depth,thereby demonstrating superior stability,accuracy,and potential for broader and more complex autonomous underwater tasks.展开更多
An eigenaxis maneuver strategy with global robustness is studied for large angle attitude maneuver of rigid spacecraft. A sliding mode attitude control algorithm with an exponential time-varying sliding surface is des...An eigenaxis maneuver strategy with global robustness is studied for large angle attitude maneuver of rigid spacecraft. A sliding mode attitude control algorithm with an exponential time-varying sliding surface is designed, which guarantees the sliding mode occurrence at the beginning and eliminates the reaching phase of time-invariant sliding mode control. The proposed control law is global robust against matched external disturbances and system uncertainties, and ensures the eigenaxis rotation in the presence of disturbances and parametric uncertainties. The stability of the control law and the existence of global siding mode are proved by Lyapunov method. Furthermore, the system states can be fully predicted by the analytical solution of state equations, which indicates that the attitude error does not exhibit any overshoots and the system has a good dynamic response. A control torque command regulator is introduced to ensure the eigenaxis rotation under the actuator saturation. Finally, a numerical simulation is employed to illustrate the advantages of the proposed control law.展开更多
This article addresses the design of the trajectory transferring from Earth to Halo orbit, and proposes a timing closed-loop strategy of correction maneuver during the transfer in the frame of circular restricted thre...This article addresses the design of the trajectory transferring from Earth to Halo orbit, and proposes a timing closed-loop strategy of correction maneuver during the transfer in the frame of circular restricted three body problem （CR3BP）. The relation between the Floquet multipliers and the magnitudes of Halo orbit is established, so that the suitable magnitude for the aerospace mission is chosen in terms of the stability of Halo orbit. The stable manifold is investigated from the Poincar6 mapping defined which is different from the previous researches, and six types of single-impulse transfer trajectories are attained from the geometry of the invariant manifolds. Based on one of the trajectories of indirect transfer which are ignored in the most of literatures, the stochastic control theory for imperfect information of the discrete linear stochastic system is applied to design the trajectory correction maneuver. The statistical dispersion analysis is performed by Monte-Carlo simulation,展开更多
The aim is to establish an automatic system to analyze the maneuver performance of fish. A high speed camera （1 000 frame/s） is employed to record fast-start maneuver. Three steps are taken to analyze the kinematics...The aim is to establish an automatic system to analyze the maneuver performance of fish. A high speed camera （1 000 frame/s） is employed to record fast-start maneuver. Three steps are taken to analyze the kinematics： first, the midline in the first image is partitioned into equal interval lengths and the coordinates of all inter segmental points are saved. Secondly, these points coordinates are searched in the next frame with the digital image correlation （DIC） method, then these points are fitted with a spline curve function. Repeat this step until all the midlines are figured out frame by frame. Finally, according to the variety of midlines, the kinematics of the fast-start is calculated. Using this system to test carp C-start, the duration is divided into two stages： stage 1 is defined as the formation of the C shape and stage 2 as the return flip of the tail followed with forward motion. By tracing the middle line, the kinematic parameters of turning rate, centre of mass （CM） turning rate, CM turning radius, etc. are obtained.展开更多
The effects of active control on the vehicle roll were studied. Based on the theory that distributing the greater roll stiffness to the rear axle can improve tracking trajectory capacity and increase maneuver stabilit...The effects of active control on the vehicle roll were studied. Based on the theory that distributing the greater roll stiffness to the rear axle can improve tracking trajectory capacity and increase maneuver stability, an eight degrees of freedom vehicle model was established and feedforward feedback control strategy was devised to control distribution of lateral load transfer on the front axle and the rear one. Simulation results showed that the proposed control strategy can improve comfort, maneuver stability and safety effectively.展开更多
