This study can play an important role in addressing the issue of achieving stable controlof launch vehicles when the first-order elastic frequency is near or overlaps with the rigid-body fre-quency,especially without ...This study can play an important role in addressing the issue of achieving stable controlof launch vehicles when the first-order elastic frequency is near or overlaps with the rigid-body fre-quency,especially without prior frequency knowledge.Much of the research up to now,such asthose based on notch-filter or signal-processing techniques,requires a gap of 3 to 5 times betweenthe low-order elastic frequencies and the rigid-body cutoff frequency.Observer-based methods,onthe other hand,require prior knowledge of the frequency data.In this paper,a method is proposed,which takes advantage of the fact that attitude measurements of the rigid-body,obtained by InertialMeasurement Units(IMUs)installed at different locations,are identical,whereas elastic-mode sig-nals differ only in their modal slopes.By differentially processing these IMU measurements,we canextract only the elastic information,thus identifying the frequencies of the elastic modes,and designan observer to distinguish the first-order elastic signal using redundant measurements.Simulationsdemonstrate that this method can autonomously identify low-order elastic frequencies,even whenthey are identical to or less than the rigid-body frequency,thereby enhancing controller perfor-mance.展开更多
This article investigates the approaching control for fixed-wing Unmanned Aerial Vehi-cle(UAV)aerial recovery in the presence of pre-specified performance requirements,complex air-flows,maneuvering flight of transport...This article investigates the approaching control for fixed-wing Unmanned Aerial Vehi-cle(UAV)aerial recovery in the presence of pre-specified performance requirements,complex air-flows,maneuvering flight of transport aircraft,and different initial deviations.First,a novelcontrol-oriented Six-Degree-Of-Freedom(6-DOF)UAV model considering airflow disturbancesis established for better consistency with the actual UAV system.Then,to achieve satisfactory per-formance in the approaching process,a Flexible Appointed-time Prescribed Performance Control(FAPPC)algorithm,with the features of user-specified time convergence,no overshoot,indepen-dence from the initial value,and singularity-free,is proposed.Specifically,to solve the singularityissue encountered by the existing PPC methods in dealing with sudden disturbances,an adaptiveadjustment signal is introduced in FAPPC to perceive the threat of increasing error and relax thepreset boundaries appropriately.Moreover,minimum learning parameter-based neural networkestimators are developed to approximate unknown lumped disturbances at a low computationalcost.Finally,the stability of the closed system is analyzed via Lyapunov synthesis,and the effective-ness and advantages of the proposed control scheme are demonstrated via simulation andHardware-In-the-Loop(HIL)experimental validation.展开更多
To ensure the safety, comfort, and effectiveness of lower limb rehabilitation exoskeleton robots in the rehabilitation training process, compliance is a prerequisite for human–machine interaction safety. First, under...To ensure the safety, comfort, and effectiveness of lower limb rehabilitation exoskeleton robots in the rehabilitation training process, compliance is a prerequisite for human–machine interaction safety. First, under the premise of considering the mechanical structure of the lower limb rehabilitation exoskeleton robot (LLRER), when conducting the dynamic transmission of the exoskeleton knee joint, the soft axis is added to ensure that the rotation motion and torque are flexibly transmitted to any position to achieve flexible force transmission. Second, to realize the active compliance control of LLRER, the sliding mode impedance closed-loop controller is developed based on the kinematics and dynamics model of LLRER, and the stability of the designed control system is verified by Lyapunov method. Then the experiment is designed to track the collected bicycle rehabilitation motion data stably, and the algorithm and dynamic model are verified to satisfy the experimental requirements. Finally, aiming at the transmission efficiency and response performance of the soft shaft in the torque transmission process of the knee joint, the soft shaft transmission performance test is carried out to test the soft shaft transmission performance and realize the compliance of the LLRER, so as to ensure that the rehabilitation training can be carried out in a safe and comfortable interactive environment. Through the design of rehabilitation exercise training, it is verified that the LLRER of flexible transmission under sliding mode impedance control has good adaptability in the actual environment, and can achieve accurate and flexible control. During the experiment, the effectiveness of monitoring rehabilitation training is brought through the respiratory belt.展开更多
A flexible hingeless control surface model was proposed for motion control of Underwater Vehicles (UVs),which is inspiredby the flexible bending control surfaces of underwater creatures,such as fish and squid.Computat...A flexible hingeless control surface model was proposed for motion control of Underwater Vehicles (UVs),which is inspiredby the flexible bending control surfaces of underwater creatures,such as fish and squid.Computational Fluid Dynamics(CFD) simulation demonstrates that,in comparison with the hinged or rigid control surface,the proposed flexible bendingcontrol surface can suppress the flow separation so as to improve the turning performance.A prototype of the flexible controlsurface was fabricated,in which Shape Memory Alloy (SMA) wires were selected as the actuators.The elastic energy storageand exchange mechanism was incorporated into the actuation of the control surface to improve the efficiency.Thermal analysisof SMA wires was performed to find proper actuating condition.Open-loop bending experiments were carried out.The resultsshow that the proposed control surface can achieve the maximum bending angle of 104°.Moreover,the power and energyconsumption under different pulse conditions were compared.展开更多
To eliminate the load weight limit of carrier rockets and reduce the burden on support structures,in-orbit assembly is a key technology to make design of scattering a large diameter telescope into submirror modules,wh...To eliminate the load weight limit of carrier rockets and reduce the burden on support structures,in-orbit assembly is a key technology to make design of scattering a large diameter telescope into submirror modules,which requires smooth operation of assembly robots,and flexible force control technology is necessary. A ground demonstration system is presented for in-orbit assembly focusing on flexible force control. A six-dimensional force/torque sensor and its data acquisition system are used to compensate for gravity. For translation and rotation,an algorithm for flexible control is proposed. A ground transportation demonstration verifies accuracy and smoothness of flexible force control,and the transportation and assembly task is completed automatically. The proposed system is suitable for the development of in-orbit assembly robots.展开更多
