Aiming at the actuator time delay caused by the drive-by-wire technology,a novel manoeuvre stability controller based on model predictive control is proposed for full drive-by-wire vehicles.Firstly,the future vehicle ...Aiming at the actuator time delay caused by the drive-by-wire technology,a novel manoeuvre stability controller based on model predictive control is proposed for full drive-by-wire vehicles.Firstly,the future vehicle dynamics are predicted by a twodegree-of-freedom vehicle model with input delay.Secondly,in order to prevent the vehicle from destabilizing due to excessive side slip angles,the determined ideal yaw rate and side slip angle are tracked simultaneously by optimizing the front wheel angle and additional yaw moment.Moreover,in order to improve the trajectory tracking ability,a side slip angle constraint determined by phase plane stability boundaries is added to the cost function.The results of Matlab and veDYNA co-simulation show that the regulated yaw rate can track the reference value well and the side slip angle decreases.Meanwhile,the trajectory tracking ability is improved obviously by compensating the time delay.展开更多
In order to effectively achieve torque demand in electric vehicles （EVs）, this paper presents a torque control strategy based on model predictive control （MPC） for permanent magnet synchronous motor （PMSM） drive...In order to effectively achieve torque demand in electric vehicles （EVs）, this paper presents a torque control strategy based on model predictive control （MPC） for permanent magnet synchronous motor （PMSM） driven by a two-level three-phase inverter. A centralized control strategy is established in the MPC framework to track the torque demand and reduce energy loss, by directly optimizing the switch states of inverter. To fast determine the optimal control sequence in predictive process, a searching tree is built to look for optimal inputs by dynamic programming （DP） algorithm on the basis of the principle of optimality. Then we design a pruning method to check the candidate inputs that can enter the next predictive loop in order to decrease the computational burden of evaluation of input sequences. Finally, the simulation results on different conditions indicate that the proposed strategy can achieve a tradeoff between control performance and computational efficiency.展开更多
Autonomous marine vehicles(AMVs)have received considerable attention in the past few decades,mainly because they play essential roles in broad marine applications such as environmental monitoring and resource explorat...Autonomous marine vehicles(AMVs)have received considerable attention in the past few decades,mainly because they play essential roles in broad marine applications such as environmental monitoring and resource exploration.Recent advances in the field of communication technologies,perception capability,computational power and advanced optimization algorithms have stimulated new interest in the development of AMVs.In order to deploy the constrained AMVs in the complex dynamic maritime environment,it is crucial to enhance the guidance and control capabilities through effective and practical planning,and control algorithms.Model predictive control(MPC)has been exceptionally successful in different fields due to its ability to systematically handle constraints while optimizing control performance.This paper aims to provide a review of recent progress in the context of motion planning and control for AMVs from the perceptive of MPC.Finally,future research trends and directions in this substantial research area of AMVs are highlighted.展开更多
In order to track the desired path as fast as possible,a novel autonomous vehicle path tracking based on model predictive control(MPC)and PID speed control was proposed for high-speed automated vehicles considering th...In order to track the desired path as fast as possible,a novel autonomous vehicle path tracking based on model predictive control(MPC)and PID speed control was proposed for high-speed automated vehicles considering the constraints of vehicle physical limits,in which a forward-backward integration scheme was introduced to generate a time-optimal speed profile subject to the tire-road friction limit.Moreover,this scheme was further extended along one moving prediction window.In the MPC controller,the prediction model was an 8-degree-of-freedom(DOF)vehicle model,while the plant was a 14-DOF vehicle model.For lateral control,a sequence of optimal wheel steering angles was generated from the MPC controller;for longitudinal control,the total wheel torque was generated from the PID speed controller embedded in the MPC framework.The proposed controller was implemented in MATLAB considering arbitrary curves of continuously varying curvature as the reference trajectory.The simulation test results show that the tracking errors are small for vehicle lateral and longitudinal positions and the tracking performances for trajectory and speed are good using the proposed controller.Additionally,the case of extended implementation in one moving prediction window requires shorter travel time than the case implemented along the entire path.展开更多
Steady speed control of agricultural machinery can improve operating quality and efficiency.To address the impact of farmland slope variations on the speed stability of unmanned operation agricultural machinery,a hybr...Steady speed control of agricultural machinery can improve operating quality and efficiency.To address the impact of farmland slope variations on the speed stability of unmanned operation agricultural machinery,a hybrid control method was proposed.This method included a hybrid controller composed of a slope-based controller and a proportional-integral-derivative(PID)controller.The speed of agricultural machinery was influenced by longitudinal forces,which were divided into two parts:one part was slope-related forces and conventional resistance,and the other was hard-to-estimate forces,such as sliding friction.For the first part,a slope-based controller was designed;for the second part,a PID controller was implemented.By combining these two controllers,the system can dynamically adjust the throttle opening and the brake master cylinder pressure,ensuring steady speed travel on sloping farmland.Simulation tests at a target speed of 7 km/h demonstrated that the proposed controller maintained a stable speed,achieving a root mean square error of 0.13 km/h and a mean absolute percentage error of 1.6%.Field tests on a practical experimental platform validated the method’s effectiveness,with results showing consistent control performance across varying slope conditions.The proposed controller demonstrated superior control performance.Experimental data verified that this method can achieve precise control of the agricultural machinery’s movement speed,meeting the stability requirements for agricultural operations.展开更多
