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Papers by Nguyen Dinh That

The 2nd International Conference on Control, Automation and Information Sciences, Nov 2013

The 2nd International Conference on Control, Automation and Information Sciences , Nov 2013

Sliding mode control has been shown to be a robust and effective control approach for stabiliza... more Sliding mode control has been shown to be a
robust and effective control approach for stabilization of
nonlinear systems. However the dynamic performance of the
controller is a complex function of the system parameters, which
is often uncertain or partially known. This paper presents an
adaptive fuzzy sliding mode control for a class of underactuated
nonlinear mechanical systems. An adaptive fuzzy system is
used to approximate the uncertain parts of the underactuated
system. The adaptive law is designed based on the Lyapunov
method. The proof for the stability and the convergence of the
system is presented. Robust performance of the adaptive fuzzy
sliding mode control is illustrated using a gantry crane system.
Simulation results demonstrate that the system output can track
the reference signal in the presence of modelling uncertainties,
external disturbances and parameter variation.

The 2nd International Conference on Control, Automation and Information Sciences, Nov 2013

This article addresses the robust exponential stabilization problem of underactuated mechanical... more This article addresses the robust exponential stabilization
problem of underactuated mechanical systems in the
presence of bounded external disturbances using sliding mode
control. Based on the Lyapunov method, a sufficient condition
for the existence of the smallest possible ball which bounds the
reduced-order sliding mode dynamics, is first derived in terms
of linear matrix inequality (LMI). A sliding mode controller
is then synthesized to guarantee that system state trajectories
are exponentially convergent to another ball with a prespecified
convergence rate. A case study of the Pendubot is provided to
illustrate the effectiveness of the proposed approach.

ISA transactions, Jan 2014

This paper deals with the problem of partial state observer design for linear systems that are su... more This paper deals with the problem of partial state observer design for linear systems that are subject to time delays in the measured output as well as the control input. By choosing a set of appropriate augmented Lyapunov-Krasovskii functionals with a triple-integral term and using the information of both the delayed output and input, a novel approach to design a minimal-order observer is proposed to guarantee that the observer error is ε-convergent with an exponential rate. Existence conditions of such an observer are derived in terms of matrix inequalities for the cases with time delays in both the output and input and with output delay only. Constructive design algorithms are introduced. Numerical examples are provided to illustrate the design procedure, practicality and effectiveness of the proposed observer.

Springer, Apr 2013

This paper addresses the problem of reachable set bounding for linear discrete-time systems that ... more This paper addresses the problem of reachable set bounding for linear discrete-time systems that are subject to state delay and bounded disturbances. Based on the Lyapunov method, a sufficient condition for the existence of ellipsoid-based
bounds of reachable sets of a linear uncertain discrete system is derived in terms of matrix inequalities. Here, a new idea is to minimize the projection distances of the ellipsoids on each axis with different exponential convergence rates, instead of minimization of their radius with a single exponential rate. A smaller bound can thus be obtained from the intersection of these ellipsoids. A numerical example is given to illustrate the effectiveness of the proposed approach.

The 1st IEEE International Conference on Control, Automation and Information Sciences, 2012

A decentralised model predictive control (DeMPC) scheme for nonlinear interconnected systems is ... more A decentralised model predictive control (DeMPC)
scheme for nonlinear interconnected systems is developed with
parameterised stability constraints in this paper. Both control
and state constraints are considered in the development for
the stabilisability condition. An extension to the input-tostate
stabilisation framework is given with a newly derived
input-to-power-and-state stabilisability (IpSS) condition for interconnected
systems. The ADC–asymptotically dissipative constraint
that prescribes an approaching characteristic towards
a dissipative-bounded property of input and output profiles
is employed in the IpSS condition herein. With an open-loop
perspective, the DeMPC stability constraint in this approach
is a dynamic quadratic constraint on the initial control vector.
In this work, we consider C1 continuous nonlinear input-affine
state-space models with unknown but bounded input disturbances
and develop an LMI-based (linear matrix inequality -
based) robust stabilisability condition. The interactive signals
are also unknown and bounded in this development. Numerical
simulations for two network systems are provided to illustrate
the theoretical developments.