An adaptive inverse optimal attitude controller for flexible spacecraft with fault-free actuator is designed based on adaptive control Lyapunov function and inverse optimal methodology subjected to unknown parameter u...An adaptive inverse optimal attitude controller for flexible spacecraft with fault-free actuator is designed based on adaptive control Lyapunov function and inverse optimal methodology subjected to unknown parameter uncertainties,external disturbances and input saturation.The partial loss of actuator effectiveness and the additive faults are considered simultaneously to deal with actuator faults,and the prior knowledge of bounds on the effectiveness factors of the actuators is assumed to be unknown.A fault-tolerant control version is designed to handle the system with actuator fault by introducing a parameter update law to estimate the lower bound of the partial loss of actuator effectiveness faults.The proposed fault-tolerant attitude controller ensures robustness and stabilization,and it achieves H_∞ optimality with respect to a family of cost functionals.The usefulness of the proposed algorithms is assessed and compared with the conventional approaches through numerical simulations.展开更多
Focusing on the ball double-screw hydraulic knee joint as the research object,this paper analyzes the load driving performance of the hydraulic knee joint.Taking the posture data of the human body such as walking,squa...Focusing on the ball double-screw hydraulic knee joint as the research object,this paper analyzes the load driving performance of the hydraulic knee joint.Taking the posture data of the human body such as walking,squatting and landing buffer as initial learning objects,motion features are extracted.By simplifying the trajectories of different motion actions into key feature control points and flexible trajectory fitting,the trajectory of joint actions is optimized.This method can realize the adaptability of the hydraulic robot knee joint in different movements,and take the flexible action as the optimization goal under the condition of ensuring the movement performance,so as to reduce the damage to the knee joint caused by the foot impact in motion.The simulation model was built by Adams and Matlab to complete the performance analysis and motion optimization experiment of the knee joint.The simulation results show that the foot impact force of the experimental model decreases gradually through optimization.Finally,the method is applied to the hydraulic joint experimental prototype to prove its load capacity and flexible motion control performance.展开更多
Forming of various customized bending parts,small batches,as well as numerous types of materials is a new challenges for Industry 4.0,the current control strategies can not meet the precision and flexibility requireme...Forming of various customized bending parts,small batches,as well as numerous types of materials is a new challenges for Industry 4.0,the current control strategies can not meet the precision and flexibility requirement,expected control strategy of bending processes need to not only resist unknown interferences of process condition and models,but also produce various new parts automatically and efficiently.In this paper,a precision and flexible bending control strategy based on analytical models and data models is proposed to build adaptive bending systems.New analytical prediction models for loading and unloading are established and suitable for various materials,a sequential identification strategy is proposed to search nominal properties using the four sub-optimization models.A data-based feedback model is established to prevent over-bending and eliminate online deviation.Above models are merged into a precision and flexible control strategy.The system firstly uses sub-optimization models to search the nominal point which is near to target point,secondly the system further uses feedback model to eliminate residual error between the nominal point and target point.Compared with four kinds sheet metals,the allowable ranges for variables are determined for a good convergence.The target bending angles were set to 20°,40°,and 60°.Forty parts were tracked for each kind material,the adaptive bending system converged after one iteration,and exhibited better performances.展开更多
From the mathematical point of view,the flexible inventory control model is proved in the practical problem application and the rationality of the capacity parameter selection and calculation.The purpose is to activel...From the mathematical point of view,the flexible inventory control model is proved in the practical problem application and the rationality of the capacity parameter selection and calculation.The purpose is to actively respond to demand fluctuations when there is a demand forecast error or a missing part of the demand information,and to avoid the risk of passive variable demand forecasting to set the immutable inventory capacity.At the same time,the game is controlled by the flexible and variable inventory control strategy and the customer’s willingness to demand.The paper mainly studies the influence of the setting of capacity parameters on the booking-limit decision and its benefits under the control of flexible space with variable total capacity.Through the two trends of capacity increase flexibility and capacity reduction flexibility in the flexible inventory control model,the mathematical performance and marginal utility methods are introduced to change the performance of the booking-limit control decision model under different scenarios.The correlation analysis between the capacity limit level and the return under the optimal Bookinglimit decision,and the above two flexibility parameters are obtained.展开更多
This work aims to control pulsed power for biomedical fields,which demands sensitive parameters.The pulsed power consists of a voltage rise time of less than 50 ns and charging energy to 1.0 J/pulse;also,the pulse con...This work aims to control pulsed power for biomedical fields,which demands sensitive parameters.The pulsed power consists of a voltage rise time of less than 50 ns and charging energy to 1.0 J/pulse;also,the pulse control area includes pulse interval pulse shot number,output voltage.To achieve this system,a pulsed power system exists including software running on PC,universal serial bus(UgB~for connection,and FPGA controller.Using the software for complex control of pulsed power will enable expansion into various fields with easy operation.展开更多
Passive-active control of a flexible isolation system is investigated from the viewpoint of power flow. Dynamic transfer equations of the system are deduced based on a matrix method which uses mobility or impedance re...Passive-active control of a flexible isolation system is investigated from the viewpoint of power flow. Dynamic transfer equations of the system are deduced based on a matrix method which uses mobility or impedance representations of three substructures: the source of vibration, the receiver and the mounting system which connects the source to the receiver. The cancellation of axial input forces to the receiver is considered as the active control strategy and its effects are discussed. The results of the study show that the strategy adopted herein can effectively reduce the power transmitted to the receiver.展开更多
