Wet flue gas desulphurization technology is widely used in the industrial process for its capability of efficient pollution removal.The desulphurization control system,however,is subjected to complex reaction mechanis...Wet flue gas desulphurization technology is widely used in the industrial process for its capability of efficient pollution removal.The desulphurization control system,however,is subjected to complex reaction mechanisms and severe disturbances,which make for it difficult to achieve certain practically relevant control goals including emission and economic performances as well as system robustness.To address these challenges,a new robust control scheme based on uncertainty and disturbance estimator(UDE)and model predictive control(MPC)is proposed in this paper.The UDE is used to estimate and dynamically compensate acting disturbances,whereas MPC is deployed for optimal feedback regulation of the resultant dynamics.By viewing the system nonlinearities and unknown dynamics as disturbances,the proposed control framework allows to locally treat the considered nonlinear plant as a linear one.The obtained simulation results confirm that the utilization of UDE makes the tracking error negligibly small,even in the presence of unmodeled dynamics.In the conducted comparison study,the introduced control scheme outperforms both the standard MPC and PID(proportional-integral-derivative)control strategies in terms of transient performance and robustness.Furthermore,the results reveal that a lowpass-filter time constant has a significant effect on the robustness and the convergence range of the tracking error.展开更多
A theoretical framework of nonlinear flight control for a flexible air-breathing hypersonic vehicle(FAHV)is proposed in this paper.In order to suppress the system uncertainty and external disturbance,an uncertainty an...A theoretical framework of nonlinear flight control for a flexible air-breathing hypersonic vehicle(FAHV)is proposed in this paper.In order to suppress the system uncertainty and external disturbance,an uncertainty and disturbance estimator(UDE)based back-stepping control strategy is designed for a dynamic state-feedback controller to provide stable velocity and altitude tracking.Firstly,the longitudinal dynamics of FAHV is simplified into a closure loop form with lumped uncertainty and disturbance.Then the UDE is applied to estimate the lumped uncertainty and disturbance for the purpose of control input compensation.While a nonlinear tracking differentiator is introduced to solve the problem of“explosion of term”in the back-stepping control.The stability of the UDE-based control strategy is proved by using Lyapunov stability theorem.Finally,simulation results are presented to demonstrate the capacity of the proposed control strategy.展开更多
为解决船舶在外界扰动和模型不确定条件下自动靠泊控制精度降低的问题,基于不确定和扰动估计器(uncertainty and disturbance estimator,UDE),提出一种自适应反步控制方法。利用指令滤波器,抑制传统反步法虚拟控制求导产生的微分爆炸现...为解决船舶在外界扰动和模型不确定条件下自动靠泊控制精度降低的问题,基于不确定和扰动估计器(uncertainty and disturbance estimator,UDE),提出一种自适应反步控制方法。利用指令滤波器,抑制传统反步法虚拟控制求导产生的微分爆炸现象。通过设计辅助系统,补偿指令滤波器误差,达到三自由度船舶自动靠泊控制的目的。通过Lyapunov理论证明UDE与控制器相结合的闭环系统的稳定性和信号的一致最终有界性。仿真实验表明,所设计的控制器能较准确地估计复杂扰动,并保证船舶到达期望的位置和艏向。展开更多
为解决电机弱磁区下电流畸变、转矩波动大等问题,提出一种改进的不确定性扰动估计(uncertainty and disturbance estimator,UDE)控制策略,应用于弱磁工况下的内置式永磁同步电机电流谐波抑制。分析了弱磁区下永磁体谐波、逆变器非线性...为解决电机弱磁区下电流畸变、转矩波动大等问题,提出一种改进的不确定性扰动估计(uncertainty and disturbance estimator,UDE)控制策略,应用于弱磁工况下的内置式永磁同步电机电流谐波抑制。分析了弱磁区下永磁体谐波、逆变器非线性等因素对电流谐波产生的影响;在此基础上采用UDE控制理论,引入具有高增益特性的延时滤波器,抑制电机系统存在的电流谐波;此外,针对电机从恒转矩区向弱磁区过渡过程中存在的波动问题,提出了一种新的弱磁切换方法,并以一台20 kW的内置式永磁同步电机为被控对象进行仿真研究。结果表明:与传统PI控制相比,本文所提控制策略能使永磁同步电机的d、q轴电流波动分别降低69%与28%,转矩波动降低56%,弱磁工况下的空载及带载电流谐波含量分别降低37%与55%;使用本文所提出的弱磁切换方法能够有效实现永磁同步电机在恒转矩区与弱磁区之间的平滑切换。展开更多
This paper investigates the velocity and altitude tracking control problem for airbreathing hypersonic vehicle(AHV)in the presence of external disturbances and parameter uncertainties.A composite controller containing...This paper investigates the velocity and altitude tracking control problem for airbreathing hypersonic vehicle(AHV)in the presence of external disturbances and parameter uncertainties.A composite controller containing improved lines cluster approaching mode control(LCAMC)and nonlinear disturbance observer(NDO)is developed to guarantee the tracking errors converge to zero and enhance the robustness of control system.Meanwhile,considering the multiple uncertain parameters,a genetic algorithm(GA)based Pareto uncertainty estimation is employed to predict the parameter uncertainties of the AHV dynamics.Besides,the mathematical proofs of proposed method are analyzed by utilizing Lyapunov theory.Simulation results demonstrate the effective tracking performance,excellent disturbance estimation and uncertainty estimation ability of the composite method.展开更多
基金supported by the key project of the National Nature Science Foundation of China(51736002).
