An extension of L_1 adaptive control is proposed for the unmatched uncertain nonlinear system with the nonlinear reference system that defines the performance specifications. The control law adapts fast and tracks the...An extension of L_1 adaptive control is proposed for the unmatched uncertain nonlinear system with the nonlinear reference system that defines the performance specifications. The control law adapts fast and tracks the reference system with the guaranteed robustness and transient performance in the presence of unmatched uncertainties. The interval analysis is used to build the quasi-linear parameter-varying model of unmatched nonlinear system, and the robust stability of the proposed controller is addressed by sum of squares programming. The transient performance analysis shows that within the limit of hardware a large adaption gain can improve the asymptotic tracking performance. Simulation results are provided to demonstrate the theoretical findings of the proposed controller.展开更多
In this work,we address the frequency estimation problem of a complex single-tone embedded in the heavy-tailed noise.With the use of the linear prediction(LP)property and l_(1)-norm minimization,a robust frequency est...In this work,we address the frequency estimation problem of a complex single-tone embedded in the heavy-tailed noise.With the use of the linear prediction(LP)property and l_(1)-norm minimization,a robust frequency estimator is developed.Since the proposed method employs the weighted l_(1)-norm on the LP errors,it can be regarded as an extension of the l_(1)-generalized weighted linear predictor.Computer simulations are conducted in the environment of α-stable noise,indicating the superiority of the proposed algorithm,in terms of its robust to outliers and nearly optimal estimation performance.展开更多
在飞行器参数变化时,L_(1)自适应控制相对于传统比例积分微分(proportional integral derivative,PID)控制方法具有理想的控制效果。针对某型存在参数不确定性的无人机,建立了无人机横侧向动力学模型,在对L_(1)自适应控制理论进行研究...在飞行器参数变化时,L_(1)自适应控制相对于传统比例积分微分(proportional integral derivative,PID)控制方法具有理想的控制效果。针对某型存在参数不确定性的无人机,建立了无人机横侧向动力学模型,在对L_(1)自适应控制理论进行研究的基础上,分别设计了L_(1)自适应控制律和比例微分(proportional derivative,PD)控制律,通过算例仿真,对比分析了这两种控制律对无人机滚转角的控制效果。结果表明,L_(1)自适应控制律具有良好的抗飞行器参数变化能力,鲁棒性强,对无人机飞行控制系统设计具有重要的参考价值。展开更多
The mixed L1/H-infinity control problem for a class of uncertain linear singular systems is considered using a matrix inequality approach. The purpose is to design a state feedback control law such that the resultant ...The mixed L1/H-infinity control problem for a class of uncertain linear singular systems is considered using a matrix inequality approach. The purpose is to design a state feedback control law such that the resultant closed-loop system is regular, impulse-free, stable and satisfies some given mixed L1/H-infinity performance. A sufficient condition for the existence of such control law is given in terms of a set of matrix inequalities by the introduction of inescapable set and ＊-norm. When these matrix inequalities are feasible, an explicit expression of the desired state feedback control law is given. A numerical example is used to demonstrate the applicability of the proposed approach.展开更多
This paper proposes an L_(1)adaptive fault tolerant control method for trajectory tracking of tail-sitter aircraft in the state of motor loss fault.The tail-sitter model considers the uncertainties produced by the fea...This paper proposes an L_(1)adaptive fault tolerant control method for trajectory tracking of tail-sitter aircraft in the state of motor loss fault.The tail-sitter model considers the uncertainties produced by the features of nonlinearities and couplings which cause difficulties in control.An L_(1)adaptive controller is designed to reduce the position and attitude error when actuators have faults.A reference trajectory containing large maneuver flight transitions is designed,which makes it even harder for the L_(1)controller to track accurately.Compensators are designed to assist L_(1)adaptive controller tracking of the reference trajectory.The stability of the L_(1)adaptive controller including compensators is proved.Finally,the simulation results are used to analyse the effectiveness of the proposed controller.Compared to the H∞controller,the L_(1)adaptive controller with compensators has better performance in position control and attitude control under fault tolerance state even when the aircraft conducts large maneuver.Besides,as the L_(1)adaptive control method separates feedback control and adaptive law design,the response speed of the whole system is improved.展开更多
The increasing demand on robotic system performance leads to the use of advanced control strategies. A variable structure model-following adaptive control design is presented for the nonlinear robot manipulator sys...The increasing demand on robotic system performance leads to the use of advanced control strategies. A variable structure model-following adaptive control design is presented for the nonlinear robot manipulator systems, when subjected to fast and wide ranges of unknown-but-bounded parameter variations and disturbances. The design does not require any knowledge of a nonlinear robotic system. The system is robust and insensitive to the parameter variation, disturbances, as well as to the unmodeled dynamics. This insensitive property enables the elimination of interactions among the various joints of the robotic manipulator. In the closed loop, the robotic system asymptotically converges to the reference trajectory with a Prescribed transient resPOnse. The problem of chattering is discussed with the introduction of the special approaches: boundary layer, smoothing law, and nonlinear compensation.展开更多