Faced with the key problems of machinerv- induced vibration and structure-borne noise when dynamic machines are mounted on flexible foundations such as upper floors of facto- ry buildings, the vibration and...Faced with the key problems of machinerv- induced vibration and structure-borne noise when dynamic machines are mounted on flexible foundations such as upper floors of facto- ry buildings, the vibration and noise transmission mechanism and optimal control for the flexible system are systematically studied by the novel approach of power flow. A more general system of machinery-isolators一flexible foundation is modelled. Based on substructure transfer matrix tech- nique the power flow input and transmitted are formulated in closed forms, and the effects that the flexibility of foundation and the asymmetricity of system have upon the power flow transmis- sion spectra are revealed, Also the inverse problems of isolation design are discussed by using an optimum method. Optimum design for a typical example about a force fan mounted on a con- crete building floor is successfully performed to show that the model is practical, the theory and the optimisation developed are reasonable and effective. Thereby, theoretical bases for accurate prediction of isolation effectiveness and an optimum method for practical design of a general flexi- ble isolation system are provided.展开更多
Context cognition involves abstractly deriving meaning from situational information in the world and is an important psychological function of higher cognition. However, due to the complexity of contextual information...Context cognition involves abstractly deriving meaning from situational information in the world and is an important psychological function of higher cognition. However, due to the complexity of contextual information processing, along with the lack of relevant technical tools, little remains known about the neural mechanisms and behavioral regulation of context cognition. At present, behavioral training with rodents using virtual reality techniques is considered a potential key for uncovering the neurobiological mechanisms of context cognition. Although virtual reality technology has been preliminarily applied in the study of context cognition in recent years, there remains a lack of virtual scenario integration of multi-sensory information, along with a need for convenient experimental design platforms for researchers who have little programming experience. Therefore, in order to solve problems related to the authenticity, immersion, interaction, and flexibility of rodent virtual reality systems, an immersive virtual reality system based on visual programming was constructed in this study. The system had the ability to flexibly modulate rodent interactive 3 D dynamic experimental environments. The system included a central control unit, virtual perception unit, virtual motion unit, virtual vision unit, and video recording unit. The neural circuit mechanisms in various environments could be effectively studied by combining two-photon imaging and other neural activity recording methods. In addition, to verify the proposed system′s performance, licking experiments were conducted with experimental mice. The results demonstrated that the system could provide a new method and tool for analyzing the neural circuits of the higher cognitive functions in rodents.展开更多
The paper presents a novel control design,which is based on the idea of active disturbance rejection control(ADRC),for a kind of flexible aerocraft whose contolled variable cannot be measured directly.Since the origin...The paper presents a novel control design,which is based on the idea of active disturbance rejection control(ADRC),for a kind of flexible aerocraft whose contolled variable cannot be measured directly.Since the original frame of ADRC can-not be directly applied,the paper puts forward a new extended state observer(ESO)and the corresponding ADRC law.In order to assign the poles of the closed loop system to ideal positions such that the vibration can be quickly suppressed,an elastic damping term is added into feedback law.The advantages of the new ESO for fectively estimating both the rigid mode and elastic mode from the measurements are discussed.Moreover,the analysis on the stabiliy.the relative stability and the steady state of the closed-loop system is given.Finally,the efectiveness and robustness of the proposed ADRC are verified by simulations.展开更多
In the context of increasing demand for flexibility and controllability in distribution networks,this paper proposes a dual-bus parallel supply(DBPS)system based on bipolar direct AC/AC conversion.First,the topology o...In the context of increasing demand for flexibility and controllability in distribution networks,this paper proposes a dual-bus parallel supply(DBPS)system based on bipolar direct AC/AC conversion.First,the topology of the DBPS system,which is composed of both conventional and flexible bus ports,is described.Then,through analyzing the principles of the DBPS sys-tem,the voltage flexible regulation range is obtained,and its superiority over a topological reciprocity system is achieved.Then,a control strategy for the DBPS system is proposed based on the theory of power flow regulation of distribution ring networks and the principles of flexible bus regulation of the DBPS system.Finally,simulation analyses on flexible control scenarios in different net-working modes of the DBPS system verify the correctness and validity of the proposed theory.展开更多
Reinforcement learning(RL)has proven effective for AI-based building energy management.However,there is a lack of flexible framework to implement RL across various control problems in building energy management.To add...Reinforcement learning(RL)has proven effective for AI-based building energy management.However,there is a lack of flexible framework to implement RL across various control problems in building energy management.To address this gap,we propose BuildingGym,an open-source tool designed as a research-friendly and flexible framework for training RL control strategies for common challenges in building energy management.BuildingGym integrates EnergyPlus as its core simulator,making it suitable for both system-level and room-level control.Additionally,BuildingGym is able to accept external signals as control inputs instead of taking the building as a stand-alone entity.This feature makes BuildingGym applicable for more flexible environments,e.g.smart grid and EVs community.The tool provides several built-in RL algorithms for control strategy training,simplifying the process for building managers to obtain optimal control strategies.Users can achieve this by following a few straightforward steps to configure BuildingGym for optimization control for common problems in the building energy management field.Moreover,AI specialists can easily implement and test state-of-the-art control algorithms within the platform.BuildingGym bridges the gap between building managers and AI specialists by allowing for the easy configuration and replacement of RL algorithms,simulators,and control environments or problems.With BuildingGym,we efficiently set up training tasks for cooling load management,targeting both constant and dynamic cooling load management.The built-in algorithms demonstrated strong performance across both tasks,highlighting the effectiveness of BuildingGym in optimizing cooling strategies.展开更多