文摘Wet flue gas desulphurization technology is widely used in the industrial process for its capability of efficient pollution removal.The desulphurization control system,however,is subjected to complex reaction mechanisms and severe disturbances,which make for it difficult to achieve certain practically relevant control goals including emission and economic performances as well as system robustness.To address these challenges,a new robust control scheme based on uncertainty and disturbance estimator(UDE)and model predictive control(MPC)is proposed in this paper.The UDE is used to estimate and dynamically compensate acting disturbances,whereas MPC is deployed for optimal feedback regulation of the resultant dynamics.By viewing the system nonlinearities and unknown dynamics as disturbances,the proposed control framework allows to locally treat the considered nonlinear plant as a linear one.The obtained simulation results confirm that the utilization of UDE makes the tracking error negligibly small,even in the presence of unmodeled dynamics.In the conducted comparison study,the introduced control scheme outperforms both the standard MPC and PID(proportional-integral-derivative)control strategies in terms of transient performance and robustness.Furthermore,the results reveal that a lowpass-filter time constant has a significant effect on the robustness and the convergence range of the tracking error.
基金Supported by National Natural Science Foundation of China(11672235)。
文摘A theoretical framework of nonlinear flight control for a flexible air-breathing hypersonic vehicle(FAHV)is proposed in this paper.In order to suppress the system uncertainty and external disturbance,an uncertainty and disturbance estimator(UDE)based back-stepping control strategy is designed for a dynamic state-feedback controller to provide stable velocity and altitude tracking.Firstly,the longitudinal dynamics of FAHV is simplified into a closure loop form with lumped uncertainty and disturbance.Then the UDE is applied to estimate the lumped uncertainty and disturbance for the purpose of control input compensation.While a nonlinear tracking differentiator is introduced to solve the problem of“explosion of term”in the back-stepping control.The stability of the UDE-based control strategy is proved by using Lyapunov stability theorem.Finally,simulation results are presented to demonstrate the capacity of the proposed control strategy.
文摘为解决船舶在外界扰动和模型不确定条件下自动靠泊控制精度降低的问题,基于不确定和扰动估计器(uncertainty and disturbance estimator,UDE),提出一种自适应反步控制方法。利用指令滤波器,抑制传统反步法虚拟控制求导产生的微分爆炸现象。通过设计辅助系统,补偿指令滤波器误差,达到三自由度船舶自动靠泊控制的目的。通过Lyapunov理论证明UDE与控制器相结合的闭环系统的稳定性和信号的一致最终有界性。仿真实验表明,所设计的控制器能较准确地估计复杂扰动,并保证船舶到达期望的位置和艏向。
文摘为解决电机弱磁区下电流畸变、转矩波动大等问题,提出一种改进的不确定性扰动估计(uncertainty and disturbance estimator,UDE)控制策略,应用于弱磁工况下的内置式永磁同步电机电流谐波抑制。分析了弱磁区下永磁体谐波、逆变器非线性等因素对电流谐波产生的影响;在此基础上采用UDE控制理论,引入具有高增益特性的延时滤波器,抑制电机系统存在的电流谐波;此外,针对电机从恒转矩区向弱磁区过渡过程中存在的波动问题,提出了一种新的弱磁切换方法,并以一台20 kW的内置式永磁同步电机为被控对象进行仿真研究。结果表明:与传统PI控制相比,本文所提控制策略能使永磁同步电机的d、q轴电流波动分别降低69%与28%,转矩波动降低56%,弱磁工况下的空载及带载电流谐波含量分别降低37%与55%;使用本文所提出的弱磁切换方法能够有效实现永磁同步电机在恒转矩区与弱磁区之间的平滑切换。
基金the financial support provided by the National Natural Science Foundation of China(Grant Nos.91216304 and 61803357).
文摘This paper investigates the velocity and altitude tracking control problem for airbreathing hypersonic vehicle(AHV)in the presence of external disturbances and parameter uncertainties.A composite controller containing improved lines cluster approaching mode control(LCAMC)and nonlinear disturbance observer(NDO)is developed to guarantee the tracking errors converge to zero and enhance the robustness of control system.Meanwhile,considering the multiple uncertain parameters,a genetic algorithm(GA)based Pareto uncertainty estimation is employed to predict the parameter uncertainties of the AHV dynamics.Besides,the mathematical proofs of proposed method are analyzed by utilizing Lyapunov theory.Simulation results demonstrate the effective tracking performance,excellent disturbance estimation and uncertainty estimation ability of the composite method.