This study investigates prescribed-time position tracking control for electromagnetic satellite formations subject to model uncertainties and external disturbances.Using the Clohessy-Wiltshire equations as the relativ...This study investigates prescribed-time position tracking control for electromagnetic satellite formations subject to model uncertainties and external disturbances.Using the Clohessy-Wiltshire equations as the relative motion dynamics model,a prescribed time output feedback control strategy is proposed.A prescribed-time extended state observer is designed to estimate the relative velocity and external disturbances.The disturbance estimates are then used as the feedforward component of the controller.Building on this framework,a novel prescribed-time active disturbance rejection control strategy for position tracking is developed via a backstepping control design.The convergence of the extended state observer and the stability of the closed-loop system are rigorously analyzed using Lyapunov stability theory.Numerical simulations are performed to validate the effectiveness of the proposed controller.展开更多
This paper presents a PC-based automated control system operation of the Northern Grain Silo of Jordan. The system connects to a PLC (programmable logic controller) device, and combines operator interface, PLC program...This paper presents a PC-based automated control system operation of the Northern Grain Silo of Jordan. The system connects to a PLC (programmable logic controller) device, and combines operator interface, PLC programming and monitoring functions into one platform. The PLC portion handles direct operations control, while the PC portion handles interfacing and data intensive functions. A simulation package is developed. The package generates a graphical user interface for real-time graphic animations of the Grain Silo operation. We discuss anticipated benefits of such a system and phases of implementation.展开更多
Feasible sets play an important role in model predictive control(MPC) optimal control problems(OCPs). This paper proposes a multi-parametric programming-based algorithm to compute the feasible set for OCP derived from...Feasible sets play an important role in model predictive control(MPC) optimal control problems(OCPs). This paper proposes a multi-parametric programming-based algorithm to compute the feasible set for OCP derived from MPC-based algorithms involving both spectrahedron(represented by linear matrix inequalities) and polyhedral(represented by a set of inequalities) constraints. According to the geometrical meaning of the inner product of vectors, the maximum length of the projection vector from the feasible set to a unit spherical coordinates vector is computed and the optimal solution has been proved to be one of the vertices of the feasible set. After computing the vertices,the convex hull of these vertices is determined which equals the feasible set. The simulation results show that the proposed method is especially efficient for low dimensional feasible set computation and avoids the non-unicity problem of optimizers as well as the memory consumption problem that encountered by projection algorithms.展开更多
This article investigates the robust current tracking control problem of three-phase grid-connected inverters with LCL filter under external disturbance by a dynamic state feedback control method.First,this paper cons...This article investigates the robust current tracking control problem of three-phase grid-connected inverters with LCL filter under external disturbance by a dynamic state feedback control method.First,this paper constructs an internal model to learn the information of the states and input of the grid-connected inverter under steady state.Second,by utilizing the internal model principle,the paper turns the tracking control problem into the robust stabilization control problem based on some appropriate coordinate transformations.Then,The paper designs a dynamics state feedback control law to deal with this robust stabilization problem,and thus the solution of the robust current tracking control problem of three-phase grid-connected inverters can be obtained.This control method can ensure the asymptotic stability of the closedloop system.Finally,the paper illustrates the effectiveness of the proposed control approach through several groups of simulations,and compares it with the feedforward control method to verify the robustness of the proposed control method to uncertain parameters.展开更多