Cryogenic wind tunnel is a sophisticated aerodynamics ground test faility,which operates in cryogenic temperature with injection of liquid nitrogen.The multi-variable,nonlinear and coupled dynamics existing between th...Cryogenic wind tunnel is a sophisticated aerodynamics ground test faility,which operates in cryogenic temperature with injection of liquid nitrogen.The multi-variable,nonlinear and coupled dynamics existing between the temperature,pressure and Mach number in the tunnel,poses great challenges for the effective control of the tunnel.L_(1) adaptive control is a new control methodology developed in recent years with good robustness properties,which has good potentials to address these challenges.But this control method does not provide full adaptive feedforward control in its generic structure.In the paper,adaptive feedforward control action is introduced into the standard L_(1) adaptive control architecture for nonlinear systems in the presence of matched un-modeled dynamics.This new control structure is applied to the stagnation pressure control in a cryogenic wind tunnel,which could also be used for the control of temperature and Mach number in the tunnel.This new method could effectively compensate known disturbances with linear gain uncertainty,which occur in the nonlinear systems,while retaining the closed-loop control performance of L_(1) adaptive control.After the proof and discussions on the stability of this method,simulations of the stagnation pressure control in the wind tunnel are presented.The results and analysis demonstrate the effectiveness of the proposed control architecture.展开更多
The entry vehicle for the Tianwen-1 mission successfully landed on the surface of Mars at 7:18 AM BJT on May 15,2021.This successful landing made China the first country to orbit,land,and release a rover in their firs...The entry vehicle for the Tianwen-1 mission successfully landed on the surface of Mars at 7:18 AM BJT on May 15,2021.This successful landing made China the first country to orbit,land,and release a rover in their first attempt at the Mars exploration.The guidance,navigation,and control(GNC)system plays a crucial role in the entry,descent,and landing(EDL)phases.This study focused on the attitude control component of the GNC system design.The EDL phase can be divided into several sub-phases,namely the angle of attack control phase,lift control phase,parachute descent phase,and powered descent phase.Each sub-phase has unique attitude control requirements and challenges.This paper introduces the key aspects of designing attitude controllers for each phase.Furthermore,flight results are presented and analyzed.展开更多
This paper investigates the globally asymptotically stable and L_(2)-gain of robust H_(∞)control for switched nonlinear systems under sampled data.By considering the relationship between the sampling period and the d...This paper investigates the globally asymptotically stable and L_(2)-gain of robust H_(∞)control for switched nonlinear systems under sampled data.By considering the relationship between the sampling period and the dwell time,the non-switching and one switching are discussed in the sampling interval,respectively.Firstly,a state feedback sampled-data controller is constructed by the back-stepping method,and the switching converts to asynchronous switching if it happens within the sampling interval.Then,under the limiting conditions of the sampling period,which are obtained by the average dwell time method,the closed-loop system is globally asymptotically stable and has L_(2)-gain.Finally,two numerical examples are provided to demonstrate the effectiveness of the proposed method.展开更多
文摘An extension of L_1 adaptive control is proposed for the unmatched uncertain nonlinear system with the nonlinear reference system that defines the performance specifications. The control law adapts fast and tracks the reference system with the guaranteed robustness and transient performance in the presence of unmatched uncertainties. The interval analysis is used to build the quasi-linear parameter-varying model of unmatched nonlinear system, and the robust stability of the proposed controller is addressed by sum of squares programming. The transient performance analysis shows that within the limit of hardware a large adaption gain can improve the asymptotic tracking performance. Simulation results are provided to demonstrate the theoretical findings of the proposed controller.
文摘In this work,we address the frequency estimation problem of a complex single-tone embedded in the heavy-tailed noise.With the use of the linear prediction(LP)property and l_(1)-norm minimization,a robust frequency estimator is developed.Since the proposed method employs the weighted l_(1)-norm on the LP errors,it can be regarded as an extension of the l_(1)-generalized weighted linear predictor.Computer simulations are conducted in the environment of α-stable noise,indicating the superiority of the proposed algorithm,in terms of its robust to outliers and nearly optimal estimation performance.
文摘在飞行器参数变化时,L_(1)自适应控制相对于传统比例积分微分(proportional integral derivative,PID)控制方法具有理想的控制效果。针对某型存在参数不确定性的无人机,建立了无人机横侧向动力学模型,在对L_(1)自适应控制理论进行研究的基础上,分别设计了L_(1)自适应控制律和比例微分(proportional derivative,PD)控制律,通过算例仿真,对比分析了这两种控制律对无人机滚转角的控制效果。结果表明,L_(1)自适应控制律具有良好的抗飞行器参数变化能力,鲁棒性强,对无人机飞行控制系统设计具有重要的参考价值。
基金supported by the National Natural Science Foundation of China (No.60774044)the Professional Research Foundation for Advanced Talents of Jiangsu University (No.07JDG037)+2 种基金the Natural Science Fund for Colleges and Universities in Jiangsu Province (No.08KJ510010)the Open Project of National Key Laboratory of Industrial Control Technology of Zhejiang University (No.ICT0910)Qing Lan Project of Jiangsu Province
文摘The mixed L1/H-infinity control problem for a class of uncertain linear singular systems is considered using a matrix inequality approach. The purpose is to design a state feedback control law such that the resultant closed-loop system is regular, impulse-free, stable and satisfies some given mixed L1/H-infinity performance. A sufficient condition for the existence of such control law is given in terms of a set of matrix inequalities by the introduction of inescapable set and ＊-norm. When these matrix inequalities are feasible, an explicit expression of the desired state feedback control law is given. A numerical example is used to demonstrate the applicability of the proposed approach.