The robust controller design problem for switched polytopic systems under asynchronous switching is addressed.These systems exist in many aviation applications,such as dynamical systems involving rapid variations.A sw...The robust controller design problem for switched polytopic systems under asynchronous switching is addressed.These systems exist in many aviation applications,such as dynamical systems involving rapid variations.A switched polytopic system is established to describe the highly maneuverable technology vehicle within the full flight envelope and a robust dynamic output feedback control method is designed for the switched polytopic system.Combining the Lyapunov-like function method and the average dwell time method,a sufficient condition is derived for the switched polytopic system with asynchronous switching and data dropout to be globally,uniformly and asymptotically stable in terms of linear matrix inequality.The robust dynamic output feedback controller is then applied to the highly maneuverable technology vehicle to illustrate the effectiveness of the proposed approach.The simulation results show that the angle of attack tracking performance is acceptable over the time history and the control surface responses are all satisfying along the full flight trajectory.展开更多
2017-06-24,6时许,四川省茂县叠溪镇新磨村发生山体高位滑坡,造成农舍和人员被埋。灾情紧急,根据西部战区联指命令和西宁联勤保障中心指示,成都军区总医院第一时间派出两个梯队（共47人）的应急医疗救援队空陆并进赶赴灾区,提供应急医...2017-06-24,6时许,四川省茂县叠溪镇新磨村发生山体高位滑坡,造成农舍和人员被埋。灾情紧急,根据西部战区联指命令和西宁联勤保障中心指示,成都军区总医院第一时间派出两个梯队（共47人）的应急医疗救援队空陆并进赶赴灾区,提供应急医疗救治服务。此次救援,从医院接到上级预先号令,至第1梯队出发赴机场共用时1 h 14 min,至第2梯队摩托化出发共用时2 h 54 min,实现了应急医疗队快速出动的目的。展开更多
基金supported partially by National Key Research and Development Program (No. 2016YFB0200701)National Natural Science Foundation of China (Nos. 11532016 and 11672324)
文摘A CFD-based Numerical Virtual Flight(NVF)simulator is presented,which integrates an unsteady flow solver on moving hybrid grids,a Rigid-Body Dynamics(RBD)solver and a module of the Flight Control System(FCS).A technique of dynamic hybrid grids is developed to control the active control surfaces with body morphing,with a technique of parallel unstructured dynamic overlapping grids generating proper moving grids over the deflecting control surfaces(e.g.the afterbody rudders of a missile).For the flow/kinematic coupled problems,the 6 Degree-Of-Freedom(DOF)equations are solved by an explicit or implicit method coupled with the URANS CFD solver.The module of the control law is explicitly coupled into the NVF simulator and then improved by the simulation of the pitching maneuver process of a maneuverable missile model.A nonlinear dynamic inversion method is then implemented to design the control law for the pitching process of the maneuverable missile model.Simulations and analysis of the pitching maneuver process are carried out by the NVF simulator to improve the flight control law.Higher control response performance is obtained by adjusting the gain factors and adding an integrator into the control loop.
基金supported by the Science and Technology Development Fund of Macao SAR(File No.0117/2024/AMJ)the National Natural Science Foundation of China(No.51925503,52188102)+2 种基金the University of Macao(MYRG-GRG2023-00041-FST-UMDF,MYRG-GRG2024-00121-FST,MYRG-CRG2024-00014-FST-ICI)the Xplorer Prize(2020-1036)the Comprehensive Experiment Center for Advanced Manufacturing and Equipment Technology,HUST,Wuhan,China.
文摘Mobility,environmental adaptability,and functionality are essential attributes of robots,but these become challenging for small-scale on-water robots,also referred to as S-aquabots.Herein,we propose a programmable Marangoni motor(PM-motor)to propel centimeter-scale S-aquabots with high maneuverability and adaptability.Lightweight,compact,flexible hybrid electronics are used to precisely release ethanol to achieve controllable propulsion,smart sensing,and wireless communication functions.The PM-motor utilizes the surface tension gradient generated by the ethanol,which is released from leaf-inspired veins and improves fuel efficiency by 3.5 times when compared with traditional Marangoni effect-propelled robots.As a result,the device’s endurance is up to~226 s for a navigation distance of~5 m with just 1.2 mL ethanol.Benefiting from the leaf-like shape and negligible noise production,the S-aquabots can also blend well with their surroundings.Autonomous response capability is demonstrated by guiding an S-aquabot with laser spots to complete a butterfly-shaped trajectory.Equipped with a mini-camera or digital sensors,untethered S-aquabots deployed on an outdoor pool can capture real-time videos or monitor long-term environmental conditions.This work is beneficial for inspiring insightful design strategies to develop S-aquabots with high practical potential.