Aiming to solve the steering instability and hysteresis of agricultural robots in the process of movement,a fusion PID control method of particle swarm optimization(PSO)and genetic algorithm(GA)was proposed.The fusion...Aiming to solve the steering instability and hysteresis of agricultural robots in the process of movement,a fusion PID control method of particle swarm optimization(PSO)and genetic algorithm(GA)was proposed.The fusion algorithm took advantage of the fast optimization ability of PSO to optimize the population screening link of GA.The Simulink simulation results showed that the convergence of the fitness function of the fusion algorithm was accelerated,the system response adjustment time was reduced,and the overshoot was almost zero.Then the algorithm was applied to the steering test of agricultural robot in various scenes.After modeling the steering system of agricultural robot,the steering test results in the unloaded suspended state showed that the PID control based on fusion algorithm reduced the rise time,response adjustment time and overshoot of the system,and improved the response speed and stability of the system,compared with the artificial trial and error PID control and the PID control based on GA.The actual road steering test results showed that the PID control response rise time based on the fusion algorithm was the shortest,about 4.43 s.When the target pulse number was set to 100,the actual mean value in the steady-state regulation stage was about 102.9,which was the closest to the target value among the three control methods,and the overshoot was reduced at the same time.The steering test results under various scene states showed that the PID control based on the proposed fusion algorithm had good anti-interference ability,it can adapt to the changes of environment and load and improve the performance of the control system.It was effective in the steering control of agricultural robot.This method can provide a reference for the precise steering control of other robots.展开更多
In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to ...In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.展开更多
As an important resource in data link,time slots should be strategically allocated to enhance transmission efficiency and resist eavesdropping,especially considering the tremendous increase in the number of nodes and ...As an important resource in data link,time slots should be strategically allocated to enhance transmission efficiency and resist eavesdropping,especially considering the tremendous increase in the number of nodes and diverse communication needs.It is crucial to design control sequences with robust randomness and conflict-freeness to properly address differentiated access control in data link.In this paper,we propose a hierarchical access control scheme based on control sequences to achieve high utilization of time slots and differentiated access control.A theoretical bound of the hierarchical control sequence set is derived to characterize the constraints on the parameters of the sequence set.Moreover,two classes of optimal hierarchical control sequence sets satisfying the theoretical bound are constructed,both of which enable the scheme to achieve maximum utilization of time slots.Compared with the fixed time slot allocation scheme,our scheme reduces the symbol error rate by up to 9%,which indicates a significant improvement in anti-interference and eavesdropping capabilities.展开更多
Fluidic Thrust Vectoring(FTV)is used for the yaw attitude control of tailless flying wing,which can significantly improve stealth performance,maneuverability and lateral/heading maneuverability.The FTV control scheme ...Fluidic Thrust Vectoring(FTV)is used for the yaw attitude control of tailless flying wing,which can significantly improve stealth performance,maneuverability and lateral/heading maneuverability.The FTV control scheme of co-directional secondary flow was designed based on a 30 kgf thrust turbojet engine,an equivalent rudder deflection control variable of Mass Flow Combination(MFC)was proposed,and a control model was established to form a FTV control system scheme,which was integrated with the flight control system of a 100 kg tailless flying wing with medium aspect ratio to achieve closed-loop control of the yaw attitude based on FTV.The heading stability augmentation and maneuvering control characteristics and time response characteristics of tailless flying wing by FTV were quantitatively studied through virtual flight test in a wind tunnel at a wind speed of 35 m/s.The results show that the control strategy based on MFC achieves bidirectional continuous and stable control of thrust vector angle in a range of±11°,and the thrust vector angle varies monotonically with MFC;the co-directional FTV realizes bidirectional continuous and stable control of the yaw attitude of tailless flying wing,without longitudinal/lateral coupling moment.The increment of the maximum yawing moment coefficient is 0.0029,the maximum yaw rate is 7.55(°)/s,and the response time of the yaw rate of the vectoring nozzle actuated by the secondary flow is about 0.06 s,which satisfies the heading stability augmentation and maneuvering control response requirements of the aircraft with statically unstable heading,and provides new control means for the heading rudderless attitude control of tailless flying wing.展开更多
In this paper,we define for the trace operator,the solution of certain models of vibrating plates standards with initial data in a strategic region spaces of weak regularities.Indeed,we know that the notion of regiona...In this paper,we define for the trace operator,the solution of certain models of vibrating plates standards with initial data in a strategic region spaces of weak regularities.Indeed,we know that the notion of regional controllability is more adapted to systems described by dynamic systems.Regional controllability results in a strategic area were established for vibrating plates by the Hilbertian Uniqueness Method.展开更多
Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for ...Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for online fuel reprocessing.However,the fuel-salt flow results in the decay of delayed neutron precursors(DNPs)outside the core,causing fluctuations in the effective delayed neutron fraction and consequently impacting the reactor reactivity.Particularly in accident scenarios—such as a combined pump shutdown and the inability to rapidly scram the reactor—the sole reliance on negative temperature feedback may cause a significant increase in core temperature,posing a threat to reactor safety.To address these problems,this paper introduces an innovative design for a passive fluid-driven suspended control rod(SCR)to dynamically compensate for reactivity fluctuations caused by DNPs flowing with the fuel.The control rod operates passively by leveraging the combined effects of gravity,buoyancy,and fluid dynamic forces,thereby eliminating the need for an external drive mechanism and enabling direct integration within the active region of the core.Using a 150 MWt thorium-based molten salt reactor as the reference design,we develop a mathematical model to systematically analyze the effects of key parameters—including the geometric dimensions and density of the SCR—on its performance.We examine its motion characteristics under different core flow conditions and assess its feasibility for the dynamic compensation of reactivity changes caused by fuel flow.The results of this study demonstrate that the SCR can effectively counteract reactivity fluctuations induced by fuel flow within molten salt reactors.A sensitivity analysis reveals that the SCR’s average density exerts a profound impact on its start-up flow threshold,channel flow rate,resistance to fuel density fluctuations,and response characteristics.This underscores the critical need to optimize this parameter.Moreover,by judiciously selecting the SCR’s length,number of deployed units,and the placement we can achieve the necessary reactivity control while maintaining a favorable balance between neutron economy and heat transfer performance.Ultimately,this paper provides an innovative solution for the passive reactivity control in molten salt reactors,offering significant potential for practical engineering applications.展开更多
Electrically controlled solid propellant(ECSP)offers multiple ignition and adjustable burning rate,serving as fuel for next-generation intelligent propulsion systems.To further enhance the combustion performance of EC...Electrically controlled solid propellant(ECSP)offers multiple ignition and adjustable burning rate,serving as fuel for next-generation intelligent propulsion systems.To further enhance the combustion performance of ECSP,a method utilizing electrochemical and thermal decomposition catalysts has been proposed.In this work,we investigated the combustion characteristics of hydroxylamine nitrate(HAN)-based ECSP incorporating cerium oxide(CeO_(2))and graphene oxide(GO)by using an electrically controlled combustion test system.Electrochemical impedance spectroscopy(EIS)and linear sweep voltammetry(LSV)were used to measure the electrical conductibility and overpotential of ECSP with various additives,and Tafel curves were calculated.Thermogravimetric analysis coupled with differential scanning calorimetry(TG-DSC)was employed to investigate the thermal decomposition behavior of ECSP.While the addition of CeO_(2) and GO reduced the conductivity of ECSP,both catalysts exhibited strong electrocatalytic properties and facilitated the thermal decomposition of ECSP.Between two catalysts,GO demonstrated superior electrochemical catalytic performance but weaker thermal decomposition catalytic ability than CeO_(2).The addition of catalysts significantly enhanced the combustion performance of HAN-based ECSP.Specifically,the ignition delay time was shortened by 10%~20%.CeO_(2) raised the burning rate by approximately 20%but GO exhibited a remarkable boost of 40%in burning rate at high voltage.The combination of GO and PVA produced a flame-retardant substance that negatively impacted the ignition delay of ECSP and resulted in a smaller increase in the burning rate of ECSP at low ignition voltages.展开更多
The increasing interconnection of modern industrial control systems(ICSs)with the Internet has enhanced operational efficiency,but alsomade these systemsmore vulnerable to cyberattacks.This heightened exposure has dri...The increasing interconnection of modern industrial control systems(ICSs)with the Internet has enhanced operational efficiency,but alsomade these systemsmore vulnerable to cyberattacks.This heightened exposure has driven a growing need for robust ICS security measures.Among the key defences,intrusion detection technology is critical in identifying threats to ICS networks.This paper provides an overview of the distinctive characteristics of ICS network security,highlighting standard attack methods.It then examines various intrusion detection methods,including those based on misuse detection,anomaly detection,machine learning,and specialised requirements.This paper concludes by exploring future directions for developing intrusion detection systems to advance research and ensure the continued security and reliability of ICS operations.展开更多
With the large-scale integration of fracturing unit’s on-site construction,traditional industrial buses are increasingly unable to meet the requirements for the quantity transmission between various equipment in larg...With the large-scale integration of fracturing unit’s on-site construction,traditional industrial buses are increasingly unable to meet the requirements for the quantity transmission between various equipment in large-scale fracturing units,and different models of different equipment manufacturers cannot cooperate with each other as there are“Islands of information”in the control system.This article uses industrial Ethernet as the physical medium for data transmission.In addition,different equipment manufacturers use OPC as the core technology of the fracturing unit control system network,and set up an intelligent fracturing unit control system,so that the control network can quickly,accurately,and safely control the fracturing truck control system.The sand truck control system monitors and analyzes,saves,and prints the construction data in the vehicle instrument.At the same time,the network control system uses the vehicle instrument as the core of the network.It can control fracturing vehicles from different manufacturers.The sand mixer truck performs network control,which effectively avoids incompatibilities between various equipment manufacturers at the construction site.展开更多
基金the National Nature Science Foundation of China(Nos.61790564,U1664257)the National Key RD Program of China(No.2018YFB0104805)+1 种基金the Funds for Joint Project of Jilin Province and Jilin University(No.SXGJSF2017-2-1-1)the Funds of the Fundamental Research for the Central Universities.
