H∞ Preview Control for Discrete-Time Systems

1999 ◽  
Vol 123 (1) ◽  
pp. 117-124 ◽  
Author(s):  
Chintae Choi ◽  
Tsu-Chin Tsao
Keyword(s):  
Discrete Time ◽  
Controller Design ◽  
Problem Formulation ◽  
Strip Thickness ◽  
Feedback Controller ◽  
Algebraic Riccati Equation ◽  
Worst Case ◽  
The Future ◽  
Unknown Disturbances ◽  
Tandem Cold Mill

A preview controller to be able to prepare a plant with the future information for external disturbances will guarantee better performance to suppress their effects. A design approach for the optimal H∞ preview controller in the discrete-time domain is given. The preview and feedback controller are simultaneously designed to minimize the worst case RMS value of the regulated variables when the bounded unknown disturbances and the previewable disturbances hit the dynamic plants. Thus, a state feedback controller and the related preview controller are derived in this design, even though problem formulation and solving an algebraic Riccati equation are based on the full-information H∞ controller design scheme. The performance of the proposed preview controller is simulated with a rolling stand of the tandem cold mill in the steel-making works. The objective of the control system for the rolling stand is to minimize thickness error of the exit strip and tension variation between stands simultaneously. The entry strip thickness to the stand and the roll gap variation are considered as previewable disturbances, since they can be measured and estimated. The future informations of these physical variables are utilized in the preview controller to suppress their effects on the exit strip thickness and the inter-stand tension. The simulation results shows that the H∞ preview controller is effective to satisfy the requirements for the thickness and the tension.

Robust H2 Output Feedback Controller Design for Damping Power System Oscillations

2017 ◽  
Vol 6 (10) ◽  
pp. 8
Author(s):  
Kho Hie Kwee ◽  
Hardiansyah .
Keyword(s):  
Power System ◽  
Output Feedback ◽  
Controller Design ◽  
Sufficient Conditions ◽  
Feedback Controller ◽  
Linear Matrix ◽  
Parameter Uncertainties ◽  
Worst Case ◽  
Output Feedback Controller ◽  
Power System Oscillations

This paper addresses the design problem of robust H2 output feedback controller design for damping power system oscillations. Sufficient conditions for the existence of output feedback controllers with norm-bounded parameter uncertainties are given in terms of linear matrix inequalities (LMIs). Furthermore, a convex optimization problem with LMI constraints is formulated to design the output feedback controller which minimizes an upper bound on the worst-case H2 norm for a range of admissible plant perturbations. The technique is illustrated with applications to the design of stabilizer for a single-machine infinite-bus (SMIB) power system. The LMI based control ensures adequate damping for widely varying system operating.

Two-Stage Feedback Control Design for a Class of Linear Discrete-Time Systems With Slow and Fast Modes

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Verica Radisavljevic-Gajic
Keyword(s):  
Time Scales ◽  
Discrete Time ◽  
Controller Design ◽  
Feedback Controller ◽  
Two Stage ◽  
Stage Design ◽  
Design Algorithm ◽  
Discrete Time Systems ◽  
Two Stage Design ◽  
Time Systems

In this paper, we first review the new algorithm for the two-stage feedback controller design of linear discrete-time systems, and then provide conditions for its applicability. The design algorithm is specialized and simplified for a class of linear systems with slow and fast modes (multitime scale systems or singularly perturbed systems). The proposed design significantly reduces computational full-state feedback design requirements and provides independent and accurate feedback controller design techniques in slow and fast time scales. We present also conditions needed for applicability of the proposed two-stage design in two time scales. The power of the two-stage design lies in the fact that different types of controllers can be designed for different subsystems using the corresponding feedback gains obtained by performing calculations only with the subsystem (reduced-order) matrices.

scholarly journals Discrete-Time Robust Control With an Anticipative Action for Preview Systems

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Asma Achnib ◽  
Tudor-Bogdan Airimitoaie ◽  
Patrick Lanusse ◽  
Sergey Abrashov ◽  
Mohamed Aoun ◽  
...  
Keyword(s):  
Robust Control ◽  
Discrete Time ◽  
Controller Design ◽  
Design Method ◽  
Reference Signal ◽  
Feedback Controller ◽  
Water Tank ◽  
Level Control ◽  
Model Uncertainties ◽  
Crone Control

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.

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