The 1st IEEE International Conference on Control, Automation and Information Sciences, 2012

This paper deals with the problem of reachable set bounding for linear systems in the presence o... more This paper deals with the problem of reachable
set bounding for linear systems in the presence of both
discrete and distributed delays. The time delay is assumed
to be differentiable and vary within an interval. By using
the Lyapunov-Krasovskii approach and delay decomposition
technique, improved delay-dependent conditions for the existence
of an ellipsoid-based bound of reachable sets for the
system trajectories are derived in terms of matrix inequalities.
Here, the new idea is to minimize the ellipsoids’ projection
distances on each axis with different exponential convergence
rates, instead of minimizing the ellipsoidal radius with a single
exponential rate. A smaller bound can thus be obtained from
the projection distance of the intersection of the bounding ellipsoids.The effectiveness of the proposed approach is illustrated by a numerical example.

CASE-The 8th IEEE International Conference on Automation Science and Engineering, pp. 172-177 , 2012

This paper presents an observer-based fuzzy sliding mode controller for sensorless Permanent Mag... more This paper presents an observer-based fuzzy sliding
mode controller for sensorless Permanent Magnet Synchronous
Motor (PMSM) drive based on the Field Programmable Gate
Array (FPGA) technology. For enhancement of robustness, a
sliding mode observer (SMO) is proposed to estimate first the
current and back electromotive force (EMF), then to derive the
flux angle. These estimated values together with the computed
rotor speed of the motor are fed back for the control purpose
in both the current loop and the speed loop. To cope with the
effect of the system dynamic uncertainty and external load, a
fuzzy sliding mode control (FSMC) is designed by incorporating
a fuzzy inference mechanism into a sliding mode control scheme
to tune the gain of the sliding term in the speed control loop. An
FPGA chip is designed for implementing the current loop with
vector control as well as the speed control loop. The very high
speed integrated circuit-hardware description language (VHDL)
is adopted to describe advantageous behaviors of the proposed
control system. Integrating advantages of the sensorless technique
and fuzzy sliding mode control technique into the speed controller
of a PMSM drive can make its performance substantially
improved and its cost effectively-reduced while improving its
reliability. The validity of the proposed approach is verified
through simulation results based on the Modelsim/Simulink cosimulation
method.

-The 8th IEEE International Conference on Automation Science and Engineering, pp. 1200-1205 , 2012

Trajectory tracking control of an underactuated mechanical system is a challenging task when tra... more Trajectory tracking control of an underactuated
mechanical system is a challenging task when tracking errors of
all the system coordinates need to be minimized, while the
number of control inputs is limited. This paper addresses the
observer-based multivariable control of a class of nonlinear,
underactuated Lagrangian systems with application to
trajectory tracking and sway control of a 3D overhead gantry
crane subject to Coulomb friction. A second-order sliding mode
observer is proposed for the estimation of velocities. Based on
robust estimates, the sliding function of a second-order sliding
mode controller for trajectory tracking and anti-swing control
is proposed. The simulation results indicate that the proposed
observer-based controller can achieve high performance in
following a pre-specified trajectory with minimum tracking
errors and swing angle suppression, despite the presence of
model uncertainties and disturbances.

This paper addresses the problem of bounding the reachable set of the sliding dynamics in discret... more This paper addresses the problem of bounding the reachable set of the sliding dynamics in discrete time systems that are subject to time-varying state delay and bounded external disturbances. The sliding motion is determined from the equivalent dynamics chosen from a desired eigenstructure via the pole placement technique. New delay-dependent conditions are derived to guarantee that the trajectories in the sliding mode are prescribed in an ellipsoid with a minimal bound for each coordinate. Finally, the proposed approach is illustrated by a numerical example of a quasi-sliding mode controller.

