Fang Liao - Academia.edu (original) (raw)

Papers by Fang Liao

A discrete-time robust controller design method is proposed for optimal tracking of future refere... more A discrete-time robust controller design method is proposed for optimal tracking of future references in preview systems. In the context of preview systems, it is supposed that future values of the reference signal are available a number of time steps ahead. The objective is to design a control algorithm that minimizes a quadratic error between the reference and the output of the system and at the same time achieves a good level of the control signal. The proposed solution combines a robust feedback controller with a feedforward anticipative filter. The feedback controller's purpose is to assure robustness of the closed-loop system to model uncertainties. Any robust control methodology can be used (such as µ-synthesis, QFT, or CRONE control). The focus of this paper will be on the design of the feedforward action in order to introduce the anticipative effect with respect to known future values of the reference signal without hindering the robustness achieved through the feedback controller. As such, the model uncertainties are taken into account also in the design of the feedforward anticipative filter. The proposed solution is validated in simulation and on an experimental water tank level control system.

Proceedings of the 41st IEEE Conference on Decision and Control, 2002.

... Ai(P,L)=P+LH.i(O) + H:(0)LT (36) A2(P, K, 111, B, K)= (37) *Il(O) @12(8) Pdl+n BcjC.K+P&+... more ... Ai(P,L)=P+LH.i(O) + H:(0)LT (36) A2(P, K, 111, B, K)= (37) *Il(O) @12(8) Pdl+n BcjC.K+P&+,, *T2(0) $22 DiK 0 dT,,P K~DT -I 0 (&'C.K+PISI+n)T 0 0 -I I ... Two controllers (KSt and KTe) are tested in this study. Figure 1 shows linear simulation results. ...

Proceedings of the 39th IEEE Conference on Decision and Control (Cat. No.00CH37187)

We consider the reliable robust tracking controller design problem against actuator faults and co... more We consider the reliable robust tracking controller design problem against actuator faults and control surface damages for a LTI system with input disturbance. First, models of actuator faults and control surface damages are presented. Then a reliable tracking controller design method is developed, which guarantees the closed-loop system stability, optimizes the tracking performance of the system in normal operations, and maintains an acceptable low-level tracking performance of the system in the event of actuator faults and/of control surface damages. This method is based on LQ/H/sub /spl infin// tracking performance indices and multi-objective optimization in terms of linear matrix inequalities. A numerical example of an F-16 aircraft model and its simulation results are given.

Proceedings of the 40th IEEE Conference on Decision and Control (Cat. No.01CH37228)

... (b) Let K;o = Ki, K& = Kz, P$ = P& = P. (c) Minimize Tr(Ej) over PJ > ... more ... (b) Let K;o = Ki, K& = Kz, P$ = P& = P. (c) Minimize Tr(Ej) over PJ > 0, Qj, K{ and K; subject to and (K{--K~)~ (K~-K$<E~ where pl0 = Pio = PJ-' Kj - K3-l and Kio Ki-' ( j = . .), and pJ-I 7 1 Kj-' and K;-' are the solution of the (j - 1)th optimization. ...

Proceedings of the 17th IFAC World Congress, 2008, 2008

This paper presents a new control allocation design method for overactuated linear systems with i... more This paper presents a new control allocation design method for overactuated linear systems with internal dynamics and input constraints. The control inputs are designed to implement constrained control allocation and guaranteed stability of the closed-loop system. An LMI-based sufficient condition is provided to solve the control allocation problem. The proposed approach is demonstrated by a linear tailless aircraft model.

2007 IEEE International Conference on Control Applications, 2007

ABSTRACT This work concerns the output asymptotic trajectory tracking for the PVTOL aircraft. The... more ABSTRACT This work concerns the output asymptotic trajectory tracking for the PVTOL aircraft. The tracking is achieved based on a nonlinear optimal control allocation method, that ensures bounded internal dynamics as well as input constraints.