文摘BACKGROUND Repeated application of the Pringle maneuver is a key obstacle to safe minimally invasive repeat liver resection(MISRLR).However,limited technical guidance is available.AIM To study the utility of newly developed Pringle taping method guided by liver surface in MISRLR.METHODS We retrospectively reviewed 72 cases of MISRLR performed by a single surgeon at two centers from August 2015 to July 2024.Beginning in October 2019,a liver surface-guided encirclement of hepatoduodenal ligament(LSEH)was used for repeat Pringle taping.Perioperative outcomes including Pringle taping success,operative time,blood loss,conversion rate,morbidity,and mortality were assessed.RESULTS Laparoscopic and robotic approaches were used in 63 patients and 9 patients,respectively.The median operative time,blood loss,and hospital stay were 331.5 minutes,70 mL,and 8 days,respectively.Open conversion occurred in two cases(2.8%)due to severe adhesions and right renal vein injury.Clavien-Dindo grade≥III complications occurred in 5.6%of cases with no mortality.Anti-adhesion barriers were used in 54 patients(75.0%).LSEH was attempted in 57 cases,improving Pringle taping success from 33.0%to 91.4%(P<0.001).LSEH succeeded in all patients with prior open liver resection(n=11).Among 6 patients in whom LSEH failed,3 patients(50.0%)had undergone a third liver resection,and 1 patient had a history of distal gastrectomy with choledochoduodenostomy.CONCLUSION The newly developed LSEH technique for Pringle taping in MISRLR was feasible,enhancing safety and reproducibility even in patients with a history of open liver resection.
基金supported by the National Natural Science Foundation of China(Nos.62103052 and No.52175214)。
文摘This paper presents the design of an asymmetrically variable wingtip anhedral angles morphing aircraft,inspired by biomimetic mechanisms,to enhance lateral maneuver capability.Firstly,we establish a lateral dynamic model considering additional forces and moments resulting during the morphing process,and convert it into a Multiple Input Multiple Output(MIMO)virtual control system by importing virtual inputs.Secondly,a classical dynamics inversion controller is designed for the outer-loop system.A new Global Fast Terminal Incremental Sliding Mode Controller(NDO-GFTISMC)is proposed for the inner-loop system,in which an adaptive law is implemented to weaken control surface chattering,and a Nonlinear Disturbance Observer(NDO)is integrated to compensate for unknown disturbances.The whole control system is proven semiglobally uniformly ultimately bounded based on the multi-Lyapunov function method.Furthermore,we consider tracking errors and self-characteristics of actuators,a quadratic programmingbased dynamic control allocation law is designed,which allocates virtual control inputs to the asymmetrically deformed wingtip and rudder.Actuator dynamic models are incorporated to ensure physical realizability of designed allocation law.Finally,comparative experimental results validate the effectiveness of the designed control system and control allocation law.The NDO-GFTISMC features faster convergence,stronger robustness,and 81.25%and 75.0%reduction in maximum state tracking error under uncertainty compared to the Incremental Nonlinear Dynamic Inversion Controller based on NDO(NDO-INDI)and Incremental Sliding Mode Controller based on NDO(NDO-ISMC),respectively.The design of the morphing aircraft significantly enhances lateral maneuver capability,maintaining a substantial control margin during lateral maneuvering,reducing the burden of the rudder surface,and effectively solving the actuator saturation problem of traditional aircraft during lateral maneuvering.
基金co-supported by the Foundation of Shanghai Astronautics Science and Technology Innovation,China(No.SAST2022-114)the National Natural Science Foundation of China(No.62303378),the National Natural Science Foundation of China(Nos.124B2031,12202281)the Foundation of China National Key Laboratory of Science and Technology on Test Physics&Numerical Mathematics,China(No.08-YY-2023-R11)。
文摘The problem of collision avoidance for non-cooperative targets has received significant attention from researchers in recent years.Non-cooperative targets exhibit uncertain states and unpredictable behaviors,making collision avoidance significantly more challenging than that for space debris.Much existing research focuses on the continuous thrust model,whereas the impulsive maneuver model is more appropriate for long-duration and long-distance avoidance missions.Additionally,it is important to minimize the impact on the original mission while avoiding noncooperative targets.On the other hand,the existing avoidance algorithms are computationally complex and time-consuming especially with the limited computing capability of the on-board computer,posing challenges for practical engineering applications.To conquer these difficulties,this paper makes the following key contributions:(A)a turn-based(sequential decision-making)limited-area impulsive collision avoidance model considering the time delay of precision orbit determination is established for the first time;(B)a novel Selection Probability Learning Adaptive Search-depth Search Tree(SPL-ASST)algorithm is proposed for non-cooperative target avoidance,which improves the decision-making efficiency by introducing an adaptive-search-depth mechanism and a neural network into the traditional Monte Carlo Tree Search(MCTS).Numerical simulations confirm the effectiveness and efficiency of the proposed method.