The 2nd International Conference on Control, Automation and Information Sciences, Nov 2013

The 2nd International Conference on Control, Automation and Information Sciences , Nov 2013

Sliding mode control has been shown to be a robust and effective control approach for stabiliza... more Sliding mode control has been shown to be a
robust and effective control approach for stabilization of
nonlinear systems. However the dynamic performance of the
controller is a complex function of the system parameters, which
is often uncertain or partially known. This paper presents an
adaptive fuzzy sliding mode control for a class of underactuated
nonlinear mechanical systems. An adaptive fuzzy system is
used to approximate the uncertain parts of the underactuated
system. The adaptive law is designed based on the Lyapunov
method. The proof for the stability and the convergence of the
system is presented. Robust performance of the adaptive fuzzy
sliding mode control is illustrated using a gantry crane system.
Simulation results demonstrate that the system output can track
the reference signal in the presence of modelling uncertainties,
external disturbances and parameter variation.

The 2nd International Conference on Control, Automation and Information Sciences, Nov 2013

This article addresses the robust exponential stabilization problem of underactuated mechanical... more This article addresses the robust exponential stabilization
problem of underactuated mechanical systems in the
presence of bounded external disturbances using sliding mode
control. Based on the Lyapunov method, a sufficient condition
for the existence of the smallest possible ball which bounds the
reduced-order sliding mode dynamics, is first derived in terms
of linear matrix inequality (LMI). A sliding mode controller
is then synthesized to guarantee that system state trajectories
are exponentially convergent to another ball with a prespecified
convergence rate. A case study of the Pendubot is provided to
illustrate the effectiveness of the proposed approach.

ISA transactions, Jan 2014

This paper deals with the problem of partial state observer design for linear systems that are su... more This paper deals with the problem of partial state observer design for linear systems that are subject to time delays in the measured output as well as the control input. By choosing a set of appropriate augmented Lyapunov-Krasovskii functionals with a triple-integral term and using the information of both the delayed output and input, a novel approach to design a minimal-order observer is proposed to guarantee that the observer error is ε-convergent with an exponential rate. Existence conditions of such an observer are derived in terms of matrix inequalities for the cases with time delays in both the output and input and with output delay only. Constructive design algorithms are introduced. Numerical examples are provided to illustrate the design procedure, practicality and effectiveness of the proposed observer.

Springer, Apr 2013

This paper addresses the problem of reachable set bounding for linear discrete-time systems that ... more This paper addresses the problem of reachable set bounding for linear discrete-time systems that are subject to state delay and bounded disturbances. Based on the Lyapunov method, a sufficient condition for the existence of ellipsoid-based
bounds of reachable sets of a linear uncertain discrete system is derived in terms of matrix inequalities. Here, a new idea is to minimize the projection distances of the ellipsoids on each axis with different exponential convergence rates, instead of minimization of their radius with a single exponential rate. A smaller bound can thus be obtained from the intersection of these ellipsoids. A numerical example is given to illustrate the effectiveness of the proposed approach.

The 1st IEEE International Conference on Control, Automation and Information Sciences, 2012

A decentralised model predictive control (DeMPC) scheme for nonlinear interconnected systems is ... more A decentralised model predictive control (DeMPC)
scheme for nonlinear interconnected systems is developed with
parameterised stability constraints in this paper. Both control
and state constraints are considered in the development for
the stabilisability condition. An extension to the input-tostate
stabilisation framework is given with a newly derived
input-to-power-and-state stabilisability (IpSS) condition for interconnected
systems. The ADC–asymptotically dissipative constraint
that prescribes an approaching characteristic towards
a dissipative-bounded property of input and output profiles
is employed in the IpSS condition herein. With an open-loop
perspective, the DeMPC stability constraint in this approach
is a dynamic quadratic constraint on the initial control vector.
In this work, we consider C1 continuous nonlinear input-affine
state-space models with unknown but bounded input disturbances
and develop an LMI-based (linear matrix inequality -
based) robust stabilisability condition. The interactive signals
are also unknown and bounded in this development. Numerical
simulations for two network systems are provided to illustrate
the theoretical developments.