文摘Aiming at the actuator time delay caused by the drive-by-wire technology,a novel manoeuvre stability controller based on model predictive control is proposed for full drive-by-wire vehicles.Firstly,the future vehicle dynamics are predicted by a twodegree-of-freedom vehicle model with input delay.Secondly,in order to prevent the vehicle from destabilizing due to excessive side slip angles,the determined ideal yaw rate and side slip angle are tracked simultaneously by optimizing the front wheel angle and additional yaw moment.Moreover,in order to improve the trajectory tracking ability,a side slip angle constraint determined by phase plane stability boundaries is added to the cost function.The results of Matlab and veDYNA co-simulation show that the regulated yaw rate can track the reference value well and the side slip angle decreases.Meanwhile,the trajectory tracking ability is improved obviously by compensating the time delay.
基金This work was supported by the NSFC Projects of International Cooperation and Exchanges （No. 61520106008）, the National Natural Science Foundation of China （Nos. 61503149, U1564207） and the Graduate Innovation Fund of Jilin University （No. 2016093）.
文摘In order to effectively achieve torque demand in electric vehicles （EVs）, this paper presents a torque control strategy based on model predictive control （MPC） for permanent magnet synchronous motor （PMSM） driven by a two-level three-phase inverter. A centralized control strategy is established in the MPC framework to track the torque demand and reduce energy loss, by directly optimizing the switch states of inverter. To fast determine the optimal control sequence in predictive process, a searching tree is built to look for optimal inputs by dynamic programming （DP） algorithm on the basis of the principle of optimality. Then we design a pruning method to check the candidate inputs that can enter the next predictive loop in order to decrease the computational burden of evaluation of input sequences. Finally, the simulation results on different conditions indicate that the proposed strategy can achieve a tradeoff between control performance and computational efficiency.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)。
文摘Autonomous marine vehicles(AMVs)have received considerable attention in the past few decades,mainly because they play essential roles in broad marine applications such as environmental monitoring and resource exploration.Recent advances in the field of communication technologies,perception capability,computational power and advanced optimization algorithms have stimulated new interest in the development of AMVs.In order to deploy the constrained AMVs in the complex dynamic maritime environment,it is crucial to enhance the guidance and control capabilities through effective and practical planning,and control algorithms.Model predictive control(MPC)has been exceptionally successful in different fields due to its ability to systematically handle constraints while optimizing control performance.This paper aims to provide a review of recent progress in the context of motion planning and control for AMVs from the perceptive of MPC.Finally,future research trends and directions in this substantial research area of AMVs are highlighted.
基金Project(20180608005600843855-19)supported by the International Graduate Exchange Program of Beijing Institute of Technology,China。
文摘In order to track the desired path as fast as possible,a novel autonomous vehicle path tracking based on model predictive control(MPC)and PID speed control was proposed for high-speed automated vehicles considering the constraints of vehicle physical limits,in which a forward-backward integration scheme was introduced to generate a time-optimal speed profile subject to the tire-road friction limit.Moreover,this scheme was further extended along one moving prediction window.In the MPC controller,the prediction model was an 8-degree-of-freedom(DOF)vehicle model,while the plant was a 14-DOF vehicle model.For lateral control,a sequence of optimal wheel steering angles was generated from the MPC controller;for longitudinal control,the total wheel torque was generated from the PID speed controller embedded in the MPC framework.The proposed controller was implemented in MATLAB considering arbitrary curves of continuously varying curvature as the reference trajectory.The simulation test results show that the tracking errors are small for vehicle lateral and longitudinal positions and the tracking performances for trajectory and speed are good using the proposed controller.Additionally,the case of extended implementation in one moving prediction window requires shorter travel time than the case implemented along the entire path.