The emerging medium voltage direct current(MVDC)distribution networks are becoming more attractive due to their flexible power flow control and lower losses compared to traditional AC networks.This will significantly ...The emerging medium voltage direct current(MVDC)distribution networks are becoming more attractive due to their flexible power flow control and lower losses compared to traditional AC networks.This will significantly increase the wide uptake of renewable energy sources.The optimum utilization of the existing assets is an important aspect in grid upgrading and planning.One feasible option is to convert existing MVAC lines into MVDC operation.One of the practical demonstrations is the“ANGLE-DC”project which is also the first MVDC link in the UK.This paper highlights the innovative approach,challenges and key benefits delivered by the ANGLE-DC project.展开更多
Open Air Interface(OAI)alliance recently introduced a new disaggregated Open Radio Access Networks(O-RAN)framework for next generation telecommunications and networks.This disaggregated architecture is open,automated,...Open Air Interface(OAI)alliance recently introduced a new disaggregated Open Radio Access Networks(O-RAN)framework for next generation telecommunications and networks.This disaggregated architecture is open,automated,software defined,virtual,and supports the latest advanced technologies like Artificial Intelligence(AI)Machine Learning(AI/ML).This novel intelligent architecture enables programmers to design and customize automated applications according to the business needs and to improve quality of service in fifth generation(5G)and Beyond 5G(B5G).Its disaggregated and multivendor nature gives the opportunity to new startups and small vendors to participate and provide cheap hardware software solutions to keep the market competitive.This paper presents the disaggregated and programmable O-RAN architecture focused on automation,AI/ML services,and applications with Flexible Radio access network Intelligent Controller(FRIC).We schematically demonstrate the reinforcement learning,external applications(xApps),and automation steps to implement this disaggregated O-RAN architecture.The idea of this research paper is to implement an AI/ML enabled automation system for software defined disaggregated O-RAN,which monitors,manages,and performs AI/ML-related services,including the model deployment,optimization,inference,and training.展开更多
Triboelectric nanogenerator （TENG） is an efficient way to convert ambient mechanical energy into electricity to power up portable electronics. In this work, a flexible inflared electrochromical device （IR-ECD） wit...Triboelectric nanogenerator （TENG） is an efficient way to convert ambient mechanical energy into electricity to power up portable electronics. In this work, a flexible inflared electrochromical device （IR-ECD） with stable performances was assembled with a TENG for building self-powered infrared detector with tunable intensity. As driven by TENG, the electrochromic device could be operated in the mid-lR region due to the reversible electrochromic reactions. An average infrared reflectance contrast of 46% was achieved in 8-14 μm regions and as well a clear thermal image change can be observed. This work indicates that the TENG-driven infrared electrochromical device has potential for use in self-powered camouflage and tbermal control.展开更多
Personally identifiable information(PII)refers to any information that links to an individual.Sharing PII is extremely useful in public affairs yet hard to implement due to the worries about privacy violations.Buildin...Personally identifiable information(PII)refers to any information that links to an individual.Sharing PII is extremely useful in public affairs yet hard to implement due to the worries about privacy violations.Building a PII retrieval service over multi-cloud,which is a modern strategy to make services stable where multiple servers are deployed,seems to be a promising solution.However,three major technical challenges remain to be solved.The first is the privacy and access control of PII.In fact,each entry in PII can be shared to different users with different access rights.Hence,flexible and fine-grained access control is needed.Second,a reliable user revocation mechanism is required to ensure that users can be revoked efficiently,even if few cloud servers are compromised or collapse,to avoid data leakage.Third,verifying the correctness of received PII and locating a misbehaved server when wrong data are returned is crucial to guarantee user’s privacy,but challenging to realize.In this paper,we propose Rainbow,a secure and practical PII retrieval scheme to solve the above issues.In particular,we design an important cryptographic tool,called Reliable Outsourced Attribute Based Encryption(ROABE)which provides data privacy,flexible and fine-grained access control,reliable immediate user revocation and verification for multiple servers simultaneously,to support Rainbow.Moreover,we present how to build Rainbow with ROABE and several necessary cloud techniques in real world.To evaluate the performance,we deploy Rainbow on multiple mainstream clouds,namely,AWS,GCP and Microsoft Azure,and experiment in browsers on mobile phones and computers.Both theoretical analysis and experimental results indicate that Rainbow is secure and practical.展开更多
文摘This study can play an important role in addressing the issue of achieving stable controlof launch vehicles when the first-order elastic frequency is near or overlaps with the rigid-body fre-quency,especially without prior frequency knowledge.Much of the research up to now,such asthose based on notch-filter or signal-processing techniques,requires a gap of 3 to 5 times betweenthe low-order elastic frequencies and the rigid-body cutoff frequency.Observer-based methods,onthe other hand,require prior knowledge of the frequency data.In this paper,a method is proposed,which takes advantage of the fact that attitude measurements of the rigid-body,obtained by InertialMeasurement Units(IMUs)installed at different locations,are identical,whereas elastic-mode sig-nals differ only in their modal slopes.By differentially processing these IMU measurements,we canextract only the elastic information,thus identifying the frequencies of the elastic modes,and designan observer to distinguish the first-order elastic signal using redundant measurements.Simulationsdemonstrate that this method can autonomously identify low-order elastic frequencies,even whenthey are identical to or less than the rigid-body frequency,thereby enhancing controller perfor-mance.