The 1st IEEE International Conference on Control, Automation and Information Sciences, 2012

This paper deals with the problem of reachable set bounding for linear systems in the presence o... more This paper deals with the problem of reachable
set bounding for linear systems in the presence of both
discrete and distributed delays. The time delay is assumed
to be differentiable and vary within an interval. By using
the Lyapunov-Krasovskii approach and delay decomposition
technique, improved delay-dependent conditions for the existence
of an ellipsoid-based bound of reachable sets for the
system trajectories are derived in terms of matrix inequalities.
Here, the new idea is to minimize the ellipsoids’ projection
distances on each axis with different exponential convergence
rates, instead of minimizing the ellipsoidal radius with a single
exponential rate. A smaller bound can thus be obtained from
the projection distance of the intersection of the bounding ellipsoids.The effectiveness of the proposed approach is illustrated by a numerical example.

CASE-The 8th IEEE International Conference on Automation Science and Engineering, pp. 172-177 , 2012

This paper presents an observer-based fuzzy sliding mode controller for sensorless Permanent Mag... more This paper presents an observer-based fuzzy sliding
mode controller for sensorless Permanent Magnet Synchronous
Motor (PMSM) drive based on the Field Programmable Gate
Array (FPGA) technology. For enhancement of robustness, a
sliding mode observer (SMO) is proposed to estimate first the
current and back electromotive force (EMF), then to derive the
flux angle. These estimated values together with the computed
rotor speed of the motor are fed back for the control purpose
in both the current loop and the speed loop. To cope with the
effect of the system dynamic uncertainty and external load, a
fuzzy sliding mode control (FSMC) is designed by incorporating
a fuzzy inference mechanism into a sliding mode control scheme
to tune the gain of the sliding term in the speed control loop. An
FPGA chip is designed for implementing the current loop with
vector control as well as the speed control loop. The very high
speed integrated circuit-hardware description language (VHDL)
is adopted to describe advantageous behaviors of the proposed
control system. Integrating advantages of the sensorless technique
and fuzzy sliding mode control technique into the speed controller
of a PMSM drive can make its performance substantially
improved and its cost effectively-reduced while improving its
reliability. The validity of the proposed approach is verified
through simulation results based on the Modelsim/Simulink cosimulation
method.

-The 8th IEEE International Conference on Automation Science and Engineering, pp. 1200-1205 , 2012

Trajectory tracking control of an underactuated mechanical system is a challenging task when tra... more Trajectory tracking control of an underactuated
mechanical system is a challenging task when tracking errors of
all the system coordinates need to be minimized, while the
number of control inputs is limited. This paper addresses the
observer-based multivariable control of a class of nonlinear,
underactuated Lagrangian systems with application to
trajectory tracking and sway control of a 3D overhead gantry
crane subject to Coulomb friction. A second-order sliding mode
observer is proposed for the estimation of velocities. Based on
robust estimates, the sliding function of a second-order sliding
mode controller for trajectory tracking and anti-swing control
is proposed. The simulation results indicate that the proposed
observer-based controller can achieve high performance in
following a pre-specified trajectory with minimum tracking
errors and swing angle suppression, despite the presence of
model uncertainties and disturbances.

This paper addresses the problem of bounding the reachable set of the sliding dynamics in discret... more This paper addresses the problem of bounding the reachable set of the sliding dynamics in discrete time systems that are subject to time-varying state delay and bounded external disturbances. The sliding motion is determined from the equivalent dynamics chosen from a desired eigenstructure via the pole placement technique. New delay-dependent conditions are derived to guarantee that the trajectories in the sliding mode are prescribed in an ellipsoid with a minimal bound for each coordinate. Finally, the proposed approach is illustrated by a numerical example of a quasi-sliding mode controller.