文摘Steady speed control of agricultural machinery can improve operating quality and efficiency.To address the impact of farmland slope variations on the speed stability of unmanned operation agricultural machinery,a hybrid control method was proposed.This method included a hybrid controller composed of a slope-based controller and a proportional-integral-derivative(PID)controller.The speed of agricultural machinery was influenced by longitudinal forces,which were divided into two parts:one part was slope-related forces and conventional resistance,and the other was hard-to-estimate forces,such as sliding friction.For the first part,a slope-based controller was designed;for the second part,a PID controller was implemented.By combining these two controllers,the system can dynamically adjust the throttle opening and the brake master cylinder pressure,ensuring steady speed travel on sloping farmland.Simulation tests at a target speed of 7 km/h demonstrated that the proposed controller maintained a stable speed,achieving a root mean square error of 0.13 km/h and a mean absolute percentage error of 1.6%.Field tests on a practical experimental platform validated the method’s effectiveness,with results showing consistent control performance across varying slope conditions.The proposed controller demonstrated superior control performance.Experimental data verified that this method can achieve precise control of the agricultural machinery’s movement speed,meeting the stability requirements for agricultural operations.
文摘This study investigates prescribed-time position tracking control for electromagnetic satellite formations subject to model uncertainties and external disturbances.Using the Clohessy-Wiltshire equations as the relative motion dynamics model,a prescribed time output feedback control strategy is proposed.A prescribed-time extended state observer is designed to estimate the relative velocity and external disturbances.The disturbance estimates are then used as the feedforward component of the controller.Building on this framework,a novel prescribed-time active disturbance rejection control strategy for position tracking is developed via a backstepping control design.The convergence of the extended state observer and the stability of the closed-loop system are rigorously analyzed using Lyapunov stability theory.Numerical simulations are performed to validate the effectiveness of the proposed controller.
文摘This paper presents a PC-based automated control system operation of the Northern Grain Silo of Jordan. The system connects to a PLC (programmable logic controller) device, and combines operator interface, PLC programming and monitoring functions into one platform. The PLC portion handles direct operations control, while the PC portion handles interfacing and data intensive functions. A simulation package is developed. The package generates a graphical user interface for real-time graphic animations of the Grain Silo operation. We discuss anticipated benefits of such a system and phases of implementation.
基金supported by the Natural Science Foundation of Zhejiang Province(LR17F030002)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(61621002)
文摘Feasible sets play an important role in model predictive control(MPC) optimal control problems(OCPs). This paper proposes a multi-parametric programming-based algorithm to compute the feasible set for OCP derived from MPC-based algorithms involving both spectrahedron(represented by linear matrix inequalities) and polyhedral(represented by a set of inequalities) constraints. According to the geometrical meaning of the inner product of vectors, the maximum length of the projection vector from the feasible set to a unit spherical coordinates vector is computed and the optimal solution has been proved to be one of the vertices of the feasible set. After computing the vertices,the convex hull of these vertices is determined which equals the feasible set. The simulation results show that the proposed method is especially efficient for low dimensional feasible set computation and avoids the non-unicity problem of optimizers as well as the memory consumption problem that encountered by projection algorithms.
基金Supported by the Fundamental Research Funds for the Central Universities(2024ZYGXZR047)the National Natural Science Foundation of China(62373156)the Guangdong Basic and Applied Basic Research Foundation(2024A1515011736)。
文摘This article investigates the robust current tracking control problem of three-phase grid-connected inverters with LCL filter under external disturbance by a dynamic state feedback control method.First,this paper constructs an internal model to learn the information of the states and input of the grid-connected inverter under steady state.Second,by utilizing the internal model principle,the paper turns the tracking control problem into the robust stabilization control problem based on some appropriate coordinate transformations.Then,The paper designs a dynamics state feedback control law to deal with this robust stabilization problem,and thus the solution of the robust current tracking control problem of three-phase grid-connected inverters can be obtained.This control method can ensure the asymptotic stability of the closedloop system.Finally,the paper illustrates the effectiveness of the proposed control approach through several groups of simulations,and compares it with the feedforward control method to verify the robustness of the proposed control method to uncertain parameters.