基金funded by the National Natural Science Foundation of China(Nos.62173022,61673042)the Academic Excellence Foundation of Beihang University for Ph.D.Studentsthe Outstanding Research Project of Shen Yuan Honors College,Beihang University,China(No.230123104)。
文摘This article investigates the approaching control for fixed-wing Unmanned Aerial Vehi-cle(UAV)aerial recovery in the presence of pre-specified performance requirements,complex air-flows,maneuvering flight of transport aircraft,and different initial deviations.First,a novelcontrol-oriented Six-Degree-Of-Freedom(6-DOF)UAV model considering airflow disturbancesis established for better consistency with the actual UAV system.Then,to achieve satisfactory per-formance in the approaching process,a Flexible Appointed-time Prescribed Performance Control(FAPPC)algorithm,with the features of user-specified time convergence,no overshoot,indepen-dence from the initial value,and singularity-free,is proposed.Specifically,to solve the singularityissue encountered by the existing PPC methods in dealing with sudden disturbances,an adaptiveadjustment signal is introduced in FAPPC to perceive the threat of increasing error and relax thepreset boundaries appropriately.Moreover,minimum learning parameter-based neural networkestimators are developed to approximate unknown lumped disturbances at a low computationalcost.Finally,the stability of the closed system is analyzed via Lyapunov synthesis,and the effective-ness and advantages of the proposed control scheme are demonstrated via simulation andHardware-In-the-Loop(HIL)experimental validation.
基金supported in part by the National Natural Science Foundation of China under grants 61873304 and 62173048in part by the China Postdoctoral Science Foundation Funded Project under grant 2018M641784also in part by the Key Science and Technology Project of Jilin Province,China,grant nos.20200404208YY.
文摘To ensure the safety, comfort, and effectiveness of lower limb rehabilitation exoskeleton robots in the rehabilitation training process, compliance is a prerequisite for human–machine interaction safety. First, under the premise of considering the mechanical structure of the lower limb rehabilitation exoskeleton robot (LLRER), when conducting the dynamic transmission of the exoskeleton knee joint, the soft axis is added to ensure that the rotation motion and torque are flexibly transmitted to any position to achieve flexible force transmission. Second, to realize the active compliance control of LLRER, the sliding mode impedance closed-loop controller is developed based on the kinematics and dynamics model of LLRER, and the stability of the designed control system is verified by Lyapunov method. Then the experiment is designed to track the collected bicycle rehabilitation motion data stably, and the algorithm and dynamic model are verified to satisfy the experimental requirements. Finally, aiming at the transmission efficiency and response performance of the soft shaft in the torque transmission process of the knee joint, the soft shaft transmission performance test is carried out to test the soft shaft transmission performance and realize the compliance of the LLRER, so as to ensure that the rehabilitation training can be carried out in a safe and comfortable interactive environment. Through the design of rehabilitation exercise training, it is verified that the LLRER of flexible transmission under sliding mode impedance control has good adaptability in the actual environment, and can achieve accurate and flexible control. During the experiment, the effectiveness of monitoring rehabilitation training is brought through the respiratory belt.
基金supported by the Self-Planned Task (No.SKLRS200805C) of State Key Laboratory of Robotics and System (HIT)the National Natural Science Foundation of China (Grant No.50775049)
文摘A flexible hingeless control surface model was proposed for motion control of Underwater Vehicles (UVs),which is inspiredby the flexible bending control surfaces of underwater creatures,such as fish and squid.Computational Fluid Dynamics(CFD) simulation demonstrates that,in comparison with the hinged or rigid control surface,the proposed flexible bendingcontrol surface can suppress the flow separation so as to improve the turning performance.A prototype of the flexible controlsurface was fabricated,in which Shape Memory Alloy (SMA) wires were selected as the actuators.The elastic energy storageand exchange mechanism was incorporated into the actuation of the control surface to improve the efficiency.Thermal analysisof SMA wires was performed to find proper actuating condition.Open-loop bending experiments were carried out.The resultsshow that the proposed control surface can achieve the maximum bending angle of 104°.Moreover,the power and energyconsumption under different pulse conditions were compared.
