Abstract:An integrated attitude-orbit controller based on extended state observer (ESO) is designed for spacecraft to settle down the unavailability of angular velocity and centroid velocity during on-orbit flight.First,the spacecraft's integrated attitude-orbit kinematics and dynamics model is presented based on dual quaternion.Second,an extended state observer is designed for the case of velocity screw information missing,which takes the model parameter error and external disturbance into account,and the finite time convergence of the observation error is analyzed by using Lyapunov stability theorem.Then a fast terminal sliding mode controller for integrated attitude-orbit control is designed based on the above extended state observer,and its finite time convergence is analyzed.Finally,a numerical simulation is given to verify the effectiveness of the control system.

Abstract:When ships are sailing on the sea,roll motion will greatly reduce the safety of ships and cargo,as well as the health of the crew.Therefore,the ship roll stabilization device has become one of the indispensable equipment on the ship.As an active roll reduction device,fin stabilizer is widely used for roll reduction due to its good anti-rolling performance.In this paper,an online learning optimal controller based on action dependent heuristic dynamic programming (ADHDP) is proposed for the ship fin stabilizer system.The input and output data,instead of a system model,are used in the design to obtain the system state.Two back propagation neural networks,including a critic network and an action network,are used to approximate the performance function and obtain the control law,respectively.The two neural networks can use real-time measurement data,and reduce internal model error and the uncertainty disturbance,thus improve the robustness of the system.Finally,the effectiveness of the proposed ADHDP controller is validated by simulation results.

Abstract:The influence of comments is ignored in traditional rumor spreading models,however,it has recently become an important factor,especially with the wide and diversified application of comments in online social networks,such as bullet-screen,like button,and comment ranking.To address this,we propose an ICST rumor spreading model taking comment mechanism into account,which classifies the population involved in rumor spreading processes into ignorants (I),commentators (C),spreaders (S),and stiflers (T).The existence of the equilibriums is proved,based on which the sharp threshold of rumor propagation is given.Global stability of the information-elimination equilibrium and the information-prevailing equilibrium is proved by constructing Lyapunov function.Numerical examples are given to verify the above theoretical analysis.

Abstract:In this paper,the design problem of intelligent ship autopilot with input saturation,unmeasured yaw rate and prescribed performance is investigated.An adaptive fuzzy output feedback controller is proposed based on state observer,auxiliary system and error transformation system.The fuzzy logic system (FLS) is employed to estimate the unknown nonlinear function,a state observer is designed to estimate the unmeasured yaw rate,an auxiliary signal for input saturation is established to compensate the mismatch between the controller signal and the actuator signal,and an error transformation system is also established to handle the ship heading tracking error.According to Lyapunov theory,the closed-loop system is proved to be bounded for all signals.Finally,simulation results are given to verify the effectiveness of the proposed scheme.

Abstract:The cooperative attitude control is addressed for spacecraft formation with unreliable communication and signal quantization among spacecrafts.First,to save the data rate and bandwidth among the spacecrafts,a signal quantization communication strategy is proposed among each two spacecrafts in the formation,and a terminal sliding mode attitude control law is developed to ensure the asymptotic stability of the spacecraft formation attitude synchronization systems.Second,to compensate the effects of communication delay and signal quantization,an exponent-logarithmic sliding mode surface design is presented,based on which a cooperative attitude control strategy is developed for spacecraft formation to achieve desirable attitude in finite-time.Finally,a simulation example with four spacecrafts in a formation system is provided to verify the effectiveness of the proposed cooperative control method.

Abstract:A new static output-feedback gain-scheduled controller is proposed for the autonomous vehicle to track the desired path and ensure the lateral stability under varying velocity and unmeasurable state.With control the steering angle of front wheel,the lateral offset and heading offset are minimized,which guarantees the path-following performance.In order to describe the velocity-related varying parameters,a polytopic linear parameter-varying vehicle model is established which takes the time-varying velocity into account,and a shrunk polytope is constructed to reduce the conservativeness of the design.The system H_∞ performance is analyzed with matrix transformation.Gain-scheduled control strategy and two-step method are adopted to design the H_∞ static output-feedback controller.Compared with previous iterative algorithms,the proposed method is easy to implement,and more desirable for application.Simulations are carried out on two typical road scenarios,and the results verify the effectiveness of the proposed method in path-following control of autonomous vehicles.

Abstract:This paper considers the consensus problem of nonlinear leader-following multi-agent system under quantized impulsive control.According to matrix theory,Lyapunov function and Lipshitz inequalities,some assumptions and sufficient conditions are given to make sure that the leader-following multi-agent system achieve fixed-time consensus.By constructing comparison system and using differential equations,the criteria for fixed-time consensus are set and the time interval to achieve consensus is calculated.Finally,the above theoretical analyses are verified by a simulation example.

Abstract:In this paper,the adaptive neural network tracking control is addressed based on event-triggering mechanism for a class of nonstrict-feedback nonlinear systems.By combining backstepping technology,neural network and event-triggering mechanism,an adaptive neural network control scheme is proposed,which reduces the data amount transmitted between the controller and the actuator,ensures the output signal to track the reference signal as much as possible,and guarantees all the signals of the closed-loop system to be bounded.In addition,the feasibility of the proposed event-triggering mechanism is ensured by avoiding Zeno phenomenon.Finally,an example is given to verify the effectiveness of the proposed scheme.