基金supported by Natural Science Basic Research Plan in Shaanxi Province of China(No.2023-JC-QN-0733)Guangdong Basic and Applied Basic Research Foundation,China(No.2022A1515110753)+2 种基金China Postdoctoral Science Foundation(No.2022M722583)China Industry-UniversityResearch Innovation Foundation(No.2022IT188)National Key Laboratory of Air-based Information Perception and Fusion and the Aeronautic Science Foundation of China(No.20220001068001)。
文摘The paper presents a two-layer,disturbance-resistant,and fault-tolerant affine formation maneuver control scheme that accomplishes the surrounding of a dynamic target with multiple underactuated Quadrotor Unmanned Aerial Vehicles(QUAVs).This scheme mainly consists of predefinedtime estimators and fixed-time tracking controllers,with a hybrid Laplacian matrix describing the communication among these QUAVs.At the first layer,we devise predefined time estimators for leading and following QUAVs,enabling accurate estimation of desired information.In the second layer,we initially devise a fixed-time hybrid observer to estimate unknown disturbances and actuator faults.Fixedtime translational tracking controllers are then proposed,and the intermediary control input from these controllers is used to extract the desired attitude and angular velocities for the fixed-time rotational tracking controllers.We employ an exact tracking differentiator to handle variables that are challenging to differentiate directly.The paper includes a demonstration of the control system stability through mathematical proof,as well as the presentation of simulation results and comparative simulations.
基金supported by the European Union by the Next Generation EU Project ECS00000017‘Ecosistema dell’Innovazione’Tuscany Health Ecosystem(THE,PNRR,Spoke 9:Robotics and Automation for Health)by the Italian Ministry of Education and Research(MUR)in the framework of the FoReLab project(Departments of Excellence).
文摘Muscle Shortening Maneuver(MSM)is a rehabilitation technique successfully applied to several pathological conditions.The concept is to passively elongate and shorten the target muscle group of the affected limb.As a result,the functionality(muscle strength and range of motion)of that limb is improved.The existing system induces these oscillations manually or without any feedback control,which can compromise the effectiveness and standardization of MSM.In this paper,we present a mechatronic system that can precisely deliver motion oscillations to the upper limb for a controllable execution of MSM.First,we collected the parameters(frequency and amplitude of the oscillations)from a system where a motor was heuristically used by a well-experienced therapist to induce the oscillations(without any feedback control).Based on these specifications,we chose the motor and rebuilt the experimental setup,implementing a sliding mode control with a sliding perturbation observer.With our system,the operator can choose a given frequency and amplitude of the oscillations within the range we experimentally observed.We tested our system with ten participants of different anthropometry.We found that our system can accurately reproduce oscillations in the frequency range 0.8 to 1.2 Hz and amplitude range 2 to 6 cm,with a maximum percentage normalized root mean square error around 7%.