基金supported by the National Natural Science Foundation of China(61873012)。
文摘This paper proposes an L_(1)adaptive fault tolerant control method for trajectory tracking of tail-sitter aircraft in the state of motor loss fault.The tail-sitter model considers the uncertainties produced by the features of nonlinearities and couplings which cause difficulties in control.An L_(1)adaptive controller is designed to reduce the position and attitude error when actuators have faults.A reference trajectory containing large maneuver flight transitions is designed,which makes it even harder for the L_(1)controller to track accurately.Compensators are designed to assist L_(1)adaptive controller tracking of the reference trajectory.The stability of the L_(1)adaptive controller including compensators is proved.Finally,the simulation results are used to analyse the effectiveness of the proposed controller.Compared to the H∞controller,the L_(1)adaptive controller with compensators has better performance in position control and attitude control under fault tolerance state even when the aircraft conducts large maneuver.Besides,as the L_(1)adaptive control method separates feedback control and adaptive law design,the response speed of the whole system is improved.
文摘The increasing demand on robotic system performance leads to the use of advanced control strategies. A variable structure model-following adaptive control design is presented for the nonlinear robot manipulator systems, when subjected to fast and wide ranges of unknown-but-bounded parameter variations and disturbances. The design does not require any knowledge of a nonlinear robotic system. The system is robust and insensitive to the parameter variation, disturbances, as well as to the unmodeled dynamics. This insensitive property enables the elimination of interactions among the various joints of the robotic manipulator. In the closed loop, the robotic system asymptotically converges to the reference trajectory with a Prescribed transient resPOnse. The problem of chattering is discussed with the introduction of the special approaches: boundary layer, smoothing law, and nonlinear compensation.
文摘Cryogenic wind tunnel is a sophisticated aerodynamics ground test faility,which operates in cryogenic temperature with injection of liquid nitrogen.The multi-variable,nonlinear and coupled dynamics existing between the temperature,pressure and Mach number in the tunnel,poses great challenges for the effective control of the tunnel.L_(1) adaptive control is a new control methodology developed in recent years with good robustness properties,which has good potentials to address these challenges.But this control method does not provide full adaptive feedforward control in its generic structure.In the paper,adaptive feedforward control action is introduced into the standard L_(1) adaptive control architecture for nonlinear systems in the presence of matched un-modeled dynamics.This new control structure is applied to the stagnation pressure control in a cryogenic wind tunnel,which could also be used for the control of temperature and Mach number in the tunnel.This new method could effectively compensate known disturbances with linear gain uncertainty,which occur in the nonlinear systems,while retaining the closed-loop control performance of L_(1) adaptive control.After the proof and discussions on the stability of this method,simulations of the stagnation pressure control in the wind tunnel are presented.The results and analysis demonstrate the effectiveness of the proposed control architecture.
基金This work was supported by the National Natural Science Foundation of China(Grant No.61673057)and the Civil Aerospace Advance Research Project.
文摘The entry vehicle for the Tianwen-1 mission successfully landed on the surface of Mars at 7:18 AM BJT on May 15,2021.This successful landing made China the first country to orbit,land,and release a rover in their first attempt at the Mars exploration.The guidance,navigation,and control(GNC)system plays a crucial role in the entry,descent,and landing(EDL)phases.This study focused on the attitude control component of the GNC system design.The EDL phase can be divided into several sub-phases,namely the angle of attack control phase,lift control phase,parachute descent phase,and powered descent phase.Each sub-phase has unique attitude control requirements and challenges.This paper introduces the key aspects of designing attitude controllers for each phase.Furthermore,flight results are presented and analyzed.
文摘This paper investigates the globally asymptotically stable and L_(2)-gain of robust H_(∞)control for switched nonlinear systems under sampled data.By considering the relationship between the sampling period and the dwell time,the non-switching and one switching are discussed in the sampling interval,respectively.Firstly,a state feedback sampled-data controller is constructed by the back-stepping method,and the switching converts to asynchronous switching if it happens within the sampling interval.Then,under the limiting conditions of the sampling period,which are obtained by the average dwell time method,the closed-loop system is globally asymptotically stable and has L_(2)-gain.Finally,two numerical examples are provided to demonstrate the effectiveness of the proposed method.