AIAA Guidance, Navigation and Control Conference and Exhibit, 2008

Modeling, Simulation, and Visualization for Real and Virtual Environments, 1999

The configuration and characteristics of the flight management and control system of an UAV is qu... more The configuration and characteristics of the flight management and control system of an UAV is quite different from that of a manned aircraft. A visual flight simulation is a most important way to improve the performance and effectiveness of UAVs in the practical field use. In this paper, a visual flight Real Time Simulation Environment (RTSE) for UAVs are programmed in Java language combined with Virtual Reality Modeling Language (VRML) and C++ language. The advantages of Java program in this project are introduced. Its disadvantages are overcome through three layer program. The bottom layer is the device-driven system layer with the hardware access capability programmed in C language. The middle layer is the dynamical link library that is made up of the native methods of JAVA application programmed in C++ language. The top layer is the application program programmed in Java language and VRML. The RTSE has the ability to provide significant training, demonstration and assessment of the UAVs economically, and reduce the operator workload.

Proceedings of the 16th IFAC World Congress, 2005, 2005

This paper presents a new methodology to solve the optimization problem of integrated aircraft/dy... more This paper presents a new methodology to solve the optimization problem of integrated aircraft/dynamic output-feedback controller design where both polytopic model uncertainties and multi-missions are considered. This design optimization is based on mixed H 2 /H ∞ performance requirement. According to the projection lemma, the integrated design optimization problem is separated into aircraft parameter optimization problem and controller optimization problem. An LMI-based sub-optimization approach is proposed for the aircraft parameter design. Then for the obtained sub-optimal aircraft parameters, an optimization approach is given to solve for the dynamic output-feedback controllers corresponding to different missions. Copyright c°2005 IFAC Keywords: integrated aircraft/controller design; optimization; mixed H 2 /H ∞ control; polytopic uncertainty; parameter-dependent; linear matrix inequalities(LMIs).

AIAA Guidance, Navigation, and Control Conference and Exhibit, 2004

This paper presents a new LMI-based approach for developing reliable automatic landing controller... more This paper presents a new LMI-based approach for developing reliable automatic landing controllers which can tolerate actuator stuck faults. The H2 control technique is used to guarantee tracking performance with respect to a given glide slope trajectory. A realistic fighter aircraft model is studied to illustrate the proposed approach. Nonlinear simulation under various faults and wind disturbances are included in this study. Simulation results show that the proposed reliable controller design approach can achieve zero steady-state tracking error, robustness against wind disturbances and reliability against actuator stuck faults.

Proceedings of the 2005, American Control Conference, 2005., 2005

In this paper, a special integrated plant/output-feedback controller optimization problem is stud... more In this paper, a special integrated plant/output-feedback controller optimization problem is studied, which optimizes a single plant parameter while satisfying open-and closed-loop static and dynamic performance requirements. Both polytopic model uncertainties and multi-mission optimization are considered in the integrated design optimization. A necessary and su cient condition is given for the solvability of such an optimization problem. Based on the condition, a design optimization method is presented in terms of linear matrix inequalities. An aircraft example is applied to demonstrate the proposed method.

Proceedings of the 2010 American Control Conference, 2010

ABSTRACT In this paper, a Lyapunov-based approach is proposed for control allocation problem base... more ABSTRACT In this paper, a Lyapunov-based approach is proposed for control allocation problem based on output feedback and model reference control. A nonlinear observer design approach for a general class of nonlinear systems is used to estimate the unmeasurable system states. The proposed approach ensures that the estimated states exponentially converge to their true values and the designed closed-loop system converges to a given stable reference model as t → ∞.

AIAA Guidance, Navigation, and Control Conference, 2010

In this paper, a new output feedback control system design method for a VTOL quadrotor aircraft i... more In this paper, a new output feedback control system design method for a VTOL quadrotor aircraft is proposed. A nonlinear observer is developed to estimate the unmeasurable vehicle speed vector. Based on the speed estimation, a cascade control strategy consisting of a kernel loop and a reference command generator is presented for the control system design. A nonlinear approach using model reference control and control allocation techniques is proposed to design the kernel loop control. The control allocation technique adopted in this paper can handle actuator saturations and is applicable to both overactuated and underactuated systems. The designed kernel control law is in the form of dynamic update law. The reference of the kernel loop control is generated by a reference command generator consisting of attitude and position controls. Dynamic inversion method is used in the design of the reference command generator. The proposed approach is applied to a quadrotor aircraft and simulation results show the effectiveness of the proposed approach.