基金Supported by the National Natural Science Foundation of China(No.11672290)
文摘To eliminate the load weight limit of carrier rockets and reduce the burden on support structures,in-orbit assembly is a key technology to make design of scattering a large diameter telescope into submirror modules,which requires smooth operation of assembly robots,and flexible force control technology is necessary. A ground demonstration system is presented for in-orbit assembly focusing on flexible force control. A six-dimensional force/torque sensor and its data acquisition system are used to compensate for gravity. For translation and rotation,an algorithm for flexible control is proposed. A ground transportation demonstration verifies accuracy and smoothness of flexible force control,and the transportation and assembly task is completed automatically. The proposed system is suitable for the development of in-orbit assembly robots.
基金the National High Technology Research and Development Program(863)of China(No.2012AA121602)the Preliminary Research Program of the General Armament Department of China(No.51322050202)
文摘An adaptive inverse optimal attitude controller for flexible spacecraft with fault-free actuator is designed based on adaptive control Lyapunov function and inverse optimal methodology subjected to unknown parameter uncertainties,external disturbances and input saturation.The partial loss of actuator effectiveness and the additive faults are considered simultaneously to deal with actuator faults,and the prior knowledge of bounds on the effectiveness factors of the actuators is assumed to be unknown.A fault-tolerant control version is designed to handle the system with actuator fault by introducing a parameter update law to estimate the lower bound of the partial loss of actuator effectiveness faults.The proposed fault-tolerant attitude controller ensures robustness and stabilization,and it achieves H_∞ optimality with respect to a family of cost functionals.The usefulness of the proposed algorithms is assessed and compared with the conventional approaches through numerical simulations.
基金supported by the Top Discipline Plan of Shanghai Universities-Class I,the National Natural Science Foundation of China(52205279)the China National Postdoctoral Program for Innovative Talents(BX20190242)+1 种基金the Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(GZKF-202017)the Open Foundation of the National Engineering Technology Research Center for Prefabrication Construction in Civil Engineering(2021CPCCE-K02).
文摘Focusing on the ball double-screw hydraulic knee joint as the research object,this paper analyzes the load driving performance of the hydraulic knee joint.Taking the posture data of the human body such as walking,squatting and landing buffer as initial learning objects,motion features are extracted.By simplifying the trajectories of different motion actions into key feature control points and flexible trajectory fitting,the trajectory of joint actions is optimized.This method can realize the adaptability of the hydraulic robot knee joint in different movements,and take the flexible action as the optimization goal under the condition of ensuring the movement performance,so as to reduce the damage to the knee joint caused by the foot impact in motion.The simulation model was built by Adams and Matlab to complete the performance analysis and motion optimization experiment of the knee joint.The simulation results show that the foot impact force of the experimental model decreases gradually through optimization.Finally,the method is applied to the hydraulic joint experimental prototype to prove its load capacity and flexible motion control performance.
基金Natural Science Foundation of Hebei Province Iron and Steel Joint Research Fund(Grant No.E2021203163)Hebei Provincial Natural Science Foundation of China(Grant No.E2021203210).
文摘Forming of various customized bending parts,small batches,as well as numerous types of materials is a new challenges for Industry 4.0,the current control strategies can not meet the precision and flexibility requirement,expected control strategy of bending processes need to not only resist unknown interferences of process condition and models,but also produce various new parts automatically and efficiently.In this paper,a precision and flexible bending control strategy based on analytical models and data models is proposed to build adaptive bending systems.New analytical prediction models for loading and unloading are established and suitable for various materials,a sequential identification strategy is proposed to search nominal properties using the four sub-optimization models.A data-based feedback model is established to prevent over-bending and eliminate online deviation.Above models are merged into a precision and flexible control strategy.The system firstly uses sub-optimization models to search the nominal point which is near to target point,secondly the system further uses feedback model to eliminate residual error between the nominal point and target point.Compared with four kinds sheet metals,the allowable ranges for variables are determined for a good convergence.The target bending angles were set to 20°,40°,and 60°.Forty parts were tracked for each kind material,the adaptive bending system converged after one iteration,and exhibited better performances.
文摘From the mathematical point of view,the flexible inventory control model is proved in the practical problem application and the rationality of the capacity parameter selection and calculation.The purpose is to actively respond to demand fluctuations when there is a demand forecast error or a missing part of the demand information,and to avoid the risk of passive variable demand forecasting to set the immutable inventory capacity.At the same time,the game is controlled by the flexible and variable inventory control strategy and the customer’s willingness to demand.The paper mainly studies the influence of the setting of capacity parameters on the booking-limit decision and its benefits under the control of flexible space with variable total capacity.Through the two trends of capacity increase flexibility and capacity reduction flexibility in the flexible inventory control model,the mathematical performance and marginal utility methods are introduced to change the performance of the booking-limit control decision model under different scenarios.The correlation analysis between the capacity limit level and the return under the optimal Bookinglimit decision,and the above two flexibility parameters are obtained.