文摘1) Introduction: Ventilation disorders of the middle ear play a major role in everyday clinical ENT-practice and sometimes represent a major therapeutic challenge. In addition to the conventional therapy of tympanostomy tube insertion, tuboplasty (TP) offers a less invasive option for treating this problem. The study should examine whether TP can be performed in a rural setting. 2) Material and methods: This is a prospective, monocentric study of patients scheduled for TP because of tubal ventilation disorder (TVD) in a rural region of Germany. The diagnosis was established after a thorough clinical examination and by assessing the possibility of performing the Valsalva maneuver, the tympanogram type, recording the middle ear pressure and air-bone gap. The subjective impairment caused by the TVD was evaluated using the EDTQ-7 questionnaire pre- and approximately 3 months postoperatively. 3) Results: Sixty-two patients with 92 TP were included with a mean age of 44.1 years. The EDTQ-7 score decreased highly significantly from 3.6 to 1.7 (p < 0.0001) without correlating with parameters such as age, sex, BMI, allergies or smoking. Middle ear pressure fell in average by −87 daPa, resulting in an improvement of the tympanogram type. The preoperative air-bone gap of 10.2 dB also was reduced significantly in most patients to 8.0 dB after the procedure. No notable complications occurred beside a sore throat due to the use of a laryngeal mask for ventilation during anesthesia in two cases. 4) Conclusion: In our experience, TP represents a less invasive and, in many cases, successful alternative to the established tympanostomy tube insertion with the advantage of an intact eardrum. It can also be offered and successfully performed in a rural setting.
基金supported by the National Natural Science Foundation of China(Nos.12372052,12125207)the Young Elite Scientists Sponsorship Program,China(No.2021JCJQ-QT-047)+1 种基金the Natural Science Foundation of Hunan Province,China(No.2023JJ20047)the Technology Innovation Team of Manned Space Engineering,China。
文摘The concept of the spacecraft Reachable Domain(RD)has garnered significant scholarly attention due to its crucial role in space situational awareness and on-orbit service applications.While the existing research has largely focused on single-impulse RD analysis,the challenge of Multi-Impulse RD(MIRD)remains a key area of interest.This study introduces a methodology for the precise calculation of spacecraft MIRD.The reachability constraints specific to MIRD are first formulated through coordinate transformations.Two restricted maneuvering strategies are examined.The derivation of two extremum conditions allows for determining the accessible orientation range and the nodes encompassing the MIRD.Subsequently,four nonlinear programming models are developed to address two types of MIRD by skillfully relaxing constraints using scale factors.Numerical results validate the robustness and effectiveness of the proposed approach,showing substantial agreement with Monte Carlo simulations and confirming its applicability to spacecraft on various elliptical orbits.
文摘1 The grandfather was choking on a mouthful of food,unable to breathe and unable to cough.The grandson,recalling the important lesson learned during the 8-13 Project organized by the Italian Red Cross⁃Poggi⁃Sermide Committee,suggested performing the Heimlich manoeuvre(海姆立克急救法)on the elderly man.
基金Natural Science Foundation of Heilongjiang Province of China(Grant No.YQ2022F012)the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2023010)to provide fund for conducting experiments.
文摘Aiming at the missile avoidance problem of the unmanned aerial vehicle(UAV)in complex obstacle environments,this work proposes a collision-avoidance method based on receding horizon optimization.The proposed method generated a specific trajectory for the UAV to effectively induce the proportional navigation missile to successfully intercept the obstacle,thereby accomplishing the evasive maneuver.The evasive maneuver was divided into two distinct stages,namely the collision-inducing phase and the fast departure phase.The obstacle potential field-based target selection algorithm was employed to identify the most appropriate target obstacle,while the induced trajectory was determined through a combination of receding horizon optimization and the hp-adaptive pseudo-spectral method.Simulation experiments were carried out under three different types of obstacle environments and one multiobstacle environment,and the simulation results show that the method proposed in this paper greatly improves the success rate of UAV evasive maneuvers,proving the effectiveness of this method.
基金Sponsored by National Natural Science Foundation of China(Grant No.61973326)Shenzhen Science and Technology Program(Grant No.ZDSYS20210623091808026)Key Laboratory of Cross-Domain Flight Interdisciplinary Technology(Grant No.2024-KF02201).
文摘In order to enhance the penetration performance of hypersonic gliding vehicle,a chaotification method of gliding midcourse based on flight dynamics is proposed.Firstly,a chaotic series⁃based angle of attack(AOA)control algorithm and an AOA switching control algorithm considering flight altitude are proposed in this study based on a simple chaotic system with considerations of AOA constraints and process constraints.Secondly,the Lyapunov exponent Algorithm Of Continuous system is applied to verify the chaotic characteristic of flight trajectories.Thirdly,a stability region analysis method is proposed based on a conservative dynamics,which can be applied to the stability region analysis of general complex dynamics.Finally,the simulations show that both control algorithms can realize the chaotification of trajectories,and the flight trajectories obtained by the AOA switching control algorithm are feasible.