2007 American Control Conference, 2007

This paper proposed an optimal control allocation method for a general class of overactuated nonl... more This paper proposed an optimal control allocation method for a general class of overactuated nonlinear systems with internal dynamics. Dynamic inversion technique is used for the commanded subsystem to track a stable model reference control law. The corresponding control allocation law has to guarantee the stability of the internal dynamics and satisfy control constraints. The proposed method is based on

Applications of Nonlinear Control, 2012

2009 American Control Conference, Vols 1-9, 2009

This paper presents an adaptive nonlinear control allocation method for a general class of non-mi... more This paper presents an adaptive nonlinear control allocation method for a general class of non-minimum phase uncertain systems. Indirect adaptive approach and Lyapunov design approach are applied to the design of adaptive control allocation. The derived adaptive control allocation law, together with a stable model reference control, guarantees that the closed-loop nonlinear system is input-to-state stable.

Proceedings of the 2005, American Control Conference, 2005., 2005

2007 American Control Conference, 2007

ABSTRACT This paper proposed a novel LMI based robust multi-objective model predictive control te... more ABSTRACT This paper proposed a novel LMI based robust multi-objective model predictive control technique. Such technique can be used to solve a trajectory tracking problem. The system is supposed to have polytopic uncertainty and subjected to asymmetric input constraints. With the proposed approach, we can guarantee the closed-loop stability and zero steady state tracking error. Finally, a canonical numerical example is used to illustrate the effectiveness.

2007 IEEE International Conference on Control and Automation, 2007

ABSTRACT In this paper, we address the nonlinear optimal control problem for parameter-dependent ... more ABSTRACT In this paper, we address the nonlinear optimal control problem for parameter-dependent nonlinear systems with polynomial vector fields. Based on the state dependent coefficient form, sufficient conditions to guarantee the closed-loop stability and bounded performance index are presented as state dependent linear matrix inequalities, which can be formulated as sum-of-squares based conditions and solved by semidefinite programming. A parameter-dependant Lyapunov function is adopted to reduce the conservativeness of the controller design.

A discrete-time robust controller design method is proposed for optimal tracking of future refere... more A discrete-time robust controller design method is proposed for optimal tracking of future references in preview systems. In the context of preview systems, it is supposed that future values of the reference signal are available a number of time steps ahead. The objective is to design a control algorithm that minimizes a quadratic error between the reference and the output of the system and at the same time achieves a good level of the control signal. The proposed solution combines a robust feedback controller with a feedforward anticipative filter. The feedback controller's purpose is to assure robustness of the closed-loop system to model uncertainties. Any robust control methodology can be used (such as µ-synthesis, QFT, or CRONE control). The focus of this paper will be on the design of the feedforward action in order to introduce the anticipative effect with respect to known future values of the reference signal without hindering the robustness achieved through the feedback controller. As such, the model uncertainties are taken into account also in the design of the feedforward anticipative filter. The proposed solution is validated in simulation and on an experimental water tank level control system.

Proceedings of the 41st IEEE Conference on Decision and Control, 2002.

... Ai(P,L)=P+LH.i(O) + H:(0)LT (36) A2(P, K, 111, B, K)= (37) *Il(O) @12(8) Pdl+n BcjC.K+P&+... more ... Ai(P,L)=P+LH.i(O) + H:(0)LT (36) A2(P, K, 111, B, K)= (37) *Il(O) @12(8) Pdl+n BcjC.K+P&+,, *T2(0) $22 DiK 0 dT,,P K~DT -I 0 (&'C.K+PISI+n)T 0 0 -I I ... Two controllers (KSt and KTe) are tested in this study. Figure 1 shows linear simulation results. ...

Proceedings of the 39th IEEE Conference on Decision and Control (Cat. No.00CH37187)

We consider the reliable robust tracking controller design problem against actuator faults and co... more We consider the reliable robust tracking controller design problem against actuator faults and control surface damages for a LTI system with input disturbance. First, models of actuator faults and control surface damages are presented. Then a reliable tracking controller design method is developed, which guarantees the closed-loop system stability, optimizes the tracking performance of the system in normal operations, and maintains an acceptable low-level tracking performance of the system in the event of actuator faults and/of control surface damages. This method is based on LQ/H/sub /spl infin// tracking performance indices and multi-objective optimization in terms of linear matrix inequalities. A numerical example of an F-16 aircraft model and its simulation results are given.