文摘This work aims to control pulsed power for biomedical fields,which demands sensitive parameters.The pulsed power consists of a voltage rise time of less than 50 ns and charging energy to 1.0 J/pulse;also,the pulse control area includes pulse interval pulse shot number,output voltage.To achieve this system,a pulsed power system exists including software running on PC,universal serial bus(UgB~for connection,and FPGA controller.Using the software for complex control of pulsed power will enable expansion into various fields with easy operation.
基金National Natural Science Foundation of China (No.50275085)
文摘Passive-active control of a flexible isolation system is investigated from the viewpoint of power flow. Dynamic transfer equations of the system are deduced based on a matrix method which uses mobility or impedance representations of three substructures: the source of vibration, the receiver and the mounting system which connects the source to the receiver. The cancellation of axial input forces to the receiver is considered as the active control strategy and its effects are discussed. The results of the study show that the strategy adopted herein can effectively reduce the power transmitted to the receiver.
文摘Faced with the key problems of machinerv- induced vibration and structure-borne noise when dynamic machines are mounted on flexible foundations such as upper floors of facto- ry buildings, the vibration and noise transmission mechanism and optimal control for the flexible system are systematically studied by the novel approach of power flow. A more general system of machinery-isolators一flexible foundation is modelled. Based on substructure transfer matrix tech- nique the power flow input and transmitted are formulated in closed forms, and the effects that the flexibility of foundation and the asymmetricity of system have upon the power flow transmis- sion spectra are revealed, Also the inverse problems of isolation design are discussed by using an optimum method. Optimum design for a typical example about a force fan mounted on a con- crete building floor is successfully performed to show that the model is practical, the theory and the optimisation developed are reasonable and effective. Thereby, theoretical bases for accurate prediction of isolation effectiveness and an optimum method for practical design of a general flexi- ble isolation system are provided.
文摘Context cognition involves abstractly deriving meaning from situational information in the world and is an important psychological function of higher cognition. However, due to the complexity of contextual information processing, along with the lack of relevant technical tools, little remains known about the neural mechanisms and behavioral regulation of context cognition. At present, behavioral training with rodents using virtual reality techniques is considered a potential key for uncovering the neurobiological mechanisms of context cognition. Although virtual reality technology has been preliminarily applied in the study of context cognition in recent years, there remains a lack of virtual scenario integration of multi-sensory information, along with a need for convenient experimental design platforms for researchers who have little programming experience. Therefore, in order to solve problems related to the authenticity, immersion, interaction, and flexibility of rodent virtual reality systems, an immersive virtual reality system based on visual programming was constructed in this study. The system had the ability to flexibly modulate rodent interactive 3 D dynamic experimental environments. The system included a central control unit, virtual perception unit, virtual motion unit, virtual vision unit, and video recording unit. The neural circuit mechanisms in various environments could be effectively studied by combining two-photon imaging and other neural activity recording methods. In addition, to verify the proposed system′s performance, licking experiments were conducted with experimental mice. The results demonstrated that the system could provide a new method and tool for analyzing the neural circuits of the higher cognitive functions in rodents.
基金This work was supported by the National Key R&D Program of China(No.2018YFA0703800)the National Center for Mathematics and Interdisciplinary Sciences,Chinese Acad-emy of Sciences.
文摘The paper presents a novel control design,which is based on the idea of active disturbance rejection control(ADRC),for a kind of flexible aerocraft whose contolled variable cannot be measured directly.Since the original frame of ADRC can-not be directly applied,the paper puts forward a new extended state observer(ESO)and the corresponding ADRC law.In order to assign the poles of the closed loop system to ideal positions such that the vibration can be quickly suppressed,an elastic damping term is added into feedback law.The advantages of the new ESO for fectively estimating both the rigid mode and elastic mode from the measurements are discussed.Moreover,the analysis on the stabiliy.the relative stability and the steady state of the closed-loop system is given.Finally,the efectiveness and robustness of the proposed ADRC are verified by simulations.
基金supported in part by the National Natural Science Foundation of China(No.52107182).
文摘In the context of increasing demand for flexibility and controllability in distribution networks,this paper proposes a dual-bus parallel supply(DBPS)system based on bipolar direct AC/AC conversion.First,the topology of the DBPS system,which is composed of both conventional and flexible bus ports,is described.Then,through analyzing the principles of the DBPS sys-tem,the voltage flexible regulation range is obtained,and its superiority over a topological reciprocity system is achieved.Then,a control strategy for the DBPS system is proposed based on the theory of power flow regulation of distribution ring networks and the principles of flexible bus regulation of the DBPS system.Finally,simulation analyses on flexible control scenarios in different net-working modes of the DBPS system verify the correctness and validity of the proposed theory.
基金supported by AI Singapore under its project of Development of NetZero BEMS through AI-based HVAC System Control(AISG2-TC-2023-008-SGKR).