基金supported by National Key R&D Program of China:Gravitational Wave Detection Project(Grant Nos.2021YFC22026,2021YFC2202601,2021YFC2202603)National Natural Science Foundation of China(Grant Nos.12172288 and 12472046)。
文摘This paper investigates impulsive orbital attack-defense(AD)games under multiple constraints and victory conditions,involving three spacecraft:attacker,target,and defender.In the AD scenario,the attacker aims to breach the defender's interception to rendezvous with the target,while the defender seeks to protect the target by blocking or actively pursuing the attacker.Four different maneuvering constraints and five potential game outcomes are incorporated to more accurately model AD game problems and increase complexity,thereby reducing the effectiveness of traditional methods such as differential games and game-tree searches.To address these challenges,this study proposes a multiagent deep reinforcement learning solution with variable reward functions.Two attack strategies,Direct attack(DA)and Bypass attack(BA),are developed for the attacker,each focusing on different mission priorities.Similarly,two defense strategies,Direct interdiction(DI)and Collinear interdiction(CI),are designed for the defender,each optimizing specific defensive actions through tailored reward functions.Each reward function incorporates both process rewards(e.g.,distance and angle)and outcome rewards,derived from physical principles and validated via geometric analysis.Extensive simulations of four strategy confrontations demonstrate average defensive success rates of 75%for DI vs.DA,40%for DI vs.BA,80%for CI vs.DA,and 70%for CI vs.BA.Results indicate that CI outperforms DI for defenders,while BA outperforms DA for attackers.Moreover,defenders achieve their objectives more effectively under identical maneuvering capabilities.Trajectory evolution analyses further illustrate the effectiveness of the proposed variable reward function-driven strategies.These strategies and analyses offer valuable guidance for practical orbital defense scenarios and lay a foundation for future multi-agent game research.
基金supported by the National Science and Technology Council,Taiwan[Grant NSTC 111-2628-E-006-005-MY3]supported by the Ocean Affairs Council,Taiwansponsored in part by Higher Education Sprout Project,Ministry of Education to the Headquarters of University Advancement at National Cheng Kung University(NCKU).
文摘This study proposes an automatic control system for Autonomous Underwater Vehicle(AUV)docking,utilizing a digital twin(DT)environment based on the HoloOcean platform,which integrates six-degree-of-freedom(6-DOF)motion equations and hydrodynamic coefficients to create a realistic simulation.Although conventional model-based and visual servoing approaches often struggle in dynamic underwater environments due to limited adaptability and extensive parameter tuning requirements,deep reinforcement learning(DRL)offers a promising alternative.In the positioning stage,the Twin Delayed Deep Deterministic Policy Gradient(TD3)algorithm is employed for synchronized depth and heading control,which offers stable training,reduced overestimation bias,and superior handling of continuous control compared to other DRL methods.During the searching stage,zig-zag heading motion combined with a state-of-the-art object detection algorithm facilitates docking station localization.For the docking stage,this study proposes an innovative Image-based DDPG(I-DDPG),enhanced and trained in a Unity-MATLAB simulation environment,to achieve visual target tracking.Furthermore,integrating a DT environment enables efficient and safe policy training,reduces dependence on costly real-world tests,and improves sim-to-real transfer performance.Both simulation and real-world experiments were conducted,demonstrating the effectiveness of the system in improving AUV control strategies and supporting the transition from simulation to real-world operations in underwater environments.The results highlight the scalability and robustness of the proposed system,as evidenced by the TD3 controller achieving 25%less oscillation than the adaptive fuzzy controller when reaching the target depth,thereby demonstrating superior stability,accuracy,and potential for broader and more complex autonomous underwater tasks.