Proceedings of the 40th IEEE Conference on Decision and Control (Cat. No.01CH37228)

... (b) Let K;o = Ki, K& = Kz, P$ = P& = P. (c) Minimize Tr(Ej) over PJ > ... more ... (b) Let K;o = Ki, K& = Kz, P$ = P& = P. (c) Minimize Tr(Ej) over PJ > 0, Qj, K{ and K; subject to and (K{--K~)~ (K~-K$<E~ where pl0 = Pio = PJ-' Kj - K3-l and Kio Ki-' ( j = . .), and pJ-I 7 1 Kj-' and K;-' are the solution of the (j - 1)th optimization. ...

Proceedings of the 17th IFAC World Congress, 2008, 2008

This paper presents a new control allocation design method for overactuated linear systems with i... more This paper presents a new control allocation design method for overactuated linear systems with internal dynamics and input constraints. The control inputs are designed to implement constrained control allocation and guaranteed stability of the closed-loop system. An LMI-based sufficient condition is provided to solve the control allocation problem. The proposed approach is demonstrated by a linear tailless aircraft model.

2007 IEEE International Conference on Control Applications, 2007

ABSTRACT This work concerns the output asymptotic trajectory tracking for the PVTOL aircraft. The... more ABSTRACT This work concerns the output asymptotic trajectory tracking for the PVTOL aircraft. The tracking is achieved based on a nonlinear optimal control allocation method, that ensures bounded internal dynamics as well as input constraints.

AIAA Guidance, Navigation and Control Conference and Exhibit, 2008

Modeling, Simulation, and Visualization for Real and Virtual Environments, 1999

The configuration and characteristics of the flight management and control system of an UAV is qu... more The configuration and characteristics of the flight management and control system of an UAV is quite different from that of a manned aircraft. A visual flight simulation is a most important way to improve the performance and effectiveness of UAVs in the practical field use. In this paper, a visual flight Real Time Simulation Environment (RTSE) for UAVs are programmed in Java language combined with Virtual Reality Modeling Language (VRML) and C++ language. The advantages of Java program in this project are introduced. Its disadvantages are overcome through three layer program. The bottom layer is the device-driven system layer with the hardware access capability programmed in C language. The middle layer is the dynamical link library that is made up of the native methods of JAVA application programmed in C++ language. The top layer is the application program programmed in Java language and VRML. The RTSE has the ability to provide significant training, demonstration and assessment of the UAVs economically, and reduce the operator workload.

Proceedings of the 16th IFAC World Congress, 2005, 2005

This paper presents a new methodology to solve the optimization problem of integrated aircraft/dy... more This paper presents a new methodology to solve the optimization problem of integrated aircraft/dynamic output-feedback controller design where both polytopic model uncertainties and multi-missions are considered. This design optimization is based on mixed H 2 /H ∞ performance requirement. According to the projection lemma, the integrated design optimization problem is separated into aircraft parameter optimization problem and controller optimization problem. An LMI-based sub-optimization approach is proposed for the aircraft parameter design. Then for the obtained sub-optimal aircraft parameters, an optimization approach is given to solve for the dynamic output-feedback controllers corresponding to different missions. Copyright c°2005 IFAC Keywords: integrated aircraft/controller design; optimization; mixed H 2 /H ∞ control; polytopic uncertainty; parameter-dependent; linear matrix inequalities(LMIs).

AIAA Guidance, Navigation, and Control Conference and Exhibit, 2004

This paper presents a new LMI-based approach for developing reliable automatic landing controller... more This paper presents a new LMI-based approach for developing reliable automatic landing controllers which can tolerate actuator stuck faults. The H2 control technique is used to guarantee tracking performance with respect to a given glide slope trajectory. A realistic fighter aircraft model is studied to illustrate the proposed approach. Nonlinear simulation under various faults and wind disturbances are included in this study. Simulation results show that the proposed reliable controller design approach can achieve zero steady-state tracking error, robustness against wind disturbances and reliability against actuator stuck faults.