文摘Reinforcement learning(RL)has proven effective for AI-based building energy management.However,there is a lack of flexible framework to implement RL across various control problems in building energy management.To address this gap,we propose BuildingGym,an open-source tool designed as a research-friendly and flexible framework for training RL control strategies for common challenges in building energy management.BuildingGym integrates EnergyPlus as its core simulator,making it suitable for both system-level and room-level control.Additionally,BuildingGym is able to accept external signals as control inputs instead of taking the building as a stand-alone entity.This feature makes BuildingGym applicable for more flexible environments,e.g.smart grid and EVs community.The tool provides several built-in RL algorithms for control strategy training,simplifying the process for building managers to obtain optimal control strategies.Users can achieve this by following a few straightforward steps to configure BuildingGym for optimization control for common problems in the building energy management field.Moreover,AI specialists can easily implement and test state-of-the-art control algorithms within the platform.BuildingGym bridges the gap between building managers and AI specialists by allowing for the easy configuration and replacement of RL algorithms,simulators,and control environments or problems.With BuildingGym,we efficiently set up training tasks for cooling load management,targeting both constant and dynamic cooling load management.The built-in algorithms demonstrated strong performance across both tasks,highlighting the effectiveness of BuildingGym in optimizing cooling strategies.
基金ANGLE-DC,The Office of Gas and Electricity Markets(Ofgem)of UK Government funded Network Innovation Competition(NIC)project.
文摘The emerging medium voltage direct current(MVDC)distribution networks are becoming more attractive due to their flexible power flow control and lower losses compared to traditional AC networks.This will significantly increase the wide uptake of renewable energy sources.The optimum utilization of the existing assets is an important aspect in grid upgrading and planning.One feasible option is to convert existing MVAC lines into MVDC operation.One of the practical demonstrations is the“ANGLE-DC”project which is also the first MVDC link in the UK.This paper highlights the innovative approach,challenges and key benefits delivered by the ANGLE-DC project.
文摘Open Air Interface(OAI)alliance recently introduced a new disaggregated Open Radio Access Networks(O-RAN)framework for next generation telecommunications and networks.This disaggregated architecture is open,automated,software defined,virtual,and supports the latest advanced technologies like Artificial Intelligence(AI)Machine Learning(AI/ML).This novel intelligent architecture enables programmers to design and customize automated applications according to the business needs and to improve quality of service in fifth generation(5G)and Beyond 5G(B5G).Its disaggregated and multivendor nature gives the opportunity to new startups and small vendors to participate and provide cheap hardware software solutions to keep the market competitive.This paper presents the disaggregated and programmable O-RAN architecture focused on automation,AI/ML services,and applications with Flexible Radio access network Intelligent Controller(FRIC).We schematically demonstrate the reinforcement learning,external applications(xApps),and automation steps to implement this disaggregated O-RAN architecture.The idea of this research paper is to implement an AI/ML enabled automation system for software defined disaggregated O-RAN,which monitors,manages,and performs AI/ML-related services,including the model deployment,optimization,inference,and training.
基金supported by the‘‘Thousands Talents”Program for Pioneer Researcher and his Innovation Team,the National Key Research and Development Program from Ministry of Science and Technology of China(2016YFA0202703)the National Natural Science Foundation of China(51432005)+1 种基金Hubei Technology Innovation Major Project(2016AAA030)Petro China Innovation Foundation(2015D-5006-0211)
文摘Triboelectric nanogenerator （TENG） is an efficient way to convert ambient mechanical energy into electricity to power up portable electronics. In this work, a flexible inflared electrochromical device （IR-ECD） with stable performances was assembled with a TENG for building self-powered infrared detector with tunable intensity. As driven by TENG, the electrochromic device could be operated in the mid-lR region due to the reversible electrochromic reactions. An average infrared reflectance contrast of 46% was achieved in 8-14 μm regions and as well a clear thermal image change can be observed. This work indicates that the TENG-driven infrared electrochromical device has potential for use in self-powered camouflage and tbermal control.
基金This work was supported by National Natural Science Foundation of China(Nos.62172411,62172404,61972094)。
文摘Personally identifiable information(PII)refers to any information that links to an individual.Sharing PII is extremely useful in public affairs yet hard to implement due to the worries about privacy violations.Building a PII retrieval service over multi-cloud,which is a modern strategy to make services stable where multiple servers are deployed,seems to be a promising solution.However,three major technical challenges remain to be solved.The first is the privacy and access control of PII.In fact,each entry in PII can be shared to different users with different access rights.Hence,flexible and fine-grained access control is needed.Second,a reliable user revocation mechanism is required to ensure that users can be revoked efficiently,even if few cloud servers are compromised or collapse,to avoid data leakage.Third,verifying the correctness of received PII and locating a misbehaved server when wrong data are returned is crucial to guarantee user’s privacy,but challenging to realize.In this paper,we propose Rainbow,a secure and practical PII retrieval scheme to solve the above issues.In particular,we design an important cryptographic tool,called Reliable Outsourced Attribute Based Encryption(ROABE)which provides data privacy,flexible and fine-grained access control,reliable immediate user revocation and verification for multiple servers simultaneously,to support Rainbow.Moreover,we present how to build Rainbow with ROABE and several necessary cloud techniques in real world.To evaluate the performance,we deploy Rainbow on multiple mainstream clouds,namely,AWS,GCP and Microsoft Azure,and experiment in browsers on mobile phones and computers.Both theoretical analysis and experimental results indicate that Rainbow is secure and practical.