文摘Aiming to solve the steering instability and hysteresis of agricultural robots in the process of movement,a fusion PID control method of particle swarm optimization(PSO)and genetic algorithm(GA)was proposed.The fusion algorithm took advantage of the fast optimization ability of PSO to optimize the population screening link of GA.The Simulink simulation results showed that the convergence of the fitness function of the fusion algorithm was accelerated,the system response adjustment time was reduced,and the overshoot was almost zero.Then the algorithm was applied to the steering test of agricultural robot in various scenes.After modeling the steering system of agricultural robot,the steering test results in the unloaded suspended state showed that the PID control based on fusion algorithm reduced the rise time,response adjustment time and overshoot of the system,and improved the response speed and stability of the system,compared with the artificial trial and error PID control and the PID control based on GA.The actual road steering test results showed that the PID control response rise time based on the fusion algorithm was the shortest,about 4.43 s.When the target pulse number was set to 100,the actual mean value in the steady-state regulation stage was about 102.9,which was the closest to the target value among the three control methods,and the overshoot was reduced at the same time.The steering test results under various scene states showed that the PID control based on the proposed fusion algorithm had good anti-interference ability,it can adapt to the changes of environment and load and improve the performance of the control system.It was effective in the steering control of agricultural robot.This method can provide a reference for the precise steering control of other robots.
基金Supported in part by Natural Science Foundation of Guangxi(2023GXNSFAA026246)in part by the Central Government's Guide to Local Science and Technology Development Fund(GuikeZY23055044)in part by the National Natural Science Foundation of China(62363003)。
文摘In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.
基金supported by the National Science Foundation of China(No.62171387)the Science and Technology Program of Sichuan Province(No.2024NSFSC0468)the China Postdoctoral Science Foundation(No.2019M663475).
文摘As an important resource in data link,time slots should be strategically allocated to enhance transmission efficiency and resist eavesdropping,especially considering the tremendous increase in the number of nodes and diverse communication needs.It is crucial to design control sequences with robust randomness and conflict-freeness to properly address differentiated access control in data link.In this paper,we propose a hierarchical access control scheme based on control sequences to achieve high utilization of time slots and differentiated access control.A theoretical bound of the hierarchical control sequence set is derived to characterize the constraints on the parameters of the sequence set.Moreover,two classes of optimal hierarchical control sequence sets satisfying the theoretical bound are constructed,both of which enable the scheme to achieve maximum utilization of time slots.Compared with the fixed time slot allocation scheme,our scheme reduces the symbol error rate by up to 9%,which indicates a significant improvement in anti-interference and eavesdropping capabilities.
文摘Fluidic Thrust Vectoring(FTV)is used for the yaw attitude control of tailless flying wing,which can significantly improve stealth performance,maneuverability and lateral/heading maneuverability.The FTV control scheme of co-directional secondary flow was designed based on a 30 kgf thrust turbojet engine,an equivalent rudder deflection control variable of Mass Flow Combination(MFC)was proposed,and a control model was established to form a FTV control system scheme,which was integrated with the flight control system of a 100 kg tailless flying wing with medium aspect ratio to achieve closed-loop control of the yaw attitude based on FTV.The heading stability augmentation and maneuvering control characteristics and time response characteristics of tailless flying wing by FTV were quantitatively studied through virtual flight test in a wind tunnel at a wind speed of 35 m/s.The results show that the control strategy based on MFC achieves bidirectional continuous and stable control of thrust vector angle in a range of±11°,and the thrust vector angle varies monotonically with MFC;the co-directional FTV realizes bidirectional continuous and stable control of the yaw attitude of tailless flying wing,without longitudinal/lateral coupling moment.The increment of the maximum yawing moment coefficient is 0.0029,the maximum yaw rate is 7.55(°)/s,and the response time of the yaw rate of the vectoring nozzle actuated by the secondary flow is about 0.06 s,which satisfies the heading stability augmentation and maneuvering control response requirements of the aircraft with statically unstable heading,and provides new control means for the heading rudderless attitude control of tailless flying wing.
文摘In this paper,we define for the trace operator,the solution of certain models of vibrating plates standards with initial data in a strategic region spaces of weak regularities.Indeed,we know that the notion of regional controllability is more adapted to systems described by dynamic systems.Regional controllability results in a strategic area were established for vibrating plates by the Hilbertian Uniqueness Method.
基金supported by Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2020261)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA02010000)the Young Potential Program of Shanghai Institute of Applied Physics,Chinese Academy of Sciences(No.SINAP-YXJH-202412).