Proceedings of the 2005, American Control Conference, 2005., 2005

In this paper, a special integrated plant/output-feedback controller optimization problem is stud... more In this paper, a special integrated plant/output-feedback controller optimization problem is studied, which optimizes a single plant parameter while satisfying open-and closed-loop static and dynamic performance requirements. Both polytopic model uncertainties and multi-mission optimization are considered in the integrated design optimization. A necessary and su cient condition is given for the solvability of such an optimization problem. Based on the condition, a design optimization method is presented in terms of linear matrix inequalities. An aircraft example is applied to demonstrate the proposed method.

Proceedings of the 2010 American Control Conference, 2010

ABSTRACT In this paper, a Lyapunov-based approach is proposed for control allocation problem base... more ABSTRACT In this paper, a Lyapunov-based approach is proposed for control allocation problem based on output feedback and model reference control. A nonlinear observer design approach for a general class of nonlinear systems is used to estimate the unmeasurable system states. The proposed approach ensures that the estimated states exponentially converge to their true values and the designed closed-loop system converges to a given stable reference model as t → ∞.

AIAA Guidance, Navigation, and Control Conference, 2010

In this paper, a new output feedback control system design method for a VTOL quadrotor aircraft i... more In this paper, a new output feedback control system design method for a VTOL quadrotor aircraft is proposed. A nonlinear observer is developed to estimate the unmeasurable vehicle speed vector. Based on the speed estimation, a cascade control strategy consisting of a kernel loop and a reference command generator is presented for the control system design. A nonlinear approach using model reference control and control allocation techniques is proposed to design the kernel loop control. The control allocation technique adopted in this paper can handle actuator saturations and is applicable to both overactuated and underactuated systems. The designed kernel control law is in the form of dynamic update law. The reference of the kernel loop control is generated by a reference command generator consisting of attitude and position controls. Dynamic inversion method is used in the design of the reference command generator. The proposed approach is applied to a quadrotor aircraft and simulation results show the effectiveness of the proposed approach.

2007 American Control Conference, 2007

This paper proposed an optimal control allocation method for a general class of overactuated nonl... more This paper proposed an optimal control allocation method for a general class of overactuated nonlinear systems with internal dynamics. Dynamic inversion technique is used for the commanded subsystem to track a stable model reference control law. The corresponding control allocation law has to guarantee the stability of the internal dynamics and satisfy control constraints. The proposed method is based on

Applications of Nonlinear Control, 2012

2009 American Control Conference, Vols 1-9, 2009

This paper presents an adaptive nonlinear control allocation method for a general class of non-mi... more This paper presents an adaptive nonlinear control allocation method for a general class of non-minimum phase uncertain systems. Indirect adaptive approach and Lyapunov design approach are applied to the design of adaptive control allocation. The derived adaptive control allocation law, together with a stable model reference control, guarantees that the closed-loop nonlinear system is input-to-state stable.

Proceedings of the 2005, American Control Conference, 2005., 2005

2007 American Control Conference, 2007

ABSTRACT This paper proposed a novel LMI based robust multi-objective model predictive control te... more ABSTRACT This paper proposed a novel LMI based robust multi-objective model predictive control technique. Such technique can be used to solve a trajectory tracking problem. The system is supposed to have polytopic uncertainty and subjected to asymmetric input constraints. With the proposed approach, we can guarantee the closed-loop stability and zero steady state tracking error. Finally, a canonical numerical example is used to illustrate the effectiveness.

2007 IEEE International Conference on Control and Automation, 2007

ABSTRACT In this paper, we address the nonlinear optimal control problem for parameter-dependent ... more ABSTRACT In this paper, we address the nonlinear optimal control problem for parameter-dependent nonlinear systems with polynomial vector fields. Based on the state dependent coefficient form, sufficient conditions to guarantee the closed-loop stability and bounded performance index are presented as state dependent linear matrix inequalities, which can be formulated as sum-of-squares based conditions and solved by semidefinite programming. A parameter-dependant Lyapunov function is adopted to reduce the conservativeness of the controller design.