基金National Natural Science Foundation of China (10872030)
文摘An eigenaxis maneuver strategy with global robustness is studied for large angle attitude maneuver of rigid spacecraft. A sliding mode attitude control algorithm with an exponential time-varying sliding surface is designed, which guarantees the sliding mode occurrence at the beginning and eliminates the reaching phase of time-invariant sliding mode control. The proposed control law is global robust against matched external disturbances and system uncertainties, and ensures the eigenaxis rotation in the presence of disturbances and parametric uncertainties. The stability of the control law and the existence of global siding mode are proved by Lyapunov method. Furthermore, the system states can be fully predicted by the analytical solution of state equations, which indicates that the attitude error does not exhibit any overshoots and the system has a good dynamic response. A control torque command regulator is introduced to ensure the eigenaxis rotation under the actuator saturation. Finally, a numerical simulation is employed to illustrate the advantages of the proposed control law.
基金National Natural Science Foundation of China (10702003)Innovation Foundation of Beijing University of Aeronautics and Astronautics for Ph.D. Graduates
文摘This article addresses the design of the trajectory transferring from Earth to Halo orbit, and proposes a timing closed-loop strategy of correction maneuver during the transfer in the frame of circular restricted three body problem （CR3BP）. The relation between the Floquet multipliers and the magnitudes of Halo orbit is established, so that the suitable magnitude for the aerospace mission is chosen in terms of the stability of Halo orbit. The stable manifold is investigated from the Poincar6 mapping defined which is different from the previous researches, and six types of single-impulse transfer trajectories are attained from the geometry of the invariant manifolds. Based on one of the trajectories of indirect transfer which are ignored in the most of literatures, the stochastic control theory for imperfect information of the discrete linear stochastic system is applied to design the trajectory correction maneuver. The statistical dispersion analysis is performed by Monte-Carlo simulation,
基金The National Natural Science Foundation of China (No.10872139)
文摘The aim is to establish an automatic system to analyze the maneuver performance of fish. A high speed camera （1 000 frame/s） is employed to record fast-start maneuver. Three steps are taken to analyze the kinematics： first, the midline in the first image is partitioned into equal interval lengths and the coordinates of all inter segmental points are saved. Secondly, these points coordinates are searched in the next frame with the digital image correlation （DIC） method, then these points are fitted with a spline curve function. Repeat this step until all the midlines are figured out frame by frame. Finally, according to the variety of midlines, the kinematics of the fast-start is calculated. Using this system to test carp C-start, the duration is divided into two stages： stage 1 is defined as the formation of the C shape and stage 2 as the return flip of the tail followed with forward motion. By tracing the middle line, the kinematic parameters of turning rate, centre of mass （CM） turning rate, CM turning radius, etc. are obtained.
文摘The effects of active control on the vehicle roll were studied. Based on the theory that distributing the greater roll stiffness to the rear axle can improve tracking trajectory capacity and increase maneuver stability, an eight degrees of freedom vehicle model was established and feedforward feedback control strategy was devised to control distribution of lateral load transfer on the front axle and the rear one. Simulation results showed that the proposed control strategy can improve comfort, maneuver stability and safety effectively.
基金co-supported by the National Natural Science Foundation of China(No.61374032)the Aeronautical Science Foundation of China(No.20130753005)
文摘The robust controller design problem for switched polytopic systems under asynchronous switching is addressed.These systems exist in many aviation applications,such as dynamical systems involving rapid variations.A switched polytopic system is established to describe the highly maneuverable technology vehicle within the full flight envelope and a robust dynamic output feedback control method is designed for the switched polytopic system.Combining the Lyapunov-like function method and the average dwell time method,a sufficient condition is derived for the switched polytopic system with asynchronous switching and data dropout to be globally,uniformly and asymptotically stable in terms of linear matrix inequality.The robust dynamic output feedback controller is then applied to the highly maneuverable technology vehicle to illustrate the effectiveness of the proposed approach.The simulation results show that the angle of attack tracking performance is acceptable over the time history and the control surface responses are all satisfying along the full flight trajectory.
文摘2017-06-24,6时许,四川省茂县叠溪镇新磨村发生山体高位滑坡,造成农舍和人员被埋。灾情紧急,根据西部战区联指命令和西宁联勤保障中心指示,成都军区总医院第一时间派出两个梯队（共47人）的应急医疗救援队空陆并进赶赴灾区,提供应急医疗救治服务。此次救援,从医院接到上级预先号令,至第1梯队出发赴机场共用时1 h 14 min,至第2梯队摩托化出发共用时2 h 54 min,实现了应急医疗队快速出动的目的。