文摘Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for online fuel reprocessing.However,the fuel-salt flow results in the decay of delayed neutron precursors(DNPs)outside the core,causing fluctuations in the effective delayed neutron fraction and consequently impacting the reactor reactivity.Particularly in accident scenarios—such as a combined pump shutdown and the inability to rapidly scram the reactor—the sole reliance on negative temperature feedback may cause a significant increase in core temperature,posing a threat to reactor safety.To address these problems,this paper introduces an innovative design for a passive fluid-driven suspended control rod(SCR)to dynamically compensate for reactivity fluctuations caused by DNPs flowing with the fuel.The control rod operates passively by leveraging the combined effects of gravity,buoyancy,and fluid dynamic forces,thereby eliminating the need for an external drive mechanism and enabling direct integration within the active region of the core.Using a 150 MWt thorium-based molten salt reactor as the reference design,we develop a mathematical model to systematically analyze the effects of key parameters—including the geometric dimensions and density of the SCR—on its performance.We examine its motion characteristics under different core flow conditions and assess its feasibility for the dynamic compensation of reactivity changes caused by fuel flow.The results of this study demonstrate that the SCR can effectively counteract reactivity fluctuations induced by fuel flow within molten salt reactors.A sensitivity analysis reveals that the SCR’s average density exerts a profound impact on its start-up flow threshold,channel flow rate,resistance to fuel density fluctuations,and response characteristics.This underscores the critical need to optimize this parameter.Moreover,by judiciously selecting the SCR’s length,number of deployed units,and the placement we can achieve the necessary reactivity control while maintaining a favorable balance between neutron economy and heat transfer performance.Ultimately,this paper provides an innovative solution for the passive reactivity control in molten salt reactors,offering significant potential for practical engineering applications.
基金supported by the National Natural Science Foundation of China(Grant No.12074187).
文摘Electrically controlled solid propellant(ECSP)offers multiple ignition and adjustable burning rate,serving as fuel for next-generation intelligent propulsion systems.To further enhance the combustion performance of ECSP,a method utilizing electrochemical and thermal decomposition catalysts has been proposed.In this work,we investigated the combustion characteristics of hydroxylamine nitrate(HAN)-based ECSP incorporating cerium oxide(CeO_(2))and graphene oxide(GO)by using an electrically controlled combustion test system.Electrochemical impedance spectroscopy(EIS)and linear sweep voltammetry(LSV)were used to measure the electrical conductibility and overpotential of ECSP with various additives,and Tafel curves were calculated.Thermogravimetric analysis coupled with differential scanning calorimetry(TG-DSC)was employed to investigate the thermal decomposition behavior of ECSP.While the addition of CeO_(2) and GO reduced the conductivity of ECSP,both catalysts exhibited strong electrocatalytic properties and facilitated the thermal decomposition of ECSP.Between two catalysts,GO demonstrated superior electrochemical catalytic performance but weaker thermal decomposition catalytic ability than CeO_(2).The addition of catalysts significantly enhanced the combustion performance of HAN-based ECSP.Specifically,the ignition delay time was shortened by 10%~20%.CeO_(2) raised the burning rate by approximately 20%but GO exhibited a remarkable boost of 40%in burning rate at high voltage.The combination of GO and PVA produced a flame-retardant substance that negatively impacted the ignition delay of ECSP and resulted in a smaller increase in the burning rate of ECSP at low ignition voltages.
文摘The increasing interconnection of modern industrial control systems(ICSs)with the Internet has enhanced operational efficiency,but alsomade these systemsmore vulnerable to cyberattacks.This heightened exposure has driven a growing need for robust ICS security measures.Among the key defences,intrusion detection technology is critical in identifying threats to ICS networks.This paper provides an overview of the distinctive characteristics of ICS network security,highlighting standard attack methods.It then examines various intrusion detection methods,including those based on misuse detection,anomaly detection,machine learning,and specialised requirements.This paper concludes by exploring future directions for developing intrusion detection systems to advance research and ensure the continued security and reliability of ICS operations.
文摘With the large-scale integration of fracturing unit’s on-site construction,traditional industrial buses are increasingly unable to meet the requirements for the quantity transmission between various equipment in large-scale fracturing units,and different models of different equipment manufacturers cannot cooperate with each other as there are“Islands of information”in the control system.This article uses industrial Ethernet as the physical medium for data transmission.In addition,different equipment manufacturers use OPC as the core technology of the fracturing unit control system network,and set up an intelligent fracturing unit control system,so that the control network can quickly,accurately,and safely control the fracturing truck control system.The sand truck control system monitors and analyzes,saves,and prints the construction data in the vehicle instrument.At the same time,the network control system uses the vehicle instrument as the core of the network.It can control fracturing vehicles from different manufacturers.The sand mixer truck performs network control,which effectively avoids incompatibilities between various equipment manufacturers at the construction site.