Abstract:The task of patrolling,seed sowing and industrial production of wheeled robots is a strongly nonlinear intermittent process.In this paper,a data-driven high-order iterative learning control algorithm is proposed for the path tracking of wheeled mobile robots in repeated running scenes.First,the model of wheeled mobile robot is derived and designed,and the discrete-time model in state space is transformed into linear input/output data model by using iterative dynamic linearization method based on state transition.Second,a high-order iterative optimization objective function is designed to obtain the control law,and the parameter update law is used to estimate the unknown parameters in the linear data model.By using high order learning control method,more control input information of previous iteration is used in the control law to improve the control performance.Finally,the simulation results verify the effectiveness of this method in the trajectory tracking control of wheeled robot.

Abstract:The current carrying capacity of the overhead transmission lines is lowered due to the conservative value of the boundary conditions.We propose an approach to calculate the carrying capacity based on K-Means algorithm,with purpose to fully exploit the carrying capacity of the overhead transmission lines.Meteorological data of Guangzhou in recent 10 years were summarized to analyze the variation of monthly ambient temperature and wind speed,based on which the K-Means algorithm was employed to rate the 12 months into several time periods,then appropriate boundary conditions were given for each time period.The Morgan formula was used to simulate the current carrying capacity under the new boundary conditions.Simulation results showed that the current carrying capacity can be effectively increased on the premise of ensuring safe operation of overhead transmission lines.

Abstract:The adaptive fuzzy finite-time output tracking control is addressed for a class of non-strict feedback high-order nonlinear systems with state constraints.The fuzzy logic systems are utilized to identify the unknown nonlinearities of the controlled systems,based on which the problem of state constraints is tackled by adopting barrier Lyapunov function.An adaptive finite-time control approach is developed combining backstepping control algorithm with adding a barrier power integrator.According to the finite-time Lyapunov stability theory,the proposed adaptive finite-time control scheme could guarantee the closed-loop system to be semi-globally practically finite-time stable and the states are ensured not to transgress their constrained sets.Moreover,the goal of finite-time tracking control is achieved.Finally,a numerical simulation is given to verify the effectiveness of the proposed adaptive finite-time control approach.

Abstract:As an important and complex mechanical and electrical part of CNC machine tools,the position servo system is difficult to control and affected by many factors,however,its position precison will affect the machining accuracy of CNC machine tools.In this paper,we use the Compact Format Dynamic Linearization (CFDL) and traditional PI control to improve the speed loop and position loop,and then improve the design of Model-Free Adaptive Control (MFAC) by adding control items.The Matlab/Simulink simulation results show that the proposed scheme keeps the advantages of MFAC,and improves in position following performance as well as robustness.

Abstract:For the short-range hover control of tracking spacecraft during rendezvous and docking,a linear sliding mode control law is designed based on the coupled attitude and orbit dynamics.To constrain the system state during the system convergence,an attitude and orbit coupled controller is developed with prescribed performance.Furthermore,a new finite time convergence performance function is used in the design of prescribed performance control law,and the sliding mode controller is improved in structure,with the purpose to reduce the system state convergence time.Finally,simulations and comparisons are given to verify the effectiveness of the designed spacecraft control law.

Abstract:The H_∞ filter design is addressed for the discrete-time neural networks subject to deception attacks.Considering the information exchange between the controlled system and the filter over the shared communication network with limited bandwidth and vulnerability to external network attacks,an adaptive event triggering mechanism (AETM) is proposed to reduce the communication burden of data transmission.In addition,due to the open access and interconnection of the communication network,the information transmitted via the shared communication network may be tampered by the fabricated information injected by the attacker.On this basis,by using Lyapunov-Krasovski functional and linear matrix inequality,the sufficient conditions for the asymptotic stability of the filtering error system are given,and the H_∞ filter satisfying the preset performance is designed.Finally,a simulation example is provided to verify the effectiveness of the proposed method.

Abstract:The leader-follower formation control of the multi-robot system is studied in this paper.The expected trajectory of the follower is given according to the formation constraints,thus the formation issue is turned into trajectory tracking of a single follower.Then the linear velocity controller and angular velocity controller for the follower are designed based on dual power reaching law method,which can ensure that the tracking error quickly converge to zero,so as to keep the formation stability.Finally,a numerical example is given to verify the effectiveness of the proposed method.

Abstract:Urban spatial planning mainly relies on multiband remote sensing images.However,it is difficult for traditional pattern recognition methods to accurately analyze land covers from remote sensing images.On the premise of accurate land type classification,we propose a method of remote sensing image segmentation and contour extraction based on Mask R-CNN with ResNet-101-RPN as backbone network.The method includes the following steps:data acquisition,image defogging,statistical analysis of land covers on remote sensing image,land segmentation and contour acquisition.The proposed method is trained and tested on a challenging satellite tile dataset.Experimental results show that the method can obtain satisfactory land segmentation and contour extraction results by 0.907 of mean average precision (mAP) and 31.33 pixel of mean average distance error (mADE).

Abstract:To improve the reliability of tracking system in data transmission,a multichannel strategy is adopted instead of single channel transmission to reduce the possibility of packet dropout.The system output is measured and tracked,and the tracking error and output error are analyzed to find the conditions for stability.A discrete random sequence satisfying the Markov distribution is used to describe the channel choice states,and the Markov state transition matrix is used to represent the transition probability between different states,so as to carry out stability analysis.By constructing Lyapunov function and utilizing linear matrix inequality,the sufficient conditions for stability and strict (Q,S,R)-γ-dissipativeness are obtained for the multi-channel transmission system,thus a mode-dependent controller is designed to achieve desired system tracking.Finally,a simulation example is provided to verify the effectiveness of the proposed multichannel transmission strategy.